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Measurement of the photon polarization in Λb0→Λγ decays

R. Aaij32, A. S. W. Abdelmotteleb56, C. Abellán Beteta50, F. Abudinén56, T. Ackernley60, B. Adeva46, M. Adinolfi54, H. Afsharnia9, C. Agapopoulou13 et al. (LHCb Collaboration)

C. Agapopoulou13, C. A. Aidala87, S. Aiola25, Z. Ajaltouni9, S. Akar65, J. Albrecht15, F. Alessio48, M. Alexander59, A. Alfonso Albero45, Z. Aliouche62, G. Alkhazov38, P. Alvarez Cartelle55, S. Amato2, J. L. Amey54, Y. Amhis11, L. An48, L. Anderlini22, A. Andreianov38, M. Andreotti21, F. Archilli17, A. Artamonov44, M. Artuso68, K. Arzymatov42, E. Aslanides10, M. Atzeni50, B. Audurier12, S. Bachmann17, M. Bachmayer49, J. J. Back56, P. Baladron Rodriguez46, V. Balagura12, W. Baldini21, J. Baptista Leite1, M. Barbetti22, R. J. Barlow62, S. Barsuk11, W. Barter61, M. Bartolini24,b, F. Baryshnikov83, J. M. Basels14, S. Bashir34, G. Bassi29, B. Batsukh68, A. Battig15, A. Bay49, A. Beck56, M. Becker15, F. Bedeschi29, I. Bediaga1, A. Beiter68, V. Belavin42, S. Belin27, V. Bellee50, K. Belous44, I. Belov40, I. Belyaev41, G. Bencivenni23, E. Ben-Haim13, A. Berezhnoy40, R. Bernet50, D. Berninghoff17, H. C. Bernstein68, C. Bertella62, A. Bertolin28, C. Betancourt50, F. Betti48, Ia. Bezshyiko50, S. Bhasin54, J. Bhom35, L. Bian73, M. S. Bieker15, S. Bifani53, P. Billoir13, M. Birch61, F. C. R. Bishop55, A. Bitadze62, A. Bizzeti22,c, M. Bjørn63, M. P. Blago48, T. Blake56, F. Blanc49, S. Blusk68, D. Bobulska59, J. A. Boelhauve15, O. Boente Garcia46, T. Boettcher65, A. Boldyrev82, A. Bondar43, N. Bondar38,48, S. Borghi62, M. Borisyak42, M. Borsato17, J. T. Borsuk35, S. A. Bouchiba49, T. J. V. Bowcock60, A. Boyer48, C. Bozzi21, M. J. Bradley61, S. Braun66, A. Brea Rodriguez46, J. Brodzicka35, A. Brossa Gonzalo56, D. Brundu27, A. Buonaura50, L. Buonincontri28, A. T. Burke62, C. Burr48, A. Bursche72, A. Butkevich39, J. S. Butter32, J. Buytaert48, W. Byczynski48, S. Cadeddu27, H. Cai73, R. Calabrese21,d, L. Calefice15,13, L. Calero Diaz23, S. Cali23, R. Calladine53, M. Calvi26,e, M. Calvo Gomez85, P. Camargo Magalhaes54, P. Campana23, A. F. Campoverde Quezada6, S. Capelli26,e, L. Capriotti20,f, A. Carbone20,f, G. Carboni31, R. Cardinale24,b, A. Cardini27, I. Carli4, P. Carniti26,e, L. Carus14, K. Carvalho Akiba32, A. Casais Vidal46, G. Casse60, M. Cattaneo48, G. Cavallero48, S. Celani49, J. Cerasoli10, D. Cervenkov63, A. J. Chadwick60, M. G. Chapman54, M. Charles13, Ph. Charpentier48, G. Chatzikonstantinidis53, C. A. Chavez Barajas60, M. Chefdeville8, C. Chen3, S. Chen4, A. Chernov35, V. Chobanova46, S. Cholak49, M. Chrzaszcz35, A. Chubykin38, V. Chulikov38, P. Ciambrone23, M. F. Cicala56, X. Cid Vidal46, G. Ciezarek48, P. E. L. Clarke58, M. Clemencic48, H. V. Cliff55, J. Closier48, J. L. Cobbledick62, V. Coco48, J. A. B. Coelho11, J. Cogan10, E. Cogneras9, L. Cojocariu37, P. Collins48, T. Colombo48, L. Congedo19,g, A. Contu27, N. Cooke53, G. Coombs59, I. Corredoira46, G. Corti48, C. M. Costa Sobral56, B. Couturier48, D. C. Craik64, J. Crkovská67, M. Cruz Torres1, R. Currie58, C. L. Da Silva67, S. Dadabaev83, L. Dai71, E. Dall’Occo15, J. Dalseno46, C. D’Ambrosio48, A. Danilina41, P. d’Argent48, J. E. Davies62, A. Davis62, O. De Aguiar Francisco62, K. De Bruyn79, S. De Capua62, M. De Cian49, J. M. De Miranda1, L. De Paula2, M. De Serio19,g, D. De Simone50, P. De Simone23, F. De Vellis15, J. A. de Vries80, C. T. Dean67, F. Debernardis19,g, D. Decamp8, V. Dedu10, L. Del Buono13, B. Delaney55, H.-P. Dembinski15, A. Dendek34, V. Denysenko50, D. Derkach82, O. Deschamps9, F. Desse11, F. Dettori27,h, B. Dey77, A. Di Cicco23, P. Di Nezza23, S. Didenko83, L. Dieste Maronas46, H. Dijkstra48, V. Dobishuk52, C. Dong3, A. M. Donohoe18, F. Dordei27, A. C. dos Reis1, L. Douglas59, A. Dovbnya51, A. G. Downes8, M. W. Dudek35, L. Dufour48, V. Duk78, P. Durante48, J. M. Durham67, D. Dutta62, A. Dziurda35, A. Dzyuba38, S. Easo57, U. Egede69, V. Egorychev41, S. Eidelman43,a,i, S. Eisenhardt58, S. Ek-In49, L. Eklund59,86, S. Ely68, A. Ene37, E. Epple67, S. Escher14, J. Eschle50, S. Esen13, T. Evans48, A. Falabella20, J. Fan3, Y. Fan6, B. Fang73, S. Farry60, D. Fazzini26,e, M. Féo48, A. Fernandez Prieto46, A. D. Fernez66, F. Ferrari20,f, L. Ferreira Lopes49, F. Ferreira Rodrigues2, S. Ferreres Sole32, M. Ferrillo50, M. Ferro-Luzzi48, S. Filippov39, R. A. Fini19, M. Fiorini21,d, M. Firlej34, K. M. Fischer63, D. S. Fitzgerald87, C. Fitzpatrick62, T. Fiutowski34, A. Fkiaras48, F. Fleuret12, M. Fontana13, F. Fontanelli24,b, R. Forty48, D. Foulds-Holt55, V. Franco Lima60, M. Franco Sevilla66, M. Frank48, E. Franzoso21, G. Frau17, C. Frei48, D. A. Friday59, J. Fu6, Q. Fuehring15, E. Gabriel32, G. Galati19,g, A. Gallas Torreira46, D. Galli20,f, S. Gambetta58,48, Y. Gan3, M. Gandelman2, P. Gandini25, Y. Gao5, M. Garau27, L. M. Garcia Martin56, P. Garcia Moreno45, J. García Pardiñas26,e, B. Garcia Plana46, F. A. Garcia Rosales12, L. Garrido45, C. Gaspar48, R. E. Geertsema32, D. Gerick17, L. L. Gerken15, E. Gersabeck62, M. Gersabeck62, T. Gershon56, D. Gerstel10, L. Giambastiani28, V. Gibson55, H. K. Giemza36, A. L. Gilman63, M. Giovannetti23,j, A. Gioventù46, P. Gironella Gironell45, L. Giubega37, C. Giugliano21,48,d, K. Gizdov58, E. L. Gkougkousis48, V. V. Gligorov13, C. Göbel70, E. Golobardes85, D. Golubkov41, A. Golutvin61,83, A. Gomes1,k, S. Gomez Fernandez45, F. Goncalves Abrantes63, M. Goncerz35, G. Gong3, P. Gorbounov41, I. V. Gorelov40, C. Gotti26, E. Govorkova48, J. P. Grabowski17, T. Grammatico13, L. A. Granado Cardoso48, E. Graugés45, E. Graverini49, G. Graziani22, A. Grecu37, L. M. Greeven32, N. A. Grieser4, L. Grillo62, S. Gromov83, B. R. Gruberg Cazon63, C. Gu3, M. Guarise21, M. Guittiere11, P. A. Günther17, E. Gushchin39, A. Guth14, Y. Guz44, T. Gys48, T. Hadavizadeh69, G. Haefeli49, C. Haen48, J. Haimberger48, T. Halewood-leagas60, P. M. Hamilton66, J. P. Hammerich60, Q. Han7, X. Han17, T. H. Hancock63, E. B. Hansen62, S. Hansmann-Menzemer17, N. Harnew63, T. Harrison60, C. Hasse48, M. Hatch48, J. He6,l, M. Hecker61, K. Heijhoff32, K. Heinicke15, A. M. Hennequin48, K. Hennessy60, L. Henry48, J. Heuel14, A. Hicheur2, D. Hill49, M. Hilton62, S. E. Hollitt15, R. Hou7, Y. Hou8, J. Hu17, J. Hu72, W. Hu7, X. Hu3, W. Huang6, X. Huang73, W. Hulsbergen32, R. J. Hunter56, M. Hushchyn82, D. Hutchcroft60, D. Hynds32, P. Ibis15, M. Idzik34, D. Ilin38, P. Ilten65, A. Inglessi38, A. Ishteev83, K. Ivshin38, R. Jacobsson48, H. Jage14, S. Jakobsen48, E. Jans32, B. K. Jashal47, A. Jawahery66, V. Jevtic15, F. Jiang3, M. John63, D. Johnson48, C. R. Jones55, T. P. Jones56, B. Jost48, N. Jurik48, S. H. Kalavan Kadavath34, S. Kandybei51, Y. Kang3, M. Karacson48, M. Karpov82, F. Keizer48, D. M. Keller68, M. Kenzie56, T. Ketel33, B. Khanji15, A. Kharisova84, S. Kholodenko44, T. Kirn14, V. S. Kirsebom49, O. Kitouni64, S. Klaver32, N. Kleijne29, K. Klimaszewski36, M. R. Kmiec36, S. Koliiev52, A. Kondybayeva83, A. Konoplyannikov41, P. Kopciewicz34, R. Kopecna17, P. Koppenburg32, M. Korolev40, I. Kostiuk32,52, O. Kot52, S. Kotriakhova21,38, P. Kravchenko38, L. Kravchuk39, R. D. Krawczyk48, M. Kreps56, F. Kress61, S. Kretzschmar14, P. Krokovny43,i, W. Krupa34, W. Krzemien36, M. Kucharczyk35, V. Kudryavtsev43,i, H. S. Kuindersma32,33, G. J. Kunde67, T. Kvaratskheliya41, D. Lacarrere48, G. Lafferty62, A. Lai27, A. Lampis27, D. Lancierini50, J. J. Lane62, R. Lane54, G. Lanfranchi23, C. Langenbruch14, J. Langer15, O. Lantwin83, T. Latham56, F. Lazzari29,m, R. Le Gac10, S. H. Lee87, R. Lefèvre9, A. Leflat40, S. Legotin83, O. Leroy10, T. Lesiak35, B. Leverington17, H. Li72, P. Li17, S. Li7, Y. Li4, Y. Li4, Z. Li68, X. Liang68, T. Lin61, R. Lindner48, V. Lisovskyi15, R. Litvinov27, G. Liu72, H. Liu6, Q. Liu6, S. Liu4, A. Lobo Salvia45, A. Loi27, J. Lomba Castro46, I. Longstaff59, J. H. Lopes2, S. López Soliño46, G. H. Lovell55, Y. Lu4, C. Lucarelli22, D. Lucchesi28,n, S. Luchuk39, M. Lucio Martinez32, V. Lukashenko32,52, Y. Luo3, A. Lupato62, E. Luppi21,d, O. Lupton56, A. Lusiani29,o, X. Lyu6, L. Ma4, R. Ma6, S. Maccolini20,f, F. Machefert11, F. Maciuc37, V. Macko49, P. Mackowiak15, S. Maddrell-Mander54, O. Madejczyk34, L. R. Madhan Mohan54, O. Maev38, A. Maevskiy82, D. Maisuzenko38, M. W. Majewski34, J. J. Malczewski35, S. Malde63, B. Malecki48, A. Malinin81, T. Maltsev43,i, H. Malygina17, G. Manca27,h, G. Mancinelli10, D. Manuzzi20,f, D. Marangotto25,p, J. Maratas9,q, J. F. Marchand8, U. Marconi20, S. Mariani22,r, C. Marin Benito48, M. Marinangeli49, J. Marks17, A. M. Marshall54, P. J. Marshall60, G. Martelli78, G. Martellotti30, L. Martinazzoli48,e, M. Martinelli26,e, D. Martinez Santos46, F. Martinez Vidal47, A. Massafferri1, M. Materok14, R. Matev48, A. Mathad50, V. Matiunin41, C. Matteuzzi26, K. R. Mattioli87, A. Mauri32, E. Maurice12, J. Mauricio45, M. Mazurek48, M. McCann61, L. Mcconnell18, T. H. Mcgrath62, N. T. Mchugh59, A. McNab62, R. McNulty18, J. V. Mead60, B. Meadows65, G. Meier15, N. Meinert76, D. Melnychuk36, S. Meloni26,e, M. Merk32,80, A. Merli25,p, L. Meyer Garcia2, M. Mikhasenko48, D. A. Milanes74, E. Millard56, M. Milovanovic48, M.-N. Minard8, A. Minotti26,e, L. Minzoni21,d, S. E. Mitchell58, B. Mitreska62, D. S. Mitzel15, A. Mödden15, R. A. Mohammed63, R. D. Moise61, S. Mokhnenko82, T. Mombächer46, I. A. Monroy74, S. Monteil9, M. Morandin28, G. Morello23, M. J. Morello29,o, J. Moron34, A. B. Morris75, A. G. Morris56, R. Mountain68, H. Mu3, F. Muheim58,48, M. Mulder48, D. Müller48, K. Müller50, C. H. Murphy63, D. Murray62, P. Muzzetto27,48, P. Naik54, T. Nakada49, R. Nandakumar57, T. Nanut49, I. Nasteva2, M. Needham58, I. Neri21, N. Neri25,p, S. Neubert75, N. Neufeld48, R. Newcombe61, E. M. Niel11, S. Nieswand14, N. Nikitin40, N. S. Nolte64, C. Normand8, C. Nunez87, A. Oblakowska-Mucha34, V. Obraztsov44, T. Oeser14, D. P. O’Hanlon54, S. Okamura21, R. Oldeman27,h, F. Oliva58, M. E. Olivares68, C. J. G. Onderwater79, R. H. O’Neil58, J. M. Otalora Goicochea2, T. Ovsiannikova41, P. Owen50, A. Oyanguren47, K. O. Padeken75, B. Pagare56, P. R. Pais48, T. Pajero63, A. Palano19, M. Palutan23, Y. Pan62, G. Panshin84, A. Papanestis57, M. Pappagallo19,g, L. L. Pappalardo21,d, C. Pappenheimer65, W. Parker66, C. Parkes62, B. Passalacqua21, G. Passaleva22, A. Pastore19, M. Patel61, C. Patrignani20,f, C. J. Pawley80, A. Pearce48, A. Pellegrino32, M. Pepe Altarelli48, S. Perazzini20, D. Pereima41, A. Pereiro Castro46, P. Perret9, M. Petric59,48, K. Petridis54, A. Petrolini24,b, A. Petrov81, S. Petrucci58, M. Petruzzo25, T. T. H. Pham68, A. Philippov42, L. Pica29,o, M. Piccini78, B. Pietrzyk8, G. Pietrzyk49, M. Pili63, D. Pinci30, F. Pisani48, M. Pizzichemi26,48,e, Resmi P. K10, V. Placinta37, J. Plews53, M. Plo Casasus46, F. Polci13, M. Poli Lener23, M. Poliakova68, A. Poluektov10, N. Polukhina83,s, I. Polyakov68, E. Polycarpo2, S. Ponce48, D. Popov6,48, S. Popov42, S. Poslavskii44, K. Prasanth35, L. Promberger48, C. Prouve46, V. Pugatch52, V. Puill11, H. Pullen63, G. Punzi29,t, H. Qi3, W. Qian6, J. Qin6, N. Qin3, R. Quagliani49, B. Quintana8, N. V. Raab18, R. I. Rabadan Trejo6, B. Rachwal34, J. H. Rademacker54, M. Rama29, M. Ramos Pernas56, M. S. Rangel2, F. Ratnikov42,82, G. Raven33, M. Reboud8, F. Redi49, F. Reiss62, C. Remon Alepuz47, Z. Ren3, V. Renaudin63, R. Ribatti29, S. Ricciardi57, K. Rinnert60, P. Robbe11, G. Robertson58, A. B. Rodrigues49, E. Rodrigues60, J. A. Rodriguez Lopez74, E. R. R. Rodriguez Rodriguez46, A. Rollings63, P. Roloff48, V. Romanovskiy44, M. Romero Lamas46, A. Romero Vidal46, J. D. Roth87, M. Rotondo23, M. S. Rudolph68, T. Ruf48, R. A. Ruiz Fernandez46, J. Ruiz Vidal47, A. Ryzhikov82, J. Ryzka34, J. J. Saborido Silva46, N. Sagidova38, N. Sahoo56, B. Saitta27,h, M. Salomoni48, C. Sanchez Gras32, R. Santacesaria30, C. Santamarina Rios46, M. Santimaria23, E. Santovetti31,j, D. Saranin83, G. Sarpis14, M. Sarpis75, A. Sarti30, C. Satriano30,u, A. Satta31, M. Saur15, D. Savrina41,40, H. Sazak9, L. G. Scantlebury Smead63, A. Scarabotto13, S. Schael14, S. Scherl60, M. Schiller59, H. Schindler48, M. Schmelling16, B. Schmidt48, S. Schmitt14, O. Schneider49, A. Schopper48, M. Schubiger32, S. Schulte49, M. H. Schune11, R. Schwemmer48, B. 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Zunica62 (LHCb Collaboration)

  • 1Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
  • 2Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
  • 3Center for High Energy Physics, Tsinghua University, Beijing, China
  • 4Institute Of High Energy Physics (IHEP), Beijing, China
  • 5School of Physics State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
  • 6University of Chinese Academy of Sciences, Beijing, China
  • 7Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China
  • 8Univ. Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France
  • 9Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
  • 10Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
  • 11Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • 12Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France
  • 13LPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, France
  • 14I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
  • 15Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
  • 16Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
  • 17Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
  • 18School of Physics, University College Dublin, Dublin, Ireland
  • 19INFN Sezione di Bari, Bari, Italy
  • 20INFN Sezione di Bologna, Bologna, Italy
  • 21INFN Sezione di Ferrara, Ferrara, Italy
  • 22INFN Sezione di Firenze, Firenze, Italy
  • 23INFN Laboratori Nazionali di Frascati, Frascati, Italy
  • 24INFN Sezione di Genova, Genova, Italy
  • 25INFN Sezione di Milano, Milano, Italy
  • 26INFN Sezione di Milano-Bicocca, Milano, Italy
  • 27INFN Sezione di Cagliari, Monserrato, Italy
  • 28Universita degli Studi di Padova, Universita e INFN, Padova, Padova, Italy
  • 29INFN Sezione di Pisa, Pisa, Italy
  • 30INFN Sezione di Roma La Sapienza, Roma, Italy
  • 31INFN Sezione di Roma Tor Vergata, Roma, Italy
  • 32Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands
  • 33Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, Netherlands
  • 34AGH—University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland
  • 35Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
  • 36National Center for Nuclear Research (NCBJ), Warsaw, Poland
  • 37Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania
  • 38Petersburg Nuclear Physics Institute NRC Kurchatov Institute (PNPI NRC KI), Gatchina, Russia
  • 39Institute for Nuclear Research of the Russian Academy of Sciences (INR RAS), Moscow, Russia
  • 40Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia
  • 41Institute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, Russia
  • 42Yandex School of Data Analysis, Moscow, Russia
  • 43Budker Institute of Nuclear Physics (SB RAS), Novosibirsk, Russia
  • 44Institute for High Energy Physics NRC Kurchatov Institute (IHEP NRC KI), Protvino, Russia, Protvino, Russia
  • 45ICCUB, Universitat de Barcelona, Barcelona, Spain
  • 46Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
  • 47Instituto de Fisica Corpuscular, Centro Mixto Universidad de Valencia—CSIC, Valencia, Spain
  • 48European Organization for Nuclear Research (CERN), Geneva, Switzerland
  • 49Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
  • 50Physik-Institut, Universität Zürich, Zürich, Switzerland
  • 51NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
  • 52Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine
  • 53University of Birmingham, Birmingham, United Kingdom
  • 54H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom
  • 55Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
  • 56Department of Physics, University of Warwick, Coventry, United Kingdom
  • 57STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
  • 58School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
  • 59School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom
  • 60Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom
  • 61Imperial College London, London, United Kingdom
  • 62Department of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
  • 63Department of Physics, University of Oxford, Oxford, United Kingdom
  • 64Massachusetts Institute of Technology, Cambridge, MA, United States
  • 65University of Cincinnati, Cincinnati, OH, United States
  • 66University of Maryland, College Park, MD, United States
  • 67Los Alamos National Laboratory (LANL), Los Alamos, United States
  • 68Syracuse University, Syracuse, NY, United States
  • 69School of Physics and Astronomy, Monash University, Melbourne, Australia (associated with Department of Physics, University of Warwick, Coventry, United Kingdom)
  • 70Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil (associated with Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil)
  • 71Physics and Micro Electronic College, Hunan University, Changsha City, China (associated with Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China)
  • 72Guangdong Provincial Key Laboratory of Nuclear Science, Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Institute of Quantum Matter, South China Normal University, Guangzhou, China (associated with Center for High Energy Physics, Tsinghua University, Beijing, China)
  • 73School of Physics and Technology, Wuhan University, Wuhan, China (associated with Center for High Energy Physics, Tsinghua University, Beijing, China)
  • 74Departamento de Fisica, Universidad Nacional de Colombia, Bogota, Colombia (associated with LPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, France)
  • 75Universität Bonn—Helmholtz-Institut für Strahlen und Kernphysik, Bonn, Germany (associated with Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany)
  • 76Institut für Physik, Universität Rostock, Rostock, Germany (associated with Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany)
  • 77Eotvos Lorand University, Budapest, Hungary (associated with European Organization for Nuclear Research (CERN), Geneva, Switzerland)
  • 78INFN Sezione di Perugia, Perugia, Italy (associated with INFN Sezione di Ferrara, Ferrara, Italy)
  • 79Van Swinderen Institute, University of Groningen, Groningen, Netherlands (associated with Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands)
  • 80Universiteit Maastricht, Maastricht, Netherlands (associated with Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands)
  • 81National Research Centre Kurchatov Institute, Moscow, Russia (associated with Institute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, Russia)
  • 82National Research University Higher School of Economics, Moscow, Russia (associated with Yandex School of Data Analysis, Moscow, Russia)
  • 83National University of Science and Technology “MISIS”, Moscow, Russia (associated with Institute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, Russia)
  • 84National Research Tomsk Polytechnic University, Tomsk, Russia (associated with Institute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, Russia)
  • 85DS4DS, La Salle, Universitat Ramon Llull, Barcelona, Spain (associated with ICCUB, Universitat de Barcelona, Barcelona, Spain)
  • 86Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden (associated with School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom)
  • 87University of Michigan, Ann Arbor, United States (associated with Syracuse University, Syracuse, NY, United States)

  • *Full author list given at the end of the article.
  • aDeceased.
  • bAlso at Università di Genova, Genova, Italy.
  • cAlso at Università di Modena e Reggio Emilia, Modena, Italy.
  • dAlso at Università di Ferrara, Ferrara, Italy.
  • eAlso at Università di Milano Bicocca, Milano, Italy.
  • fAlso at Università di Bologna, Bologna, Italy.
  • gAlso at Università di Bari, Bari, Italy.
  • hAlso at Università di Cagliari, Cagliari, Italy.
  • iAlso at Novosibirsk State University, Novosibirsk, Russia.
  • jAlso at Università di Roma Tor Vergata, Roma, Italy.
  • kAlso at Universidade Federal do Triângulo Mineiro (UFTM), Uberaba-MG, Brazil.
  • lAlso at Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China.
  • mAlso at Università di Siena, Siena, Italy.
  • nAlso at Università di Padova, Padova, Italy.
  • oAlso at Scuola Normale Superiore, Pisa, Italy.
  • pAlso at Università degli Studi di Milano, Milano, Italy.
  • qAlso at MSU—Iligan Institute of Technology (MSU-IIT), Iligan, Philippines.
  • rAlso at Università di Firenze, Firenze, Italy.
  • sAlso at P.N. Lebedev Physical Institute, Russian Academy of Science (LPI RAS), Moscow, Russia.
  • tAlso at Università di Pisa, Pisa, Italy.
  • uAlso at Università della Basilicata, Potenza, Italy.
  • vAlso at Università di Urbino, Urbino, Italy.

Phys. Rev. D 105, L051104 – Published 23 March, 2022

DOI: https://doi.org/10.1103/PhysRevD.105.L051104

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.

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