## Thursday, December 14, 2006

### Tevatron produces 60 unpaired top-quarks for D0

The production of the Higgs boson has a very small cross section. It is therefore a difficult task for gadgets such as Tevatron to create one (or more).

There are many other processes that have rather small cross sections. As Tevatron is announcing the discovery of ever more unlikely events, it is getting closer to the possible discovery of the God particle, namely the scalar particle that is giving mass and body to all those initially massless excitations of the Standard Model i.e. to all those ghostly spirits including Himself (via self-interaction). The last word of the previous sentence explains why the scalar particle is called "h".

Incidentally, while your humble correspondent is an atheist, he is not a hysterical one. Those somewhat hysterical atheists have a lot of trouble with the term "God particle" coined by Leon Lederman, a Nobel prize winner for neutrinos and a member of the "Physics first" movement that attempts to put physics before chemistry and biology at the high school. Recall that Lederman has also said:
• Physics isn't a religion. If it were, we'd have a much easier time raising money.
He at least tried to improve the funding situation by renaming the symmetry-breaking particle of the electroweak theory and we hope that his plan will eventually succeed.

Last time, we celebrated that the CDF team has announced the WZ production, a rather unlikely event that the D0 team has considered to be a part of reality since June 2006.

Today, the D0 team has announced a discovery that was explained during a Fermilab seminar last Friday:
The top quarks are normally produced in quark-antiquark pairs. You only need a lot of energy to produce such a pair but the production is only suppressed by the QCD coupling constant which is not particularly small. The top quarks decay to the bottom quarks and W bosons.

However, the nontrivial CKM matrix allows the flavor of the quarks to change. But because the off-diagonal matrix elements of the CKM matrix are small and they must moreover be squared to obtain the probabilities, the processes in which only one top quark is seen are rare and we had to wait until December 2006 before this particular prediction of the Standard Model - an otherwise unimpressive prediction that doesn't depend on the existence of the God particle - was confirmed.

I was cheating: the single top production actually arises from an intermediate W boson decaying into a bottom quark and a top antiquark, or vice versa.

Picture by Reinhard Schwienhorst.

The discovery claim depends on 60 events. If the resolution of the physicists at Fermilab keeps on increasing, they could also eventually discover the Higgs boson, maybe before the LHC does so. The D0-discovery is also a success for type IIA string theory because D0-branes are crucial objects whose bound states become the Kaluza-Klein modes in the 11th dimension as type IIA becomes M-theory. ;-)

We wish a lot of good luck with the God particle to the D0-brains.

#### 1 comment:

1. Why are the physics teachers in our district (Providence RI) pushing back at the Physics First program?