This christmas collider physicists at the LHC have a reason to look forward with optimism to the near future: the experiments have collected unprecedented amounts of data at the highest collision energy ever achieved in a laboratory - 13 TeV. We have already produced a few early results with partial datasets in the past few months, but the bulk of the new results, based on the full available statistics, is expected for March 2017 - when international "winter conferences" will attract to skiing resorts the colleagues who manage to get assigned a talk, along with many others who can justify otherwise their presence.
What is it to expect from those conferences ? Here is a quick and incomplete list of things that it should be possible to hear about in experimental particle physics talks - mind you, I am not speaking for my experiment and am just guessing based on general principles here: no insider information, sorry.
As far as Higgs boson measurements, what I may imagine we will get in the next few months will be a further improvement in the precision of the Higgs boson mass; but that will not be very exciting. We already know it with a precision of 0.2 percent, so even a factor of two further improvement will not break much ground. We should also manage to obtain significant improvements in the coupling of the Higgs to fermions and bosons across the board, which will push the possible models of new physics in the Higgs sector away to higher masses and smaller effects. The LHC experiments will also produce upper limits on Higgs pair production cross section down to maybe 20 times the SM predictions or so, as well as a host of results of searches for anomalous effects, with limits and no real hint of new physics.
A large number of other new Standard Model measurements will likely be produced, including a wide variety of improved cross section determinations, again not very exciting. And maybe some new top mass measurements, which will probably not increase by much the precision of global fits. Similarly, I doubt we will see significant improvements in other fundamental SM parameters. The LHCb collaboration will possibly be showing some new resonance and improved understanding of the B sector, but again, none of that kind of results have caused a revolution in the past, and there's little hope that the future will change that dramatically.
The above experimental output is pretty much guaranteed, sort of. Don't get me wrong: it is stuff that will require a huge effort by hundreds of active analysts in the LHC collaborations, an impressive battery of review teams, frantic meeting schedules, and gazillions of CPU hours. But these large experiments have a proven record of delivering what everybody expects from them, and next March will not be an exception.
So what could really we hope for ? Maybe a new fluctuation in some improbable final state (like the 750 GeV resonance found one year ago) ? Or a real new physics signal finally appearing in some targeted search ? Well, if you have read this blog for long enough you know my answer: as a sceptic, I cannot bring myself to look with optimism at the forthcoming new results. Rather, I have to stick to what I have been preaching during the past few months, when I have been touring the world giving a seminar titled "Extraordinary Evidence: the 0.000029% Solution".
In the seminar I made the point that today's collider experiments are making such a large number of independent searches for anomalous effects, repeatedly as data piles up, that they are bound to hit a very odd fluctuation sooner or later. The five-sigma criterion (five sigma corresponds to a 2.9x10^-7 probability of data under the null hypothesis) was designed in 1968 by Arthur Rosenfeld to prevent the publication of flukes in mass histograms constructed from bubble chamber experimentalists; but we have changed the size of our experiments in the past 50 years, and the trials factor has increased so much that five sigma can and will appear in the data at some point.
Below is a snapshot of the conclusions slide in my seminar (I showed it in Oslo, Lisbon, SLAC, Northwestern, DESY, at LHCb, in Clermont-Ferrand, at RHU London, among other places). You probably cannot read the underlying text, but just the banner - but the banner is the message after all.
In summary, I do not know whether you should wish for a 5 sigma effect in LHC data: even if we got it, this would still most likely be only a spurious effect, and one that would draw far too much attention and divert theorists from more principled studies. These days I think there is much more to hope from other fundamental physics searches: gravitational waves, for sure; and studies in the neutrino sector. If I could choose, that is what I would be working on nowadays. But I am a particle physicist, so I will just stick to that. Probably there's no Nobel prize in sight, yet is still quite a lot of fun!
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