arXiv · 2608.14119
Improved measurement of $C\!P$ violation in $B^{0}_{s} \!\to J/\psi \pi^{+}\pi^{-}$ decays
Abstract
The time-dependent $C\!P$ asymmetry in $B^{0}_{s} \!\to J/\psi \pi^{+}\pi^{-}$ decays is measured using proton-proton collision data, corresponding to an integrated luminosity of $6\,\text{fb}^{-1}$, collected with the LHCb detector at a centre-of-mass energy of $13\,\text{TeV}$ during $\mbox{2015--2018}$. The $C\!P$-violating phase, $\phi_{s}$, the direct $C\!P$-violation parameter, $\left|\lambda\right|$, and the decay width of the heavy mass eigenstate in the $B^{0}_{s}$ system, $\Gamma_{\mathrm{ H}}$, are measured respectively to be $\phi_{s} = -0.077 \pm 0.034 \pm 0.007\,\text{rad}$, $\left|\lambda\right| = 0.993 \pm 0.026 \pm 0.007$ and $\Gamma_{\mathrm{ H}} = 0.610 \pm 0.002 \pm 0.004\,\text{ps}^{-1}$, where the first uncertainties are statistical and the second systematic. These results are consistent with previous measurements and the expectation based on the Standard Model. The combination with previous measurements in $B^{0}_{s} \!\to J/\psi \pi^{+}\pi^{-}$ decays using $7\,\text{TeV}$ and $8\,\text{TeV}$ proton-proton collision data yields $\phi_{s} = -0.046 \pm 0.031\,\text{rad}$, $\left|\lambda\right| = 0.975 \pm 0.024$ and $\Gamma_{\mathrm{ H}} = 0.610 \pm 0.004\,\text{ps}^{-1}$, while the combination including all other LHCb measurements gives $\phi_{s} = -0.041 \pm 0.017\,\text{rad}$.
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LHCb collaboration, R. Aaij, M. Abdelfatah, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, S. Akar, K. Akiba, H. Al Saleh, P. Albicocco, J. Albrecht, R. Aleksiejunas, F. Alessio, P. Alvarez Cartelle, S. Amato, J. L. Amey, Y. Amhis, L. An, L. Anderlini, M. Andersson, P. Andreola, M. Andreotti, S. Andres Estrada, A. Anelli, D. Ao, C. Arata, F. Archilli, Z. Areg, M. Argenton, S. Arguedas Cuendis, L. Arnone, M. Artuso, E. Aslanides, R. Ataíde Da Silva, M. Atzeni, B. Audurier, J. A. Authier, D. Bacher, I. Bachiller Perea, S. Bachmann, M. Bachmayer, J. J. Back, Z. B. Bai, V. Balagura, A. Balboni, W. Baldini, Z. Baldwin, L. Balzani, H. Bao, J. Baptista de Souza Leite, C. Barbero Pretel, M. Barbetti, I. R. Barbosa, R. J. Barlow, M. Barnyakov, S. Baron, S. Barsuk, W. Barter, J. Bartz, S. Bashir, B. Batsukh, P. B. Battista, A. Bavarchee, A. Bay, A. Beck, M. Becker, F. Bedeschi, I. B. Bediaga, N. A. Behling, S. Belin, A. Bellavista, I. Belyaev, G. Bencivenni, E. Ben-Haim, J. L. M. Berkey, R. Bernet, A. Bertolin, F. Betti, J. Bex, O. Bezshyyko, S. Bhattacharya, M. S. Bieker, N. V. Biesuz, A. Biolchini, M. Birch, F. C. R. Bishop, A. Bitadze, A. Bizzeti, T. Blake, F. Blanc, J. E. Blank, S. Blusk, J. A. Boelhauve. 2026-08-14. Improved measurement of $C\!P$ violation in $B^{0}_{s} \!\to J/\psi \pi^{+}\pi^{-}$ decays. https://arxiv.org/abs/2608.14119
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