Evidence for X(3872) --> psi(2S) gamma in B+/- --> X(3872) K+/- decays, and a study of B --> ccbar gamma K

TL;DR

This paper reports evidence for the decay of X(3872) into J/psi gamma and psi(2S) gamma in B meson decays, providing measurements of the associated branching fractions with significance levels around 3.5 sigma.

Contribution

It presents the first evidence for X(3872) decaying into psi(2S) gamma in B decays and measures the relevant branching fractions.

Findings

Evidence for X(3872) --> J/psi gamma at 3.6 sigma

Evidence for X(3872) --> psi(2S) gamma at 3.5 sigma

Measured product branching fractions for both decay modes

Abstract

In a search for B --> ccbar gamma K decays with the BaBar detector, where ccbar includes J/psi and psi(2S), and K includes K+, Ks, and K*(892), we find evidence for X(3872) --> J/psi gamma and X(3872) --> psi(2S) gamma with 3.6 sigma and 3.5 sigma significance, respectively. We measure the product of branching fractions BR(B+ --> X(3872) K+) x BR(X(3872) --> J/psi gamma) = (2.8 +/- 0.8(stat.) +/- 0.2(syst.)) x 10^(-6) and BR(B+ --> X(3872) K+) x BR(X(3872) --> psi(2S) gamma) = (9.9 +/- 2.9(stat.) +/- 0.6(syst.)) x 10^(-6).