Measurement of CP Violation in ${\mathrm{B}}_{\mathrm{s}}^0\to \mathrm{J}/\psi \varphi$ decays with the CMS detector

Abstract

The CP-violating weak phase ${\varphi }_{\mathrm{s}}$ and the decay width difference $\Delta {\Gamma }_{\mathrm{s}}$ of ${\mathrm{B}}_{\mathrm{s}}^0$ mesons are measured by the CMS experiment at the LHC using a data sample of ${\mathrm{B}}_{\mathrm{s}}^0\to \mathrm{J}/\psi \varphi$ decays. The analysed dataset corresponds to an integrated luminosity of about $20{\mathrm{fb}}^{-1}$ collected in $pp$ collisions at a centre-of-mass energy $\sqrt{s}=8\mathrm{TeV}$. A total of $49000$ reconstructed ${\mathrm{B}}_{\mathrm{s}}^0$ decays are used to extract the values ${\varphi }_{\mathrm{s}}$ and $\Delta {\Gamma }_{\mathrm{s}}$ by performing a time-dependent and flavour-tagged angular analysis of the ${\mu }^{+}{\mu }^{-}{\mathrm{K}}^{+}{\mathrm{K}}^{-}$ final state.The weak phase is measured to be ${\varphi }_{\mathrm{s}}=-0.03\pm 0.11(stat.)\pm 0.03(syst.)\mathrm{rad}$, and the decay width difference between the ${\mathrm{B}}_{\mathrm{s}}^0$ mass eigenstates is $\Delta {\Gamma }_{\mathrm{s}}=0.096\pm 0.014(stat.)\pm 0.007(syst.){\mathrm{ps}}^{-1}$.

arXiv commentProceedings of the 8th International Workshop on the CKM Unitarity Triangle (CKM 2014), Vienna, Austria, September 8-12, 2014