Measurement of the Ratio of Branching Fractions Br(B+ -> JPsi pi+)/Br(B+ ->JPsi K+)

TL;DR

This paper measures the ratio of branching fractions between B+ decays to J/psi pi+ and J/psi K+ using data from the Fermilab Tevatron, providing insights into decay dynamics and CP violation.

Contribution

It presents the first measurement of the ratio of these branching fractions using invariant mass and kinematic analysis at the Tevatron.

Findings

Ratio of branching fractions: (4.86 ± 0.82(stat) ± 0.15(syst))%.

Observation of 91 ± 15 B+ -> J/psi pi+ events.

Data sample of 220 pb^-1 from pbar-p collisions.

Abstract

We report a measurement of the ratio of branching fractions of the decays B+ ->JPsi pi+ and B+ -> Jpsi K+ using the CDF II detector at the Fermilab Tevatron Collider. The signal from the Cabbibo-suppressed B+->JPsi pi+ decay is separated from B+->JPsi K+ using the invariant mass distribution and the kinematics differences of the hadron track in the two decay modes. From a sample of 220 pb^-1 of pbar-p collisions at sqrt(s)= 1.96 TeV, we observe 91 +- 15 B+->JPsi pi+ events together with 1883 +- 34 B+->JPsi K+ events. The ratio of branching fractions is found to be Br(B+ -> JPsi pi+)/Br(B+ ->JPsi K+) = (4.86 +- 0.82(stat.) +- 0.15(syst.)) %.