2019/03/31 by LHCb Collaboration, R. Aaij, C. Abellán Beteta +842 · 1 citation
Physics and Astronomy · #hep-ex
paper · pdf · doi:10.1103/physrevlett.122.231802
published as Phys. Rev. Lett. 122, 231802 (2019) · All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-001.html (LHCb public pages)
arxiv created 2019/06/15 · arxiv updated 2019/06/19
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.