I’m trying to get over my Higgs obsession, and move on to other topics, but one last posting about this for now…
The first thing to say is that this is the biggest thing to happen in fundamental physics in about 30 years (i.e. since the discovery of the W and Z). It’s a remarkable event and huge success for high energy physics, vindicating at the same time the colossal efforts that have gone into making the LHC and its detectors work, as well as the theoretical framework of the electroweak part of the Standard Model. Today’s New York Times has a front-page story by Dennis Overbye, above the fold, which is very well done. In general the press reports that I’ve seen have been quite good, with minimal speculative nonsense thrown in. According to Overbye, CERN DG Heuer made the right decision to go ahead and simply claim discovery only on Tuesday afternoon. All in all, CERN has done an excellent job of communicating this story to the public (except perhaps for the “don’t believe the bloggers” business, but what else could they do…).
Attention will turn now to who gets rewarded for all this, in particular, who gets a Nobel Prize? Personally I think the experimentalists are first in line, and with no obvious figureheads, a prize for three groups: ATLAS, CMS and the CERN accelerator engineers and physicists would be highly appropriate. If it’s not too late in their process, maybe this could even be done in time for this year’s prize, announced October 9.
As far as theorists go, Frank Close has posted something about this here. With the restriction to three people, he argues for Englert, Higgs, Kibble. Personally I think Anderson deserves a piece of it, see here. There’s also a good argument to be made that what has just been validated is not the older work on the Higgs mechanism, but the Weinberg-Salam model of 1967 (extended to quarks), and that has already been rewarded with a Nobel.
I’ve been trying to get accurate numbers for the signal sizes seen by CMS and ATLAS in the various channels, but the only information out there now is the slides from the two talks. Resonaances includes the crucial plot from each experiment giving the signal sizes normalized to the SM, and eyeballing these and averaging, one gets 1.0 in the ZZ channel, 1.75 in gamma-gamma channel, about .75 in the WW channel (only CMS reports 2012 data). In the bb and tau-tau channels, no significant signal is seen, but the expected signal size there is very small. The errors per experiment are something like +/- .4, which you can make your own judgement about how to reduce for the combination. The bottom line is that, within errors, everything is consistent with the SM predictions. The gamma-gamma channel is the one to watch, it is about 2 sigma high.
The DG also announced a new LHC schedule, extending this year’s proton-proton run by two months, to mid-December. This will hopefully allow the experiments to each accumulate another 20 inverse fb of data, finishing this run and going into a two year shutdown with a total of 30 inverse fb to analyze and use to improve the results on the Higgs.
While this announcement is a great triumph for physics, unfortunately it significantly increases the probability of what has become known as the “Nightmare Scenario”: a SM Higgs discovery and nothing else at LHC energies. Before the LHC results started to come in, this scenario and its consequences was easy to ignore, but we may be getting closer to the point where it needs to be taken very seriously.
Update: For a rather complete analysis of the data about the different Higgs decay channels, see this new preprint.
Alas, Nobel prizes (other than peace) can’t be awarded to groups, so it can’t go to the collaborations (if so, would they each get $200?). Any thoughts on what individuals would get it for the experimental discovery?
Peter, you’re exactly right that the ATLAS and CMS teams deserve recognition, and it wouldn’t be surprising if the next Nobel honored them first as opposed to the large numbers of folk behind the well-known mechanism. For one thing, there may be residual doubts about the Higgs-ness of the new particle (which I do not share, but very cautious people may have ’em.)
All that said, had Brout not died, I think that the next Nobel should have gone to Higgs, Englert and Brout. I’m sorry that the Nobel statutes limit it to three; I have said here before that I think the Sakurai Prize committee did the right thing (though, now that I hear about the brilliant Migdal and Polyakov having had similar ideas, maybe they were short two.) I don’t feel so strongly about Anderson who (a) has one, well deserved, and (b) did not, as far as I am aware, ever write down a model, not even a non-relativistic model. Were Nobels given for brilliant insights alone, Gamow would have won three (well, at least two in physics and maybe one in medicine/biology.) Frank Close’s Infinity Puzzle is really excellent (and not only on weak interactions, either.) If he thinks Tom Kibble should get a third, the Nobel folks ought perhaps to listen to him. (Disclaimer: I almost went to study with Kibble and/or Salam, but very happily Peter Higgs took me on.)
There are however two other avenues for a Higgs theory prize: give it only to Higgs and Englert; or give it to Higgs and Englert and a third not directly connected to the scalar, to be named later. I can think of several who might reasonably fit here. My only concern, very frankly, is that it come soon, as none of the founding fathers of this stuff are getting any younger, and they don’t award ’em posthumously.
If the obstruction to awarding the prize to groups can be overcome, this is the time to do it. And this case makes clear why it should be done. As far as I know, there’s no sensible way to pick out specific people in CMS/ATLAS to award the prize to. On the other hand, if any experimental discovery is worth a Nobel prize, this one is. Effectively making HEP experimentalists ineligible for the prize, while instead devoting a lot of time to picking out theorists for their often somewhat obscure and marginally relevant contributions (the models BEHGHK worked with are far from the SM Higgs model that has just been experimentally validated) seems to me a really bad idea.
If the prize goes to Higgs-Englert-Kibble, then the tag line is going to be that the LHC did not find any new physics so they gave the prize for work done 50 years ago.
I really like this particular post. Nice have something nice to talk about, eh? 😉
Let me remind everyone that the Tevatron experiments showed their update just five days ago, on Monday. While their signals are not strong enough to claim evidence for a new state, and don’t match the significance of the CMS and ATLAS results, the fairly significant excess in a bb final state (showing up in a the associate production VH channel) is an important piece of information. Apparently this Higgs boson does decay to bb at a rate close to what the SM predicts.
I am puzzled that the CMS tau results show a deficit, but the statistical power of the tautau analyses is not strong enough for this to be important yet (especially since we do have the bb signal at the Tevatron). As you say, gammagamma is the interesting channel at present…
You’re right that I should have included the Tevatron bb result in the summary of signal sizes here. It’s 1.97 +.74/-.68 (where 1 is the SM), so, a bit high, but not very significantly so.
I would suggest that the prize be divided like this: one half to Higgs and Englert, one half to CERN (that would cover the LHC scientists, and the ATLAS, and CMS collaborations). They should find a way to make this happen, and make it happen this year before the theorists pass away.
I’m curious about what happens if this “nightmare scenario” comes to pass. I’m a layman, so forgive my ignorance. If this plays out and nothing beyond the standard model is found, is it possible that the LHC could be upgraded to probe deeper, or would this pretty much require a whole new system to be built?
“While this announcement is a great triumph for physics, unfortunately it significantly increases the probability of what has become known as the “Nighmare Scenario”: a SM Higgs discovery and nothing else at LHC energies. Before the LHC results started to come in, this scenario and its consequences was easy to ignore, but we may be getting closer to the point where it needs to be taken very seriously.”
How does this finding “increases the probability of what has become known as the “Nighmare Scenario”: a SM Higgs discovery and nothing else at LHC energies.”
125GEV Higgs is compatible with MSSM/SUSY and there is still the hierarchy problem
I think the Higgs breakthrough signals not just a potential ‘end of an era’ in discovery in physics, but the end of the ‘Nobel prize’ approach to discovery itself. The heroic model of breakthroughs driven by individual genius, on the model of Einstein, Dirac and Rutherford is, as the whole LHC experience shows, a thing of the past. The first great advance in forty years required the work of literally thousands of experimentalists and, arguably, a dozen or so so prominent theorists at the very least, and the fact that there’s so much room for debate about who deserves a share of the Nobel suggests that the award criteria for the prize should be rethought from the ground up.
Peter, emile –Alas, the restriction to individuals is explicitly in Nobel’s will, so it can’t be given to ATLAS/CMS/CERN. I agree that if there were ever a time to change it, this is the time, but it was Nobel’s money, and his right to put those conditions on it.
It would have been fun if Kibble’s paper had been a little earlier. Then we would be talking about how vector bosons eat Kibbles to get mass.
Peter, what do you mean that the excess in gamma gamma channel is intriguing and what could it mean that the signal is 2 sigma higher than expected. Any informed speculation for us physics junkies?
There is lots of precedent for giving the Nobel Peace Prize to groups (IPCC, IAEA, UN, Médecins Sans Frontières, etc., International Campaign to Ban Landmines) the Swedes merely have to get with the program
And in a somewhat fitting commentary on the entire announcement event, we have What if Steve Jobs Had Discovered the Higgs Boson? It’s fun …
At some point, there should also be a Nobel Prize for Ellis, Gaillard, and Nanopoulos for
J. R. Ellis, M. K. Gaillard and D. V. Nanopoulos, Nucl. Phys. B 106 (1976) 292
which basically told the experimentalists how to produce and search for the Higgs.
Nice post, but I disagree about the Nobel.
Q; Who cares? This discovery is bigger than any prize. It is too important to be reduced to ‘who gets the prize’. For example, in the case of Higgs himself, having an important particle named after you is far more important (though it is a little unfair on the others)
I have an idea; perhaps physicists around the world should use this occassion as an opportunity to persuade the Swedish Academy of Science to relax their self-imposed rule. The three-body rule is an anachronism that has no relevance to the way science is done today, at least for experimentalists
In Nobel’s time Physics wasn’t done by huge collaborations, and discoveries were often the result of the brilliant insight of a single individual or experimental work by a small group . Similarly for Biology and Chemistry.
I am sure that Nobel himself would have wished the rules be changed to reflect changing times.
Give the award to CERN/ATLAS/CMS, maybe donate the prize money to charity.
Higgs, Englert, Kibble etc have already had plenty of recognition (and honours), I’m sure they wouldn’t begrudge the experimentalists their recognition.
The LHC can be upgraded to produce more collisions, and that plan is already in place. In principle it can also be upgraded to go to higher energies (you need to design and build higher field magnets). There are also proposals for other machines that could get to higher energies. The problem with the “nightmare scenario” is that it suggests that if you do build a higher energy machine, you’ll see nothing new, i.e. no new phenomena will appear unless you go to some astronomically high energy scale like the Planck scale, and that is way beyond any conceivable technology.
Finding a Higgs particle with exactly the right SM couplings is not evidence for SUSY, no matter how many people say that “125 GeV is good for SUSY” or something similar. It’s evidence that for the non-SUSY SM.
As for the “hierarchy problem” argument, the popular version of it: “to stabilize the Higgs mass (125 GeV) or EW breaking scale (246 GeV), you need new physics at the TeV scale” has already fallen flat on its face. As far as SUSY goes gluinos and squarks limits are at 1 TeV and above (yes, the stop limit is lower, but there’s no good reason for a light stop and every other squark heavy). I’ve argued endless here that the “hierarchy problem” is not so obvious unless you insist that you know what physics looks like at GUT or Planck scales, and want to keep those separate from the electroweak scale.
For informed speculation about what would enhance decays in the gamma-gamma channel, I suggest Matt Strassler’s blog or Adam Falkowski’s (Resonaances). They’re phenomenologists who know lots more than I do about the possibilities. My general impression is that there are lots of models you can imagine, but nothing really motivates any particular one.
> If this plays out and nothing beyond the standard model is found, is it possible that the
> LHC could be upgraded to probe deeper, or would this pretty much require a whole
> new system to be built?
It would be very hard to increase LHC’s energy: theoretically it is possible to change LHC’s NbTi magnets to Nb3Sn ones and have 2-times stronger magnetic fields and double energy (28 TeV instead of 14 TeV) but the cost would be quite high.
Nevertheless properties of Higgs boson couldn’t be measured precisely in the proton collider – high energy lepton collider must be built to do that and this would be next step. Currently 3 options are considered here: linear e+e- colliders (ILC or CLIC) and the recirculating mu+mu- collider (Muon Collider).
Thanks for the information, Peter and yyy. I appreciate it.
It seems that the only game in town based on the data to date to avert a “Nightmare Scenario” is the possibility that the diphoton excess relative to the Standard Model expectation will continue to appear and not fade into the realm of a statistical fluke.
If it does, you have some new physics (SUSY or a composite Higgs, perhaps) and good clues about where to look for it. If the excess fades as more data becomes available, then we are in the particle physics “desert” and it is likely there there will be “no new physics” at the LHC other than the discovery of a SM Higgs.
Peter says “this is the biggest thing to happen in fundamental physics in about 30 years (i.e. since the discovery of the W and Z)” and I agree as I was there in the middle of it doing the analysis. The first Z event (after the W was in the bag) was found at midnight and I examined it for 7 hours before I called Carlo Rubbia at home and told him we discovered the Z. With 4 events we wrote the paper (see http://www.symmetrymagazine.org/cms/?pid=1000630). Now I am on CMS. This analysis is infinitely more complicated. There is a lot to do to show that this is the higgs. The lack of tau signal is a big deal because the Z -> tau tau is cleanly measured. In my opinion this (proving the higgs has been seen) will be difficult to do this this year and I have made two bets last December to that effect, one with my grad student and another with a CMS colleague. I hope I am wrong.
For whatever it’s worth Sean Carroll over at CV says “Preliminary thought #1: There is a “nightmare scenario” that particle physicists have worried about for years. Namely: find exactly the Standard Model Higgs and nothing else at the LHC. I personally assign the nightmare scenario very low probability.”
Please don’t get over your obsession with the Higgs. We are all obsessed with the Higgs
and will be for a long time. Any thoughts or information about the Higgs that you can share will be greatly appreciated .
The arguments that Sean gives aren’t very strong, and he admits that some of them, e.g. the idea that the Higgs is a “portal” to dark matter is just a “wishful hope”. I also don’t see how the idea that the LHC will solve the dark energy, strong CP or baryogenesis problems is much more than wishful thinking. About the “hierarchy problem” argument, that just hasn’t worked out.
Maybe dark matter is a phenomenon that will be explained by the LHC. Could be, but I don’t see a reason to assign this very high probability. And the other arguments he gives just don’t seem to me to add up to a very high probability either. So, I think the “nightmare scenario” gets quite a bit more than “very low probability”.
Hooray for Jim Rolph. He is a gem!
If this particle is the Higgs… sure it will take a while to prove it. Not just with decays to b-bbar and tautau, but also no signals in ee and mumu (is that already done??) and c-cbar and 0-life jets. But if it is the Higgs it is super interesting what keeps it so darned light! SUSY is a good candidate… but whatever it is, it seems to have something to do with the Weak interaction, which is real interesting.
If this particle is not the Higgs… yoo-hoo, that is an even bigger deal.
What a great post, Peter, and don’t we all have smiles on our faces? 🙂
Attention will turn to the excess in the yy channel, let’s hear what you think.
A long distance since “String Theory, an Evaluation”.
Peter, if you were the dictator of CERN, where would you suggest they focus their detectors, outside exploring the properties of the new boson?
My knowledge of experimental HEP is good enough to know I have no business advising people at the LHC how to do their jobs. As far as I can tell, they’re doing just fine without me. About the only not very useful comment I can make that might be relevant is that they might want to not take so seriously what some theorists tell them about SUSY models…
Is it unreasonable to consider the 7 and 8 GeV CMS and ATLAS data as 4 independent experiments? In all of them an excess of about 2 has been observed in the 2 gamma channel. There is then a 1:16 chance for this to happen if it is only for statistical reasons.
For this and other oddities, I think it is really premature to discuss who of the theorists should get a
Nobel prize. If we eventually know better, this is clearly the merit of the experimentalists. Leaving them out would put the whole thing upside down.
[P.Higgs original paper was one page! ]
When you have time, I’d love to hear your thoughts on the 4-sigma signal of a gamma-ray emission line (that could be a dark matter annihilation line) toward the Galactic center at an energy 130 GeV,
A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope
Best analysis to date:
Strong Evidence for Gamma-ray Line Emission from the Inner Galaxy
Meng Su, Douglas P. Finkbeiner
The first version of the abstract of the second paper comments on how the energy is very close to that of the Higgs, I think they suggest the dark matter particle might decay into the Higgs. That is removed in the abstract of the second version.
My main thought about that is that I’m not an astrophysicist, and know pretty much nothing about the tricky subject of trying to extract some sort of dark matter annihilation signal from astrophysical sources. So, for this topic you have to go elsewhere…
woits claims that the hierarchy problem requires us to known what happens at GUT or Planck scales is wrong. If the SM is correct to very high energies it is fine tuned. If it breaks down at a lower scale there is a chance to avoid the fine tuning. Those are just facts. we don’t know which way it will go. will it be a fine tuned universe, or new physics? hopefully we’ll be able to find out.
what has so far been missed in almost all the discussions of the Higgs boson is the most central issue of all. Namely, the purpose of the Higgs boson:
THE ENTIRE PURPOSE OF THE HIGGS BOSON IS TO RESTORE UNITARITY!
The Goldstone models couple to the W, Z bosons to give them mass and the vev gives mass to the fermions. None of that requires the extra degree of freedom which is the Higgs boson. The only reason we have to add this extra degree of freedom is to ensure the theory is unitary at high energies.
So what the LHC has discovered is that unitarity is respected by nature. This is the real content of the discovery. It is quite interesting to me that unitarity is the guiding principle of string theory, i.e., string theory is the only known consistent theory of gravity that exactly respects unitarity. This is extremely interesting.
Purely in terms of securing funding, I’m not sure the nightmare scenario is something to be feared. I think there’s been sufficient publicity surrounding CERN and the Higgs that it’s become part of the public and – more “importantly” – media conciousness, at least in certain European countries. Given the sickening power that the media has these days, such awareness will be all that’s needed to make The Higher Ups sign off on the next accelerator proposal. (Scientifically, well, that’s another matter, but if no-one tells them we’ve no clue then we’ll probably get away with it.)
Isn’t the “nightmare scenario”, that the LHC doesn’t find anything other than the Standard Model, exactly what Occam’s razor predicts? (Although I have been told that you can easily add sterile heavy right-handed neutrinos to the Standard Model, and that these could both explain dark matter and the low mass of the left-handed neutrinos [using the see-saw mechanism], so maybe Occam’s razor actually predicts the Standard Model with added heavy sterile neutrinos. I don’t know whether these could be observed by the LHC.)
While I agree this is big, I think the discovery of massive neutrino was a bigger discovery of the last 30 years. The Higgs was long anticipated, and “merely” completed the Standard Model. Neutrino masses were the first, and so far only, extension beyond the original standard model. At the very least massive neutrinos compete with Higgs as a major discovery of the last 30 years.
To be sure, this is big…
Peter I don’t get your philosophy.
On the one hand you are saying that there is a good chance of the “nightmare scenario”; this is the scenario where there is a great desert between electroweak physics and whatever is the physics that relates the SM to gravity, and the other mysteries we have. Here you seem to be attacking phenomenologists for suggesting new physics would should up at the low electroweak scales.
On the other hand you dislike most research into quantum gravity, especially string theory. Here theorists speculate on physics at the highest of energy scales, possible related to the Planck scale, etc.
So you seem to be attacking both the PHENOMENOLOGISTS, who look at hints from the world around us, such as dark matter or hierarchy problems etc, to speculate on “low energy physics” (meaning directly accessible energy scales).
But you are also attacking quantum-gravity THEORISTS, who use logical consistency and mathematics etc, to speculate on “fundamental high energy physics” (meaning not-directly accessible, as it might be Planckian, etc).
So you seem to be having your cake and eating it too. If someone thinks that new physics will show up just around the corner, you say that there is a nightmare-scenario that means there will be nothing. If someone thinks that new physics will come in at the Planck scale and formulates a theory of this, you say that this is just wild crazy speculation. So all groups of theoretical physicists interested in expanding our knowledge of the fundamental laws seem to garner your attacks. It seems rather illogical and inconsistent.
I’m not sure that’s what Occam’s razor would say here. The Occam razor would say that the simplest explanation consistent with all the facts is probably the right one. Well, the Standard Model is not consistent with dark matter, unification, gravity, baryogenesis, inflation, hierarchy of scales, smallness of \theta angle, etc, i.e., various facts about the world. So Occam would prefer the simplest theory that encompasses all this, which cannot be the Standard Model, since it doesn’t. After all, that’s why we built the LHC.
Now I’m not saying that these things will show up at LHC. Some of them might, some might not. Its just that its unclear which way Occam’s razor points with regards to the scales the LHC can probe.
How about celebrating the experimental discovery of the Higgs with a one-week moratorium on hype about string theory?
As for my “philosophy”, it’s pretty much that hyping ideas that don’t work is not a good idea, during Higgs week or any other.
Of course I am celebrating the great experimental work. I am also celebrating the great theoretical work from almost 50 years ago to predict this. Quite amazing. Around 50 years ago theorists started putting together a highly abstract theory built on consistency, logic, and extrapolation of the principles of quantum field theory to understand the weak interaction. This was put together despite the fact that there was no direct experimental evidence for the Higgs whatsoever. Back then there were skeptics calling into question the audacity of such theorists to speculate on such high energy physics without the necessary experimental input, and physics was faced with a tremendously daunting task to ever sort it out experimentally. In fact we could even go back to the first observations of the weak interaction and the Fermi theory in the early part of the century. Well here we are, many decades later, finally seeing direct evidence that a consistent QFT describes the weak interaction (first the W and Z bosons were introduced to make the theory renormalizable, and then the Higgs to make it unitary; It was not some ad hoc set of ingredients, but the minimal set of ingredients necessary to describe a short-ranged interaction that mediates decays). Those so-called theoretical “speculations” were actually built on consistency and fundamental principles, and they proved to be entirely correct. This is the great accomplishment of theory and of course the follow up by experiment and observation many decades later. I would argue that theorists who study quantum gravity are engaged in the same qualitative exercise, even if there are skeptics who won’t admit it. It is yet another great triumph of the scientific method.
‘t Hooft wrote an interesting letter criticising an attempt to expand the Nobel prize to include other areas (http://www.staff.science.uu.nl/~hooft101/NobelPrizesExtend_09.html). In some of these disciplines institutions would need to be acknowledged and not individuals. He’s pretty much against it in those cases. I wonder what his attitude is to particle physics collaborations.
I’m surprised to see that none of you paid attention to the most important thing Peter mentioned in his post: the two month extension of this year’s run. Don’t you wonder why this is? Ask a knowledgeable CMS experimentalist if you can find one.
The ~2 month extension of the pp running at the LHC is to allow the experiments to gather as much data as possible on the Higgs decays before the long shutdown starting in early 2013. The schedule has been announced. The pp run will end December 17, at which point the machine will go into a “technical stop” until January 7. At that point operations will resume to prepare for the heavy ion run, actually p+Pb, which will go from January 17 to February 11. After that the LHC goes into the shutdown for the upgrades needed to double to the design collision energy.
In the latest issue of Symmetry Magazine, Joe Incandela draws an analogy with the discovery and gradual excavation of King Tutankhamen’s tomb.
so p+Pb is the data what we need for precise obsevation for a certain model?
The p+Pb running is not related to the Higgs physics. It does serve as a baseline (“cold nuclear matter effect”) for the heavy ion physics program at the LHC where there are Pb+Pb collisions which happened in 2010 and 2011. The heavy ion physics program studies the Quark Gluon Plasma, an extended region of nuclear matter which has become so hot that the constituent protons and neutrons have melted into quarks and gluons and many more pairs of quarks and antiquarks have been produced. While the ICHEP 2012 is the big international conference celebrating the pp type high energy physics, the Quark Matter 2012 conference in August at Washington DC (http://qm2012.bnl.gov/) is the premier conference in that physics. During the shorter heavy ion runs, the CMS, ATLAS, and ALICE collaborators are focused on acquiring that data.
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On the origin of mass; the hype seems to be that the Higgs field imbues all elementary particles with mass. Frank Wilczek (http://lanl.arxiv.org/abs/1206.7114) and Tom Kibble (http://www.scholarpedia.org/article/Englert-Brout-Higgs-Guralnik-Hagen-Kibble_mechanism)
tell a different story.
Kibble – “It is sometimes said that the Higgs field gives masses to all other particles, but that is not strictly correct. It is important to note that most of the mass of the nucleon in particular does not arise in this way. Only the masses of the quarks come from the Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism. The larger part of the nucleon mass comes from a mechanism along the lines sketched out earlier by Nambu (see Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism (history)).”
Can someone explain.