Some more detail on Higgs rumors I’ve been hearing recently. Evidently the latest ATLAS data shows an excess in the gamma-gamma channel around 126 GeV, of the size expected if the Higgs is there, and CMS is also seeing an excess (2 sigma?) around 125 GeV in the same channel. I haven’t heard anything about confirmation of this in other channels. Independently, someone has posted a similar rumor at viXra log, and Philip Gibbs is writing about it here. This looks to be still not a conclusive Higgs signal, but the closest thing yet. More details may or may not emerge before the public talks on December 13.
Update: Latest rumor is that the significance of the ATLAS gamma gamma bump is almost 3 sigma.
Update: This morning’s rumors are a 3.5 sigma 126 GeV excess at ATLAS in the ATLAS-only combination, and 2.5 sigma at 124 GeV for CMS. Heuer’s message to all CERN personnel says the December 13 announcements will be “significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or non-existence of the Higgs.” Presumably they’re waiting for 5 sigma before claiming conclusive proof.
That would be weird, given that in the summer dataset both ATLAS and CMS had a deficit in gamma-gamma around 125 GeV…
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According to Motl, this is very close to Kane’s favorite value 127 GeV !
Has to be close to *someone’s* favorite value.
Gibbs says “at this mass the standard model has problems with vacuum stability that are likely to require supersymmetry or something similar to stabilize.”
Can someone explain that?
Amos—if the Higgs mass is 125 GeV, then the quartic self-coupling of the Higgs, which (like all couplings) changes as the energy scale changes, will become negative at an energy scale well below the Planck or unification scale. That means the vacuum becomes unstable. Supersymmetry would cure this, and so would many other theories. Since the energy scale at which the self-coupling goes negative is well above the reach of accelerators, it is possible that whatever new physics solves the problem can’t be seen in accelerators. Of course, we all hope that the new physics is at the TeV scale.
Gordon Kanes work has been really interesting to me even before the rumors of a 125-127 GeV Higgs… So this result has me a little bit excited.
You can confirm from his presentation here that 127 GeV is indeed the preferred value (see the conclusions page of the slide):
http://conferencing.uwex.edu/conferences/stringpheno2011/documents/kane.pdf
I actually downloaded this a while ago, so I can confirm that he didnt just make a different pdf for each possible mass haha
Take a look at this one: The Standard Model (SM) plus gravity could be valid up to arbitrarily high energies. Supposing that this is indeed the case and assuming that there are no intermediate energy scales between the Fermi and Planck scales we address the question of whether the mass of the Higgs boson m_H can be predicted.
http://arxiv.org/abs/0912.0208
Wired magazine has an article about impending Higgs news (or non-news):
http://www.wired.com/wiredscience/2011/12/higgs-lhc-anticipated/
Disclaimer: No Brian Greene has been harmed in the making of this message.
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I remember that an indian guy applied the four colour theorem to the SM finding that the best value for Higgs mass is ( 2 M_W + M_Z ) / 2, i.e. a 125 GeV Higgs mass!
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Doesn’t the primary decay of a 4th quark family b’ quark also involve a photon? Then a b’-b’bar would produce gamma-gamma signal also, confusing the interpretation until a complete analysis determines the spin of the original particle.
Frank,
In principle lots of things could produce a gamma-gamma signal. But remember that the SM Higgs predicts exactly the width and size of such a signal, and my understanding is that this is consistent with what the experiments are seeing.
Width ans size may be and of course since it is consistent it will be tempting to interpret the signal as a SM Higgs, but until its spin is measured, which will take a lot of data, even this consistency can be put into question.
Hi Marc Sher (who I used to know at Santa Cruz many years ago),
Though the basic thrust of your argument is right (i.e. that scalar fields are problematic at high energies), it is not true that the quartic Higgs coupling becomes negative. I am pretty sure you are thinking about Landau’s pole.
I hope Peter W. will indulge my discussing the technical issues, so to avoid causing too much trouble, I’ll be brief. He may permit my comment because they directly concern the Higgs mechanism.
Landau’s formula for the effective coupling is only good for small couplings. It breaks down at high energies, where it predicts the sign change. The pole/sign change is fictitious.
The real problem is that if the coupling at high energy (say with a Planck-scale cut-off) is not fine-tuned to some enormous value, the coupling at the TeV scale is nearly zero. This can checked by the renormalization group in 4-epsilon dimensions, by 1/n-expansions and by numerical simulations. It is also strongly indicated by some rigorous results about triviality, but these don’t quite work in four dimensions. There is no change in the sign of the coupling.
Some field-theory books present the Landau pole as gospel, even though it is completely unphysical. The real problem is triviality/fine-tuning.
Bernard,
How long it takes depends on the mass of the Higgs (assuming it exists). With a WW signal, the spin can be checked without that more data IF there is a Higgs and that the mass is not too far from 130. In the case of WW->lnln analyses, both experiments use a delta(phi) cut between the two leptons which assumes a spin 0 particle decaying to two vectors. That distribution can be measured too. If there is a Higgs and if the mass is in the 115-120 range, then it would be a lot harder and would indeed take a lot more time.
What I heard: CMS’s 119GeV peak in gammagamma is still strong, but another at 124GeV appears.
Peter O:
I believe Marc does mean what he wrote (Higgs self coupling goes negative). This is due to the contribution from Yukawa couplings (primarily the top), which will drive the Higgs coupling negative if m_top/m_H is too large. This is known as the vacuum stability bound (and it has been checked in lattice calculations).
Thomas,
This is something I should know about. Thanks, I’ll look into it.
Peter and everyone
If the signal remains at 3~4 sigma level until 6th 1212, what will CERN conclude?
They will conclude that Higgs exists or not?
If the level of the signal doesn’t come up to 5 sigma, what will happen?
I’m sorry. 6th 1212 -> june 2012 or december 2012
Peter:
Thomas’ comment was enough to locate this article : http://arxiv.org/abs/hep-ph/9307342v1 which seems to sum it up.
Peter–Thomas and Amos are correct, although the reference Amos gives is quite outdated–the papers of Quiros and others are more updated with the proper top quark mass (http://arxiv.org/abs/hep-ph/9703412 is a good summary). It has nothing to do with the Landau pole. The quartic coupling goes “negative” above some scale, or if you wish to not think about negative couplings, solve the RGE for the Higgs potential and there will be an instability at high scales. But frankly, since few people believe it’s just the SM up to huge energy scales, it doesn’t matter that much.
Pardon me for asking, but aren’t 124 GeV and 126 GeV miles apart? I mean even physicists wouldn’t claim to have found a particle with a mass of “about 125GeV,” would they? Is someone expecting one or the other of these numbers to move a percent or two when more data comes in? I don’t see how you could possibly combine these results to claim you have found something, if anything it would indicate exactly the opposite.
I guess the peaks come out as distributions centered at 124GeV and 126GeV. So if you combine both experiments we get a larger and broader peak with a 125GeV mean value.
@Cesar,
Yes, I’m sure that is the case, and I’m sure the statisticians have ways of combining that sort of data, but I have issues with that even in more “normal” cases like population sampling. Guess it’s just that I’m a mathematician, and I just don’t trust statistics about things like this, too much flexibility with your assumptions. Could just be that I never liked the SM, elegant as it is, too many parameters…
Jeff,
You can look up the expected width of the bump, I think it’s very roughly 2 GeV or so. Remember, right now the bumps are near the limit of statistical significance, not something well-resolved where you can precisely locate a peak. The numbers being quoted are also not as precise as possible. It could very well be that the ATLAS peak is near 125.5, the CMS one near 124.5. So, the small discrepancy in mass value is probably not significant.
Yonghun Park,
As you accumulate better statistics, if there’s a Higgs there, the statistical significance should increase. If there’s nothing there, it should decrease. Both statements are probabilistic, but with very high probability if substantially more data is accumulated.
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Are there other channels besides the WW signal to verify the results or is this the only data that will verify the Higgs existence? What does the Tevatron data say about this channel? How much more data collection (and how long) is required going into 2012 to get to the 5-sigma level?
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I think the natural width of a Standard Model Higgs at M_h=125 MeV or so is only… 5 MeV.
http://www-library.desy.de/preparch/desy/proc/proc02-02/Proceedings/pl.1a/haber_pr.pdf
I think detector resolution broadens that observed full width to maybe 3-4 GeV, or a sigma of about 1.5 GeV.
http://hal.in2p3.fr/docs/00/36/46/31/PDF/LAPP-EXP-2008-09.pdf
Whoops M_h=125 GeV.
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Being both a statistician & former physist 124 & 126 could be the same point – depends how many points were measured in the empirical distributions, how smeared out the empirical peaks are in the two distributions & the standard deviation of the underlying distributions. I am sure somebody has figured this out at CERN. It is such an obvious point that I suspect that they are checking this point closely.
STRING/M SUSY theory PREDICTS the HIGGS mass to be 126 ± 2 GeV
http://arxiv.org/pdf/1112.1059
in full agreement with the fully correct rumors.
By the way, can I post the main plots that will be presented on Dec 13?
@The show must go on, in case you did not know, Kane had made this exact point about the Higgs mass, including the plot, a while ago. See the corresponding post on Motl’s blog.
The only prediction that was confirmed up to now is that whatever one finds at the LHC is is of course a prediction of string theory, despite the fact that is this very thread people pointed out to other articles (e.g. Shaposhnikov and Wetterich) that make a even more accurate prediction regarding the Higgs mass (I’m not saying the model is correct) and very importantly in 2009. Kane’s article was sent on Monday December 5 when the whole world already heard the rumors, really, what kind of “prediction” is that? It may be that Kane wrote about it before, but THIS specific article cannot be used as a serious prediction. Best case scenario is a postdiction.
It is interesting to note that from global analysis of low energy data~(electroweak data, with high statistics but very low energy),
e.g., In Fig 1 of arXiv:1110.5807 [hep-ph]~(and references therein) , always appears an small “bump” between 120-130
(there is a shark peak between 115-120, but that is due the Lep2 constrains).
The bumps coming from global data analysis have different meaning~(They are not so crazy as the colliders or any Single experiment. It remains for years and are very difficult to wash away )
Hello guyz, I’m not a scientist, I just like reading about science, and I don’t know if it’s my english that is really bad (I’m brazilian), but I can’t until now undertand the implications of string theory and SUSY in the search for the higgs boson, can someone help me? I was reading about it, some blogs, comments, etc, and I got some understandings…
What I did understand is that string theory (M theory included) predicts SUSY, but if SUSY is not found, that’s OK, string theory can survive without it, correct? Then, I read that SUSY predicts some particles to be found at LHC, but if you don’t find, that’s OK, because it can be hiding somewhere else, I got it right? Then, about the higgs mass, if what I understood is correct, SUSY accept a really good range for it’s mass, but if the higgs is about 125GeV, even if it minimize the need for SUSY to explain somethings, that would be a prediction from SUSY, if you find it in some other areas, you’ll need SUSY to stabilize the system, and if you don’t find it at all, then you need SUSY again!
That’s correct? I mean, or my english is really bad or SUSY is such a lank theory that can answer just about everything and cannot be proven wrong, that’s really weird.
Here is @iansample ‘s blog entry from today’s Guardian in the UK
http://www.guardian.co.uk/science/blog/2011/dec/06/is-higgs-boson-real
It includes some reactions from Glashow, Wilczek, Randall, Veltman, t’Hooft ….etc
brazilian,
String theory has nothing at all to say about the Higgs, it makes no prediction about this at all. So, discussion of the pros and cons of string theory is off-topic here.
The show must go on,
You certainly can send me copies, and I’ll summarize for our readers.
It’s interesting that somebody compared the Kane “prediction” with the “prediction” of Shaposhnikov et al. They’re are pretty much on the same footing: pure wishful thinking.
I mean, it’s OK to play that kind of game, but you shouldn’t call that a prediction. In the case of Kane, because of the huge amount of implicit or explicit assumptions. In the case of Shaposhnikov et al, because of the lack of any theory behind the whole construction.
I just love it when I get people on a *physics* blog trying to teach me elementary mathematics 🙂 My issue about 124 vs 126 GeV is my surprise that the HEP peaks are wide enough to allow something like that, combined with my mathematicians inherent mistrust of things like the assumptions that go into statistical calculations like combining peaks. Actually, I’m kind of curious, for things like particle signatures, what are the theoretical rationales for what distribution you expect to see?
Readers of other blogs who wonder about some disturbing material about me they might see there should refer to
http://www.math.columbia.edu/~woit/wordpress/?p=4127
and ignore it.
Peter,
off-topic: will you comment on this paper: http://arxiv.org/abs/1112.0788 at some point?