Measurement of 𝐷0−¯𝐷0 mixing and search for 𝐶𝑃 violation with 𝐷0→𝐾+𝜋− decays

Physical Review D - Particles, Fields, Gravitation and Cosmology. 2025. Vol. 111. Article 012001.

Ratnikov F., Hushchyn M., Bocharnikov V., Boldyrev A., Ryzhikov A.

A measurement of the time-dependent ratio of the 𝐷0 →𝐾+⁢𝜋− to ¯𝐷0→𝐾+⁢𝜋− decay rates is reported. The analysis uses a sample of proton-proton collisions corresponding to an integrated luminosity of 6  fb−1 recorded by the LHCb experiment from 2015 through 2018 at a center-of-mass energy of 13 TeV. The 𝐷0 meson is required to originate from a 𝐷*⁢(2010)+→𝐷0⁢𝜋+ decay, such that its flavor at production is inferred from the charge of the accompanying pion. The measurement is performed simultaneously for the 𝐾+ 𝜋− and 𝐾− 𝜋+ final states, allowing both mixing and 𝐶⁢𝑃-violation parameters to be determined. The value of the ratio of the decay rates at production is determined to be 𝑅𝐾⁢𝜋=(343.1±2.0)×10−5. The mixing parameters are measured to be 𝑐𝐾⁢𝜋 =(51.4 ±3.5) ×10−4 and 𝑐′𝐾⁢𝜋=(13±4)×10−6, where √𝑅𝐾⁢𝜋⁢𝑐𝐾⁢𝜋 is the linear coefficient of the expansion of the ratio as a function of decay time in units of the 𝐷0 lifetime, and 𝑐′𝐾⁢𝜋 is the quadratic coefficient, both averaged between the 𝐾+ 𝜋− and 𝐾− 𝜋+ final states. The precision is improved relative to the previous best measurement by approximately 60%. No evidence for 𝐶⁢𝑃 violation is found.

Keywords: физика частиц, elementary particle physics

Publication based on the results of: Development of theoretical foundations and methods of generative artificial intelligence and their application to heterogeneous domain area (2025)