A year ago I started to get fired up about the prospects for the Higgs boson discovery as it become clear that the Large Hadron Collider was performing so well that they would either find it, or prove that it does not exist, at least not in the form most expected. We had three major progress updates from the LHC last year with the amount of data being analysed doubling each time bringing better and better signs that a signal was emerging from the noise. At first the heavier ranges for its mass were ruled out. Then, in December the last major announcement left many theorists such as myself cautiously optimistic that the Higgs boson has finally been glimpsed in its last refuge at a mass of about 125 GeV. Officially the physicists who speak for the experiments have remained cautious but now they have enough data to settle the matter conclusively. This years initial runs of the proton accelerator have already delivered as much collision data as it produced last year, and CERN has announced another meeting to update the figures once again.
Rumours have spread that the new data contains the same signal seen before by both the large detectors CMS and ATLAS that have been searching for the Higgs boson at the collision points of the Large Hadron Collider. If this is true then it is just possible that either or both of the teams that run the detectors will be able to tell us that they have seen a signal with the 5 sigma significance required to claim a discovery. If they don’t reach that goal individually, the combination of the two almost certainly will.
As I write the auditorium at CERN is letting in the physicists who have been queueing all night for their place. Several will be live blogging from there but I will be reporting from home using the live webcast.
Is 5-sigma necessary for a discovery?
We have been assuming that a discovery announcement would require a level of significance of 5 sigma equivalent 30 a one in 3 million chance of the signal happening as just a background fluctuation is there is really nothing there. This morning some of the live bloggers are playing down this requirement which suggests that they might not reach 5 sigma but that the overall levels of significance could be considered sufficient. We will see what they actually say shortly.
08:55 Higgs applauded as he takes his seat
09:00 DG opens the meeting
Incandela, CMS spokesman starts with pile-up slide. Pile-up could be an excuse for any anomalies.
8:24 Far too much detail for time allowed 
8:30 Amazing signal from combining 7 TeV + 8 TeV in diphoton channel for CMS
They have used 5.5/fb from 2012 data.
Here is the exclusion plot
4lepton also looks good. Combined significance is 5 sigma! = Discovery
WW looks OK too, only 8 TeV not combined with 7 TeV
Mass of Higgs is 125.3 += 0.6 GeV, combined significance 4.9 sigma
All channels consistent with SM but diphoton a little enhanced
8:53: Now starting the ATLAS presentation
Diphoton channel for ATLAS also showing a distinct signal. They get 4.5 sigma combining 2011 with 2012, used 5.9 sigma
Signal is nearly twice the standard model
Even in the 4-lepton channel the signal looks clear on the evnt plots
3.6 sigma in this channel
In combined channels ATLAS reach 5 sigma at 126.5 GeV = discovery!
Interesting that the mass value is still a little inconsistent with CMS.
Both experiments are showing exvess anove standard model in diphoton channel. This is even nore exciting than the discovery
DG says “I think we have it, do you agree?”
“We have a discovery, a particle consistent with the Higgs boson”
Now I have to combine those diphoton channels to see how significant the excess really is, BRB
11:47 This is what DG warned you against…
The combined diphoton plot gives a 6 sigma signal. It is 2.4 sigma stronger than the standard model.
This is what the signal plot lokks like. Rememner the grenn line is the standard model level, red line is background level
I will refine these when I have clearer plots to work from
The slides are now online.
13:44 I have been occupied with other things but will add some more combos later. There are lots of plots to digitise,
14:10 For those patiently waiting here is the unofficial combination for ZZ to four leptons. Significance is an impressive 4.6 sigma
The signal plot shows that in this channel it matches perfectly the standard model Higgs
For completeness here is the combination of the two low resolution channels across ATLAS+CMS. This one gives 7.4 sigma
Notice that we have now eliminated any possibility of a second boson nearby, unless they are too close to separate.
[...] das Teilchen ist, hören wir gleich. der Webcast läuft stabil; Live-Blogs laufen z.B. hier, hier, hier, hier und hier. Nach einer kurzen Begrüssung durch den CERN-Chef spricht als erster der [...]
Completely off topic question: do you know, who is the girl in the first row?
Well, CMS got 5 sigma, so the question is moot
Diphoton channel excluds SM Higgs from what I see
Same impression here. The production rate is more than twice the predicted one. Perhaps we should be indeed cautious before concluding that Higgs has been discovered. Why not just speak about new particle?;-)
diphoton channel excess – is there a (simple) modification of SM which explain this? (*** attention *** layman here)
My own conclusion is that situation remains still unresolved despite the strong and psychologically perfectly understandable tendency to interpret the particle as Higgs. For year ago one could interpret twice too large gamma pair signal as luck but this not appropriate anymore. Candela indeed stressed in the video that new physics might be there.
Perhaps the proposal of Jochum van der Bij (Freiburg) for the decay of a tandem Higgs pair (around 125 GeV) at the same time into diphoton is not so bad idea?
Jochum van der Bij wrote on Vixra:
June 24, 2012 at 5:10 pm
yes, you could have two Higgs bosons, for instance one with
mass 125 GeV and the other with mass 125.02 GeV both with
half the cross section of a standard model Higgs. This cannot be resolved by the LHC. This is the Hill model from 1986. It is
the simplest (least extra parameters) extension of the standard model. There are also more interesting possibilities along these
lines (HEIDI models). It shows why it is important to measure
the width, more precisely the line-shape of the Higgs boson
The data is consistent with the Higgs particle. These data do not tell us much detail, such as whether the Higgs field has connections to extra large dimensions SUSY and so forth. I think the Higgs field may have some connection to quantum gravity. Yet today we have pretty clear evidence forthe standard model Higgs to a fair degree of approximation.
LC
Sika, yes, a decay of a composite Higgs.
-drl
What are the actual numbers of Higgs observed in each channel?
They’re just playing the Incandela interview leaked yesterday. What an accident that among the zilions of parallel Universe, we just happen to live in ours!
You are not taking into account the correlations
Very true, Phil, correlations are there. For example, most of us who chat with each other are probably objects in the same – very correlated – universe.
It could be interesting to try to analyze this apparently non-serious topic – what were the chances that they would really have lots of parallel videos – in as serious a way as possible. How we evaluate the probabilities etc.
I think the facts are still consistent with my theory yesterday evening. They did have a suposition of different videos but has already made the observation that selected this one.
A wave function collapse?
Maybe we actually are there in the other Universes too, celebrating the ‘discovery’? But it somehow feels troublesome imaging more than one Lubos.
Happily we don’t know anything about those Universes.
This new ‘Higgs’ is on the edge of our own Universe, maybe something to think more seriously of? Maybe this finding also ‘collapses’ some extra dimensions?
The results indicate inquisitiveness of humanity to understand nature which all of us share. They also indicate the progress we have made collectively to relate which was previously demised as signal noise to real physical phenomenon. This inquistiveness defines us as humans.
From outside, we celebrate with three cheers to all those involved in this investigation. Humanity will remain debted to scientific community not only because of prosperity it brough to us, but also peace of mind by packaging explaination of nature in simple words and concepts.
Ulla I am convinced that we need to have mirro symmetrical selves in other universes too.!! to have some sort of a shared free will.
see;
Wavefunction Collapse and Human Choice-Making Inside an Entangled Mirror Symmetrical Multiverse.
If the process of wave function collapse of two entangled particles into mirror symmetrical states, is the basic process for all created particles, then we should live inside one part of a mirror symmetrical entangled copy MULTIVERSE with one central origin. We will give it the name: Raspberry Multiverse. Even human choice making should be subjected to this mirror symmetrical process. Benjamin Libet described a choice experiment, which we could use and extend to measure how many copy universes there should be.
http://vixra.org/pdf/1103.0015v1.pdf
Lubos, can you please try for 1 hour to restrain your buffoonery?
-drl
@ D R Lunsford: Dont be such a sourball …
Happy higgs day to all and thanks Phil for the nice pictures and plots
Cheers
Happy Higgs Day, Dilaton, and even Happy Higgs Day to all the sourballs, too!
In Czech, the Higgsdependence Day sounds even better. I invented the term “Den nezáhiggslosti”.
D R Lunsford just wants to say that he realizes damn well that I have lots of reasons to present kilotons of buffoonery today!
Thanks Lumo
You are probably right; maybe I should go to the sites of my “favorite” sourballs and wish them a happy higgs day too, LOL …
?
This is not any particle with determinate mass – it either a clutch of particles in the familiar sense, or its an integral isospin – something quite unfamiliar.
With the diphoton signal leading the range, the whole array of new diphoton results comes sharply into focus. Is this unaccounted torsion – as in Einstein-Cartan theory – as by frame-dragging from the central black hole in our galaxy?
If results otherwise are SM-consistent, the theory still badly underpredicts the data! A bow-wave analogy looks viable, but the point now is to identify unaccounted uncertainty. The mass/kinematic viscocity split of action is certainly relevant, and links to the torsion theme.
Like I said, this is Copenhagen II – The Mass Factor. So how can indeterminate mas determine any??? Looks like the mechanism is first out….
Is this the correlation of the diphotonic isospin? So this is like a Bose-Einstein particle that strenthen one side , due to the enrgetic input? Usually this picture is seen for weak BE condensates, the opposite to this? Or…?
Photonic interaction should create em-forse, or spin?
http://prd.aps.org/abstract/PRD/v85/i11/e115023 Something like this?
I am no expert on this, but it brings in my mind a chirality, which is also at the base of the Higgs mechanism, but there linked to G.
Q: Why does the Higgs field only couple to opposite-chiralities fermions?
the Higgs field interact with fermions through a Yukawa interaction coupling only left to right chiralities.
A: because once the Higgs couples two Weyl fermions together, they become the two chiralities of a massive charged fermion. The standard 4-component spinor formalism disguises how natural this coupling is because it makes every fermion into a Dirac fermion, and projects out the unphysical states at every vertex.
You can think of a Yukawa coupling as a mass term with a scalar field taking the role of the mass. The mass term for a charged fermion has to be of Dirac type, because it must be invariant under phase rotations, and only the term ψˉψ is invariant. This means that Higgs fields will always couple opposite chiralities of charged massive fermions, i.e. everything in the standard model that couples to the Higgs.
http://physics.stackexchange.com/questions/17263/why-does-the-higgs-field-only-couple-to-opposite-chiralities-fermions?rq=1
http://iopscience.iop.org/0295-5075/72/5/733/fulltext/
Quark masses without Yukawa hierarchies
H. Fanchiotti et al 2005 Europhys. Lett. 72 733
Oh for heaven’s sake! It’s not gravitational frame dragging! The question is, what is the statistical significance of the excess rate in yy channel?
-drl
[...] of the discovery of a Higgs-like boson. I have nothing to add to the huge amount of coverage of the physics itself, but I do want to note what an excellent job CERN’s director general Rolf Heuer has done in [...]
What is a particle?
Would like to register here, an opinion which is very different than most of us.
We all know photon is a particle. The wavelength of which is function of its energy. In PicoPhysics plank’s constant represents natural unit for existence of Knergy. The magnitude of Knergy, in a self supporting confinement in equilibrium (particle), can only be an integer multiple of this unit. This gives us Energy of a particle as Sum of terms each representing an internal energy level hc/l where l is wave length.
Energy of Particle = Sum of terms (q1,q2,q3……) ; Where q = nhc/l
The above approach to understanding matter consisting of particles (defined by closely interacting units of Knergy acting together) is compatible to human knowledge as transferred to common interested individuals by scientists through various means of communications.
Each term can be seen as an elementary particle along with total configuration. Each elementry particle itself can be constrinued as multiple units of knergy. When a knergy unit is seperated from elementary particle (emmission of photon), we have a new particle, as well as photon energy that is function of environment including the source itself.
How the confinement of knergy units come about, its stability and particle-energy cycle is explainable at level-3 in picophysics. Level-1 is available at http://www.picophysics.org
May be above thought process can have an impact analysis of 5-sigma results.
Action at a distance
Many concepts that lead us believe and confirm existence of a particle originates from attempts to explain action at a distance using Hermann Minkowski (Space). Minkowski Space enabled us to visualize photons. This led to generalization of physical interaction to be a result of particle exchange.
PicoPhysics have a different take on action at a distance. It attributes the same to combination of two factors; Konservation of Knergy and Anti-Konservation of Space. Interaction or action at a difference does not need a particle, but density (space or Knergy) gradient to exist at a distance from the object. The resulting action is quantized as a result of possible arrangement of Knergy units in the observer (Experiencing Object).
The proof the pudding shall be seen is deviation from Newton’s law of motion (To every action there is equal and opposite reaction). This quantization being secondary to natural quantization of Knergy is governed by individual object and its local conditions. Uncertainty principle epitomises this.
It can be visualized that the 5-sigma data can prove to be as significant to physics as Minkowski space was to photons which were conclusively established by photo-electric effect.
[...] di superare un limite dell’attuale formulazione. Le scoperte comunicate oggi, tuttavia, gettano una luce positiva sul Modello Standard, e l’euforia dei fisici in sala dice molto anche sulla soddisfazione dei [...]
Congratulations to all at LHC who together have made this discovery of a New Particle.
Super job Phil – We all thank you too!
To Phil and Lubos:
Today is a clear milestone in the history of Physics. Regardless what the future holds in store for us, it is quite clear that we are on an exciting journey towards new discoveries and a deeper understanding of Nature.
Imagine for a moment the reverse of where we are today: no Higgs signal and no evidence for BSM physics. This scenario would have been a real disaster.
Let me congratulate both of you for sticking with early hints for the discovery and unveiling the news to everyone in real time!
Cheers,
Ervin Goldfain
OK, I will be one who has questioned the Higgs to publicly admit there is now some good evidence that correlates with some version of the originally proposed Higgs mechanism. The branching ratios are out of whack and maybe we need more data for WW, but it does look like the fundamentals (with some changes in the prediction of rates) for a Higgs field/boson. Give Peter Higgs and others who proposed this theory credit – they did a fantastic job 50 years ago!
A question for the experts here for the basic understanding:
The Higgs-Field allows to generates (inert!) mass terms in the lagrangian describing the SM. But how is inert mass defined? “Inert mass” is defined by Newton’s F=m*a. Correct? The acceleration of something “a” is described using “space” and “time”. Ok. But F itself again is described using “mass”. It seems like a loop leading to nowhere. F is defined using a and m but m itself is again defined using F and a…..
Please help me understand what this inert “mass” in these generated mass terms of the lagrangians is.
I would like to add to question to include the interpretation of equation E=Mc2. Does it mean energy and mass are inter-convertible or identical realities.
To people outside of current scientific community, the higgs boson is being presented in media as the reason for existence of mass in universe. Till now, books on physics have portrayed photon as energy particle with mass as reflected in the path traced around planets.
May be some day, a person from scientific community will put a blog for benefit of people like me and satisfy our curiosity.
There are many places that answer this type of question. Try the Physics FAQ, Wikipedia or Physics stack exchange for example
Nice work Phillip, btw it seems the mass difference between CMS and ATLAS comes from ATLAS diphoton, because ZZ, which should be more precise gives more or less the same mass, also your combination gives 125.5 GeV. CMS result is those 125.3+-0.6 GeV. Does that contain both statistical and systematic uncertainties?
.
I wonder when they release update on fermiophobic Higgs it seemed to follow diphoton channel.
Btw there is usefull app for reading data from plots http://www.datathief.org/
Have you watched the press conference, video is available on cern webcast, they said theey will prolonge LHC run by 2-3 months, it also seemed LHC will be offline whole 2013 a 2014 and will come back in 2015.
Does that mean they will run through winter of 2012/13?
Thanks in advance.
Yes, I heard about the extension. You probably remember Myers saying recently that they did not need the extra two months but the long shutdown was getting longer. Seems they hatched another plan where they would run longer and let the shutdown continue longer. What will we do for two years?
I think fermiophobic Higgs is badly wounded.
If I remove diphoton I get 4.3 sigma but it is still too broad to tell who has the better photon calibration
I dont need datathief because I wrote a similar feature into the viXra combination applet, but thanks anyway.