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R. F. Harr

Publications and source records attributed to R. F. Harr.

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Review of Bs mesons and b Baryons

The measurements of B_s mesons and b baryons advanced greatly in the past year. The ground state b baryon Xi_b^0 was observed for the first time; numerous decay modes of the B_s^0 and b baryons were newly seen; measurements of CP violation in B_s^0 decays were improved, generally improving the agreement with the standard model; and the search for rare decays sensitive to new physics were pushed to new levels. It was a very productive year for measurements of b baryons and B_s^0 mesons.

hep-ex

Flavor Physics in the Quark Sector

One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of $K, D$, and $B$ mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field.

hep-ph

Rare Decays of B and D Hadrons at CDF

Decays that are highly suppressed in the standard model are excellent places to search for effects of new physics. Decays mediated by flavor-changing neutral currents are forbidden at tree level in the SM, and are often further suppressed by helicity and the Glashow-Iliopoulos-Maiani mechanism. Exclusive final states with charged lepton pairs are a particular strength of the CDF experiment due to the large bottom and charm production cross section and the ability to efficiently separate signal from background. CDF has searched for and set the world's best limits on the rare flavor-changing neutral current decays B^0_(s) rightarrow mu^+mu^-, B^0_(s) rightarrow e^+ e^-, and D^0 rightarrow mu^+mu^-, and the lepton flavor violating decay B^0_(s) rightarrow e^+/- μ^-/+.

hep-ex

Design and Operation of Front-End Electronics for the HERA-B Muon Detector

We have implemented a cost-effective design for the readout electronics of both the anode wires and the cathode pads of large area proportional wire chambers for the HERA-B muon system based on the ASD-08 integrated circuit. To control and monitor the large number of readout channels, we have built a distributed control system based on Philips Semiconductors' I2C bus and microcontrollers. To date we have installed about 10800 channels of muon chambers and electronics. The average single channel noise occupancy is less than 10**-5, and the detectors have been operated with target interaction rates as high as 70 MHz.

physics.ins-det