First Observation of CP Violation and Measurement of Polarization in B+ →ρ (770)0K            ∗(892)+ Decays

LHCb collaboration

doi:10.1103/9zhl-kkwg

First Observation of CP Violation and Measurement of Polarization in B⁺ →ρ (770)⁰K ^∗(892)⁺ Decays

LHCb collaboration

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

Abstract

An amplitude analysis of the B+→(π+π-)(KS0π+) decay is performed in the mass regions 0.30<mπ+π-<1.10 GeV/c2 and 0.75<mKS0π+<1.20 GeV/c2, using pp collision data recorded with the LHCb detector corresponding to an integrated luminosity of 9 fb-1. The polarization fractions and CP asymmetries for B+→ρ(770)0K∗(892)+ decays are measured. Violation of the CP symmetry in the decay B+→ρ(770)0K∗(892)+ is observed for the first time, with a significance exceeding 9 standard deviations. The CP asymmetry is measured to be ACP=0.507±0.062(stat)±0.024(syst) and the CP-averaged longitudinal polarization fraction of fL=0.720±0.028(stat)±0.009(syst). The measurements help to shed light on the polarization puzzle of B mesons decaying to two vector mesons.

Original language	English
Article number	021803
Journal	Physical Review Letters
Volume	136
Issue number	2
DOIs	https://doi.org/10.1103/9zhl-kkwg
Publication status	Published - 16 Jan 2026

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@article{d92c42d005f94c288c484723152a7a31,

title = "First Observation of CP Violation and Measurement of Polarization in B+ →ρ (770)0K ∗(892)+ Decays",

abstract = "An amplitude analysis of the B+→(π+π-)(KS0π+) decay is performed in the mass regions 0.30",

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 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 \{Baladron Rodriguez\}, P. 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); BMBF, 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 (USA). 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 Skaodowska-Curie Actions, ERC and NextGenerationEU (European Union); A*MIDEX, ANR, IPhU, and Labex P2IO, and Region Auvergne-Rhne-Alpes (France); Alexander-von-Humboldt Foundation (Germany); ICSC (Italy); Severo Ochoa and Mar-a de Maeztu Units of Excellence, GVA, XuntaGal, GENCAT, InTalent-Inditex and Prog. Atraccian Talento CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom). Publisher Copyright: {\textcopyright} 2026 CERN.",

year = "2026",

month = jan,

day = "16",

doi = "10.1103/9zhl-kkwg",

language = "English",

volume = "136",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "2",

}

TY - JOUR

T1 - First Observation of CP Violation and Measurement of Polarization in B+ →ρ (770)0K ∗(892)+ Decays

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 - 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 - Baladron Rodriguez, P.

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); BMBF, 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 (USA). 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 Skaodowska-Curie Actions, ERC and NextGenerationEU (European Union); A*MIDEX, ANR, IPhU, and Labex P2IO, and Region Auvergne-Rhne-Alpes (France); Alexander-von-Humboldt Foundation (Germany); ICSC (Italy); Severo Ochoa and Mar-a de Maeztu Units of Excellence, GVA, XuntaGal, GENCAT, InTalent-Inditex and Prog. Atraccian Talento CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom). Publisher Copyright: © 2026 CERN.

PY - 2026/1/16

Y1 - 2026/1/16

N2 - An amplitude analysis of the B+→(π+π-)(KS0π+) decay is performed in the mass regions 0.30

AB - An amplitude analysis of the B+→(π+π-)(KS0π+) decay is performed in the mass regions 0.30

U2 - 10.1103/9zhl-kkwg

DO - 10.1103/9zhl-kkwg

M3 - Article

SN - 0031-9007

VL - 136

JO - Physical Review Letters

JF - Physical Review Letters

IS - 2

M1 - 021803

ER -

First Observation of CP Violation and Measurement of Polarization in B+ →ρ (770)0K ∗(892)+ Decays

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First Observation of CP Violation and Measurement of Polarization in B⁺ →ρ (770)⁰K ^∗(892)⁺ Decays