The Higgs: To be, or not to be?

[Note from Shaun: The following is a guest post from Higgs Hunter, Mikko Voutilainen. Mikko is a colleague of mine here in Helsinki. He is a postdoc working on the CMS experiment at the LHC in CERN. Below, he rhetorically asks the Higgs boson whether it exists or not. The irony of this is that Mikko asks this question, non-rhetorically, for a living and it is quite possible that he has already received an answer. He cannot (unfortunately) tell us this answer, yet. You should consider the following a teaser for what will follow next Wednesday when CERN unveils its latest results to the world. On that date, Mikko has promised to give us another guest post where he will reveal everything he knows about, The Higgs... (I've even heard rumours that this follow-up post has already been written)]

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.]

Total Perspective Vortex

[I apologise to all readers of the blog who also take the time to read the comments because you have probably already have seen the following videos. For those who don't read the comments, you're missing out on half of the purpose of the blog.]

Michelle asked in this post what role cinema plays in science. I think this is an interesting question and a smart choice of post from Michelle. Opening a dialogue between science and art isn't easy. We speak very different languages. We sometimes tackle similar questions, but we do the tackling in very different ways. Moving images though are something that exist in both worlds. They may be used very differently, but that's the interesting thing; how are they used differently? How are they used similarly? There are tools such as sculpture and advanced mathematics that probably aren't used in both worlds, but moving images are.

So moving images are a great example for this blog because they give us that first piece of common ground from which to begin a conversation. 

My first contributions to Michelle's questions were the following two films. They are the best examples I know of that properly show how insignificant the Earth is. Watch them in high definition.

The first film, above, is a film of the dark matter particles in the Millenium Simulation. This is what we expect the universe should look like if we could see the dark matter in it. As stated in the wikipedia link, each individual particle in this simulation (i.e. pinprick of light in the film) has a mass one billion times the mass of the sun. Not only that, but the total volume of the simulation is much less than the total volume of the observed universe. Keep that in perspective when watching... this video shows only a small fraction of the total volume of the universe and each dot in the video is much bigger than an entire galaxy! (don't forget that one galaxy will itself be 100,000 light years wide - this is so big that in one human lifetime light could only travel 0.1% of its width - and that is just one galaxy, something just big enough [edited from the original - "not big enough"] to be seen in this video.)

The film above is the real world equivalent. This film shows the locations of individual galaxies in the observed universe as seen by the Sloan Digital Sky Survey. SDSS has only mapped a fraction of the sky and can only see galaxies that are within a certain distance of us. So you see less of the universe, but at a finer resolution. In each galaxy in this video there will be billions and billions of stars just like our sun. This website helps if you find it hard to visualise what the number one billion actually means.

As the conversation develops I will hopefully find time to explain the scientific gains from both SDSS and the Millenium Simulation as well as what a scientist gains from watching the films themselves. But for now, let's just treat these as eye candy for the weekend as we wait for James' next proper post, due to arrive on Monday.

Follow @just_shaun