Abstract
A search for time-dependent violation of the charge-parity symmetry in D0→K+K− and D0→π+π− decays is performed at the LHCb experiment using proton-proton collision data recorded from 2015 to 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb−1. The D0 meson is required to originate from a D*(2010)+→D0π+ decay, such that its flavor at production is identified by the charge of the accompanying pion. The slope of the time-dependent asymmetry of the decay rates of D0 and D¯0 mesons into the final states under consideration is measured to be ΔYK+K−=(−2.3±1.5±0.3)×10−4, ΔYπ+π−=(−4.0±2.8±0.4)×10−4, where the first uncertainties are statistical and the second are systematic. These results are compatible with the conservation of the charge-parity symmetry at the level of 2 standard deviations and improve the precision by nearly a factor of 2.5 MoreReceived 21 May 2021Accepted 9 September 2021DOI:https://doi.org/10.1103/PhysRevD.104.072010Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.© 2021 CERN, for the LHCb CollaborationPhysics Subject Headings (PhySH)Research AreasHadronic decaysParticle decaysQuark mixingPhysical SystemsCharmed mesonsPropertiesCP symmetryParticles & Fields
Highlights
The breaking of the invariance of fundamental interactions under the combined charge conjugation (C) and parity (P) transformation, commonly named CP violation, is a necessary condition to explain the much larger abundance of matter with respect to antimatter in the universe [1]
Within the standard model (SM) of particle physics, the weak interaction provides a source of CP violation through a single complex phase in the CabibboKobayashi-Maskawa (CKM) matrix that governs the interaction of quarks with the W boson [2,3]
Hamiltonian governing the time evolution of the D0–D 0 system and Γ is the average decay width of the mass eigenstates. Since both mixing parameters are smaller than 1% [23,24,25,26,27,28,29,30], the asymmetry can be expanded to linear order in the mixing parameters as
Summary
The breaking of the invariance of fundamental interactions under the combined charge conjugation (C) and parity (P) transformation, commonly named CP violation, is a necessary condition to explain the much larger abundance of matter with respect to antimatter in the universe [1]. Hamiltonian governing the time evolution of the D0–D 0 system and Γ is the average decay width of the mass eigenstates Since both mixing parameters are smaller than 1% [23,24,25,26,27,28,29,30], the asymmetry can be expanded to linear order in the mixing parameters as. The parameter ΔYf is approximately equal to the negative of the parameter AfΓ defined as the asymmetry of the effective decay widths of D0 and D 0 mesons into the final state f, as detailed in Appendix A. Reducing the uncertainty on ΔYf is essential to determine the parameter adKþK− from the measurements of the time-integrated asymmetry of D0 → KþK− decays [37,38,39,40,41], which is equal to.
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