Measurement of CP asymmetry in D0 → K0s K0s decays with the LHCb Run 3 detector

LHCb collaboration

doi:10.1007/JHEP02(2026)253

Measurement of CP asymmetry in D0 → K0s K0s decays with the LHCb Run 3 detector

LHCb collaboration

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

A measurement of CP asymmetry in D0→KS0KS0 decays is reported, based on a data sample of proton-proton collisions collected with the LHCb detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb ⁻¹. The D0→KS0π+π− decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→KS0KS0 mode is measured to be (Formula presented.) where the first uncertainty is statistical, and the second is systematic. This measurement represents the most precise single-experiment determination of this quantity to date.

Original language	English
Article number	253
Journal	Journal of High Energy Physics
Volume	2026
Issue number	2
DOIs	https://doi.org/10.1007/JHEP02(2026)253
Publication status	Published - 1 Feb 2026

Keywords

Charm Physics
CP Violation
Flavour Physics
Hadron-Hadron Scattering

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10.1007/JHEP02(2026)253Licence: CC BY

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@article{0fe310b06fea439da5bf002fd497b86e,

title = "Measurement of CP asymmetry in D0 → K0s K0s decays with the LHCb Run 3 detector",

abstract = "A measurement of CP asymmetry in D0→KS0KS0 decays is reported, based on a data sample of proton-proton collisions collected with the LHCb detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb −1. The D0→KS0π+π− decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→KS0KS0 mode is measured to be (Formula presented.) where the first uncertainty is statistical, and the second is systematic. This measurement represents the most precise single-experiment determination of this quantity to date.",

keywords = "Charm Physics, CP Violation, Flavour Physics, Hadron-Hadron Scattering",

author = "R. Aaij and Abdelmotteleb, \{A. S.W.\} and \{Abellan Beteta\}, C. and F. Abudin{\'e}n and T. Ackernley and Adefisoye, \{A. A.\} and B. Adeva and M. Adinolfi and P. Adlarson and C. Agapopoulou and Aidala, \{C. A.\} and Z. Ajaltouni and S. Akar and K. Akiba and M. Akthar and P. Albicocco and J. Albrecht and R. Aleksiejunas and F. Alessio and \{Alvarez Cartelle\}, P. and R. Amalric and S. Amato and Amey, \{J. L.\} and Y. Amhis and L. An and L. Anderlini and M. Andersson and P. Andreola and M. Andreotti and \{Andres Estrada\}, S. and A. Anelli and D. Ao and C. Arata and F. Archilli and Z. Areg and M. Argenton and \{Arguedas Cuendis\}, S. and L. Arnone and A. Artamonov and M. Artuso and E. Aslanides and \{Ata{\'i}de Da Silva\}, R. and M. Atzeni and B. Audurier and Authier, \{J. A.\} and D. Bacher and \{Bachiller Perea\}, I. and S. Bachmann and M. Bachmayer and Back, \{J. J.\} and \{LHCb collaboration\} and \{da silva Bolognani\}, Carolina and \{Burgos Marcos\}, Marta and \{C{\'a}mpora P{\'e}rez\}, \{Daniel Hugo\} and Xenofon Chiotopoulos and \{de Vries\}, Jacco and Marcel Merk and Davide Nicotra and Gerco Onderwater and Chris Pawley and \{Ruiz Vidal\}, Joan and George Scriven and Keri Vos",

note = "Funding Information: 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: ARC (Australia); CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMFTR, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MCID/IFA (Romania); MICIU and AEI (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (U.S.A.). We acknowledge the computing resources that are provided by ARDC (Australia), CBPF (Brazil), CERN, IHEP and LZU (China), IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), Polish WLCG (Poland), IFIN-HH (Romania), PIC (Spain), CSCS (Switzerland), and GridPP (United Kingdom). 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 Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. \& Tech. Program of Guangzhou (China); Minciencias (Colombia); EPLANET, Marie Sk\textbackslash{}u0142odowska-Curie Actions, ERC and NextGenerationEU (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R\textbackslash{}u00E9gion Auvergne-Rh\textbackslash{}u00F4ne-Alpes (France); Alexander-von-Humboldt Foundation (Germany); ICSC (Italy); Severo Ochoa and Mar\textbackslash{}u00EDa de Maeztu Units of Excellence, GVA, XuntaGal, GENCAT, InTalent-Inditex and Prog. Atracci\textbackslash{}u00F3n Talento CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom). Publisher Copyright: {\textcopyright} The Author(s) 2026.",

year = "2026",

month = feb,

day = "1",

doi = "10.1007/JHEP02(2026)253",

language = "English",

volume = "2026",

journal = "Journal of High Energy Physics",

issn = "1029-8479",

publisher = "Springer Verlag",

number = "2",

}

TY - JOUR

T1 - Measurement of CP asymmetry in D0 → K0s K0s decays with the LHCb Run 3 detector

AU - Aaij, R.

AU - Abdelmotteleb, A. S.W.

AU - Abellan Beteta, C.

AU - Abudinén, F.

AU - Ackernley, T.

AU - Adefisoye, A. A.

AU - Adeva, B.

AU - Adinolfi, M.

AU - Adlarson, P.

AU - Agapopoulou, C.

AU - Aidala, C. A.

AU - Ajaltouni, Z.

AU - Akar, S.

AU - Akiba, K.

AU - Akthar, M.

AU - Albicocco, P.

AU - Albrecht, J.

AU - Aleksiejunas, R.

AU - Alessio, F.

AU - Alvarez Cartelle, P.

AU - Amalric, R.

AU - Amato, S.

AU - Amey, J. L.

AU - Amhis, Y.

AU - An, L.

AU - Anderlini, L.

AU - Andersson, M.

AU - Andreola, P.

AU - Andreotti, M.

AU - Andres Estrada, S.

AU - Anelli, A.

AU - Ao, D.

AU - Arata, C.

AU - Archilli, F.

AU - Areg, Z.

AU - Argenton, M.

AU - Arguedas Cuendis, S.

AU - Arnone, L.

AU - Artamonov, A.

AU - Artuso, M.

AU - Aslanides, E.

AU - Ataíde Da Silva, R.

AU - Atzeni, M.

AU - Audurier, B.

AU - Authier, J. A.

AU - Bacher, D.

AU - Bachiller Perea, I.

AU - Bachmann, S.

AU - Bachmayer, M.

AU - Back, J. J.

AU - LHCb collaboration

AU - da silva Bolognani, Carolina

AU - Burgos Marcos, Marta

AU - Cámpora Pérez, Daniel Hugo

AU - Chiotopoulos, Xenofon

AU - de Vries, Jacco

AU - Merk, Marcel

AU - Nicotra, Davide

AU - Onderwater, Gerco

AU - Pawley, Chris

AU - Ruiz Vidal, Joan

AU - Scriven, George

AU - Vos, Keri

N1 - Funding Information: 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: ARC (Australia); CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMFTR, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MCID/IFA (Romania); MICIU and AEI (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (U.S.A.). We acknowledge the computing resources that are provided by ARDC (Australia), CBPF (Brazil), CERN, IHEP and LZU (China), IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), Polish WLCG (Poland), IFIN-HH (Romania), PIC (Spain), CSCS (Switzerland), and GridPP (United Kingdom). 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 Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. & Tech. Program of Guangzhou (China); Minciencias (Colombia); EPLANET, Marie Sk\u0142odowska-Curie Actions, ERC and NextGenerationEU (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R\u00E9gion Auvergne-Rh\u00F4ne-Alpes (France); Alexander-von-Humboldt Foundation (Germany); ICSC (Italy); Severo Ochoa and Mar\u00EDa de Maeztu Units of Excellence, GVA, XuntaGal, GENCAT, InTalent-Inditex and Prog. Atracci\u00F3n Talento CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom). Publisher Copyright: © The Author(s) 2026.

PY - 2026/2/1

Y1 - 2026/2/1

N2 - A measurement of CP asymmetry in D0→KS0KS0 decays is reported, based on a data sample of proton-proton collisions collected with the LHCb detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb −1. The D0→KS0π+π− decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→KS0KS0 mode is measured to be (Formula presented.) where the first uncertainty is statistical, and the second is systematic. This measurement represents the most precise single-experiment determination of this quantity to date.

AB - A measurement of CP asymmetry in D0→KS0KS0 decays is reported, based on a data sample of proton-proton collisions collected with the LHCb detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb −1. The D0→KS0π+π− decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→KS0KS0 mode is measured to be (Formula presented.) where the first uncertainty is statistical, and the second is systematic. This measurement represents the most precise single-experiment determination of this quantity to date.

KW - Charm Physics

KW - CP Violation

KW - Flavour Physics

KW - Hadron-Hadron Scattering

U2 - 10.1007/JHEP02(2026)253

DO - 10.1007/JHEP02(2026)253

M3 - Article

SN - 1029-8479

VL - 2026

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 2

M1 - 253

ER -

Measurement of CP asymmetry in D0 → K0s K0s decays with the LHCb Run 3 detector

Abstract

Keywords

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