Measurement of the Mass Difference between Neutral Charm-Meson Eigenstates

Academic Article


  • © 2019 CERN. for the LHCb Collaboration. Published 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 SCOAP 3 . We report a measurement of the mass difference between neutral charm-meson eigenstates using a novel approach that enhances sensitivity to this parameter. We use 2.3×106 D0→KS0π+π- decays reconstructed in proton-proton collisions collected by the LHCb experiment in 2011 and 2012. Allowing for CP violation in mixing and in the interference between mixing and decay, we measure the CP-averaged normalized mass difference xCP=[2.7±1.6(stat)±0.4(syst)]×10-3 and the CP-violating parameter Δx=[-0.53±0.70(stat)±0.22(syst)]×10-3. The results are consistent with CP symmetry. These determinations are the most precise from a single experiment and, combined with current world-average results, yield the first evidence that the masses of the neutral charm-meson eigenstates differ.
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    Author List

  • Aaij R; Abellán Beteta C; Adeva B; Adinolfi M; Aidala CA; Ajaltouni Z; Akar S; Albicocco P; Albrecht J; Alessio F
  • Volume

  • 122
  • Issue

  • 23