Will the Standard Model of physics be verified sooner?

reposted from: http://blog.wired.com/wiredscience/2007/01/the_god_particl.html

Tuesday, 9 January 2007

The God Particle Maybe Loses Some Weight
Topic: physics

Fascinating story today over at Nature's web site (here) on a new calculation for the mass of the W particle, the particle that carries the weak nuclear force—the one that does radioactive decay.

See, you're yawning. But author Jenny Hogan does a fantastic job of putting the W's lighter weight into context.

If the W is lighter, then so must be the much-sought-after Higgs boson, the theoretical particle that is responsible for mass—everything weighs something, and the Higgs is thought to explain why. It's so important that physicists have nicknamed it "the God particle."

And if the Higgs is lighter than physicists thought, then we might not have to wait for the Large Hadron Collider, a brand new, massive particle smasher, to come online at CERN, the European particle physics lab. The LHC is scheduled to start smacking stuff into each other this year. Instead, the folks who run the Tevatron, the big collider at Fermilab in Illinois, might be able to nab the Higgs first.

On 8 January, the estimate was tightened when the CDF [Collider Detector at Fermilab] announced it had pinned down the mass of the W boson, which mediates the weak nuclear force involved in processes such as radioactive decay. The new measurement is in agreement with previous estimates, but towards the upper end of the range. This, along with the added precision in the measurement, brings the upper limit for the Higgs' mass down to 153 giga electronvolts from 166 GeV. Previous experiments have shown that the Higgs must be heavier than 114 GeV.

A lighter Higgs suits the Tevatron, which is only capable of finding the particle if its mass is less than around 170 GeV. The closer a particle's mass is to this upper limit, the harder it would be to find.

Anything heavier than 170 GeV would certainly have to wait for the LHC, which will smash protons together harder to probe higher energies.

So I suppose you might ask, why would anyone believe the Fermilab guys on the new weight for the W when it clearly favors them in the race for the Higgs. And the answer is...um...physics? And the folks at Fermilab readily admit their desire to get there first. But author Hogan rightly points out that finding the Higgs is going to take years of data collection and analysis at both labs (see this Wired story if you want to know more about the LHC's number-crunching plans). She further points out that if the Standard Model of physics, the one that lists all the known and theoretical particles, is wrong, then there might not be a Higgs boson.

That, my friends, is context.