Finally, a post I can make in just a few minutes! The blogs of the physics world are abuzz with a rumor that the LHC experiments have… well, what have they (supposedly) found? If you read some of the more sensationalist physics websites out there, or the popular media (the news has even made it to the New York Times, although to their credit they’re being pretty reserved about it), you might get the idea that scientists at CMS and ATLAS have found the Higgs boson already and are just keeping the news officially under wraps until they can present it with much fanfare at a conference next month. That is not true.
It’s important to remember that finding the Higgs boson is not like finding a lost key or something: you can’t just look at it and say “yep, there’s a Higgs boson,” even if you do have what is essentially a giant microscope. Instead, it’s a probability thing. You analyze the results of the experiment and get out a result like “90% chance that the Higgs boson exists” or “95% chance that the Higgs boson does not exist” (actually even there I’m oversimplifying, but that’s the gist of it). The more data you have to analyze, the higher your probability one way or another.
When the last batch of LHC results were announced in December, there was a bump in the data of the sort that could signify the presence of the Higgs boson, but it wasn’t conclusive. I don’t know the exact probabilities, but to give you a rough sense of scale, you might say it seemed 50-70% likely that the Higgs boson existed. Now, though, the LHC has been taking more data over the past three months, and once that data is analyzed, we should be able to say with a lot more confidence that the Higgs boson exists or doesn’t exist. Again, just to give a sense of scale, you can imagine this new data pushing the probability of existence up to 95-99% — or down to less than ten percent. It may even be enough for physicists to call it a “discovery.” And even though that would only mean that the probability crossed some arbitrary threshold, it’s a threshold at which we can be pretty confident that the particle exists. That’s what everyone is hoping to get excited about.
Now then, the rumors that I’ve heard suggest that the two LHC detectors have individually found enough evidence that the Higgs boson exists that, if you put their results together, it would cross that arbitrary threshold. I don’t know whether that’s true, and it’s not even clear whether anyone (even the scientists doing the analysis) knows whether it’s true, but personally I wouldn’t be too surprised if that is the result they do wind up announcing. The hints we saw in December were reasonably solid, for hints. Either way, we’ll find out at the International Conference on High-Energy Physics next month. It starts on July 4, and you can be sure that whatever result comes out of the Higgs search, you’ll see it here — as well as probably everywhere else on the internet. Stay tuned!