A Measurement of the B0 -> J/psi pi+pi- Branching Fraction

TL;DR

This paper reports a precise measurement of the branching fraction for the decay of the neutral B meson into J/psi and pion pairs, using data from the BaBar detector, providing key insights into B meson decay processes.

Contribution

First measurement of the B0 -> J/psi pi+ pi- branching fraction using a large data set from BaBar, with detailed statistical and systematic analysis.

Findings

Branching fraction for B0 -> J/psi pi+ pi- is (4.6 ± 0.7 ± 0.6) x 10^-5.

Branching fraction for B0 -> J/psi rho0 is (1.6 ± 0.6 ± 0.4) x 10^-5.

Data set contains approximately 56 million B Bbar pairs.

Abstract

We present a measurement of the branching fraction for the decay of the neutral $B$ meson into the final state $J/\psi\pi^+\pi^-$. The data set contains approximately 56 million $B\bar{B}$ pairs produced at the $\Upsilon(4S)$ resonance and recorded with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ storage ring. The result of this analysis is $\mathcal{B}$($B^0\to J/\psi\pi^+\pi^-$) = (4.6 $\pm$ 0.7 $\pm$ 0.6)$\times 10^{-5}$, where the first error is statistical and the second is systematic. In addition we measure $\mathcal{B}(B^0\to J/\psi\rho^0) = (1.6 \pm 0.6 \pm 0.4 )\times 10^{-5}$.