14.10.2026

T. V. Lyubushkina "Study of $B_{c}^{+}$ → $J/\psi D_{s}^{()+}$ decays and observation of the $B_{c}^{+}$-meson with the ATLAS detector at the LHC"

The talk presents the study of the spectroscopy and decay properties of the $B_{c}^{+}$ meson family using the full Run 2 dataset of $pp$ collisions collected by the ATLAS detector at a center-of-mass energy of √s = 13 TeV and an integrated luminosity of 139 $fb^{−1}$. Precise measurements of the branching fractions of the decays $B_{c}^{+}$ → $J/\psi and $B_{c}^{+}$ → $J/\psi D_{s}^{*+}$ relative to the reference mode $B_{c}^{+}$ → $J/\psi \pi^{+}$ are reported.

ATLAS

The transverse polarization fraction $\Gamma_{\pm \pm}/\Gamma$ in the $B_{c}^{+}$ → $J/\psi D_{s}^{*+}$ decay is measured. The first experimental observation of the lightest vector excited state of the $\bar{b}c$ system, the $B_{c}^{*+}$ meson, within the ATLAS data is demonstrated. An original procedure is described to reconstruct the radiative cascade transition $B_{c}^{*+}$ → $B_{c}^{+}\gamma$ by using soft low-energy conversion photons combined with the inclusive semileptonic decay mode of the ground state, $B_{c}^{+}$ → $J/\psi \mu^{+} \nu_{\mu}X$. The measured values of the mass difference $\Delta{m_{B_{c}^{*+}}}$ and the corresponding mass of the $B_{c}^{*+}$ meson are provided.

(Based on the materials of the candidate dissertation)

Presentation

Link to watch the video on the JINR resource:
https://disk.jinr.ru/index.php/s/9X3fbGSRg6n2Df7

Link to watch the video on VK:
https://vkvideo.ru/video-179241683_456239899