First experimental study of photon polarization in radiative $B_s^0$ decays

Abstract

The polarization of photons produced in radiative $B_s^0$ decays is studied for the first time. The data are recorded by the LHCb experiment in $pp$ collisions corresponding to an integrated luminosity of 3fb${}^{-1}$ at center-of-mass energies of $7$ and $8$TeV. A time-dependent analysis of the $B_s^0\to \ddot{I}•{\hat{I}}^3$ decay rate is conducted to determine the parameter ${\mathcal{A}}^{\hat{I}}”$, which is related to the ratio of right- over left-handed photon polarization amplitudes in $b\to s{\hat{I}}^3$ transitions. A value of ${\mathcal{A}}^{\hat{I}}”=-0.98_{-0.52-0.20}^{+0.46+0.23}$ is measured. This result is consistent with the Standard Model prediction within two standard deviations.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-034.html