Observation of the Mass Difference Between Neutral Charm-Meson Eigenstates

LHCb collaboration, R.H. O'Neil

Research output: Contribution to journal β€Ί Article β€Ί peer-review

Abstract / Description of output

A measurement of mixing and 𝐢⁒𝑃 violation in neutral charm mesons is performed using data reconstructed in proton-proton collisions collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4  fbβˆ’1. A total of 30.6 million 𝐷0→𝐾0Sβ’πœ‹+β’πœ‹βˆ’ decays are analyzed using a method optimized for the measurement of the mass difference between neutral charm-meson eigenstates. Allowing for 𝐢⁒𝑃 violation in mixing and in the interference between mixing and decay, the mass and decay-width differences are measured to be π‘₯𝐢⁒𝑃=[3.97Β±0.46⁒(stat)Β±0.29⁒(syst)]Γ—1⁒0βˆ’3 and 𝑦𝐢⁒𝑃=[4.59Β±1.20⁒(stat)Β±0.85⁒(syst)]Γ—1⁒0βˆ’3, respectively. The 𝐢⁒𝑃-violating parameters are measured as Δ⁒π‘₯=[βˆ’0.27Β±0.18⁒(stat)Β±0.01⁒(syst)]Γ—1⁒0βˆ’3 and Δ⁒𝑦=[0.20Β±0.36⁒(stat)Β±0.13⁒(syst)]Γ—1⁒0βˆ’3. This is the first observation of a nonzero mass difference in the 𝐷0 meson system, with a significance exceeding seven standard deviations. The data are consistent with 𝐢⁒𝑃 symmetry and improve existing constraints on the associated parameters.
Original languageEnglish
Article number111801
Pages (from-to)1-12
Number of pages12
JournalPhysical Review Letters
Issue number11
Publication statusPublished - 7 Sept 2021


Dive into the research topics of 'Observation of the Mass Difference Between Neutral Charm-Meson Eigenstates'. Together they form a unique fingerprint.

Cite this