To be, or not to be?
That's a question for the Higgs boson to answer, and we might know soon enough. CERN just (well, three days ago really, but everybody here was out in the countryside celebrating Midsummer) published a press release about having a seminar on the new results on Wednesday 4th of July.
Coincidence that it's also Independence Day for the folks in the US? Probably yes, although my collaboration, the Compact Muon Solenoid (CMS) experiment at CERN, does have a strong representation from the States, including our spokesperson Joe Incandela.
The real reason, though, is that the 4th of July is also the eve of a major particle physics conference, ICHEP, starting in Melbourne. The ATLAS and CMS experiments will deliver the preliminary results of their 2012 data analysis there, and the seminar will be a kickoff for these presentations (you can see the live broadcast at webcast.cern.ch).
The experiments at the Large Hadron Collider stopped collecting data only on the 18th of June, and everybody is now busily analysing this dataset. We actually collected quite a nice bunch of data, just over 6/fb, which is a bit better than last year. The collision energy was also raised from 7 TeV to 8 TeV, which should increase the production rate of possible Higgs bosons by 20--30%.
|The amount of data collected in 2010, 2011 and 2012. One fb-1 amounts to almost 100 trillion proton-proton collisions.|
People are really eager to see the new results, and for a reason. The data collected in 2011 showed some hints of a Higgs boson in the 124-126 GeV range. The amount of data collected this year is nearly equal to that collected last year so the results are directly comparable. We should be able to see whether the earlier trends are still there, or whether they've gone away. Either way, it should be pretty exciting.
The predictions made earlier indicate that a combination of the 2011 and 2012 datasets should get pretty close to five sigma, the traditional standard for a discovery in the field. Or, we should be able to rule the existence of the Higgs boson out at a 95% confidence level from the whole remaining mass window.
|Predictions for the significance of a Higgs signal as a function of the boson mass. The combination of 2011 (5 fb-1, 7 TeV) and 2012 (5 fb-1, 8 TeV) data will correspond to roughly the average of the two red lines.|
What happens in a week depends both on the hard work of the physicists, who are improving the sensitivity of their analysis, and, due to statistical fluctuations, pure luck. If we're unlucky, the existence of the Higgs boson may still remain a mystery, but if we're lucky, we might end the quest earlier than expected.
So, what if we find the Higgs or not? Is it the answer to Life, the Universe, and Everything? Or a piece in the puzzle of the origin of mass for the elementary particles? The latter, more likely.
If we find that the Higgs boson lacks existence, much of the theoretical work done in particle physics for the past few decades will end up in the dustbin. It's not all that bad, really, because it will allow the theorists to start from a clean slate, and that's often been a very fruitful thing. The experimentalists will continue to hunt for other particles that could replace the Higgs boson.
If the Higgs boson is found, it's properties will have to be scrutinized carefully. There are many theories out there besides the Standard Model of particle physics that predict the Higgs boson (or bosons) so determining it's precise identity might take a while. Many of the alternative theories also predict other particles, leaving plenty of work to be done for the experimentalists.
[Note: Mikko writes for a Finnish language blog, Higgs Hunters. This post is an English translation of his latest post at Higgs Hunters.]