Search for violations of Lorentz invariance and $CPT$ symmetry in $B_{(s)}^0$ mixing

Abstract

Violations of $CPT$ symmetry and Lorentz invariance are searched for by studying interference effects in $B^0$ mixing and in $B_s^0$ mixing. Samples of $B^0\to J/\ddot{I}ˆK_{\mathrm{S}}^0$ and $B_s^0\to J/\ddot{I}ˆK^{+}{K}^{-}$ decays are recorded by the LHCb detector in proton--proton collisions at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb${}^{-1}$. No periodic variations of the particle-antiparticle mass differences are found, consistent with Lorentz invariance and $CPT$ symmetry. Results are expressed in terms of the Standard Model Extension parameter $\hat{I}”a_{\hat{I}}¼$ with precisions of $\mathcal{O}(10^{-15})$ and $\mathcal{O}(10^{-14})$ GeV for the $B^0$ and $B_s^0$ systems, respectively. With no assumption on Lorentz (non-)invariance, the $CPT$-violating parameter $z$ in the $B_s^0$ system is measured for the first time and found to be $\mathcal{R}e(z)=-0.022\pm 0.033\pm 0.005$ and $\mathcal{I}m(z)=0.004\pm 0.011\pm 0.002$, where the first uncertainties are statistical and the second systematic.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-005.html