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# Search results

1,392 records were found.

## Search for Physics Beyond the Standard Model at BaBar and Belle

Comment: On behalf of BaBar and Belle Collaborations - Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 4 pages, 6 figure

## Studies of B decays to Charmonium at BABAR

Comment: 6 pages, 7 postscript figues, submitted to ICHEP2001

## B Decays to Charm States at BaBar

Comment: 6 pages, 6 postscript figues, submitted to Moriond QCD 2004

## Simulations of planar pixel sensors for the ATLAS high luminosity upgrade

A physics-based device simulation was used to study the charge carrier distribution and the electric field configuration inside simplified two-dimensional models for pixel layouts based on the ATLAS pixel sensor. In order to study the behavior of such detectors under different levels of irradiation, a three-level defect model was implemented into the simulation. Using these models, the number of guard rings, the dead edge width and the detector thickness were modified to investigate their influence on the detector depletion at the edge and on its internal electric field distribution in order to optimize the layout parameters. Simulations indicate that the number of guard rings can be reduced by a few hundred microns with respect to the layout used for the present ATLAS sensors, with a corresponding extension of the active area of the s...

## Study of the Radiation Hardness of Irradiated AToM Front-End Chips of the BaBar Silicon Vertex Tracker

Comment: Submitted to IEEE Transaction on Nuclear Science

## Measurement of the Charge Collection Efficiency after Heavy Non-Uniform Irradiation in BaBar Silicon Detectors

Comment: 7 pages, 13 figures. Presented at the 2004 IEEE Nuclear Science Symposium, October 18-21, Rome, Italy. Accepted for publication by IEEE Transactions on Nuclear Science

## Evidence for an excess of B -> D(*) Tau Nu decays

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. We also report the observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.

## Search for the decay modes D0 -> e+e-, D0 -> mu+mu-, and D0 -> e mu

We present searches for the rare decay modes D0 to e+e-, D0 to mu+mu- and D0 to e mu in continuum e+e- to cbar c events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468 f^-1. These decays are highly GIM suppressed but may be enhanced in several extensions of the Standard Model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D0 to mu+mu- channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman-Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D0 to e+e-)<1.7 x 10^-7, B(D0 to mu+mu-) within [0.6, 8.1] x 10^-7, and B(D0 to e mu)<3.3 x 10^-7.