I hear reports that mobs of possibly violent physics live-bloggers have massed outside the CERN auditorium where the Higgs results will be discussed tomorrow morning. I’m going to sleep through this, then wake up late tomorrow (it’s a vacation day here…), have a leisurely breakfast and check to see where the numbers ended up, then try out Philip Gibbs’s applet.
I don’t know exactly what numbers the experiments will be reporting, but basically both CMS and ATLAS should each have 4 sigma-ish or better evidence for the Higgs in two separate channels, gamma-gamma and ZZ. So, that’s four independent measurements of a narrow resonance, any one of which would be strong evidence for the Higgs. Best bet for one of these coming in at over 5 sigma is probably the ATLAS gamma-gamma result. Or, just combine any two out of four of these results using Philip’s software.
Things to look for if you’re following the talks and press conference:
- The “D” word. Will it be used? Kind of a silly question though. July 4, 2012 will go down in history as the date of the announcement of the discovery of the Higgs, no matter what people say tomorrow.
- What are the signal sizes in the two channels? You should be able to use Philip’s applet to combine the CMS and ATLAS numbers, and get a combined gamma-gamma number and ZZ number. Are these consistent with the SM prediction? Already tonight, hep-ph is starting to overflow with phenomenology papers describing models where gamma-gamma is enhanced with respect to the SM. I guess that indicates that tomorrow’s numbers will be higher than the SM prediction.
I hope there will be plenty of champagne involved!
Update: Today so far I’ve been mostly on vacation, celebrating Higgs/Independence Day by sleeping late, doing a short piece on TV for Al Jazeera, going out for an excellent lunch, and lying around in the air conditioning checking out the news from other sources (it’s brutally hot out there…). Later maybe a movie, dinner and fireworks.
The news was pretty much as expected: a strong signal from both experiments in two channels, very close to a 5 sigma level when combined. CERN did the right thing by simply claiming discovery, avoiding the situation suggested by the early AP story, where they seemed to be trying to say that they weren’t quite at the discovery level. For details, the slides are here, and the usual suspects (Philip Gibbs, Tommaso Dorigo, Resonaances, Matt Strassler) all did an excellent job of providing details in real time as they came available. Probably also other bloggers I haven’t had time to look at.
I’m still trying to get together combined numbers for the signal size in the various channels. It looks though that in the ZZ channel the size is close to the SM prediction, 2-3 sigma too high in gamma-gamma (nearly twice the expected size). So, still compatible with the SM, but the gamma-gamma excess is intriguing. Theorists with even better information than me have already started yesterday flooding hep-ph with papers supposedly explaining it.
Now, back to vacation….