Monday, January 8, 2007

Where are those #$%@ keys??

So, remember from the last post that conversation we had about the supposed hint of the Higgs from a university team in Iowa? Turns out that our folks at Fermilab were about to find some interesting data of their own. On December 14 they "opened the box" on the year's intake of data collected from the Tevatron. All year they work on simulated data so that the work they do doesn't get biased by what's really there. Then, all at once, they reveal the actual data and compare it to what they had been working with.

As I said before, the Higgs exists for a tiny fraction of an instant before decaying into something else. So, while the physicists at Fermilab are searching for the Higgs all the time, sometimes this search takes the shape of a search for something else. In this case, they had been looking for the mass of something called the W-boson, which is "a key parameter of the Standard Model of particles and forces." What this means is that if they can nail down the W-boson's mass, they can get a much better understanding of the mass for the Higgs boson. It's kind of like walking into a dark room nightclub. You know your keys are on the floor somewhere because someone at the party last night told you they kicked them and heard them sliding around. The more ways you can eliminate places you know your keys AREN'T, the quicker you can figure out where they might be. The physicists at Fermilab now have TWO limiters: they already famously found the mass of the top-quark a few years ago, and now the W-boson. It might be the equivalent of stumbling around the room until you suddenly realize half the room is carpeted (keys can't slide on carpet) AND one whole corner is taken up by a huge entertainment system. That only leaves one corner where the keys must be!

Luckily for Fermilab, this plays right into their hand. It turns out that their beloved Tevatron, that beautiful 4-mile accelerator we have spent 3 years getting to know, is suited best for searching the particular range that the Higgs is limited to. It's as if, after eliminating three of the four corners of the room where your keys could be, it turns out that the remaining fourth corner happens to be right under the stage lights! The best place they could possibly be in order to be found. Now all you have to do is flip on those blazing lights and start looking. With a little luck...

This makes the scientists very excited. In fact, Rob Roser wrote back to us and said the enthusiasm is high --- he's sounding suddenly confident they will find the Higgs there in two years! He says it's still a risk, of course, but that the risk is looking better and better, which means people will be willing to "wager" their professional time and energy to keep looking for it at Fermilab. He said they've restructured their group to better search this range, and that "we are now getting the tools in place we need to nail this baby."

They officially published this result today. You can read about it here,but I'll paste in a couple of important comments:

The new W-mass value leads to an estimate for the mass of the yet-undiscovered Higgs boson that is lighter than previously predicted, in principle making observation of this elusive particle more likely by experiments at the Tevatron particle collider at Fermilab. By measuring the W-boson and top-quark masses with ever greater precision, physicists can restrict the allowable mass range of the Higgs boson, the missing keystone of the Standard Model.

"This new precision determination of the W boson mass by CDF is one of the most challenging and most important measurements from the Tevatron," said Associate Director for High Energy Physics at DOE's Office of Science Dr. Robin Staffin. "Together, the W-boson and top-quark masses allow us to triangulate the location of the elusive Higgs boson."


There's a link from that page to some graphics and pictures and some pretty clear explanations, including one that makes it look like instead of limiting the search to one corner of the room, it's more like one single floor tile... very exciting.

Some context: remember, CERN, the huge accelerator in Geneva, is scheduled to come online sometime this year. John Conway has said that while this is true, they'll still have to do tests, probably have a few snafus, a false start or two, some tweaks, adjustments, and THEN get it going. He estimates 2008 or even early 2009 before real, meaningful data can happen. And that's about exactly two years...

More on this next time...

1 comment:

Thomas Dent said...

Do you remember where the idea for the 'lost keys' analogy from?

I wrote a letter to New Scientist some years ago, reacting to some absurdly overblown reporting by Eugenie Samuel (now Reich) about the revision of the final LEP results, using a very similar idea - ie where are those keys. Not three corners of a room but three rooms out of four in a house.

Of course it may have become common currency since then...