The new Silicon detector at RunIIb Tevatron II: the world’s highest energy collider What’s new? ...

The new Silicon detector at RunIIbTevatron II: the world’s highest energy collider

What’s new? Data will be collected from 5 to 15 fb-1 at s=1.96 TeV Instantaneous luminosity will increase up to L=5X1032 cm-2s-1

Average number of interactions per bunch crossing will be 15 at 396 ns (peak luminosity)

What is the goal? The Fermilab collider program has the potential for revolutionizing our understanding of elementary particle physics. The combination of the upgrade of the Tevatron complex and the greatly improved detectors provides extraordinary opportunities for discovery

The new Silicon detector at RunIIb

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Physics program at RunIIb

How do we obtain high jet tagging efficiency ?

We need a robust tracking efficiency, good impact parameter resolution & patter recognition. The success of RunIIb relies and benefits from excellent Silicon Detector. A new silicon detector, SVXIIb, will replace the actual SVXIIa to handle the high density tracking environmentand to survive the higher luminosity

The physics goals of RunIIb are broad and fundamental: Tevatron is the world’s only source of top quarks: the top seems to be uniquely connected to the mechanism of mass generation Tevatron can uniquely access the BS meson: its mixing rate can determine the length of one of the sides of the unitary triangle Tevatron will experimentally test the new idea that gravity may propagate in more than 4dim ofspace-time Search for light boson Higgsin the range 80 < mH < 120 GeV the Higgs mainly decay into b-bbar . This gives the signature of 2 jets. We will also search for associated production WH, ZH.

A full replacement of SVXIIa is required due to the sensor lifetime:

L00, r=1.3 cm 7 fb-1

L0, r=2.5 cm 4 fb-1

L1, r=4.1 cm 8 fb-1

L2, r=6.5 cm 11 fb-1

Significance of a potential Higgs discovery: L* 2

with =the b-jets tagging efficiency, L=luminosity

Silicon Vertex Trigger at RunIIaCDF is running the first trigger for B mesons using displaced tracks from the Silicon detector at a hadron collider and it is working well.

The measurement of the mass difference is interesting because it establishes the performance of the upgraded trackingsystems in CDF II.

From a total of 236070 Ds candidates and 135060 D candidates in 11.6 pb-1 of data, we find: M=99.280.43(stat.)0.27(syst.)MeV/c^2.This will be the first published result by CDF II.

Lifetime measurements of the B and B0 serve as a proving groundfor the techniques needed for Bs lifetime and mixing analyses.Samples of B, B0, and Bs mesons have been exclusivelyreconstructed using a J/ trigger sample. In particular, 55 Bs events are selected in the J/channel from 70 pb-1 data.Fits to the c distributions yield the following results: cB+=1.570.07(stat.)0.02(syst.)ps c=1.420.09(stat.)0.02(syst.)ps cBs=1.260.20(stat.)0.02(syst.)ps(The statistical errors are already comparable to the Run I results.)

The flavor-changing neutral current decay D0 to is highly suppressed in the Standard Model B(D010-13).

We reconstruct D0 to +- as a normalization modeand use the ratio of the two modes to set a limit on the D0branching ratio. Systematic uncertainties from detector and trigger efficiencies and selection requirements cancel in this ratio.We observe 0 events in the signal mass region when a side band calculation predicts a background of 1.7 0.7 events. As a result,we obtain B(D0) 2.4*10-6 at 90%confidence level. This limit is more stringent than the current PDG world average of B(D0) 4.1*10-6

We have also extracted samples of exclusively reconstructed B mesonsin fully hadronic modes using the Silicon Vertex Trigger. This plotshows reconstructed mass distributions for B0 meson.