Measurement of the neutral Lambda-bottom decaying to positive Lambda-charm negavtive pion branching ratio.

摘要

We present a measurement of the L0b→L+ cp- branching ratio in pp¯ collisions at s = 1.96 TeV using 65 pb-1 data collected by the Collider Detector at FermiLab (CDF). The measurement starts from reconstructing two decay modes: L0b→L+ cp-,where L+c→p K-p+ B&d1;0→D+ p-,where D+→p+K-p +. We obtained 96 +/- 13 L0b and 321 +/- 22 B¯0 candidates from the CDF Run II Two-Track Hadronic Trigger data sample. The relative branching ratio of the two decays is then measured based on the equation: fLbfd BRLb→L +cp- BRB&d1;0 →D+p- =BRD+→Kpp BRL+ c→pKp NLbNB&d1; 0eB&d1; 0eLb . The measurement gives fLbfd BRLb→L +cp- BRB&d1;0 →D+p- =0.66+/-0.11stat +/-0.09syst +/-0.18BR . The L0b→L+ cp- branching ratio is then extracted, giving BRL0 b→L+cp- =6.6+/-1.2 stat.+/-0.9 syst.+/-2.3 BR+FR x10-3. The L0b sample we reconstructed in this analysis is the largest fully reconstructed L0b sample in existence. The result we report here on the L0b→L+ cp- branching ratio is the world's first such measurement.