Measurement of the Mass Difference between Neutral Charm-Meson Eigenstates

(LHCb Collaboration)

Research output: Contribution to JournalArticleAcademicpeer-review

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 2.3×106 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.

Original languageEnglish
Article number231802
JournalPhysical Review Letters
Volume122
Issue number23
DOIs
Publication statusPublished - 14 Jun 2019

Funding

We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG, and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland), and OSC (USA). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from the AvH Foundation (Germany); EPLANET, Marie Skłodowska-Curie Actions, and ERC (European Union); ANR, Labex P2IO, OCEVU, and Région Auvergne-Rhône-Alpes (France); the Key Research Program of Frontier Sciences of CAS, CAS PIFI, and the Thousand Talents Program (China); RFBR, RSF, and Yandex, LLC (Russia); GVA, XuntaGal, and GENCAT (Spain); the Royal Society and the Leverhulme Trust (United Kingdom); and Laboratory Directed Research and Development program of LANL (USA).

FundersFunder number
Not addedST/J004332/1, ST/N000250/1, ST/K003410/1, 1796908, ST/N000331/1, ST/L003163/1, ST/N000242/1
AvH Foundation
CNRS/IN2P3
EPLANET
MSHE
OCEVU
XuntaGal
National Science Foundation
Laboratory Directed Research and Development
Los Alamos National Laboratory
School of Energy Resources, University of Wyoming
Horizon 2020 Framework Programme792684
H2020 Marie Skłodowska-Curie Actions
CERN
College of Arts and Sciences, University of Nebraska-Lincoln
Science and Technology Facilities CouncilST/N000234/1, GRIDPP
Leverhulme Trust
Royal Society
European Research Council
Deutsche Forschungsgemeinschaft
Agence Nationale de la Recherche
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
National Natural Science Foundation of China
Russian Foundation for Basic Research
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Bundesministerium für Bildung und Forschung
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Generalitat Valenciana
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Ministry of Science and Technology
Instituto Nazionale di Fisica Nucleare
Narodowe Centrum Nauki
Ministerstwo Nauki i Szkolnictwa Wyższego
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
National Academy of Sciences of Ukraine
Financiadora de Estudos e Projetos
Russian Science Foundation
Région Auvergne-Rhône-Alpes
Recruitment Program of Global Experts

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