Speaker
Dr
Guillaume Pietrzyk
(IJCLab)
Description
In December 2022, LHCb released a new test a lepton flavor universality through the simultaneous measurement of $R_{K}$ and $R_{K^{\ast}}$ in two intervals of the dilepton invariant mass: $q^2 \in [0.1,1.1] \, \text{GeV}^2$ (low-$q^2$) and $q^2 \in [1.1,6.0] \, \text{GeV}^2$ (central-$q^2$). This talk presents the analysis of a measurement of $R_{K^{\ast}}$ in a region of high values of $q^2$, located above the $J/\psi$ and $\psi(2S)$ resonances and never performed by LHCb. In particular, this challenging measurement demands a high control of the pollution of $\psi(2S)$ contributions.
Author
Dr
Guillaume Pietrzyk
(IJCLab)