# Branching fraction and charge asymmetry measurements in B to J/psi pi pi decays

## TL;DR

This paper reports measurements of branching fractions and charge asymmetry in B meson decays to J/psi and two pions, using a large data sample from the BaBar experiment, including intermediate resonances and setting upper limits for non-resonant decays.

## Contribution

First precise measurements of branching fractions and charge asymmetry in B to J/psi pi pi decays, including resonance contributions and upper limits for non-resonant modes.

## Key findings

- Measured B(B0 -> J/psi rho0) = (2.7 +/- 0.3 +/- 0.17) x 10^-5
- Measured B(B+ -> J/psi rho+) = (5.0 +/- 0.7 +/- 0.31) x 10^-5
- Charge asymmetry in B+ decays to J/psi rho is -0.11 +/- 0.12 +/- 0.08

## Abstract

We study the decays B0 to J/psi pi+pi- and B+ to J/psi pi+pi0, including intermediate resonances, using a sample of 382 million BBbar pairs recorded by the BaBar detector at the PEP-II e+e- B factory. We measure the branching fractions B(B0 ->J/psi rho0) = (2.7 +/- 0.3 +/- 0.17) x 10-5 and B(B+ ->J/psi rho+) = (5.0 +/- 0.7 +/-0.31) x 10-5. We also set the following upper limits at the 90% confidence level: B(B0 -> J/psi pi+ \pi- non-resonant) < 1.2 x 10-5, B(B0 -> J/psi f_2(1270)) < 4.6 x 10-6, and B(B+ -> J/psi pi+ pi0 non-resonant) < 4.4 x 10-6. We measure the charge asymmetry in charged B decays to J/psi rho to be -0.11 +/- 0.12 +/- 0.08.