Measurement of Branching Fractions in B0 -> J/Psi pi+pi- Decay

TL;DR

This paper measures the branching fractions of B0 decays into J/Psi and pion pairs, identifying dominant resonant contributions and setting upper limits on non-resonant processes using data from the Belle detector.

Contribution

It provides the first precise measurements of B0->J/Psi rho0 and f2 decay modes, including upper limits on non-resonant contributions, enhancing understanding of B meson decay dynamics.

Findings

Br(B0->J/Psi rho0)=(2.8+-0.3+-0.3)*10^{-5}

Br(B0->J/Psi f2)<1.5*10^{-5} at 90% C.L.

Non-resonant contribution is limited to less than 1.5*10^{-5} at 90% C.L.

Abstract

We report a measurement of the branching fractions in the B0->J/Psi pi+pi- decay based on a 140/fb data sample collected at the Upsilon(4S) energy with the Belle detector at the KEKB e+e- collider. Charged pion pairs are found to arise mainly from rho0 and f2 mesons; an upper limit for the non-resonant contribution is also set. The following branching fractions are obtained: Br(B0->J/Psi rho0)=(2.8+-0.3+-0.3)*10^{-5}, Br(B0->J/Psi f2)<1.5*10^{-5}(at 90% C.L.) and Br(B0->J/Psi (pi+pi-)non-res.)<1.5*10^{-5}(at 90% C.L.).