# $\Delta m_{s}$ precision measurements at LHCb.

Lorenzon A.

Comunicazione
I - Fisica nucleare e subnucleare
Aula Palazzo dell'Emiciclo - Sala Ipogea - Mercoledì 25 h 16:30 - 19:00
Indirect searches for new physics (NP) can be performed comparing measurements of the CKM angle $\gamma$ from tree-processes with the results of global CKM fits. Assuming no NP in tree-level decays, any disagreement between tree-level determinations and the value inferred from global fits would indicate NP, due to new particles/mediators being exchanged in loops. $B^{0}_{s}\rightarrow D_{s} K$ is a very sensitive tree-level decay for $\gamma$ measurements accessible with high statistic at LHCb. For a precise determination of $\gamma$ the mass difference $\Delta m_{s}$ and the reconstruction efficiency as a function of the $B^{0}_{s}$ decay time have to be determined from a suitable control channel, $B^{0}_{s}\rightarrow D_s\pi.$ Tools and methods used in LHCb will be presented as well as the results obtained for both $\Delta m_{s}$ and the decay time efficiency. The LHCb Run 2 data sample will be used for these studies. Given the size of the $D_{s}\pi$ data sample a very accurate determination of $\Delta m_{s}$ is expected. Eventually prospects for a $\gamma$ measurement from $D_{s} K$ using Run 2 data will be reported.