Nobel Anticipation

October 7, 2013

This is Nobel week and prize handouts start today with Medicine. Tomorrow is Physics, and Chemistry is on Wednesday. All others are political prizes of no interest here.

The physics prize should be awarded for the Higgs Boson and most likely Higgs himself and Englert will get it, but a third share may go to some other wildcard person or organisation. This will be decided by a vote at TRF but I can also remind you that a similar vote has been running for some time on viXra which has already been used to elect two winners of the much larger Fundamental Physics Prize.

Update 8-Oct-2013:  Congratulations to James E. Rothman, Randy W. Schekman and Thomas C. Südhof who won the Physiology or Medicine prize “for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells”.

Today will be the turn of the physics prize and it this point it may be worth hedging bets by noting that this might not even be given for the Higgs. Each year the Nobel committee has a big pile of worthy nominations and they may just decide that one of them fits better. However the chances for Higgs seem slightly better than even.

Some people are suggesting that the third share for the Higgs could go to CERN. The committee have hinted that an organisation is not ruled out even though they have never used that option before, but I think CERN would be a mistake. This is because many people in the CMS and ATLAS collaborations are not strictly speaking part of CERN. You could justify that CERN played a deserving role but to then leave out the physicists who actually made the discovery would be a new kind of mistake for the Nobel committee to make. Lumping CMS and ATLAS together as one also seems a bit forced but they could give it to Higgs, CMS and ATLAS leaving out Englert. That is more like the kind of mistake they have made before. I favour the option of reserving the prize for the theorists. If they start giving it to big organisations then they will also have to look at many other big collaborations in the future and they probably dont want to set a precedent that could radically change the nature of the award.


Oh My God Particle!

March 19, 2013

It would be amiss of me not to jump into the debate about what Michio Kaku said on CBS about the Higgs boson. If you don’t know what I am talking about see the blogs of Sean Carroll, Matt Strassler, Peter Woit, Lubos Motl etc.

The initial case for the prosecution was that Kaku had said incorrectly that the Higgs Boson caused the big bang. If you listen more carefully to the details, he is saying that the Higgs boson could be part of a family of scalars that includes the inflaton responsible for inflation. This justifies that the Higgs boson put the bang into the big bang. It is perfectly true that this could be how it works and despite accusations to the contrary Kaku used the words “think” and “could” to indicate that this was a speculative hypothesis, not settled fact. If you missed those caveats it’s your fault not his.

He rightly stresses that physicists dont like the term God particle used by the reporters but he is not making a great deal out of it. The term sticks because people remember it and it tells them that the Higgs boson is considered important. I think it has been explained enough times that it was a joke and was not intended to be taken literally. If the public still don’t get that then there is no hope for their understanding. Ina any case Kaku is not the one guilty of promoting the usage in this interview.

Motl has covered this in the blog post and I agree with what he says. There is just one thing that I think is worth adding. Kaku says that the Higgs boson could be the trigger that sets the big bang off. This is the part that has led to so much criticism  In the original inflation theory the era of rapid expansion does not start right away when the universe is created. If that is the case then it might be true to say that the Higgs boson puts the bang into the big bang but it would not be right to say that it triggered the big bang. So what is he referring to? The answer I think is a genre of big bang theory in which there is a time before the big bang when it was in a steady meta-stable state. According to these theories our universe was triggered by a transition to another vacuum in which the inflaton is responsible for its rapid growth right from the first instant of the new phase. The theory of eternal inflation is one sub-variety of this type of cosmological hypothesis. Personally I do not favour such theories because they seem to be inspired by a philosophical desire to explain the universe in terms of temporal causality and as I discussed at length in my most recent FQXi essay, that is not my philosophy. Nevertheless it has become a popular class of theory with cosmologists. Ironically Sean Carroll who sparked off this attack on Kaku seems to be one of its biggest supporters.

Matt Strassler criticises Kaku above all for not making it clear which parts of what he was saying were speculative. I invite you to listen to what he said again (see the links to the video on the other blogs). He actually stresses very clearly that “we do not know how or why” the big bang started, but “we think” the Higgs boson may be a key piece of the answer. I don’t think he could have made it any clearer that these are just possibilities.

kAKUcbs

If you are concerned that Kaku seems to think that the Higgs boson is responsible for inflation then be aware that this might actually be the case. Sean Carroll denies that this can be the case and Matt Strassler says that it is unlikely. Motl explains exactly why it could be the case and I remember hearing about this in a webcast talk at Moriond on the same day as some of the new results were being aired. The theory requires an extra coupling between the Higgs boson and the curvature tensor and it has its problems, but then so does every other theory of inflation. The model does at least have the virtue of not requiring other unknown fields. When Strassler says that this version of inflation is “unlikely” he is expressing his own opinion. He claims in a comment that he does not express his own personal opinion without indicating as much, yet here he does exactly that.

Kaku is an eloquent speaker and he knows his subject. He is very careful with his words and knows the kind of angle on a physics story that will get the general public interested. Most people do not have the time to digest the kind of details that are explained at length on some of the blogs, yet Kaku can convey a feeling of our excitement that ordinary people can appreciate immediately. Yes, the basic known facts about the Higgs boson are interesting and exciting too but the more speculative ideas that people are working on are what really gets people to sit up and listen. If some physicists fear that people cannot distinguish between known and unknown facts when words like “could” and “think” are used then they are simply not giving people enough credit.

Science reporting needs to cover the full range of news from the latest experimental results to the wildest new theories being discussed by physicists. If it does not do so then it will not inspire new young scientists to take up research. People like Kaku may not please everyone but they are getting the message across. I am sure he will not be discouraged by boring physicists who simply don’t get it.


Higgs Spin (Is It really a Higgs then, finally?)

March 14, 2013

CERN have a new press release out today while latest results are being presented at the QCD part of the Moriond conference. There are further updates since last week including the long awaited CMS results for the diphoton decay channel. The diphoton rate relative to standard model is now 0.8 +- 0.3, much lower than before and a huge disappointment for hopes of beyond-standard-model physics.

MgamgamCMS

In the press release the CMS and ATLAS spokespeople are quoted as follows

The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is.” said CMS spokesperson Joe Incandela.

“The beautiful new results represent a huge effort by many dedicated people. They point to the new particle having the spin-parity of a Higgs boson as in the Standard Model. We are now well started on the measurement programme in the Higgs sector,” said ATLAS spokesperson Dave Charlton.

So does this mean that they have officially conceded that it really is the Higgs boson and not some HHiggs-like imposter? The official line is now that “they find that the new particle is looking more and more like a Higgs boson, the particle linked to the mechanism that gives mass to elementary particles. It remains an open question, however, whether this is the Higgs boson of the Standard Model of particle physics, or possibly the lightest of several bosons predicted in some theories that go beyond the Standard Model.”

It’s a bit meally mouthed but nevertheless, most c0mmentators are interpreting this to mean that they have agreed that it is a Higgs boson of some sort.

The crux was the spin measurements which both teams agree disfavours spin 2 with positive parity at a 2 to 3 sigma level. The real Higgs boson has spin zero with positive parity and all other spin possibilities are directly ruled out by the fact that  it decays to two spin-one photons. Negative spin zero is not quite so strongly ruled out but this is not being billed as such an important observation.

particle propertty Can it be determined with LHC run 1 data? Does CERN think it is deterministic for a Higgs boson? current status
Decay modes YES YES WW,γγ,ZZ,ττ observed, bb,Zγ,μμ etc ongoing
Other Production modes NO NO gluon fusion OK, VBF, VH and ttH ongoing
no exotic decay modes NO NO preliminary results from ATLAS
Spin = 0 YES YES spin zero verified to about 2 or 3 sigma in each experiment
Parity = positive NO NO negative parity is disfavoured but not ruled out
W fusion NO NO nothing yet reported
Higgs self-coupling NO NO nothing yet reported

In summary, the things that CERN has decided are crucial for determining that this is a Higgs boson are thankfully exactly the things that can be determined from run 1 but there are plenty of other observations to keep them busy for run 2 and beyond.


CMS diphoton result approved

March 13, 2013

Todays LHCC meeting is currently being webcast and slides are going online here. Colin Bernet presenting the CMS update has confirmed that the crucial diphoton results have now been approved. He said they will be presented at Moriond today but the schedule suggests that it will be tomorrow. This part of the Moriond meeting is not being webcast so we will have to wait for slides to come online for the results.

 


Animated Higgs from ATLAS

March 7, 2013

ATLAS have provided some animated gifs showing the accumulation of Higgs events over time in the diphoton and four-lepton channels. Enjoy.

These dont seem to work in situ on the blog. You need to click on the images to get them to work.

Hgg-FloatingScale-Short2

4l-FixedScale-NoMuProf2

At what date do the Higgs bumps start to look real?

Youtube version:

https://www.youtube.com/watch?v=Ub1gcQW6rMc

 


Moriond Higgs Update

March 6, 2013

The latest Higgs updates are now being presented at Moriond. CMS have kicked off this morning with a presentation of bosonic decays including WW and ZZ but still not including the important diphoton channel. The full LHC run 1 dataset is now being used including 19.6/fb at 8 TeV

In ZZ they get a very clear signal on the event plot

MZZCMS1

Higgs Mass from ZZ is 125.8 +- 0.5(stat) +- 0.2(Syst)

The cross section relative to standard model is 0.91 +- 0.27

ATLAS also updated ZZ with 20.7/fb at 8 TeV to produce a similarly impressive plot

MZZATLAS1Higgs mass for ZZ from ATLAS is 124.3 +- 0.6(stat) +- 0.4(syst)

cross-section 1.7 +- 0.5

Unlike CMS, ATLAS have presented their diphoton results giving a mass estimate of 126.8 +- 0.2(stat) +- 0.7(stat)

MGGATLAS

diphoton cross-section is 1.65 +- 0.24(stat) +- 0.21(syst)

Rumour puts the CMS diphoton excess at 1.0 +- 0.2, to be shown at Moriond QCD next week perhaps (via Jester on twitter)

The excess over the standard model remains high but its significance has not increased because the value has gone down as more data has been added. When we first saw this excess a year ago we were excited that it may be real physics and we hoped that by this time we would have a truely significant effect. This has not happened. We still need to wait for CMS to show their diphoton results before we can draw any conclusion but rumours are that their overexcess has fallen even more dramatically. This means that expectations of significant BSM effects from run 1 are now lower.

CMS also gave us a plot of excesses in the WW channel over the standard model with Higgs at 125 GeV. In other words this plot should only show any excesses attributed to any other Higgs like particles. They said they are now doing this analysis for all the high mass searches which is a good move.

The WW cross-section from CMS is 0.76 +- 0.21

MWWCMS1

This shows that there are not yet any signs of higher mass Higgs particles as would be expected in Higgs multiplet models. If they exist then they must be quite well decoupled from the observed Higgs boson. The usual combined ZZ channel plot tells a similar story with no significant excesses beyond the known Higgs.

MZZCMS2

By the way, we are still waiting for the AMS-02 results due out soon. They had hoped to reveal them yesterday at Moriond but approval was not ready in time. Next oportunity could be the Moriond Cosmology conference next week


Looking Forward to Moriond

February 15, 2013

The LHC has ended its three-year long physics run this week and is now finishing off with some quench tests. Tomorrow (Saturday) morning the beams will be dumped for the last time for nearly two years while the collider is upgraded so that it can work at a higher energy of 12.5 – 13 TeV.

1302027_01-A4-at-144-dpi

But the fun is not quite all over yet. In just over two weeks time we should start to see the first of the final results from proton physics run that ended in December 2012. The event to watch is the Electro-Weak section of the Moriond Meeting that opens on the 2nd March. The schedule has not yet been published but when it is you should see it at this link. The following week they will hold the Moriond QCD meeting whose schedule is now available at this link. There will be a quick summary of the Higgs searches which I presume will have already been revealed the week before.

What we expect to see is an update for all the Higgs decay channels from both ATLAS and CMS. Remember that we have seen all the results for 5/fb @ 7TeV + 13/fb @ 8TeV, except that CMS choose not to publish the diphoton result because it was smaller than expected. This means that the public values for the diphoton cross-section are currently subject to a selection bias that needs to be put right. The hope is that we will get full results at something like 5/fb @ 7TeV + 20/fb @ 8TeV, In other words we will have 40% more data for most channels and about 75% more for the diphoton channel. We know that all channels other than diphoton are perfectly in line with the standard model Higgs while the diphoton channel cross-section is a bit too large. However, we need to remove the CMS selection bias before we can get excited about it.

In addition to the cross-sections we can hope for an update to the tests of spin parity on the Higgs boson. This is the final step required before CERN will be happy to declare that the Higgs-Very-Like-Boson is indeed the Higgs-Boson so that Nobel prizes can be handed out. It is unlikely that the individual results from CMS and ATLAS will be quite sufficient. These tests do not need a 5-sigma significance because they are property measurements rather than discoveries. I think they will settle for 3 or 4 sigmas but this will require the combination of CMS and ATLAS data.

The ATLAS and CMS collaborations have had plenty of time to analyse their results and have kept them under wraps with no rumours leaking out yet. This may mean that they are keeping them “blind” until the last-minute. If that is the case it will probably mean that there is not time to do an ATLAS+CMS official combination for Moriond. Unofficial combinations of the channel cross-sections can be done quickly by hand but the spin-parity is more subtle so there will be one final Higgs cliff-hanger until the summer.

Normally the biggest HEP conference of the year is either the European EPS-HEP conference or the ICHEP conference. These normally alternate in a two-year cycle but this year an extra ICHEP conference in Switzerland has been laid on. (UPDATE: It turns out that this is not an official ICHEP conference. Same committee appears to be organising over 1000 conferences this year. Do not register, ) The EPS-HEP conference looks legit and will be in Stockholm. Please always check before paying conference fees.

Update: 16-Feb-2013

nobeam2

See Mike Lamont’s final “run 1″ report in the CERN bulletin


CMS looking back

January 30, 2013

The CMS collaboration have kindly posted a pleasant video that reveals the moments when they “unblinded” their Higgs diphoton results within the collaboration in the run-up to the public discovery announcement in July.

I find it interesting to look back and see how these events relate to what was going on publicly on the blogs at the time. From the video we learn that the CMS collaboration were shown the first results on 15th June. The Higgs analysis group within CMS must have seen it at least a day or two before in order to prepare the plots for the talk. We can assume that ATLAS were seeing their results at about the same time. For two days the collaborations were able to walk around knowing that they knew stuff that the outside didn’t until Peter Woit blew the lid with his leak about the new results. This was a little upsetting for them at first as shown by the response from CMS blogger Michael Schmitt who later calmed down a bit. One argument they gave was that they did not want the information to pass between the ATLAS and CMS collaborations because it would spoil their independence but if the rumour can reach the outside world so quickly it is clear that it would not be kept secret at CERN and other institutions where 3000 excited physicists from each collaboration share the same social spaces.

The rumours were saying that the diphoton excess was at around 4 sigma and the video shows that it was indeed around 4.3 for CMS. In my own analysis the next day I estimated that this was based on about 3/fb of the data which turns out to be exactly right for CMS as seen in the video when the camera zooms in at 2:20. I also pointed out that when they add the full dataset the signal could easily go down and in fact it did descend to 4.1 sigma as seen in the next part of the video. I am not always right but I was this time. Subsequently the New York Times reported an email from the spokesperson for ATLAS saying that they should not believe the blogs. Now we know that this was a euphemism for “please don’t report what they are saying because it is perfectly accurate and we were hoping to keep it as a surprise for the next conference”.

Another point worth making here is that the collaborations like to make big statements about how they do their analysis blind. This is supposed to mean that they don’t look at the results until they have fixed the parameters of the analysis so that they cannot introduce any bias. From this video we can see what this really means in practice. They unblind the data as an early check then they “re-blind” it while they adjust the analysis. Then they unblind it again two weeks later with just 30% more data added. Come-on guys own up, this is not quite in the spirit of how blind analysis is meant to work. Luckily the signal is so clear that it is indisputable in any case.

Getting more up-to-date, remember that CMS have not yet published the diphoton update with 13/fb at 8 TeV. Rumours revealed that this was because the excess had diminished. At the Edinburgh Higgs symposium some more details about the situation were given. The talks are not online but Matt Strassler who was there has told us that the results have now been deemed correct. It may be understandable that when the results are not quite what they hope for they will scrutinize them more carefully, but I find it wrong that they do not then publish the results once checked. It was clear that they intended to publish these plots at HCP2012 in November and would have done so if they showed a bigger excess. By not releasing them now they are introducing a bias in what is publicly known and theorists are left to draw conclusions based on the ATLAS results only which still show an over-excess in the diphoton channel. It will all be history once the final results with about 20/fb are released soon but it would be helpful if they could keep this sort of biasing factor to a minimum.

The March meeting at Moriond is slated as the occasion for the final update but only of they are happy with the results. Their analysis has been used and refined many times in the last two years and by now they should be confident enough to say that they will publish regardless of the result they get. The data for the last proton run was available before Christmas so by now the collaborations should have completed their final analysis. The fact that we don’t have any rumours suggests that this time they have decided to confine knowledge of the results to the smaller Higgs groups within the collaborations and they may actually succeed in keeping them secret until the conference.

Update: See Tommaso Dorigo’s response here


We need to find the Theory of Everything

January 27, 2013

Each week the New Scientist runs a one minute interview with a scientist and last week it was Lisa Randall who told us that we shouldn’t be obsessed with finding a theory of everything. It is certainly true that there is a lot more to physics than this goal, but it is an important one and I think more effort should be made to get the right people together to solve this problem now. It is highly unlikely that NS will ever feature me in their column but there is nothing to stop me answering questions put to others so here are the answers I would give to the questions asked of Lisa Randall which also touch on the recent discovery of the Higgs(-very-like) Boson.

Doesn’t every physicist dream of one neat theory of everything?

Most physicists work on completely different things but ever since Einstein’s attempts at a unified field theory (and probably well before) many physicists at the leading edge of theoretical physics have indeed had this dream. In recent years scientific goals have been dictated more by funding agencies who want realistic proposals for projects. They have also noticed that all previous hopes that we were close to a final theory have been dashed by further discoveries that were not foreseen at the time. So physicists have drifted away from such lofty dreams.

So is a theory of everything a myth?

No. Although the so-called final theory wont explain everything in physics it is still the most important milestone we have to reach. Yes it is a challenging journey and we don’t know how far away it is but it could be just round the corner. We must always try to keep moving in the right direction. Finding it is crucial to making observable predictions based on quantum aspects of gravity.  Instead people are trying to do quantum gravity phenomenology based on very incomplete theories and it is just not working out.

But isn’t beautiful mathematics supposed to lead us to the truth?

Beauty and simplicity have played their part in the work of individual physicists such as Einstein and Dirac but what really counts in consistency. By that I mean consistency with experiment and mathematical self-consistency. Gauge theories were used in the standard model, not really because they embody the beauty of symmetry, but because gauge theories are the only renormalisable theories for vector bosons that were seen to exist. It was only when the standard model was shown to be renormalisable that it become popular and replaced other approaches. Only renormalisable theories in particle physics can lead to finite calculations that predict the outcome of experiments, but there are still many renormalisable theories and only consistency with experiment can complete the picture. Consistency is also the guide that takes us into theories beyond the standard model such as string theory that is needed for quantum gravity to be consistent at the perturbative level and the holographic principle that is needed for a consistent theory of black hole thermodynamics.

Is it a problem, then, that our best theories of particle physics and cosmology are so messy?

Relatively speaking they are mot messy at all. A few short equations are enough to account for almost everything we can observe over an enormous range of scales from particle physics to cosmology. The driving force now is the need to combine gravity and other forces in a form that is consistent non-perturbatively and to explain the few observational facts that the standard models don’t account for such as dark matter and inflation. This may lead to a final theory that is more unified but some aspects of physics may be determined by historical events not determined by the final theory, in which case particle physics could always be just as messy and complicated as biology. Even aside from those aspects, the final theory itself is unlikely to be simple in the sense that you could describe it fully to a non-expert.

Did the discovery of the Higgs boson – the “missing ingredient” of particle physics – take you by surprise last July?

We knew that it would be discovered or ruled out by the end of 2012 in the worst case. In the end it was found a little sooner. This was partly because it was not quite at the hardest place to find on the mass range which would have been around 118 GeV. Another factor was that the diphoton excess was about 70% bigger than expected. If it had been as predicted they would have required three times as much data to get it from the diphoton excess but the ZZ channel would have helped. This over-excess could be just the luck of the statistics or due to theoretical underestimates, but it could also be a sign of new physics beyond the standard model. Another factor that helped them push towards the finish line in June was that it became clear that a CMS+ATLAS combination was going to be sufficient for discovery. If they could not reach the 5-sigma goal for at least one of the individual experiments then they would have to face the embarrassment of an unofficial discovery announced on this blog and elsewhere. This drove them to use the harder multivariate analysis methods and include everything that bolstered the diphoton channel so that in the end they both got the discovery in July and not a few weeks later when an official combination could have been prepared.

toeAre you worried that the Higgs is the only discovery so far at the LHC?

It is a pity that nothing else has been found so far because the discovery of any new particles beyond the standard model would immediately lead to a new blast of theoretical work that could take us up to the next scale. If nothing else is found at the LHC after all its future upgrades it could be the end of accelerator driven physics until they invent a way of reaching much higher energies. However, negative results are not completely null. They have already ruled out whole classes of theories that could have been correct and even if there is nothing else to be seen at the electroweak scale it will force us to some surprising conclusions. It could mean that physics is fine tuned at the electroweak scale just as it is at the atomic scale. This would not be a popular outcome but you can’t argue with experiment and accepting it would enable us to move forward. Further discoveries would have to come from cosmology where inflation and dark matter remain unexplained. If accelerators have had their day then other experiments that look to the skies will take over and physics will still progress, just not quite as fast as we had hoped.

What would an extra dimension look like?

They would show up as the existence of heavy particles that are otherwise similar to known particles, plus perhaps even black holes and massive gravitons at the LHC. But the theory of large extra dimensions was always an outsider with just a few supporters. Theories with extra dimensions such as string theory probably only show these features at much higher energy scales that are inaccessible to any collider.

What if we don’t see one? Some argue that seeing nothing else at the LHC would be best, as it would motivate new ideas.

I think you are making that up. I never heard anyone say that finding nothing beyond the Higgs would be the best result. I did hear some people say that finding no Higgs would be the best result because it would have been so unexpected and would have forced us to find the alternative correct theory that would have been there. The truth of course is that this was a completely hypothetical situation. The reason we did not have a good alternative theory to the Higgs mechanism is because there isn’t one and the Higgs boson is in fact the correct answer.

Update: Motl has a followup with similar views and some additional points here


End of Year Higgs Roundup

December 20, 2012

It has been a sensational year for particle physics with the discovery of the Higgs”-like” boson making front page news and cash stuffed awards going to some of the deserving scientists at CERN who made it possible. Congratulations to them and sympathies to the many people at CERN who were overlooked from the likes of Steve Myers and John Ellis down to the humble post-grad who was pictured falling asleep at the July announcement after having queued all night for his place.

Reuters reports that they will (maybe) finally be able to remove the “-like” at Moriond in March when the analysis of the full dataset is presented. With alternative spin and parity possibilities already ruled out with low to medium confidence many of us have already reached that conclusion. Serious doubters will wait for the self-couplings to be measured in twenty years time before conceding.

In the same Reuters report it is claimed that CERN scientists have “dismissed suggestions circulating widely on blogs and even in some science journals that instead of just one type of the elementary particle they might have found a pair (of particles)” Of course the truth is that every independent blog that has been following the developments has debunked the two-Higgs claim. This is the kind of no-thanks we have become used to for our efforts, Merry Christmas (Update: see comments). To add a little more credance , here is a plot made by merging two plots from the ATLAS conference note on the ZZ analysis.

ZZobsvs125

This shows the observed signal best fit for Higgs to ZZ decays (black dotted line) overlaid on the simulated one-sigma bands for a 125 GeV Higgs boson. This makes it clear that the observed signal is perfectly consistent everywhere with a 125 GeV Higgs within about one-and-a-bit sigma. It is only when they try to do a fit to this data that they get a discrepancy with other observations. Obviously the right conclusion is that it is too soon to do the fit because the error bands below 125 GeV are still widening too rapidly.

All the channels are now giving signals close to the standard model prediction for a Higgs around 125 to 126 GeV. Most of the new data is loaded into the Unofficial Higgs Combination Applet so you can roll your own, but here are the combined signals by channel at 126 GeV on a scale where 1.0 is the standard model cross-section, with statistical only errors

bb  :  1.24 +- 0.40

ττ :  0.4 +- 0.40

WW :  0.63 +- 0.21

ZZ : 0.99 +- 0.16

γγ : 1.77 +- 0.24

All of these are close enough to the standard model signal except perhaps the γγ where the discrepancy appears to be about 3.2 sigma but with systematic errors included this will drop to about 2.5 sigma. CMS have not yet updated this channel and rumours are that they see less excess. It seems daft that they have not released the results yet especially after the ATLAS delay turned out to be a fuss over nothing. Show us what you’ve got, please.

Here too is the unofficial global combination of high-resolution channels (ZZ, γγ) showing an impressive 9.4 sigma signal at 125.5 GeV and just noise everywhere else.

HiggshiresDec2012

Where does this leave us? Everything looks standard-model-like except the diphoton over-excess which may go away. If it stays there is a good chance that it will be explained by new particles such as a charged Higgs or vector-like fermions waiting to show up in other searches. If it goes we have the possibility of split SUSY or perhaps just the standard model at the LHC scale. Many models have been swept away leaving us to contemplate the implications of an unnatural little mass hirearchy. In one year our view of particle physics has moved on a long way. It’s just not clear which direction yet.


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