Search for Violation of $CPT$ and Lorentz Invariance in $B_s^0$ Meson Oscillations

We present the first search for $CPT$-violating effects in the mixing of $B_s^0$ mesons using the full Run II data set with an integrated luminosity of $10.4{\mathrm{fb}}^{-1}$ of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. We measure the $CPT$-violating asymmetry in the decay $B_s^0\to {\mu }^{\pm }{D}_s^{\pm }$ as a function of celestial direction and sidereal phase. We find no evidence for $CPT$-violating effects and place limits on the direction and magnitude of flavor-dependent $CPT$- and Lorentz-invariance violating coupling coefficients. We find 95% confidence intervals of $\mathrm{\Delta }{a}_{\perp }<1.2\times {10}^{-12}\mathrm{GeV}$ and $(-0.8<\mathrm{\Delta }{a}_T-0.396\mathrm{\Delta }{a}_Z<3.9)\times 10^{-13}\mathrm{GeV}$.

Figure 1

(a) The $K^{+}{K}^{-}{\pi }^{\mp }$ invariant mass distribution for one of the 11 sidereal bins of the data (bin 5) of the ${\mu }^{\pm }\varphi {\pi }^{\mp }$ sample. The lower mass peak is due to the decay $D^{\mp }\to \varphi {\pi }^{\mp }$ and the second peak is due to the $D_s^{\mp }$ meson decay. (b) The fit to the $(N_{+}-N_{-})$ distribution for one of the 11 sidereal bins of the data (bin 5).

Figure 2

The measured asymmetries, $A(i)$, versus the sidereal phase. The uncertainty on each value of $A(i)$ is the sum in quadrature of the statistical and systematic uncertainties. The red boxes show the fit and its uncertainties to the data points [Eq. (6)]. The dashed line shows the extracted value of $A_0$ and the grey box shows $\mathrm{\Delta }{A}_0$.