Status of the D0 fiber tracker and preshower detectors

In this report we focus on the performance of the D0 central fiber tracker and preshower detectors during the high luminosity p{bar p} collisions at {radical}s = 1.96 GeV delivered by the Tevatron collider at Fermilab (Run IIb). Both fiber tracker and preshower detectors utilize a similar readout system based on high quantum efficiency solid state photo-detectors capable of converting light into electrical signals. We also give a brief description of the D0 detector and the central track trigger, and conclude with a summary on the central tracker performance

SUSY Higgs Searches at D0, Tevatron

During Run II of the Tevatron collider, D0 collaboration has made extensive searches for the neutral MSSM Higgs bosons ({phi}), produced in p{bar p} collisions at {radical}s = 1.96 TeV. Two such analyses, addressing inclusive {phi} production with {phi} {yields} {tau}{sup +}{tau}{sup -}, and associated {phi}b(b) production with {phi} {yields} b{bar b} are reported here. No excess of events above the background expectation has been observed in any of these analyses. The results are combined to set constraints on the MSSM parameter space

On the influence of the cosmological constant on gravitational lensing in small systems

The cosmological constant Lambda affects gravitational lensing phenomena. The contribution of Lambda to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study in the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Due to Lambda the unresolved images are slightly demagnified, the radius of the Einstein ring decreases and the time delay increases. The effect is however negligible for near lenses. In the case of null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation, references added, results unchanged, in press on PR

LC scintillator-based muon detector tail-catcher R&D

Preliminary analysis of test beam data from strip scintillator planes read-out with multi-anode PMTs (MAPMTs) is presented along with a description of the independent systematic measurements of relative response for all channels of several MAPMTs used in the tests. Test beam measurements for the response of a scintillator strip, read out with Si photo-sensors, is also described

The Charge asymmetry in W bosons produced in p anti-p collisions at center of mass energy - 1.96 TeV

The primary mode of production of W{sup +} bosons in a p{bar p} collider is u + {bar d} {yields} W{sup +}. The u quark generally carries more momentum than the {bar d} and the resultant W{sup +} tends to be boosted in the proton direction. Similarly, W bosons are boosted in the anti-proton direction. This is observed as an asymmetry in the rapidity distributions of positive and negative W bosons. Measurement of this asymmetry serves as a probe of the momentum distribution of partons within the proton. These distributions are required as input to the calculation of every p{bar p} production cross section. This thesis presents the first measurement at D0 of the charge asymmetry of the W boson production cross section as measured in W {yields} ev decays in 0.3 fb{sup -1} of p{bar p} collisions collected with the D0 Detector. Theoretical predictions made using the CTEQ6.1M and MRST(2004) parton distribution functions are compared with the measurement

Search for MSSM Higgs Boson Production in Proton Anti-Proton Collisions, with a Higgs Decaying into Taus

We present a search for the production of neutral Higgs bosons in association with bottom quarks in p{bar p} collisions at {radical}s = 1.96 TeV. The cross section for this process is enhanced in many extensions of the Standard Model (SM), such as in its Minimal Supersymmetric extension (MSSM) at large tan {beta}. The data, corresponding to a recorded integrated luminosity of 1 fb{sup -1}, were collected with the D0 detector at the Fermilab Tevatron Collider. In the absence of a signal a 95% C.L. limit is set on the production cross section times branching ratio, and the results are also interpreted in the MSSM

Inclusive high-p(T) b anti-b cross section measurement at s**(1/2) = 1.96-TeV

The Run II physics program at the Tevatron started in the spring of 2001 with protons and antiprotons colliding at an energy of {radical}s = 1.96 TeV, and is continuing with about 1.2 fb{sup -1} of data currently collected by the CDF and D0 experiments. A measurement of the b-jet cross section as function of jet transverse momentum p{perpendicular} has been performed using 312 pb{sup -1} of D0 data. The results for this measurement were obtained and are presented herein. A neural network algorithm was used to identify b jets