Measurement of the photon polarization in Λb0 → Λγ decays

LHCb Collaboration

doi:10.1103/PhysRevD.105.L051104

Measurement of the photon polarization in Λ_b⁰ → Λγ decays

LHCb Collaboration

Physics and Astronomy

Research output: Contribution to journal › Letter › peer-review

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Abstract

The photon polarization in b→sγ transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of Λ_b⁰→Λγ decays. A data sample corresponding to an integrated luminosity of 6 fb^-1 collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV is used. The photon polarization is measured to be α_γ=0.82_-0.26-0.13^+0.17+0.04, where the first uncertainty is statistical and the second systematic. This result is in agreement with the Standard Model prediction and previous measurements in b-meson decays. Charge-parity breaking effects are studied for the first time in this observable and found to be consistent with CP symmetry.

Original language	English
Article number	L051104
Number of pages	11
Journal	Physical Review D
Volume	105
Issue number	5
DOIs	https://doi.org/10.1103/PhysRevD.105.L051104
Publication status	Published - 1 Mar 2022

Bibliographical 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: 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); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and 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 NERSC (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 ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and Région Auvergne-Rhône-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and the Science and Technology Program of Guangzhou (China); RFBR, RSF, and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom).

Publisher Copyright:
© 2022 CERN.

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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Cite this

@article{3714871bfbe24fa28de23abfc10d8537,

title = "Measurement of the photon polarization in Λb0 → Λγ decays",

abstract = "The photon polarization in b→sγ transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of Λb0→Λγ decays. A data sample corresponding to an integrated luminosity of 6 fb-1 collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV is used. The photon polarization is measured to be αγ=0.82-0.26-0.13+0.17+0.04, where the first uncertainty is statistical and the second systematic. This result is in agreement with the Standard Model prediction and previous measurements in b-meson decays. Charge-parity breaking effects are studied for the first time in this observable and found to be consistent with CP symmetry.",

author = "{LHCb Collaboration} and R. Aaij and Abdelmotteleb, {A. S.W.} and {Abell{\'a}n Beteta}, C. and F. Abudin{\'e}n and T. Ackernley and B. Adeva and M. Adinolfi and H. Afsharnia and C. Agapopoulou and Aidala, {C. A.} and S. Aiola and Z. Ajaltouni and S. Akar and J. Albrecht and F. Alessio and M. Alexander and {Alfonso Albero}, A. and Z. Aliouche and G. Alkhazov and {Alvarez Cartelle}, P. and S. Amato and Amey, {J. L.} and Y. Amhis and L. An and L. Anderlini and A. Andreianov and M. Andreotti and F. Archilli and A. Artamonov and M. Artuso and K. Arzymatov and E. Aslanides and M. Atzeni and B. Audurier and S. Bachmann and M. Bachmayer and Back, {J. J.} and S. Bifani and R. Calladine and G. Chatzikonstantinidis and N. Cooke and V. Duk and P. Ilten and J. Plews and D. Popov and N. Sahoo and A. Sergi and Slater, {M. W.} and Swallow, {P. N.} and Watson, {N. K.}",

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: 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); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and 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 NERSC (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 ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Sk{\l}odowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R{\'e}gion Auvergne-Rh{\^o}ne-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and the Science and Technology Program of Guangzhou (China); RFBR, RSF, and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom). Publisher Copyright: {\textcopyright} 2022 CERN.",

year = "2022",

month = mar,

day = "1",

doi = "10.1103/PhysRevD.105.L051104",

language = "English",

volume = "105",

journal = "Physical Review D",

issn = "2470-0010",

publisher = "American Physical Society (APS)",

number = "5",

}

TY - JOUR

T1 - Measurement of the photon polarization in Λb0 → Λγ decays

AU - LHCb Collaboration

AU - Aaij, R.

AU - Abdelmotteleb, A. S.W.

AU - Abellán Beteta, C.

AU - Abudinén, F.

AU - Ackernley, T.

AU - Adeva, B.

AU - Adinolfi, M.

AU - Afsharnia, H.

AU - Agapopoulou, C.

AU - Aidala, C. A.

AU - Aiola, S.

AU - Ajaltouni, Z.

AU - Akar, S.

AU - Albrecht, J.

AU - Alessio, F.

AU - Alexander, M.

AU - Alfonso Albero, A.

AU - Aliouche, Z.

AU - Alkhazov, G.

AU - Alvarez Cartelle, P.

AU - Amato, S.

AU - Amey, J. L.

AU - Amhis, Y.

AU - An, L.

AU - Anderlini, L.

AU - Andreianov, A.

AU - Andreotti, M.

AU - Archilli, F.

AU - Artamonov, A.

AU - Artuso, M.

AU - Arzymatov, K.

AU - Aslanides, E.

AU - Atzeni, M.

AU - Audurier, B.

AU - Bachmann, S.

AU - Bachmayer, M.

AU - Back, J. J.

AU - Bifani, S.

AU - Calladine, R.

AU - Chatzikonstantinidis, G.

AU - Cooke, N.

AU - Duk, V.

AU - Ilten, P.

AU - Plews, J.

AU - Popov, D.

AU - Sahoo, N.

AU - Sergi, A.

AU - Slater, M. W.

AU - Swallow, P. N.

AU - Watson, N. K.

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: 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); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and 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 NERSC (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 ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and Région Auvergne-Rhône-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and the Science and Technology Program of Guangzhou (China); RFBR, RSF, and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom). Publisher Copyright: © 2022 CERN.

PY - 2022/3/1

Y1 - 2022/3/1

N2 - The photon polarization in b→sγ transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of Λb0→Λγ decays. A data sample corresponding to an integrated luminosity of 6 fb-1 collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV is used. The photon polarization is measured to be αγ=0.82-0.26-0.13+0.17+0.04, where the first uncertainty is statistical and the second systematic. This result is in agreement with the Standard Model prediction and previous measurements in b-meson decays. Charge-parity breaking effects are studied for the first time in this observable and found to be consistent with CP symmetry.

AB - The photon polarization in b→sγ transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of Λb0→Λγ decays. A data sample corresponding to an integrated luminosity of 6 fb-1 collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV is used. The photon polarization is measured to be αγ=0.82-0.26-0.13+0.17+0.04, where the first uncertainty is statistical and the second systematic. This result is in agreement with the Standard Model prediction and previous measurements in b-meson decays. Charge-parity breaking effects are studied for the first time in this observable and found to be consistent with CP symmetry.

UR - http://www.scopus.com/inward/record.url?scp=85128314941&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.105.L051104

DO - 10.1103/PhysRevD.105.L051104

M3 - Letter

AN - SCOPUS:85128314941

SN - 2470-0010

VL - 105

JO - Physical Review D

JF - Physical Review D

IS - 5

M1 - L051104

ER -