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arXiv · 1903.03074

Measurement of the mass difference between neutral charm-meson eigenstates

LHCb Collaboration·R. Aaij·C. Abellán Beteta·B. Adeva·M. Adinolfi·C. A. Aidala·Z. Ajaltouni·S. Akar·P. Albicocco·J. Albrecht·F. Alessio·M. Alexander·A. Alfonso Albero·G. Alkhazov·P. Alvarez Cartelle·A. A. Alves Jr·S. Amato·Y. Amhis·L. An·L. Anderlini·G. Andreassi·M. Andreotti·J. E. Andrews·F. Archilli·J. Arnau Romeu·A. Artamonov·M. Artuso·K. Arzymatov·E. Aslanides·M. Atzeni·B. Audurier·S. Bachmann·J. J. Back·S. Baker·V. Balagura·W. Baldini·A. Baranov·R. J. Barlow·G. C. Barrand·S. Barsuk·W. Barter·M. Bartolini·F. Baryshnikov·V. Batozskaya·B. Batsukh·A. Battig·V. Battista·A. Bay·F. Bedeschi·I. Bediaga·A. Beiter·L. J. Bel·S. Belin·N. Beliy·V. Bellee·N. Belloli·K. Belous·I. Belyaev·G. Bencivenni·E. Ben-Haim·S. Benson·S. Beranek·A. Berezhnoy·R. Bernet·D. Berninghoff·E. Bertholet·A. Bertolin·C. Betancourt·F. Betti·M. O. Bettler·Ia. Bezshyiko·S. Bhasin·J. Bhom·M. S. Bieker·S. Bifani·P. Billoir·A. Birnkraut·A. Bizzeti·M. Bjørn·M. P. Blago·T. Blake·F. Blanc·S. Blusk·D. Bobulska·V. Bocci·O. Boente Garcia·T. Boettcher·A. Bondar·N. Bondar·S. Borghi·M. Borisyak·M. Borsato·M. Boubdir·T. J. V. Bowcock·C. Bozzi·S. Braun·M. Brodski·J. Brodzicka·A. Brossa Gonzalo·D. Brundu
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Abstract

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 $2.3\times 10^6$ $D^0\to K_S^0\pi^+\pi^-$ 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 $x_{CP} = \left[2.7\pm1.6\text{(stat)}\pm0.4\text{(syst)}\right]\times10^{-3}$ and the $CP$-violating parameter $\Delta x = \left[-0.53\pm0.70\text{(stat)}\pm0.22\text{(syst)}\right]\times10^{-3}$. 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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LHCb Collaboration, R. Aaij, C. Abellán Beteta, B. Adeva, M. Adinolfi, C. A. Aidala, Z. Ajaltouni, S. Akar, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, J. E. Andrews, F. Archilli, J. Arnau Romeu, A. Artamonov, M. Artuso, K. Arzymatov, E. Aslanides, M. Atzeni, B. Audurier, S. Bachmann, J. J. Back, S. Baker, V. Balagura, W. Baldini, A. Baranov, R. J. Barlow, G. C. Barrand, S. Barsuk, W. Barter, M. Bartolini, F. Baryshnikov, V. Batozskaya, B. Batsukh, A. Battig, V. Battista, A. Bay, F. Bedeschi, I. Bediaga, A. Beiter, L. J. Bel, S. Belin, N. Beliy, V. Bellee, N. Belloli, K. Belous, I. Belyaev, G. Bencivenni, E. Ben-Haim, S. Benson, S. Beranek, A. Berezhnoy, R. Bernet, D. Berninghoff, E. Bertholet, A. Bertolin, C. Betancourt, F. Betti, M. O. Bettler, Ia. Bezshyiko, S. Bhasin, J. Bhom, M. S. Bieker, S. Bifani, P. Billoir, A. Birnkraut, A. Bizzeti, M. Bjørn, M. P. Blago, T. Blake, F. Blanc, S. Blusk, D. Bobulska, V. Bocci, O. Boente Garcia, T. Boettcher, A. Bondar, N. Bondar, S. Borghi, M. Borisyak, M. Borsato, M. Boubdir, T. J. V. Bowcock, C. Bozzi, S. Braun, M. Brodski, J. Brodzicka, A. Brossa Gonzalo, D. Brundu. 2019-03-07. Measurement of the mass difference between neutral charm-meson eigenstates. https://doi.org/10.1103/physrevlett.122.231802

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