Measurement of $CP$ asymmetry in $B_s^0 \to D_s^{\mp} K^{\pm}$ decays
hep-ex
/ Authors
LHCb collaboration, R. Aaij, B. Adeva, M. Adinolfi, Z. Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero
and 786 more authors
S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, J. E. Andrews, R. B. Appleby, F. Archilli, P. d'Argent, J. Arnau Romeu, A. Artamonov, M. Artuso, E. Aslanides, M. Atzeni, G. Auriemma, M. Baalouch, I. Babuschkin, S. Bachmann
/ Abstract
We report the measurements of the $CP$-violating parameters in $B_s^0 \to D_s^{\mp} K^{\pm}$ decays observed in $pp$ collisions, using a data set corresponding to an integrated luminosity of $3.0\,\text{fb}^{-1}$ recorded with the LHCb detector. We measure $C_f = 0.73 \pm 0.14 \pm 0.05$, $A^{ΔΓ}_f = 0.39 \pm 0.28 \pm 0.15$, $A^{ΔΓ}_{\overline{f}} = 0.31 \pm 0.28 \pm 0.15$, $S_f = -0.52 \pm 0.20 \pm 0.07$, $S_{\overline{f}} = -0.49 \pm 0.20 \pm 0.07$, where the uncertainties are statistical and systematic, respectively. These parameters are used together with the world-average value of the $B_s^0$ mixing phase, $-2β_s$, to obtain a measurement of the CKM angle $γ$ from $B_s^0 \to D_s^{\mp} K^{\pm}$ decays, yielding $γ= (128\,_{-22}^{+17})^\circ$ modulo $180^\circ$, where the uncertainty contains both statistical and systematic contributions. This corresponds to $3.8\,σ$ evidence for $CP$ violation in the interference between decay and decay after mixing.