Measurement of the ratio of the production cross sections times branching fractions of Bc+/- to J/psi pi+/- and B+/- to J/psi K+/- and B(Bc+/- to J/psi pi+/- pi+/- pi-/+)/B(Bc+/- to J/psi pi+/-) in pp collisions at sqrt(s) = 7 TeV

TL;DR

This study measures the production ratio of Bc+ to B+ mesons and the branching fraction ratio of Bc+ decays involving J/psi and pions in 7 TeV proton-proton collisions, providing new insights into Bc+ meson behavior.

Contribution

It presents the first measurement of the Bc+ to B+ production ratio and the Bc+ decay branching fraction ratio using CMS data at 7 TeV, employing a model-independent efficiency method.

Findings

The ratio of production cross sections times branching fractions is approximately 0.48.

The branching fraction ratio B(Bc+ to J/psi pi+ pi+ pi-) over B(Bc+ to J/psi pi+) is about 2.55.

Results are consistent with previous LHCb measurements.

Abstract

The ratio of the production cross sections times branching fractions (sigma(Bc+) B(Bc+ to J/psi pi+))/ (sigma(B+) B(B+ to J/psi K+)) is studied in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector at the LHC. The kinematic region investigated requires Bc+/- and B+/- mesons with transverse momentum pt > 15 GeV and rapidity abs(y) < 1.6. The data sample corresponds to an integrated luminosity of 5.1 inverse femtobarns. The ratio is determined to be [0.48 +/- 0.05 (stat) +/- 0.03 (syst) +/- 0.05 (tau_{Bc})]% The J/psi pi+/- pi+/- pi-/+ decay mode is also observed in the same data sample. Using a model-independent method developed to measure the efficiency given the presence of resonant behaviour in the three-pion system, the ratio of the branching fractions B(Bc+/- to J/psi pi+/- pi+/- pi-/+) / B(Bc+/- to J/psi pi+/-) is measured to be 2.55 +/- 0.80 (stat) +/- 0.33 (syst) +0.04/-0.01 (tau[Bc+]), consistent with the previous LHCb result.