Searches for violation of Lorentz invariance in $\mathrm{t}\mathrm{\overline{t}}$ production using dilepton events in proton-proton collisions at $\sqrt{s}=13\,\mathrm{TeV}$

Violation of Lorentz invariance is searched for using top quark pair ($\mathrm{t}\mathrm{\overline{t}}$) production in proton-proton collisions at the LHC, at a center-of-mass energy of $\sqrt{s}=13\,\mathrm{TeV}$. Events containing one electron and one muon collected with the CMS detector are analyzed in a data sample corresponding to an integrated luminosity of $77.4\,\mathrm{fb}^{-1}$. A measurement of the differential normalized cross section for $\mathrm{t}\mathrm{\overline{t}}$ production as a function of sidereal time is performed. Potential violation of Lorentz invariance is introduced as an extension of the standard model (SM), with an effective field theory predicting the modulation of the $\mathrm{t}\mathrm{\overline{t}}$ cross section with sidereal time. Bounds on Lorentz-violating couplings are extracted, and found to be compatible with Lorentz invariance with an absolute precision of $0.1{-}0.8\%$. This search can also be interpreted as a precision test of special relativity with top quarks, improving precision by two orders of magnitude over a previous such measurement.