A Truly Spectacular Year at the LHC

Well, yesterday’s update on the search at the Large Hadron Collider [LHC] for the Standard Model Higgs particle (the simplest possible type of Higgs particle) is past. It left us, as was widely expected, with an ambiguous situation about which, for now, intelligent people can (and do) disagree (compare my reaction with this one).  But it also left us with great hope for 2012 that all these ambiguities will be resolved, and that Phase 1 of the Higgs search will come to a definite close next year, with

1. the discovery of a Standard Model Higgs particle (or a look-alike) between 115 and 127  GeV [with best bets at 125 or so] ; or
2. confidence that there is no Standard Model Higgs, and the launch of the search for many other types of Higgs particles; or
3. the discovery of something else along the way.

There’s still a lot more to say about yesterday’s results. Is what ATLAS and CMS are detecting a real signal, or not, and what might make us nervous or confident about it? What are the implications if it really is a signal of a new particle? How confident can we be that it is a Higgs particle? How much evidence is there that it is of Standard Model type? I will write an article about these issues soon. But there’s still a tremendous amount of work left (even for a theorist) to do to help plan for LHC in 2012, and to help assure analysis of the fall 2011 data is thorough.  During the rest of my stay at CERN I will be working hard on that!

However, I would be deeply remiss if I did not follow up on yesterday’s flurry of Higgs discussion by stepping back and reminding you what has happened here.

It has been an astonishing year. I find it challenging to remember how I thought about particle physics twelve months ago, after all these changes in our understanding brought about by the new results from the LHC.  This is especially true as far as the Higgs search, which has unambiguously excluded a huge part of the mass range for Standard Model (and also many non-Standard Model) Higgs particles — with implications that I am still coming to grips with. And this reshaping of the landscape of particle physics is due in large part to the extraordinary efforts of three groups of people:

• The accelerator physics team at the LHC, the often unsung heroes who designed, built, and now operate this wonderful and incredibly reliable machine, overcoming obstacle after obstacle to bring its collision rate higher and higher, well beyond expectations for 2011, and delivering 150 times as much data as was produced last year, thereby making the achievements announced yesterday possible…
• The experimental collaborations, the large teams of physicists who collectively built and now operate the giant and complex collision detectors, which work extraordinarily well, typically close to or even beyond their design parameters; who manage to cope with the incredibly challenging conditions at the LHC to obtain high quality data; and who have shown great ingenuity in finding ways to extract more information from that data — in particular, improving the methods for the Higgs particle search so much that they have  significantly exceeded original expectations for what one could learn from the amount of data currently available…
• The theoretical physicists that you never hear about — the ones who work and sweat tirelessly on very difficult technical problems: combining high-precision theory and data carefully to provide a detailed understanding of the structure of the proton; or coming up with clever ways to calculate, with higher and higher precision, the rates for Higgs particle production, and for other processes that obscure the Higgs particle’s signals;  without these researchers the measurements that we heard about yesterday would have had much larger theoretical uncertainties and could not have led to such powerful conclusions…

I have nothing to say except:  Wow.  Wow.  You’re amazing.  I feel so privileged to be a witness to what you’ve done.

The rest of us — other particle physicists, scientists everywhere, and the public — owe you a long and deafening round of applause. May history always remember what you achieved this year.

And we also wish you the very best in 2012; may it be even more successful and historic than 2011.