Measurement of $CP$-violating and mixing-induced observables in $B_s^0 \to φγ$ decays
hep-ex
/ Authors
LHCb collaboration, R. Aaij, C. Abellán Beteta, B. Adeva, M. Adinolfi, C. A. Aidala, Z. Ajaltouni, S. Akar, P. Albicocco, J. Albrecht
and 855 more authors
F. Alessio, M. Alexander, A. Alfonso Albero, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, J. E. Andrews, F. Archilli, J. Arnau Romeu, A. Artamonov, M. Artuso, K. Arzymatov, E. Aslanides, M. Atzeni, B. Audurier, S. Bachmann, J. J. Back, S. Baker
/ Abstract
A time-dependent analysis of the $B_s^0 \to φγ$ decay rate is performed to determine the $CP$-violating observables $S_{φγ}$ and $C_{φγ}$, and the mixing-induced observable $\mathcal{A}^Δ_{φγ}$. The measurement is based on a sample of $pp$ collision data recorded with the LHCb detector, corresponding to an integrated luminosity of 3 fb$^{-1}$ at center-of-mass energies of 7 and 8 TeV. The measured values are \begin{align*} S_{φγ} &= 0.43 \pm 0.30 \pm 0.11, \\ C_{φγ} &= 0.11 \pm 0.29 \pm 0.11, \\ \mathcal{A}^Δ_{φγ} &= -0.67 \, ^{+0.37}_{-0.41} \pm 0.17, \end{align*} where the first uncertainty is statistical and the second systematic. This is the first measurement of the observables $S$ and $C$ in radiative $B_s^0$ decays. The results are consistent with the Standard Model predictions.