Wednesday, November 10, 2010

D0 at Tevatron: tan beta is probably not large

The D0 Collaboration has released a new preprint,
Search for neutral Higgs bosons in the multi-b-jet topology in 5.2fb-1 of ppbar collisions at sqrt(s)=1.96 TeV
that looked for neutral Higgs bosons with an enhanced coupling to the bottom quarks. Such an unusually strong interaction could exist if tan(beta), the ratio of the two Higgs vevs in a supersymmetric standard model, were very high.




Directly contradicting at least one of the rumors from Summer 2010 (or at least the natural models implied by that rumor), this paper rules out some region of the parameter space where tan(beta) is large enough.

More precisely, because they haven't observed any significant excess from the Standard Model background, the cross section for the Higgs production multiplied by the Higgs branching ratio to the bottom can't exceed their new threshold.

For a neutral Higgs boson of a mass slightly above 120 GeV, a weak excess of events between 2 and 2.5 sigma was observed. With this approximately 98% confidence level signal, climate scientists would have declared the Higgs discovered. It just happens that in this particular case, they could very well be right. ;-)



By the way, the LHC is currently colliding lead ions above 500 TeV of energy. Lots of junk is created in such collisions.

By the way, when you click at "lots of junk", you will get a 3D video that offers you many ways to watch the three-dimensional moving sequences. If you have no glasses or special equipment, choose "parallel" and look at infinity (parallel direction of eyes) so that the left eye sees the left image and the right eye looks at the same points of the right image. Blinking may help you to beat the distractions around the 3D image. Perfectly three-dimensional!

See also Stereograms and dinograms.



The proton-proton collisions at the energy frontier will resume after the New Year.

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