Higgs Hunting 2011

After the hectic EPS conference last week there are a number of followup workshops organised for people to discuss the new results concerning the Higgs boson and possible new physics. The first is the three day meeting “Higgs Hunting 2011″ in Orsay which ended yesterday. For such a workshop the words of the presenters and discussions after are what count, but these are not webcast so all we have to go on as outsiders are the slides (Update 5-Aug-2011: video recordings of the talks have now also been made available at the same link). Nevertheless there are some interesting points in the slides and it is worth picking out some highlights. The workshop started with a talk by Massimiliano Grazzini with this slide showing the main new Higgs results and how it makes the theorists feel These exclusion plots only tell part of the story and it is easy to be misled by excesses that look convincing because they have lots of substructure that makes them appear to show complex signals. In truth the excess comes from a small number of events often seen in just one channel, with the detailed noise coming from the background. A slide from James Olsen for CMS shows the event data from the diphoton channel. On the lefthand plot you can see some excesses at 120 GeV and 140 GeV that make bumps in the exclusion plots but on their own they don’t count for very much. If you look at enough plots you are bound to see excesses of this size somewhere. A slide shown by Elisabetta Pianori shows some signals at around 120 GeV in the same diphoton channels. These are still weak and they are not seen elsewhere. It’s easy to get carried away if you are selective about what you show Here is an more extreme example from Aurelio Juste (see also Paul Thompson). This slide shows events recorded by ATLAS in the H-> ZZ->4l channels. As you can see there are not a lot of events there. This leads to the exclusion limits on the right. As you can see there are bumps giving nearly two sigma excesses, but they correspond to single events. These are not signals on their own. When we combine all the channels and all the experiments we do get some slightly better signals, but still the signal is quite weak. Ben Kilminster has conveniently lined up the plots to show us where they agree, Draw your own conclusions. Here is the update from Matthias Schott on behalf of the gfitter group As you can see they wont include the ATLAS and CMS data anymore claiming that it is “not trivial anymore”. This did not stop John Ellis using the “bloggers combination” to draw some tentative conclusions about the standard model Higgs

The discussion was not just about Higgs but I just have the energy to show one slide summarising the mass limits on various possible new particles according to Paris Sphicas on behalf of ATLAS

17 Responses to Higgs Hunting 2011

  1. Ulla says:

    A proper explanation for the undulatory shape of the curves would still be good for a non-expert.

    The main result is a goodbye to the singularity? Loops more actual than ever. Can the Planck scale be seen as a (giant) loop?

  2. vi says:

    Excellent post!

  3. Leo Vuyk says:

    How a massless Higgs could lead to a world without attraction forces.
    If attraction is interpreted as the statistical result of double pressure forces on Fermions between opposing real Higgs and converted Higgs acting as photons then we get new physics,see below.

    Quantum FFF theory states, that the vacuum is seeded with fast oscillating massless Higgs
    particles, oscillating along a complex chiral tetrahedral vacuum lattice, which has the ability
    to transfer Photon and Graviton information in bunches of oscillations, through the vacuum
    lattice with the local speed of light. As a consequence there are no attraction forces on
    propeller shaped Fermions. Only the sum of the different kinds of vacuum impulses from all
    directions on Fermions are responsible for all energetic phenomena in the universe.


  4. anon says:

    There is a typo in the link to John Ellis’ presentation: “vixra.prg” instead of “.org”.

  5. Kea says:

    Well, I most certainly DO NOT feel like the fat dude theorist.

  6. Nice that that the Higgs issue will be eventually settled.

    In any case, the big groupthink of theoreticians enjoying monthly salary become very expensive for tax payers. SUSY is another example about this.

    Any novice would expect that the mass ordering of fermions should be inherited by sfermions. Beginner however soon learns that MSSM and its generalization predict typically that stau and stop are the lightest sfermions. The reason is the prevailing vision about massivation and GUT philosophy (implying problem with proton stability and difficulty to avoid flavor changing neutral currents) suggesting that at short scales the masses of fermion families are identical and differ in long scales because the renormalization group equations for mass squared have different beta functions.

    Taking this seriously, it is naturally to concentrate on attempts to find excess in top and tau pair production so that one can totally miss anomalies in say electron pair production. It have not checked in detail how strong this bias is on the experimental side. TGD predicts 512*me= 262 GeV selectron as the lightest charged sfermion: sneutrinos are even lighter.

    The remaining fermions would have masses about 13 TeV by simple arguments generalizing the number theoretic mass hierarchy for fermions.

    If the situation is really this, colleagues sharing standard SUSY prejudices might be able to miss the discovery of the SUSY completely at LHC. MSSM provides them with the non-discovery potential for this, believe me;-)!

    [Side remark: There is famous anomalous event from CDF which -if taken at face value - allows to deduce the masses of selectron, zino, and higgsino from mere kinematics and selectron mass comes by p-adic length scale hypothesis 131 GeV, just one half of selectron mass predicted by the number theoretic symmetry.]

  7. Sorry for two typos in the prevous posting:

    *The “big” at the second line should not be there.

    *512*me towards the end of fourth paragraph should read 2^((127-89)/2)*me= 2^(19)*me.

  8. Bill K says:

    The slide from James Olsen’s presentation gives me pause. Note the dots on the green-and-yellow plot are every 0.5 GeV, and thus a nice smooth curve is generated where in fact there was only one high data point at 120 GeV that caused it. I think what he’s saying is that the bins being used are too narrow, and if the data were presented using wider bins it would reduce the look elsewhere effect.

    At any rate, when I see a bump up there at 2-sigma and he tells me it happens 60 percent of the time(!) I get the feeling we need to think of a better way of presenting the data, one which is not as deceptive.

  9. Apparently the “Nightmare Scenario” feared by particle physicists is that the LHC sees:

    no string/brane-related exotica,
    no supersymmetry-related exotica,
    no sparticles,
    no WIMPs,
    no extra-dimensions,
    no mini-black holes,
    no Randall-Sundrum gravitons,
    not even that greased pig Higgsy,

    but rather sees only a reaffirmation of the heuristic standard model, which has 26-30 fundamental parameters that must be “put in by hand”. Moreover the standard model failed to predict the fact that most of the mass of the universe is in the form of dark matter, and even after 30 years the standard model still cannot definitively identify the dark matter, far less its specific physical properties.

    So far that is what the LHC has initially and tentatively indicated. Some are watching these developments at the LHC with certain amount of satisfaction.

    The theoretical acrobatics could get very creative.


    • Philip Gibbs says:

      There is no nightmare scenario although we can talk about the worst case scenario. Dividing up your list I would quickly disregard these

      no string/brane-related exotica,
      no extra-dimensions,
      no mini-black holes,
      no Randall-Sundrum gravitons,

      These are based on the idea that there could be large extra dimensions accessible at the TeV scale. This is regarded as a very speculative idea amongst most theorists, even the string theorists. It can be weakly motivated by the hierarchy problem and is worth searching for but nobody will be very surprised if none of these things turn up.

      no supersymmetry-related exotica,
      no sparticles,
      no WIMPs,

      These are more reasonable expectations because they are well motivated from theory and cosmology, but nature may have other solutions and many theorists have considered alternatives. These things could also exist just out of reach of the LHC. It is true that many theorists will be disappointed if supersymmetry is not found but not if something else is found instead. It is too soon for any such conclusion.

      not even that greased pig Higgsy.

      Something has to break SU(2) symmetry and the Higgs boson is the simplest candidate. Other possibilities exists as parts of larger more exotic theories so the worst case is that there is just a lone standard model Higgs. The evidence so far points towards something in the 120-150 GeV window, but with a lone standard model Higgs being heavily disfavoured. Just about any outcome is still possible and we will have a lot more information very soon.

      Only a small fraction of the possibilities considered by theorists can be right. It is not a nightmare for physics even if they are all wrong. The thing to understand is that an important discovery will be made. If the only discovery is that there is no Higgs boson below 500 GeV that would be revolutionary, but there are some theorists who predicted it and have alternatives that would need to be studied.

      I can see that some people who know little physics may think that not seeing a Higgs boson is a failure and it may be a hard case to make TV documentaries about, but surely people who know how particle physics works can see that this would not be a nightmare.

      There is still a lot of data to collect. They need hundreds or even thousands of inverse femtobarns to see clear signals in many important individual decay channels. The hints talked out lately are themselves due to just a handful of events. There will be more exciting progress on Higgs very soon but it will take much longer to get the full picture.

      The mood at the Higgs Hunting workshop seems to have been one of excitement and anticipation.

      • Dilaton says:

        It s good to read such a clear and rational evaluation of the actual state of affairs, thanks Phil :-)

      • Bill K says:

        CERN’s publicity got off to a good start a few years ago with the Large Hadron Rap, but now that interest has died down a bit, maybe what we need is a HiggsVille application.

  10. Alejandro Rivero says:

    My personal nightmare scenario is about gluinos, winos and zinos. They are spin 1/2 particles in the adjoint representation. Being in the adjoint, they should mediate between particles in the fundamental rep, but they can not, because a force particle must be a boson.
    A related issue is that I am not even sure about why should them be 1/2 instead of 3/2.
    Can someone discuss in these questions here? I could ask in stackexchange, anyway…

  11. Thanks for your comments Phil, but my concern is with deeper matters.

    Model-building quick fixes and unicorn particles are not of much interest to me.

    What would it take before the particle physics community voluntarily undertook a thorough review of the fundamental assumptions that underly the entire subatomic physics paradigm?

    For motivation:

    A vacuum energy density crisis to the tune of up to a 10^120 disparity between the VEDs of particle physics and cosmology.

    Not even a decent hint of WIMPs after 40 years of false-positives.

    43 years of string/brane hype without a prediction or theory.

    A totally unnatural Planck mass that has no counterpart in the physical world.

    A standard model that is heuristic, at best.

    A possible start:

    What empirical evidence is there for the speculative assumption that the gravitational coupling factor, i.e., G, is an absolute constant that is the same on all scales of nature’s hierarchy? None! G has never been measured within an atom or subatomic particle. If you think it has, check your claim carefully and you will find out that you are wrong.

    Discrete conformal scaling for gravitation, and all other dynamics, would give you a new fractal paradigm that fits observations well, and offers one unified physics for all of nature.

    Bottom Line:

    One can hardly think of a more natural paradigm for nature than a discrete fractal paradigm, but to say this to the particle physics community is to invite a torrent of insults. Why? Is it not time to consider something completely different? Like how a change to fractal geometry would change our entire understanding of nature.


  12. [...] based on absolutely nothing” (which is not too far from the truth). Then at the Higgs Hunting workshop that followed EPS, John Ellis showed my “bloggers conbinations” saying that they were [...]

  13. [...] Gibbs reconoce que quizás tenga razón). Sin embargo, el archifamoso John Ellis utiliza en sus presentaciones la “combinación del bloguero” afirmando que aunque sea basura, mientras sea lo único [...]


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