Quark-Gluon plasma seen in proton collisions – maybe

The CMS collaboration have released this image of a collision showing more than 100 charged particles from a single collision event. It could be the result of a quark-gluon plasma previously seen only in Heavy-Ion collisions. It also makes a good desktop wallpaper. Click to get the hi-res version.

The CMS analysis of these events looks at the correlations between particles flying off at different angles. The resulting plots look like this

In this plot Δη is a measure of how far apart the particles are in terms of the polar angle away from the beam axis. Δφ is the difference in the azimuthal angle in radians. In this plot the peak which has been cut-off at the front shows particles on a similar trajectory and is an expected observation. The ridge along the back is at a separation of 180 degrees in azimuthal angle. It extends over a range of the polar angle and is not predicted in the standard Monte-Carlo simulations based on QCD. The smaller ridge at zero azimuthal separation is not expected either. The effect intensifies for events with larger numbers of particles.

The interpretation offered by CMS is that some kind of clusters are formed, which then radiate particles isotropically. Such clusters could be droplets of quark-gluon plasma, but other explanations might be possible. Similar results have been observed at RHIC when Copper ions were collided but it is a surprise to see this with single protons.

The results presented are based on the only first inverse picobarn (1/pb) of data taken. So far 3.6/pb have been collected and much more will be generated in the next five weeks as the luminosity is pushed up by another factor of 10. Following that, the LHC will also turn to heavy-ion collisions using lead nuclei. The ALICE experiment is optimised for exploring the effects of these events, but CMS and ATLAS will also be used. Today’s report from CMS shows that interesting results could come from unexpected places.

This entry was posted on Tuesday, September 21st, 2010 at 5:44 pm and is filed under Large Hadron Collider. You can follow any responses to this entry through the RSS 2.0 feed.
Both comments and pings are currently closed.

43 Responses to Quark-Gluon plasma seen in proton collisions – maybe

The interpretation in terms of the formation and decay of quark gluon plasma looks natural but I think that quark gluon plasma is not quite what it should be according to QCD.

Since the densities of particles approach those at RHIC, I would bet that the explanation of the hydrodynamical behavior observed at RHIC for some years ago should apply also now. The description in terms of string like object proposed also by Lubos on basis of analysis of the graph showing the distributions as an explanation of correlations looks attractive. Radiating cluster does not explain the structures evolving as the transversal momentum increases.

I decided to look my own primitive model for RHIC events and found that I had mentioned stringy structures. I had also talked about critical system associated with confinement-deconfinement transition of the quark-gluon plasma formed in the collision and inhibiting long range correlations.

The proposed hydrodynamic space-time description was in terms of a scaled variant of what I call critical cosmology defining a universal space-time correlate for criticality: the specific property of this cosmology is that the mass contained by comoving volume approaches to zero at the the initial moment so that Big Bang begins as a silent whisper and is not so scaring;-). Criticality means flat 3-space instead of Lobatchevski space and means breaking of Lorentz invariance to SO(4). Breaking of Lorentz invariance was indeed observed for particle distributions but now I am notso sure whether it has much to do with this.

It seems that I have proposed at the microscopic level something like follows. A highly entangled long hadronic string like object (color-magnetic flux tube) would be formed at high density of nucleons via the fusion of ordinary hadronic color-magnetic flux tubes to much longer one and containing quark gluon plasma. In QCD plasma would not be at flux tube.

This object would straighten and split to hadrons in the subsequent “cosmological evolution” and yield large numbers of almost collinear particles. The initial situation should be apart from scaling similar as in cosmology where an entangled soup of cosmic strings (magnetic flux tubes) precedes the emergence of space-time in ordinary sense. Maybe ordinary cosmology could provide analogy as galaxies arranged to form linear structures? This structure would have also black hole like aspects but in totally different sense as the 10-D hadronic black-hole proposed by Nastase to describe the findings.

The string explanation is fine but the full answer is going to be more complex. You can already think of ordinary dijet events as the result of strings. Two quarks move apart drawing out a string of gluon flux which then breaks forming jets of hadrons.

Here there is a little more to see. What the plot is showing is that if you look at the event along the beam pipe there is a tendency for the particles to come out in one plane. The two ridges on the plot are really connected in that plane.

It could be that a droplet, or cluster is formed but it stretches out in a plane or string that then bursts.

They say they have stuck to the experimental side for this report but they will say more about the possible theories behind it later.

Are they plotting the right thing?? Diametrically opposite directions have φ1 = φ2 + π and η1 = – η2. So it seems to me instead of plotting Δφ vs Δη they should be plotting Δφ vs η1 + η2.

They should be plotting the right thing given the number of people who have been through it, but whether I have understood and explained what they are plotting correctly is another matter

η ia pseudorapidity which is -ln(tan(θ/2)) where θ is the angle relative to the beam axis. So θ should run from 0 to π. If that is the case then I think you are right that φ1 = φ2 + π and η1 = – η2 for opposite directions. Perhaps they only let θ run from 0 to π/2 so pseudorapidity is always poisitive.

It is instructive to point out that what CMS is seeing may be a manifestation of non-equilibrium dynamics. Phase transitions out of equilibrium occur in condensed matter (strongly correlated compounds or behavior of spin clusters under certain conditions) and correspond to the onset of long-range correlations in space-time or phase space. Deviations from equilibrium in such examples may be successfully described by the non-extensive statistical physics of Tsallis.

“Phase transitions out of equilibrium occur in condensed matter (strongly correlated compounds or behavior of spin clusters under certain conditions) and correspond to the onset of long-range correlations in space-time or phase space. ”
Behaviour of spin clusters? What would change the spin? Is this going through the Planck scale? Is a magnetic phase created? Most surely.

Matti might in some sense have the right suggestion. Of course it is hard to know for certain what this implies, but this does look similar to what we might expect of correlations between QCD and AdS or black hole, or BH-like, physics. I wrote the following two weeks ago about the Randall-Sundrum concept of extra large dimensions, which honestly this might be hinting at. I also think there could be some sort of renormalization group theory principle connected to a general U-duality principle, where S and T dualities are gauged symmetries. So this could be pointing to some exciting possibilities.

To start consider the Klein-Gordon equation in 4 + n dimensions

∂^2_iψ – ∂^2_tψ + ∂^2_5ψ = 0

where I have lumped all the extra dimensions into the 5th dimension. The solution to this wave equation is pretty simple

ψ ~ exp(ikx – iωt + ik_5x_5)

Now at larger scales the fifth dimension is compactified into a loop or ring, so we replace ∂_5 – -> (1/r)∂_θ and the Klein Gordon equation becomes

∂^2_iψ – ∂^2_tψ + (1/r)^2∂^2_θψ = 0,

and the solution is ψ ~ ψ_4exp(inθ), for ψ_4 the ordinary spacetime solution. Plop this into the K-G equation and we get

∂^2_iψ – ∂^2_tψ + (n/r)^2ψ = 0

and this recovers a mass. This is the whole compactification stuff, and presumably the radius of compactification r is smaller than low energy physics. There is a problem though. If r ~ L_p or L_string n/r is a huge mass!

Randall and Sundrum have argued that this radius of compactification is much larger, which softens this huge mass. However, there are some problems with this, in that we really should not expect to get real black holes at the TeV scale. We might get small amplitude for black holes, but clearly they can’t appear significantly at energies far lower that E_p or the Hagedorn energy (temperature). This is where the general U duality comes in. At low energy these extra-dimensions are large, but as we go up in energy the scale of compactification shrinks in a renormalization group flow. So at TeV or LHC energies we should get small amplitudes for black holes and AdS physics, but at the same time they can’t appear appreciably. Otherwise the hot high pressure interior of neutron stars, a quark-gluon plasma, would evaporate away and neutron stars would not be stable. Clearly they are stable. Virtual black holes are sufficiently present to influence the quantum amplitudes of scattering processes, but without causing the violation of baryon and lepton numbers.

This now takes us into questions of quantum cosmology. Assume a cosmology is in an entanglement with other spacetime cosmologies. All of these exist in the grand universe or multiverse. We then have only partial knowledge of this whole system through entanglement entropy that necessarily exists within our cosmology. Further, that entanglement entropy might have some variability to it. Even Hartle argues for something of this sort, where there are decoherent sets that under fine grained observation may reveal more information. Thus the maximal entropy minus the actual entropy determines the amount of information available. However, this might be observed in a different light. As we probe nature on a finer scale the amount of information about the other cosmologies becomes apparent. This information is obtained with the compactified dimensions that define gauge forces.

So as we enter the TeV domain of energy we begin to get more information about the extra dimensions of gauge compactification, which contain quantum bits associated with other branes. Our D3-brane is connected to other D3-branes by type II strings which share these compactified dimensions. The renormalization of the compactified scale to smaller scales is then a measure of growing experimental contact with other cosmologies — we reduce the entanglement entropy of the universe, as it is presented to us, by a tiny amount by accessing this information.

Don’t you think that is premature to invoke exotic new physics to explain what is being seen here? In my opinion much more mundane explanations need to be ruled out first. Bringing into discussion at this point the Randall-Sundrum scenario, large extra dimensions, branes, compactification and quantum cosmology may lead us astray.

Could stop-anti-stop squark production do something like this? It isn’t too far-fetched to expect a stop as the lightest squark, and a pair of stops could decay into a mess with W’s, bottom quarks, and neutralinos with missing mass and missing energy.

Of course some accelerator aficionados might weigh in here. The squark mass scaling in MSSM is m ~ Mlog(k/10^{16}GeV) up to transverse momentum k ~ 10^{15}Gev, and M ~ 100Gev. This means that at 10^3 Gev that puts squark masses in the 800-1200 GeV range. Gluino masses are comparable to this as well. With data at the 3pb^{-1} level I don’t know if that is sufficient. However, theories are being tested here, and it just might be.

Ervin, you are probably right in the sense that other explanations do need to be ruled out. However, I like to keep my sights somewhat elevated. It is my hope that we do get data that connects with these frontier areas of physics.

I also hope that new data will be conclusive enough to steer everyone in the right direction. I am almost convinced though that theorists will have to sort first through a lot of confusion and misinterpretation. It is to be expected when probing uncharted territory, nothing is for granted and surprises will most likely abound.

I agree in part with you. Tracking this physics is really tough in my opinion. You have one track theory –> phenominology, from a theory you calcuate observable outcomes. On the other track you have experiment –> phenomenology, where we try to see if the results match the phenomenology. So there can be lots of theories producing phenomenologies, but the experimental data ends up being a single set which matches one phenomenological set of predictions. The muddle really comes in when different theories have overlapping phenomenological predictions.

I don’t think the strong anthropic principle makes for good physics particularly. It is really more metaphysics. Yet I will confess that I have a closet strong AP bend to me. I suppose Einstein’s statement to the effect that God is subtle, but not malicious is something I hold to a bit. It makes less sense to me that we came about as conscious observers in the universe if it turns out we can never probe these foundations.

I agree with Lawrence. (You seem to be reasonable after all). There is nothing wrong with suggesting solutions to this fascinating problem. I see no danger in it. I want to leave to a later moment the evaluation of all ideas.

Every change occur by first creating lots of ideas, then let them go. Maybe some good idea is there? It is called brainstorming :)

I added another picture that shows better how this event looks in 3D. Notice that the particles go out in all directions. The correlations being observed are quite a subtle effect within this chaos. That is very unlike jets where the structure is much more clear, even when there are up to 10 of them!

The thing to remember about stringy effects in QCD is that these have been known about for many years. The Regge trajectory, where they first started talking about string tension as the slope of the energy of hadron states with increasing spin, is just one example. Hadron jets are the consequence of what happens when the string breaks.

What we are seeing here might be something more. I don’t mean it has to be a Beyond Standard Model phenomena (which it could be), just that it is something non-perturbative like some behavior of the quark gluon plasma. It may be that the string picture is the best view in which to describe the effect, and that would be exciting, but I think that is not the most unusual aspect of it.

To build on my earlier speculations, a signature of non-equilibrium phase transitions in condensed matter is the emergence of delocalized structures with general anisotropic properties. Processes such as direct percolation, reaction-diffusion, Taylor-Couette flows, Rayleigh-Benard convection, spin glasses may be deeply related to this weird phenomenon.
But I can be completely wrong on this one.

“The string explanation is fine but the full answer is going to be more complex. You can already think of ordinary dijet events as the result of strings. Two quarks move apart drawing out a string of gluon flux which then breaks forming jets of hadrons.

Here there is a little more to see. What the plot is showing is that if you look at the event along the beam pipe there is a tendency for the particles to come out in one plane. The two ridges on the plot are really connected in that plane.

It could be that a droplet, or cluster is formed but it stretches out in a plane or string that then bursts.”

Actually this is more or less what long string like objects identified as color magnetic flux tubes predict: they are not infinitely thin strings of hadronic string model or of QCD or of super string models. The initial state would be highly geometrically entangled flux tube- kind of spaghetti- which then straightens and splits into hadronic strings.

The basic difference between QCD plasma and TGD plasma would be that the plasma is inside this highly entangled flux tube. This would explain also the
the density of QCD plasma which was about 50 ( I hope I remember correctly) times higher in RHIC as expected.

In heavy ion collisions the exotic events were observed in almost head-on collisions so that there was a preferred plane defined by the incoming nuclei. Presumably also now a deviation from head-on collision would define that plane.

This article is a decent introduction to the concept of quark-gluon plasma. The quark gluon plasma is a case where the string energy is exceeded. In this case it is with the QCD string — otherwise known as the hadron “bag,” or for mesons a flux tube of gluons that ends at two quarks. In string theory at a much smaller scale the analogous physics is found with the Hagedorn temperature.

I think there is some connection between the two string domains. At the quark-gluon transition I think the stringy physics begins to turn on. It might be the case there is a renormalization group flow of physics at this scale and higher, where the lower energy Glasma is an IR form of the UV hagedorn temperature stringy physics. If so the two scales of stringiness then are just versions of the same physics at different energy.

The connection between GLASMA, string physics and Hagedorn temperature remains to be proven beyond doubt.

What I think is important for now is to see if GLASMA model can correctly account for the ridge at zero azimuthal separation. It might be also possible to recover the ridge from a relativistic diffusion model of quarks (by employing some form of the Fokker-Planck equation for the correlation function).

Of course the extended objects which may cause the “ridge” at high Lorentzian hyperbolic angle (rapidity) Δη are QCD strings or gluon flux tubes attached to quarks, with string tensions T ~ k^2. These are not the string tensions given by α’ near the Planck scale. There is of course the question, which I am raising, on whether some AdS/CFT physics is creeping into the picture here. The reason why this might come into play is that low energy physics might reduce the string tension far below the Planck value. This would enlarge some of the compactified dimensions and these “extra dimensions” reduce their hold on the degree to which superstrings are wrapped up. If this is so then there might be a continuous transformation between QCD-like strings and superstrings as transverse momenta is increased. This presumably occurs above the symmetry breaking domain ~ 1 TeV, where there is conformal symmetry. The principle argument for why this is the case is that at low energy these compactified dimensions contribute an enormous mass. Yet elementary particles at low energy, say the protons in the water I am drinking and everything else, have very modest masses. I believe Wilzcek commented that the reason gravity is so weak is that the masses of particles are so small. I make a phys-101 argument below on masses and compactification, The mass is m ~ 1/r, for r the radius of compactification. If this is near the Planck or string scale these masses would be enormous. This is one motivation for large extra dimensions.

Clearly though Ervin’s warning is clear, for we must make sure that we have eliminated all other possibilities before seriously considering superstringy physics here. I am though not sure this glasma model takes this into account. The first two figures indicate this physics in the dilute and saturated domains. The saturated domain pertains to the heavy ion physics. The funny thing here though is we are getting heavy ion-like saturated physics with just pp-bar collisions. To my mind this might suggest more degrees of freedom in the physics here. Of course some gluonic process might make up the difference here, so it might be best not to completely jump the gun. Yet the author of this paper http://arxiv.org/PS_cache/arxiv/pdf/1009/1009.0093v2.pdf indicates the degrees of freedom are due to partons (quarks) which are in the “fast domain.”

The argument for large mass compactification is the following. We start with the Klein-Gordon equation in 4 + n dimensions

∂^2_iψ – ∂^2_tψ + ∂^2_5ψ = 0

where I have lumped all the extra dimension into the 5th dimension. The solution to this wave equation is pretty simple

ψ ‾ exp(ikx – iωt + ik_5x_5)

Now at larger scales the fifth dimension is compactified into a loop or ring, so we replace ∂_5 – -> (1/r)∂_θ and the Klein Gordon equation becomes

∂^2_iψ – ∂^2_tψ + (1/r)^2∂^2_θψ = 0,

and the solution is ψ ‾ ψ_4exp(inθ), for ψ_4 the ordinary spacetime solution. Plop this into the K-G equation and we get

∂^2_iψ – ∂^2_tψ + (n/r)^2ψ = 0

and this recovers a mass. This is the whole compactification stuff, and presumably the radius of compactification r is smaller than low energy physics. There is a problem though. If r ‾ L_p or L_string n/r is a huge mass!

[…] de CMS del LHC os recomiendo la lectura de los comentarios de la entrada de Philip Gibbs, “Quark-Gluon plasma seen in proton collisions – maybe,” viXra log, September 21, […]

Lawrence,
“If so the two scales of stringiness then are just versions of the same physics at different energy.” – so you mean a scaled-up hiearchy? What would direct that hierarchy? pi (2 or 4)=topology? primes?

A little comment about Erwin’s link to color glass condensate model. In this phenomenological model for the dynamical at long length scales color flux tubes appear as basic structures. In TGD framework flux tubes are also in central role but now they are interpreted as space-time sheets and emerge unavoidably.

Similar flux tubes appear also in electroweak scale and realize the screening of weak interaction in terms of confinement of weak isospin. What is new that the ends of these magnetic flux tubes carry homological magnetic charges (second homology of CP_2 is non-trivial).

The elementary model with the Klein-Gordon equation I outline above is suggestive of the structure of the Randall-Sundrum model. It posits the universe is a five dimensional spacetime with negative curvature. Elementary particles are then confined on a 3 + 1 or space plus time D-brane. These elementary particles are open strings with their endpoints attached to this brain. Gravitons are closed strings, called heterotic strings, which are not so confined. These strings may cross these D4-branes within the entire 10 dimensional bulk. By this means the string tension \alpha’ is adjusted with the brane tension. In this way the cosmological constant is adjusted or “fine tuned” with the string tension, and equivalently the spectrum of particles on it. In particular the brane is the boundary of the anti-de Sitter spacetime. This boundary is similar to the boundary of a Poincar{\’e} disk, or an Escher disk with its interior formed up with the tessellations of angels and devils or fish. This is a special case of an anti-de Sitter space in two dimensions. The boundary region is where particles enter the interior at enormous energy, as the negative Gaussian curvature repels particle from it. The boundary is from a particle physics perspective the UV end of the energy spectrum. From a time perspective this may also be seen from the perspective of an observer on the disk. Clocks placed at any distance away from the observer will be seen by that observer to move faster — time speeds up At the boundary time is observed to move infinitely fast. So the frequency of any particle field near the boundary will be observed in an extremely blue shifted form. This boundary defines the Planck brane, or a D4-brane with string or Hagedorn energy.

This high energy brane is matched with a low energy IR brane. This brane is one where an observer witnesses clocks slow down as it approaches the boundary. This D-brane is then a black brane, or a black hole. The repelling gravitation of the AdS boundary means this spacetime acts as a bottle that holds the black hole. So there are two D-branes, one high energy where an observer finds clocks moving fast nearby and the other a low energy brane where clocks run slow. There is between these boundaries a conformal “flow,” or renormalization group (RG) flow, between them in the spacetime metric for the AdS spacetime. So the observer can look at conformal fields near the black hole horizon to find strings near this end of the RG flow wrapped up on orbifolds near the horizon and where the high frequency stuff is red shifted enormously and the detailed structure of the string substructure is apparent. Conversely on the AdS boundary things are blue shifted and this fine grained detail is hard to observer, and one observes structure on larger scales or equivalently on long time scales. The observer then only observes the QCD quark-gluon larger scale physics. The intervening AdS spacetime is then a space where there is an RG flow between these two perspectives.

This then means that at high energy, high energy by our accelerator physics perspective and LHC, where conformal symmetry is recovered (or there is some partial recovery with sl(2, R) conformal QM) there should then be a continuous map between the quark-gluon physics and the superstringy perspective. Do we have some signatures of this? I there is some suggestion of this, for there seem to be a larger number of degrees of freedom here at pp-bar physics than expected. Only by the introduction of more degrees of physics could you then get heavy ion-like physics with saturation and quark-gluon plasma. Of course this all might be worked out with more standard QCD physics, and that needs to be examined of course. We can’t permit our selves to be fooled; there is not point in that.

I will confess that I do have my “hopes” here, for I think it would be the height of tragedy if we can’t measure anything involving quantum gravity and superstrings. If we are absolutely unable to observe anything with this extreme scale of physics by how it continuously flows to low energy physics then after we get the Higgs and maybe SUSY it all should be closed up. There is not point in people working in string theory, or for that matter LQG or any of this. We must then close it all up and be better off perfecting the single malt scotch.

Applied chiral perturbation theory to explain the threshold production of neutral pions in proton-proton collisions.[150,153].

Originated a quantum mechanical treatment of HBT correlations that show that RHIC data was consistent with the presence of a chiral phase transition [211]. This work was discussed the Wall St. Journal (April 1, 2005) and in a Nature “News and Views” column by Wilczek Nature 435,152 (2005)

Used light front techniques to predict[151] a rapid decrease of the elastic electric form factor observed recently at Jlab, provide a qualitative explanation [188], describe all electromagnetic form factors [193], and introduce spin-dependent density operators to exhibit the non-spherical shape of the proton[200].

I do not see the situation as so gloomy as Lawrence does. Why on Earth we should see superstrings or LQG as only possible options? It is a fact that these theories do not work so that we should try to find better theories rather than continue to blow our heads on the wall. I decided to generalize string model 6 years before the first super string revolution and have excellent reasons to say that it was a success story.

The problem is not ultimately theoretical, but experimental. If there is no physics which has a conformal scaling from Planck scale to the SM, MSSM, QCD, physics at the 1-10TeV scale, then we are lost. We are not going to build a galactic proportioned accelerator to test Planck scale physics. Of course what I outline above is theory, largely not my own — though I am working on physics that has these aspects. It may turn out that the LHC data by the year 2025 produces nothing in line with Planck scale physics. If that is the case then quantum gravity, string theory, LQG and any putative physics on this scale is at best mathematical philosophy. This would be an unfortunate future where foundations of physics terminate before we get any answer to these foundational issues.

This goes back to my metaphysics, which does betray a bit of an anthropic principle bias, but if the universe exists with observers within the universe it does not make sense that we are hopelessly blocked from understanding these Planckian or stringy structures and observing some consequences of them. Of course this is metaphysics, for it implies there is some reification of existence through the occurrence of conscious beings within the universe. This is not physics, it can’t ever be physics as we understand it, but who is to say that physics contains all that can be known? In fact it borders on notions of hope or even faith. Though I don’t have exactly what would be called faith. In fact I am of such little faith that perfecting the new type of Lambric beer or single malt Scotch sounds like a good late in life career path.

1. if the universe exists with observers within = how would the observers look like? What would they be? – occurrence of conscious beings only? What about matter?
2. that physics contains all that can be known = the reason for LHC and alike is exactly to see what we don’t know.
3. Planckian or stringy structures = planckian = stringy?

4. here should then be a continuous map between the quark-gluon physics and the superstringy perspective. = no other theory is right? Look at Lubos when he says that at each end of a string can be totally different theories, means that every theory has something important to say? I want to see it like a polarity hidden dimensions – extra dimensions (size) and in between every size (TGD). Also dimensions start from zero? Zero point physics/ontology? http://www.newscientist.com/article/mg20727793.400-dimensions-vanish-in-quantum-gravity.html

Also the symmetry needs an discussion. Now symmetry is assumed in ground state or background, but maybe it isn’t so? Maybe the anti-GUT approach is the right one? Or both? The key to this is parity?

I will try to address both of these questions i by Radoslav and Ulla, n one throw. This involves how strings are generated and the “zero point physics.” A string is a D1-brane, a brane in one dimenison. A D0-brane is a point, or a particle. The endpoints of open strings are such points. The superstring near the Planck scale has similarities to the QCD string (meson) with two quarks held by a gluon flux tube. So this suggests that strings, and even higher Dp-branes for p > 1, are formed from particles or “partons.” Leonard Suskind invokes this sort of reasoning and Horava considers Dp-branes as topological forms of a Fermi surface.

I am working in much the same way, where the underlying forms are D0-branes which are elementary units of “code,” or quantum gravity bits. I am going to resist going into that level of theory here today.

Horava: suggests that the dynamics of Matrix theory is contained in the physics of magnetic vortices on the worldvolume of sixteen unstable D9-branes, described at low energies by a U(16) gauge theory. http://arxiv.org/abs/hep-th/9812135

At the higher energies to be reached at the Large Hadron Collider there should begin to emerge answers to basic questions such as:
– what is the origin of mass ? – I guess this is what we now discuss.
– why are there two distinct families of elementary particles,
each with 6 members ? – The symmetry.
– is there a grand unifying theory which links gravity to the other
fundamental forces ? – ???? Background?

The baryons has 3 ends. How is that branching happening? Can a flux tube branch? One cannot put 3 quarks to the ends of the string since it has only two ends?

Remember this was non-perturbative (gluons=strings). So no Feynman is enough. Can twistors branch? I guess this would be the quantum tunnelling, but usually the extra ends then collapse very soon.

Quarks can be 1-D or 3-D (TGD). The ‘anatomy’ of the quarks? I guess this was what Radoslav also asked for?

In TGD Universe string like objects emerge. Wormhole throats are the basic objects carrying manyfermion states. The fermionic oscillator operators span super algebra with N which can be rather large. They possess Kaehler magnetic charge and there must be second throat with opposite charge to which wormhole throat connects with magnetic flux tube. This structure should become visible in electroweak scale where second throat carries neutralizing weak isospin. Possibly also color confinement is accompanied by Kaehler magnetic confinement meaning that for quarks the Kaehler magnetic charge of the second throat in weak scale does not cancel the magnetic charge of free quark.

Emergence means that partons are massless. Massive states correspond to bound states in which light-like momenta which can have parallel or antiparallel space-like parts combine to form bound states. Also string like objects emerge in this manner so that the situation just the reversal of that in super string theory. The basic implication is that one does not lose the twistor description and bound state formation brings in the lacking IR regulation and allows also to have exact Yangian symmetry spoiled in N=4 SUSY by IR singularities whose regularization is very dirty business destroying the beauty of the theory.

An additional nice element brought in by zero energy ontology (throats of wormhole can have opposite energies so that net virtual momentum can be space-like) is that the bound state masses of virtual particles are non-vanishing but discrete so that one obtains very powerful kinematic constraints to vertices implying that loop diagrams are automatically finite and the allowed number of them is very restricted. Fundamental propagators are just propagators of massless fermions since also gauge bosons and gravitons emerge.

If there is a stringy content to these data, think of it according to partons. Partons are just phenomenological particles which have no properties other than what might be assigned to them from immediate data. Quarks were treated as partons for some time, which were form factor particles that as time went on conformed to Gel-Mann theory of QCD. It might be instructive to think in a similar mode. So assume there is this AdS_5 — > AdS_3 + sl(2,R). This is similar to a symmetry breaking, but it is really more of a splitting, or in line with the Sachs peeling theorem in general relativity. The actual symmetry breaking occurs once the conformal quantum symmetry sl(2,R) is broken at the order of ~ 1TeV. It is here that the Higgs mechanism kicks in. Now The AdS_3 is dual to QCD, and so experimentally in this IR limit we should see primarily quark-gluon physics. It we could directly probe physics near the string scale we would get primarily AdS_5 physics, which is dual to a GUT with conformal symmetry. The way the AdS_5 symmetry is so perturbed is by placing a black hole in the spacetime with a BPS charge. Near the boundary of the AdS_5 you have high energy stuff, clock rates are fast and all low energy physics is anti-dilated into high frequency physics, or the UV domain. Near the black hole you see the reverse, which is a time dilation, and all physics is reduced to an IR limit in the red shifted region. So if we are probing nature just above the Higgs domain where conformal symmetry holds, then we are looking at things near the black hole horizon at low energy and this is where we find AdS_5 – -> QCD and sl(2,R). Well that sl(2,R) is introducing some partons into the physics.

These partons are extra degrees of freedom not predicted by quark-gluon physics of QCD. Yet at around 1 TeV these should start making weak contributions of amplitudes or particle channel production. If this is the case, then proton-antiproton scattering amplitudes will start to saturate and exhibit condensate or plasma-like properties at lower energy than expected, or to appear as heavy ion collisions. Of course these partons might be due to other physics and not due to small stringy amplitudes creeping into the picture. Yet somehow it appears that partons of one sort or another might be percolating into these processes. The question is “what are they?” The LHC might be our chance at observing physics that has low energy connections to physics related to quantum gravity and strings. If this all turns out to be wrong, then while the immediate physics will still prove to be interesting it will be a grand disappointment in the long run.

Matti: The only connection I can make immediately with what you are writing is with the extremal limit on the Reissnor-Norstrom black hole. The black hole placed in the anti-de Sitter spacetime is extremal. This means that BPS charge, which in the U(1) case is just electric charge, Q is such that the two event horizons

r_{+/-} = m +/- sqrt(m^2 – Q^2}

merge as |Q| – -> m. In fact I use this to demonstrate the splitting off of AdS_5 – -> AdS_3xS^2, which leads to this “peeling off” of conformal groups. I use the plural form as this has a more general setting with exceptional groups, such as E_8, and sporadic group realizations. These extremal black holes are similar to wormholes is that the merging of the horizons squashes out the spacelike region II and there are then continuous paths between the I and III timelike regions. Of course I admonish people to avoid thinking these are running around our universe, or that in high energy physics at the LHC there are these extremal black holes are actually produced. So wormholes are not going to be flying out of pp-bar particle production and later logged into the particle data book.

Mass is a funny quantity, and we all expect that particles and fields are massless where symmetry is recovered. Presumably the grand symmetry is recovered at the highest energy. As energy is lowered to the TeV domain symmetry is perturbed by the Higgs field, until at the phase transition temperature the symmetry is completely removed.

The Higgs field is a vacuum effect which might be compared to a room full of people. Imagine you are a person who must to cross that room, but you are slowed down by bumping into people. This takes you off the light cone and your geodesic is timelike with what emerges as a mass. Well how can you get across that room faster? Well you make yourself smaller, so somehow you are a mouse who scurries across the floor to get across faster. But you still interact with people by zipping around their feet (you don’t want to get stepped on), and so you are still a bit off the light cone! So you make your self smaller still, say you become a bee or fly and you zip across the room very fast. Then by continually making yourself smaller and faster you approach the optimal speed for crossing that room and you minimize your interactions with the people in the room who will bog you down. As this happens you recover symmetry and the mass becomes a smaller proportion of the energy of the system, in the above it is you or in particle physics it is the transverse momenta of an interaction. At higher energy the wavelength of the particle becomes smaller and at higher energy, so gauge interactions are not “gummed up” by what might be thought of as the Higgsian “paste.” As you go to lower energy you are influenced by this Higgsian stickiness and the symmetry of broken at very low energy when you can get across the room. A phase transition has occurred, very analogous to a gas to solid phase transition.

As a sideline, the jamming up of traffic on freeways turns out to have analogues to phase transitions — with Higgsian or Landau-Ginsburg potential physics.

When it comes to extremal black holes in AdS spaces, these are structures which physically manifest themselves in the conformal completion of the AdS spacetime. AdS spacetime is funny, for one can’t construct a spatial surface that is the evolute of the spacetime, for the conformal completion is a spacetime with one dimension larger. So there is this additional amount of data. I don’t have quite the time to delve into this, and the structure of discrete Klien groups which define this. However, spacetime physics and even the Einstein field equation are an attractor point for certain discrete sequences.

Beyond this I have a hard time connecting up TGD ideas with M-theory and strings. The emergence of strings from something more fundamental, which Matti eludes to, is a deep question. It involves an unknown physics involving the duality between what an observer on a geodesic of constant proper spatial distance from a black hole observers of a string, and what a freely falling observer sees with the string by falling into the black hole on a commoving frame. This involves some very deep issues that equiate accelerated reference frames with inertial frames. This aspect of physics gets us into thinking according to Newton’s apple, or Galileo and masses dropped off of the tower of Pisa, or Einstein thinking about an observer commoving with an electromagnetic wave. I may indicate what I think about that later — and this gets actually deeper into what I think about.

Nominative trashing is the debating technique of labeling a debating technique to identify it as a common and low quality style of argument 2 weeks ago

More rumours :))

Yippee!!!!!

Some time ago I suggested something like this. Can’t for the life of me remember where, though.

The interpretation in terms of the formation and decay of quark gluon plasma looks natural but I think that quark gluon plasma is not quite what it should be according to QCD.

Since the densities of particles approach those at RHIC, I would bet that the explanation of the hydrodynamical behavior observed at RHIC for some years ago should apply also now. The description in terms of string like object proposed also by Lubos on basis of analysis of the graph showing the distributions as an explanation of correlations looks attractive. Radiating cluster does not explain the structures evolving as the transversal momentum increases.

I decided to look my own primitive model for RHIC events and found that I had mentioned stringy structures. I had also talked about critical system associated with confinement-deconfinement transition of the quark-gluon plasma formed in the collision and inhibiting long range correlations.

The proposed hydrodynamic space-time description was in terms of a scaled variant of what I call critical cosmology defining a universal space-time correlate for criticality: the specific property of this cosmology is that the mass contained by comoving volume approaches to zero at the the initial moment so that Big Bang begins as a silent whisper and is not so scaring;-). Criticality means flat 3-space instead of Lobatchevski space and means breaking of Lorentz invariance to SO(4). Breaking of Lorentz invariance was indeed observed for particle distributions but now I am notso sure whether it has much to do with this.

It seems that I have proposed at the microscopic level something like follows. A highly entangled long hadronic string like object (color-magnetic flux tube) would be formed at high density of nucleons via the fusion of ordinary hadronic color-magnetic flux tubes to much longer one and containing quark gluon plasma. In QCD plasma would not be at flux tube.

This object would straighten and split to hadrons in the subsequent “cosmological evolution” and yield large numbers of almost collinear particles. The initial situation should be apart from scaling similar as in cosmology where an entangled soup of cosmic strings (magnetic flux tubes) precedes the emergence of space-time in ordinary sense. Maybe ordinary cosmology could provide analogy as galaxies arranged to form linear structures? This structure would have also black hole like aspects but in totally different sense as the 10-D hadronic black-hole proposed by Nastase to describe the findings.

The string explanation is fine but the full answer is going to be more complex. You can already think of ordinary dijet events as the result of strings. Two quarks move apart drawing out a string of gluon flux which then breaks forming jets of hadrons.

Here there is a little more to see. What the plot is showing is that if you look at the event along the beam pipe there is a tendency for the particles to come out in one plane. The two ridges on the plot are really connected in that plane.

It could be that a droplet, or cluster is formed but it stretches out in a plane or string that then bursts.

They say they have stuck to the experimental side for this report but they will say more about the possible theories behind it later.

By the way, webcast right now at http://webcast.cern.ch/live.py?channel=Channel+1

Are they plotting the right thing?? Diametrically opposite directions have φ1 = φ2 + π and η1 = – η2. So it seems to me instead of plotting Δφ vs Δη they should be plotting Δφ vs η1 + η2.

They should be plotting the right thing given the number of people who have been through it, but whether I have understood and explained what they are plotting correctly is another matter

η ia pseudorapidity which is -ln(tan(θ/2)) where θ is the angle relative to the beam axis. So θ should run from 0 to π. If that is the case then I think you are right that φ1 = φ2 + π and η1 = – η2 for opposite directions. Perhaps they only let θ run from 0 to π/2 so pseudorapidity is always poisitive.

It is instructive to point out that what CMS is seeing may be a manifestation of non-equilibrium dynamics. Phase transitions out of equilibrium occur in condensed matter (strongly correlated compounds or behavior of spin clusters under certain conditions) and correspond to the onset of long-range correlations in space-time or phase space. Deviations from equilibrium in such examples may be successfully described by the non-extensive statistical physics of Tsallis.

“Phase transitions out of equilibrium occur in condensed matter (strongly correlated compounds or behavior of spin clusters under certain conditions) and correspond to the onset of long-range correlations in space-time or phase space. ”

Behaviour of spin clusters? What would change the spin? Is this going through the Planck scale? Is a magnetic phase created? Most surely.

What keeps the energy in place?

I learned from Lubos that it is not about the Planck scale. But a magnetic phase maybe.

Charged particles are created in bundles. What charged particles and why is pi directing?

Matti might in some sense have the right suggestion. Of course it is hard to know for certain what this implies, but this does look similar to what we might expect of correlations between QCD and AdS or black hole, or BH-like, physics. I wrote the following two weeks ago about the Randall-Sundrum concept of extra large dimensions, which honestly this might be hinting at. I also think there could be some sort of renormalization group theory principle connected to a general U-duality principle, where S and T dualities are gauged symmetries. So this could be pointing to some exciting possibilities.

To start consider the Klein-Gordon equation in 4 + n dimensions

∂^2_iψ – ∂^2_tψ + ∂^2_5ψ = 0

where I have lumped all the extra dimensions into the 5th dimension. The solution to this wave equation is pretty simple

ψ ~ exp(ikx – iωt + ik_5x_5)

Now at larger scales the fifth dimension is compactified into a loop or ring, so we replace ∂_5 – -> (1/r)∂_θ and the Klein Gordon equation becomes

∂^2_iψ – ∂^2_tψ + (1/r)^2∂^2_θψ = 0,

and the solution is ψ ~ ψ_4exp(inθ), for ψ_4 the ordinary spacetime solution. Plop this into the K-G equation and we get

∂^2_iψ – ∂^2_tψ + (n/r)^2ψ = 0

and this recovers a mass. This is the whole compactification stuff, and presumably the radius of compactification r is smaller than low energy physics. There is a problem though. If r ~ L_p or L_string n/r is a huge mass!

Randall and Sundrum have argued that this radius of compactification is much larger, which softens this huge mass. However, there are some problems with this, in that we really should not expect to get real black holes at the TeV scale. We might get small amplitude for black holes, but clearly they can’t appear significantly at energies far lower that E_p or the Hagedorn energy (temperature). This is where the general U duality comes in. At low energy these extra-dimensions are large, but as we go up in energy the scale of compactification shrinks in a renormalization group flow. So at TeV or LHC energies we should get small amplitudes for black holes and AdS physics, but at the same time they can’t appear appreciably. Otherwise the hot high pressure interior of neutron stars, a quark-gluon plasma, would evaporate away and neutron stars would not be stable. Clearly they are stable. Virtual black holes are sufficiently present to influence the quantum amplitudes of scattering processes, but without causing the violation of baryon and lepton numbers.

This now takes us into questions of quantum cosmology. Assume a cosmology is in an entanglement with other spacetime cosmologies. All of these exist in the grand universe or multiverse. We then have only partial knowledge of this whole system through entanglement entropy that necessarily exists within our cosmology. Further, that entanglement entropy might have some variability to it. Even Hartle argues for something of this sort, where there are decoherent sets that under fine grained observation may reveal more information. Thus the maximal entropy minus the actual entropy determines the amount of information available. However, this might be observed in a different light. As we probe nature on a finer scale the amount of information about the other cosmologies becomes apparent. This information is obtained with the compactified dimensions that define gauge forces.

So as we enter the TeV domain of energy we begin to get more information about the extra dimensions of gauge compactification, which contain quantum bits associated with other branes. Our D3-brane is connected to other D3-branes by type II strings which share these compactified dimensions. The renormalization of the compactified scale to smaller scales is then a measure of growing experimental contact with other cosmologies — we reduce the entanglement entropy of the universe, as it is presented to us, by a tiny amount by accessing this information.

Lawrence,

Don’t you think that is premature to invoke exotic new physics to explain what is being seen here? In my opinion much more mundane explanations need to be ruled out first. Bringing into discussion at this point the Randall-Sundrum scenario, large extra dimensions, branes, compactification and quantum cosmology may lead us astray.

Could stop-anti-stop squark production do something like this? It isn’t too far-fetched to expect a stop as the lightest squark, and a pair of stops could decay into a mess with W’s, bottom quarks, and neutralinos with missing mass and missing energy.

Of course some accelerator aficionados might weigh in here. The squark mass scaling in MSSM is m ~ Mlog(k/10^{16}GeV) up to transverse momentum k ~ 10^{15}Gev, and M ~ 100Gev. This means that at 10^3 Gev that puts squark masses in the 800-1200 GeV range. Gluino masses are comparable to this as well. With data at the 3pb^{-1} level I don’t know if that is sufficient. However, theories are being tested here, and it just might be.

Ervin, you are probably right in the sense that other explanations do need to be ruled out. However, I like to keep my sights somewhat elevated. It is my hope that we do get data that connects with these frontier areas of physics.

Lawrence,

I also hope that new data will be conclusive enough to steer everyone in the right direction. I am almost convinced though that theorists will have to sort first through a lot of confusion and misinterpretation. It is to be expected when probing uncharted territory, nothing is for granted and surprises will most likely abound.

Ervin,

I agree in part with you. Tracking this physics is really tough in my opinion. You have one track theory –> phenominology, from a theory you calcuate observable outcomes. On the other track you have experiment –> phenomenology, where we try to see if the results match the phenomenology. So there can be lots of theories producing phenomenologies, but the experimental data ends up being a single set which matches one phenomenological set of predictions. The muddle really comes in when different theories have overlapping phenomenological predictions.

I don’t think the strong anthropic principle makes for good physics particularly. It is really more metaphysics. Yet I will confess that I have a closet strong AP bend to me. I suppose Einstein’s statement to the effect that God is subtle, but not malicious is something I hold to a bit. It makes less sense to me that we came about as conscious observers in the universe if it turns out we can never probe these foundations.

I agree with Lawrence. (You seem to be reasonable after all). There is nothing wrong with suggesting solutions to this fascinating problem. I see no danger in it. I want to leave to a later moment the evaluation of all ideas.

Every change occur by first creating lots of ideas, then let them go. Maybe some good idea is there? It is called brainstorming :)

I added another picture that shows better how this event looks in 3D. Notice that the particles go out in all directions. The correlations being observed are quite a subtle effect within this chaos. That is very unlike jets where the structure is much more clear, even when there are up to 10 of them!

The thing to remember about stringy effects in QCD is that these have been known about for many years. The Regge trajectory, where they first started talking about string tension as the slope of the energy of hadron states with increasing spin, is just one example. Hadron jets are the consequence of what happens when the string breaks.

What we are seeing here might be something more. I don’t mean it has to be a Beyond Standard Model phenomena (which it could be), just that it is something non-perturbative like some behavior of the quark gluon plasma. It may be that the string picture is the best view in which to describe the effect, and that would be exciting, but I think that is not the most unusual aspect of it.

Non-perturbative means a fractal topology? Implies that the building blocks are already complete here?

It also says the proton is composite?

And Tommaso says the second peak comes exactly at pi.

To build on my earlier speculations, a signature of non-equilibrium phase transitions in condensed matter is the emergence of delocalized structures with general anisotropic properties. Processes such as direct percolation, reaction-diffusion, Taylor-Couette flows, Rayleigh-Benard convection, spin glasses may be deeply related to this weird phenomenon.

But I can be completely wrong on this one.

Phil said:

“The string explanation is fine but the full answer is going to be more complex. You can already think of ordinary dijet events as the result of strings. Two quarks move apart drawing out a string of gluon flux which then breaks forming jets of hadrons.

Here there is a little more to see. What the plot is showing is that if you look at the event along the beam pipe there is a tendency for the particles to come out in one plane. The two ridges on the plot are really connected in that plane.

It could be that a droplet, or cluster is formed but it stretches out in a plane or string that then bursts.”

Actually this is more or less what long string like objects identified as color magnetic flux tubes predict: they are not infinitely thin strings of hadronic string model or of QCD or of super string models. The initial state would be highly geometrically entangled flux tube- kind of spaghetti- which then straightens and splits into hadronic strings.

The basic difference between QCD plasma and TGD plasma would be that the plasma is inside this highly entangled flux tube. This would explain also the

the density of QCD plasma which was about 50 ( I hope I remember correctly) times higher in RHIC as expected.

In heavy ion collisions the exotic events were observed in almost head-on collisions so that there was a preferred plane defined by the incoming nuclei. Presumably also now a deviation from head-on collision would define that plane.

For a more details see my blog.

All,

The concept of GLASMA (color glass condensate) may be useful in understanding the underlying physics of high energy proton-proton collisions:

http://arxiv.org/PS_cache/arxiv/pdf/1009/1009.0093v2.pdf

Ervin

Ervin,

This article is a decent introduction to the concept of quark-gluon plasma. The quark gluon plasma is a case where the string energy is exceeded. In this case it is with the QCD string — otherwise known as the hadron “bag,” or for mesons a flux tube of gluons that ends at two quarks. In string theory at a much smaller scale the analogous physics is found with the Hagedorn temperature.

I think there is some connection between the two string domains. At the quark-gluon transition I think the stringy physics begins to turn on. It might be the case there is a renormalization group flow of physics at this scale and higher, where the lower energy Glasma is an IR form of the UV hagedorn temperature stringy physics. If so the two scales of stringiness then are just versions of the same physics at different energy.

Lawrence,

The connection between GLASMA, string physics and Hagedorn temperature remains to be proven beyond doubt.

What I think is important for now is to see if GLASMA model can correctly account for the ridge at zero azimuthal separation. It might be also possible to recover the ridge from a relativistic diffusion model of quarks (by employing some form of the Fokker-Planck equation for the correlation function).

Of course the extended objects which may cause the “ridge” at high Lorentzian hyperbolic angle (rapidity) Δη are QCD strings or gluon flux tubes attached to quarks, with string tensions T ~ k^2. These are not the string tensions given by α’ near the Planck scale. There is of course the question, which I am raising, on whether some AdS/CFT physics is creeping into the picture here. The reason why this might come into play is that low energy physics might reduce the string tension far below the Planck value. This would enlarge some of the compactified dimensions and these “extra dimensions” reduce their hold on the degree to which superstrings are wrapped up. If this is so then there might be a continuous transformation between QCD-like strings and superstrings as transverse momenta is increased. This presumably occurs above the symmetry breaking domain ~ 1 TeV, where there is conformal symmetry. The principle argument for why this is the case is that at low energy these compactified dimensions contribute an enormous mass. Yet elementary particles at low energy, say the protons in the water I am drinking and everything else, have very modest masses. I believe Wilzcek commented that the reason gravity is so weak is that the masses of particles are so small. I make a phys-101 argument below on masses and compactification, The mass is m ~ 1/r, for r the radius of compactification. If this is near the Planck or string scale these masses would be enormous. This is one motivation for large extra dimensions.

Clearly though Ervin’s warning is clear, for we must make sure that we have eliminated all other possibilities before seriously considering superstringy physics here. I am though not sure this glasma model takes this into account. The first two figures indicate this physics in the dilute and saturated domains. The saturated domain pertains to the heavy ion physics. The funny thing here though is we are getting heavy ion-like saturated physics with just pp-bar collisions. To my mind this might suggest more degrees of freedom in the physics here. Of course some gluonic process might make up the difference here, so it might be best not to completely jump the gun. Yet the author of this paper http://arxiv.org/PS_cache/arxiv/pdf/1009/1009.0093v2.pdf indicates the degrees of freedom are due to partons (quarks) which are in the “fast domain.”

The argument for large mass compactification is the following. We start with the Klein-Gordon equation in 4 + n dimensions

∂^2_iψ – ∂^2_tψ + ∂^2_5ψ = 0

where I have lumped all the extra dimension into the 5th dimension. The solution to this wave equation is pretty simple

ψ ‾ exp(ikx – iωt + ik_5x_5)

Now at larger scales the fifth dimension is compactified into a loop or ring, so we replace ∂_5 – -> (1/r)∂_θ and the Klein Gordon equation becomes

∂^2_iψ – ∂^2_tψ + (1/r)^2∂^2_θψ = 0,

and the solution is ψ ‾ ψ_4exp(inθ), for ψ_4 the ordinary spacetime solution. Plop this into the K-G equation and we get

∂^2_iψ – ∂^2_tψ + (n/r)^2ψ = 0

and this recovers a mass. This is the whole compactification stuff, and presumably the radius of compactification r is smaller than low energy physics. There is a problem though. If r ‾ L_p or L_string n/r is a huge mass!

[…] de CMS del LHC os recomiendo la lectura de los comentarios de la entrada de Philip Gibbs, “Quark-Gluon plasma seen in proton collisions – maybe,” viXra log, September 21, […]

[…] Quark-Gluon plasma seen in proton collisions – maybe « viXra log […]

Lawrence,

“If so the two scales of stringiness then are just versions of the same physics at different energy.” – so you mean a scaled-up hiearchy? What would direct that hierarchy? pi (2 or 4)=topology? primes?

A little comment about Erwin’s link to color glass condensate model. In this phenomenological model for the dynamical at long length scales color flux tubes appear as basic structures. In TGD framework flux tubes are also in central role but now they are interpreted as space-time sheets and emerge unavoidably.

Similar flux tubes appear also in electroweak scale and realize the screening of weak interaction in terms of confinement of weak isospin. What is new that the ends of these magnetic flux tubes carry homological magnetic charges (second homology of CP_2 is non-trivial).

The elementary model with the Klein-Gordon equation I outline above is suggestive of the structure of the Randall-Sundrum model. It posits the universe is a five dimensional spacetime with negative curvature. Elementary particles are then confined on a 3 + 1 or space plus time D-brane. These elementary particles are open strings with their endpoints attached to this brain. Gravitons are closed strings, called heterotic strings, which are not so confined. These strings may cross these D4-branes within the entire 10 dimensional bulk. By this means the string tension \alpha’ is adjusted with the brane tension. In this way the cosmological constant is adjusted or “fine tuned” with the string tension, and equivalently the spectrum of particles on it. In particular the brane is the boundary of the anti-de Sitter spacetime. This boundary is similar to the boundary of a Poincar{\’e} disk, or an Escher disk with its interior formed up with the tessellations of angels and devils or fish. This is a special case of an anti-de Sitter space in two dimensions. The boundary region is where particles enter the interior at enormous energy, as the negative Gaussian curvature repels particle from it. The boundary is from a particle physics perspective the UV end of the energy spectrum. From a time perspective this may also be seen from the perspective of an observer on the disk. Clocks placed at any distance away from the observer will be seen by that observer to move faster — time speeds up At the boundary time is observed to move infinitely fast. So the frequency of any particle field near the boundary will be observed in an extremely blue shifted form. This boundary defines the Planck brane, or a D4-brane with string or Hagedorn energy.

This high energy brane is matched with a low energy IR brane. This brane is one where an observer witnesses clocks slow down as it approaches the boundary. This D-brane is then a black brane, or a black hole. The repelling gravitation of the AdS boundary means this spacetime acts as a bottle that holds the black hole. So there are two D-branes, one high energy where an observer finds clocks moving fast nearby and the other a low energy brane where clocks run slow. There is between these boundaries a conformal “flow,” or renormalization group (RG) flow, between them in the spacetime metric for the AdS spacetime. So the observer can look at conformal fields near the black hole horizon to find strings near this end of the RG flow wrapped up on orbifolds near the horizon and where the high frequency stuff is red shifted enormously and the detailed structure of the string substructure is apparent. Conversely on the AdS boundary things are blue shifted and this fine grained detail is hard to observer, and one observes structure on larger scales or equivalently on long time scales. The observer then only observes the QCD quark-gluon larger scale physics. The intervening AdS spacetime is then a space where there is an RG flow between these two perspectives.

This then means that at high energy, high energy by our accelerator physics perspective and LHC, where conformal symmetry is recovered (or there is some partial recovery with sl(2, R) conformal QM) there should then be a continuous map between the quark-gluon physics and the superstringy perspective. Do we have some signatures of this? I there is some suggestion of this, for there seem to be a larger number of degrees of freedom here at pp-bar physics than expected. Only by the introduction of more degrees of physics could you then get heavy ion-like physics with saturation and quark-gluon plasma. Of course this all might be worked out with more standard QCD physics, and that needs to be examined of course. We can’t permit our selves to be fooled; there is not point in that.

I will confess that I do have my “hopes” here, for I think it would be the height of tragedy if we can’t measure anything involving quantum gravity and superstrings. If we are absolutely unable to observe anything with this extreme scale of physics by how it continuously flows to low energy physics then after we get the Higgs and maybe SUSY it all should be closed up. There is not point in people working in string theory, or for that matter LQG or any of this. We must then close it all up and be better off perfecting the single malt scotch.

Lawrence, that was good :) Really worth to study.

Gerald A. Miller http://www.phys.washington.edu/users/miller/

Applied chiral perturbation theory to explain the threshold production of neutral pions in proton-proton collisions.[150,153].

Originated a quantum mechanical treatment of HBT correlations that show that RHIC data was consistent with the presence of a chiral phase transition [211]. This work was discussed the Wall St. Journal (April 1, 2005) and in a Nature “News and Views” column by Wilczek Nature 435,152 (2005)

Used light front techniques to predict[151] a rapid decrease of the elastic electric form factor observed recently at Jlab, provide a qualitative explanation [188], describe all electromagnetic form factors [193], and introduce spin-dependent density operators to exhibit the non-spherical shape of the proton[200].

150 – http://arxiv.org/pdf/nucl-th/9512036

cited of 97 http://scholar.google.fi/scholar?cites=9394286054862703855&as_sdt=2005&sciodt=2000&hl=sv

199. \Nuclear spin-isospin correlations, parity violation, and the f-pi problem, Phys. Rev. C. Rapid Communications C67 042501 (2003) http://arxiv.org/abs/nucl-th/0301012

200. \Shapes of the proton” Phys. Rev. C Rapid Communications 68, 022201 (2003) http://www.informaworld.com/smpp/content~db=all~content=a794833526

http://arxiv.org/abs/nucl-th/0304076

How can the spin 1/2 object known as the proton have a non-spherical shape?

http://arxiv.org/abs/1005.1910

http://arxiv.org/find/nucl-th/1/au:+Miller_G/0/1/0/all/0/1

I found him on another interesting topic, the muonic hydrogen, discussed by Matti.

http://www.newscientist.com/article/mg20727793.500-large-proton-halo-sparks-devilish-row.html

http://dx.doi.org/10.1016/j.physletb.2010.08.074 De Rújula

http://arxiv.org/abs/1008.3861 QED is not endangered by the proton’s size

http://arxiv.org/abs/1008.4345 Third Zemach Moment of the Proton

Bon Apetit my fellows :)

I do not see the situation as so gloomy as Lawrence does. Why on Earth we should see superstrings or LQG as only possible options? It is a fact that these theories do not work so that we should try to find better theories rather than continue to blow our heads on the wall. I decided to generalize string model 6 years before the first super string revolution and have excellent reasons to say that it was a success story.

The problem is not ultimately theoretical, but experimental. If there is no physics which has a conformal scaling from Planck scale to the SM, MSSM, QCD, physics at the 1-10TeV scale, then we are lost. We are not going to build a galactic proportioned accelerator to test Planck scale physics. Of course what I outline above is theory, largely not my own — though I am working on physics that has these aspects. It may turn out that the LHC data by the year 2025 produces nothing in line with Planck scale physics. If that is the case then quantum gravity, string theory, LQG and any putative physics on this scale is at best mathematical philosophy. This would be an unfortunate future where foundations of physics terminate before we get any answer to these foundational issues.

This goes back to my metaphysics, which does betray a bit of an anthropic principle bias, but if the universe exists with observers within the universe it does not make sense that we are hopelessly blocked from understanding these Planckian or stringy structures and observing some consequences of them. Of course this is metaphysics, for it implies there is some reification of existence through the occurrence of conscious beings within the universe. This is not physics, it can’t ever be physics as we understand it, but who is to say that physics contains all that can be known? In fact it borders on notions of hope or even faith. Though I don’t have exactly what would be called faith. In fact I am of such little faith that perfecting the new type of Lambric beer or single malt Scotch sounds like a good late in life career path.

To Lawrence.

1. if the universe exists with observers within = how would the observers look like? What would they be? – occurrence of conscious beings only? What about matter?

2. that physics contains all that can be known = the reason for LHC and alike is exactly to see what we don’t know.

3. Planckian or stringy structures = planckian = stringy?

4. here should then be a continuous map between the quark-gluon physics and the superstringy perspective. = no other theory is right? Look at Lubos when he says that at each end of a string can be totally different theories, means that every theory has something important to say? I want to see it like a polarity hidden dimensions – extra dimensions (size) and in between every size (TGD). Also dimensions start from zero? Zero point physics/ontology?

http://www.newscientist.com/article/mg20727793.400-dimensions-vanish-in-quantum-gravity.html

Also the symmetry needs an discussion. Now symmetry is assumed in ground state or background, but maybe it isn’t so? Maybe the anti-GUT approach is the right one? Or both? The key to this is parity?

How are strings generated? If we designed an experimental set that proves the emergence of strings, we would find lepton-quark interference.

I will try to address both of these questions i by Radoslav and Ulla, n one throw. This involves how strings are generated and the “zero point physics.” A string is a D1-brane, a brane in one dimenison. A D0-brane is a point, or a particle. The endpoints of open strings are such points. The superstring near the Planck scale has similarities to the QCD string (meson) with two quarks held by a gluon flux tube. So this suggests that strings, and even higher Dp-branes for p > 1, are formed from particles or “partons.” Leonard Suskind invokes this sort of reasoning and Horava considers Dp-branes as topological forms of a Fermi surface.

I am working in much the same way, where the underlying forms are D0-branes which are elementary units of “code,” or quantum gravity bits. I am going to resist going into that level of theory here today.

Horava: suggests that the dynamics of Matrix theory is contained in the physics of magnetic vortices on the worldvolume of sixteen unstable D9-branes, described at low energies by a U(16) gauge theory.

http://arxiv.org/abs/hep-th/9812135

In my eyes good presentation: Strings, branes, and curled-up dimsensions are at the present time highly speculative ideas.

http://www.hyperhistory.com/online_n2/people_n2/science_n2/atomic_theory2.html

At the higher energies to be reached at the Large Hadron Collider there should begin to emerge answers to basic questions such as:

– what is the origin of mass ? – I guess this is what we now discuss.

– why are there two distinct families of elementary particles,

each with 6 members ? – The symmetry.

– is there a grand unifying theory which links gravity to the other

fundamental forces ? – ???? Background?

Thanks.

The baryons has 3 ends. How is that branching happening? Can a flux tube branch? One cannot put 3 quarks to the ends of the string since it has only two ends?

Remember this was non-perturbative (gluons=strings). So no Feynman is enough. Can twistors branch? I guess this would be the quantum tunnelling, but usually the extra ends then collapse very soon.

Quarks can be 1-D or 3-D (TGD). The ‘anatomy’ of the quarks? I guess this was what Radoslav also asked for?

In TGD Universe string like objects emerge. Wormhole throats are the basic objects carrying manyfermion states. The fermionic oscillator operators span super algebra with N which can be rather large. They possess Kaehler magnetic charge and there must be second throat with opposite charge to which wormhole throat connects with magnetic flux tube. This structure should become visible in electroweak scale where second throat carries neutralizing weak isospin. Possibly also color confinement is accompanied by Kaehler magnetic confinement meaning that for quarks the Kaehler magnetic charge of the second throat in weak scale does not cancel the magnetic charge of free quark.

Emergence means that partons are massless. Massive states correspond to bound states in which light-like momenta which can have parallel or antiparallel space-like parts combine to form bound states. Also string like objects emerge in this manner so that the situation just the reversal of that in super string theory. The basic implication is that one does not lose the twistor description and bound state formation brings in the lacking IR regulation and allows also to have exact Yangian symmetry spoiled in N=4 SUSY by IR singularities whose regularization is very dirty business destroying the beauty of the theory.

An additional nice element brought in by zero energy ontology (throats of wormhole can have opposite energies so that net virtual momentum can be space-like) is that the bound state masses of virtual particles are non-vanishing but discrete so that one obtains very powerful kinematic constraints to vertices implying that loop diagrams are automatically finite and the allowed number of them is very restricted. Fundamental propagators are just propagators of massless fermions since also gauge bosons and gravitons emerge.

Matti, I address you TGD comment further on down.

If there is a stringy content to these data, think of it according to partons. Partons are just phenomenological particles which have no properties other than what might be assigned to them from immediate data. Quarks were treated as partons for some time, which were form factor particles that as time went on conformed to Gel-Mann theory of QCD. It might be instructive to think in a similar mode. So assume there is this AdS_5 — > AdS_3 + sl(2,R). This is similar to a symmetry breaking, but it is really more of a splitting, or in line with the Sachs peeling theorem in general relativity. The actual symmetry breaking occurs once the conformal quantum symmetry sl(2,R) is broken at the order of ~ 1TeV. It is here that the Higgs mechanism kicks in. Now The AdS_3 is dual to QCD, and so experimentally in this IR limit we should see primarily quark-gluon physics. It we could directly probe physics near the string scale we would get primarily AdS_5 physics, which is dual to a GUT with conformal symmetry. The way the AdS_5 symmetry is so perturbed is by placing a black hole in the spacetime with a BPS charge. Near the boundary of the AdS_5 you have high energy stuff, clock rates are fast and all low energy physics is anti-dilated into high frequency physics, or the UV domain. Near the black hole you see the reverse, which is a time dilation, and all physics is reduced to an IR limit in the red shifted region. So if we are probing nature just above the Higgs domain where conformal symmetry holds, then we are looking at things near the black hole horizon at low energy and this is where we find AdS_5 – -> QCD and sl(2,R). Well that sl(2,R) is introducing some partons into the physics.

These partons are extra degrees of freedom not predicted by quark-gluon physics of QCD. Yet at around 1 TeV these should start making weak contributions of amplitudes or particle channel production. If this is the case, then proton-antiproton scattering amplitudes will start to saturate and exhibit condensate or plasma-like properties at lower energy than expected, or to appear as heavy ion collisions. Of course these partons might be due to other physics and not due to small stringy amplitudes creeping into the picture. Yet somehow it appears that partons of one sort or another might be percolating into these processes. The question is “what are they?” The LHC might be our chance at observing physics that has low energy connections to physics related to quantum gravity and strings. If this all turns out to be wrong, then while the immediate physics will still prove to be interesting it will be a grand disappointment in the long run.

Matti: The only connection I can make immediately with what you are writing is with the extremal limit on the Reissnor-Norstrom black hole. The black hole placed in the anti-de Sitter spacetime is extremal. This means that BPS charge, which in the U(1) case is just electric charge, Q is such that the two event horizons

r_{+/-} = m +/- sqrt(m^2 – Q^2}

merge as |Q| – -> m. In fact I use this to demonstrate the splitting off of AdS_5 – -> AdS_3xS^2, which leads to this “peeling off” of conformal groups. I use the plural form as this has a more general setting with exceptional groups, such as E_8, and sporadic group realizations. These extremal black holes are similar to wormholes is that the merging of the horizons squashes out the spacelike region II and there are then continuous paths between the I and III timelike regions. Of course I admonish people to avoid thinking these are running around our universe, or that in high energy physics at the LHC there are these extremal black holes are actually produced. So wormholes are not going to be flying out of pp-bar particle production and later logged into the particle data book.

Mass is a funny quantity, and we all expect that particles and fields are massless where symmetry is recovered. Presumably the grand symmetry is recovered at the highest energy. As energy is lowered to the TeV domain symmetry is perturbed by the Higgs field, until at the phase transition temperature the symmetry is completely removed.

The Higgs field is a vacuum effect which might be compared to a room full of people. Imagine you are a person who must to cross that room, but you are slowed down by bumping into people. This takes you off the light cone and your geodesic is timelike with what emerges as a mass. Well how can you get across that room faster? Well you make yourself smaller, so somehow you are a mouse who scurries across the floor to get across faster. But you still interact with people by zipping around their feet (you don’t want to get stepped on), and so you are still a bit off the light cone! So you make your self smaller still, say you become a bee or fly and you zip across the room very fast. Then by continually making yourself smaller and faster you approach the optimal speed for crossing that room and you minimize your interactions with the people in the room who will bog you down. As this happens you recover symmetry and the mass becomes a smaller proportion of the energy of the system, in the above it is you or in particle physics it is the transverse momenta of an interaction. At higher energy the wavelength of the particle becomes smaller and at higher energy, so gauge interactions are not “gummed up” by what might be thought of as the Higgsian “paste.” As you go to lower energy you are influenced by this Higgsian stickiness and the symmetry of broken at very low energy when you can get across the room. A phase transition has occurred, very analogous to a gas to solid phase transition.

As a sideline, the jamming up of traffic on freeways turns out to have analogues to phase transitions — with Higgsian or Landau-Ginsburg potential physics.

When it comes to extremal black holes in AdS spaces, these are structures which physically manifest themselves in the conformal completion of the AdS spacetime. AdS spacetime is funny, for one can’t construct a spatial surface that is the evolute of the spacetime, for the conformal completion is a spacetime with one dimension larger. So there is this additional amount of data. I don’t have quite the time to delve into this, and the structure of discrete Klien groups which define this. However, spacetime physics and even the Einstein field equation are an attractor point for certain discrete sequences.

Beyond this I have a hard time connecting up TGD ideas with M-theory and strings. The emergence of strings from something more fundamental, which Matti eludes to, is a deep question. It involves an unknown physics involving the duality between what an observer on a geodesic of constant proper spatial distance from a black hole observers of a string, and what a freely falling observer sees with the string by falling into the black hole on a commoving frame. This involves some very deep issues that equiate accelerated reference frames with inertial frames. This aspect of physics gets us into thinking according to Newton’s apple, or Galileo and masses dropped off of the tower of Pisa, or Einstein thinking about an observer commoving with an electromagnetic wave. I may indicate what I think about that later — and this gets actually deeper into what I think about.