New constraints on CPT symmetry violation in charm mesons

Abstract

Small CPT-violating effects are admissible in several theories beyond the Standard Model of interactions. We analyse experimental data obtained with neutral flavoured meson mixing and place bounds on the scale of such phenomena. The constraints on the CPT-violating parameter $z$ are derived by reinterpreting the LHCb measurement of the time-dependent asymmetry in the Cabbibo-favoured $D^0 \rightarrow K^{-}\pi^{+}$ and $\bar{D}^0 \rightarrow K^{+}\pi^{-}$ decay rates. The bounds provided in this paper are two orders of magnitude stricter compared to the results obtained by the FOCUS Collaboration. Among other constraints, we report bounds on the difference in the decay widths and masses of the neutral D meson flavour states at a 95 % confidence level. The decay width difference is bounded by $(-4.7<\delta\Gamma_D<2.1)\times 10^{-16}$GeV. The mass difference lies within~$(-2.0<\delta m_D<2.0)\times 10^{-15}$GeV for 95% of $\text{arg}(z)$ values. The paper includes an assessment of the influence of CP violation on the results and a discussion of the future prospects.