Observation of the Mass Difference between Neutral Charm-Meson Eigenstates
Name
PhysRevLett.127.111801.pdf
Description
Published version
Size
1.17 MB
Format
Adobe PDF
Checksum (MD5)
320c271e73781f50de57276741b8975c
Author(s)
Williams, Michael
Date Issued
2021
Journal
Physical Review Letters
Publisher
American Physical Society (APS)
Citation
Williams, Michael. 2021. "Observation of the Mass Difference between Neutral Charm-Meson Eigenstates." Physical Review Letters, 127 (11).
Version
Final published version
Abstract
A measurement of mixing and $C\!P$ 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$\textrm{fb}^{-1}$. A total of $30.6$ million $D^{0}\rightarrow
K^{0}_{\mathrm{S}}\pi^{+}\pi^{-}$ decays are analyzed using a method optimized
for the measurement of the mass difference between neutral charm-meson
eigenstates. Allowing for $C\!P$ violation in mixing and in the interference
between mixing and decay, the mass and decay-width differences are measured to
be $x_{C\!P} = \left[3.97\pm0.46\textrm{(stat)}\pm
0.29\textrm{(syst)}\right]\times10^{-3}$ and $y_{C\!P} =
\left[4.59\pm1.20\textrm{(stat)}\pm0.85\textrm{(syst)}\right]\times10^{-3}$,
respectively. The $C\!P$-violating parameters are measured as $\Delta x =
\left[-0.27\pm0.18\textrm{(stat)}\pm0.01\textrm{(syst)}\right]\times10^{-3}$
and $\Delta y =
\left[0.20\pm0.36\textrm{(stat)}\pm0.13\textrm{(syst)}\right]\times10^{-3}$.
This is the first observation of a nonzero mass difference in the $D^0$ meson
system, with a significance exceeding seven standard deviations. The data are
consistent with $C\!P$ symmetry, and improve existing constraints on the
associated parameters.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Creative Commons Attribution 4.0 International License
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DOI of Published Version
https://doi.org/10.1103/PHYSREVLETT.127.111801
