I didn’t go to ICHEP this year. In principle I could have, especially given that I have been resident at CERN for the past year, but we’re coming down to the end of our stay here and I didn’t want to squeeze in one more work trip during a week that turned out to be a pretty good opportunity for one last family vacation in Europe. So this time I just kept track of it from my office, where I plowed through the huge volume of slides shown in the plenary sessions earlier this week. It was a rather different experience for me from ICHEP 2012, which I attended in person in Melbourne and where we had the first look at the Higgs boson. (I’d have to say it was also probably the pinnacle of my career as a blogger!)
Seth’s expectations turned out to be correct — there were no earth-shattering announcements at this year’s ICHEP, but still a lot to chew on. The Standard Model of particle physics stands stronger than ever. As Pauline wrote earlier today, the particle thought to be the Higgs boson two years ago still seems to be the Higgs boson, to the best of our abilities to characterize it. The LHC experiments are starting to move beyond measurements of the “expected” properties — the dominant production and decay modes — into searches for unexpected, low-rate behavior. While there are anomalous results here and there, there’s nothing that looks like more than a fluctuation. Beyond the Higgs, all sectors of particle physics look much as predicted, and some fluctuations, such as the infamous forward-backward asymmetry of top-antitop production at the Tevatron, appear to have subsided. Perhaps the only ambiguous result out there is that of the BICEP2 experiment which might have observed gravitational waves, or maybe not. We’re all hoping that further data from that experiment and others will resolve the question by the end of the year. (See the nice talk on the subject of particle physics and cosmology by Alan Guth, one of the parents of that field.)
This success of the Standard Model is both good and bad news. It’s good that we do have a model that has stood up so well to every experimental test that we have thrown at it, in some cases to startling precision. You want models to have predictive power. But at the same time, we know that the model is almost surely incomplete. Even if it can continue to work at higher energy scales than we have yet explored, at the very least we seem to be missing some particles (those that make up the dark matter we know exists from astrophysical measurements) and it also fails to explain some basic observations (the clear dominance of matter over antimatter in the universe). We have high hopes for the next run of the LHC, which will start in Spring 2015, in which we will have higher beam energies and collision rates, and a greater chance of observing new particles (should they exist).
It was also nice to see the conference focus on the longer-term future of the field. Since the last ICHEP, every region of the world has completed long-range strategic planning exercises, driven by recent discoveries (including that of the Higgs boson, but also of various neutrino properties) and anchored by realistic funding scenarios for the field. There were several presentations about these plans during the conference, and a panel discussion featuring leaders of the field from around the world. It appears that we are having a nice sorting out of which region wants to host which future facility, and when, in such a way that we can carry on our international efforts in a straightforward way. Time will tell if we can bring all of these plans to fruition.
I’ll admit that I felt a little left out by not attending ICHEP this year. But here’s the good news: ICHEP 2016 is in Chicago, one of the few places in the world that I can reach on a single plane flight from Lincoln. I have marked my calendar!