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 the presence of NP, due to new particles being exchanged in loops. $B^0_s \to D_s^{\mp} K^{\pm}$ 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, namely $B^0_s\to D_s^-\pi^+$. Tools and methods used in LHCb will be presented as well as the preliminary results obtained for both $\Delta m_s$ and the decay time efficiency. The full 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 achievable. 

Towards a precision measurement of $\Delta m_s$ at LHCb

Lorenzon, Altea
2020/2021

Abstract

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 the presence of NP, due to new particles being exchanged in loops. $B^0_s \to D_s^{\mp} K^{\pm}$ 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, namely $B^0_s\to D_s^-\pi^+$. Tools and methods used in LHCb will be presented as well as the preliminary results obtained for both $\Delta m_s$ and the decay time efficiency. The full 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 achievable. 
2020-01-07
108
$\Delta m_s$, B physics, LHCb, CKM angle $\gamma$, subnuclear physics, data analysis
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12608/23048