Open Access

Measurement of the Ratio of Branching Fractions $B (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) / B (B_{c}^{+} \to J / ψ μ^{+} ν_{μ})$

R. Aaij ³⁹, M. Abdelfatah⁷¹, A. S. W. Abdelmotteleb ⁵⁹, C. Abellan Beteta ⁵³, F. Abudinén ⁶¹, T. Ackernley ⁶³, A. A. Adefisoye ⁷¹, B. Adeva ⁴⁹, M. Adinolfi ⁵⁷ et al. (LHCb Collaboration)

M. Adinolfi ⁵⁷, P. Adlarson ^87,44, C. Agapopoulou ¹⁵, C. A. Aidala ⁸⁹, S. Akar ¹², K. Akiba ³⁹, H. Al Saleh ⁶¹, P. Albicocco ²⁹, J. Albrecht ^20,b, R. Aleksiejunas ⁸², F. Alessio ⁵¹, P. Alvarez Cartelle ⁴⁹, S. Amato ³, J. L. Amey ⁵⁷, Y. Amhis ¹⁵, L. An ⁶, L. Anderlini ²⁸, M. Andersson ⁵³, P. Andreola ⁵³, M. Andreotti ²⁷, S. Andres Estrada ⁴⁶, A. Anelli ³³, D. Ao ⁷, C. Arata ¹³, F. Archilli ³⁸, Z. Areg ⁷¹, M. Argenton ²⁷, S. Arguedas Cuendis ^10,51, L. Arnone ^32,c, M. Artuso ⁷¹, E. Aslanides ¹⁴, R. Ataíde Da Silva⁵², M. Atzeni ⁶⁷, B. Audurier ¹³, J. A. Authier ¹⁶, D. Bacher ⁶⁶, I. Bachiller Perea ⁵², S. Bachmann ²³, M. Bachmayer ⁵², J. J. Back ⁵⁹, Z. B. Bai ⁹, V. Balagura ¹⁶, A. Balboni ²⁷, W. Baldini ²⁷, Z. Baldwin ⁸⁰, L. Balzani ²⁰, H. Bao ⁷, J. Baptista de Souza Leite ², C. Barbero Pretel ^49,13, M. Barbetti ²⁸, I. R. Barbosa ⁷², R. J. Barlow ^65,a, M. Barnyakov ²⁶, S. Baron⁵¹, S. Barsuk ¹⁵, W. Barter ⁶¹, J. Bartz ⁷¹, S. Bashir ⁴², B. Batsukh ⁸³, P. B. Battista ¹⁵, A. Bavarchee ⁸¹, A. Bay ⁵², A. Beck ⁶⁷, M. Becker ²⁰, F. Bedeschi ³⁶, I. B. Bediaga ², N. A. Behling ²⁰, S. Belin ⁴⁹, A. Bellavista ^26,51, I. Belyaev ³⁷, G. Bencivenni ²⁹, E. Ben-Haim ¹⁷, J. L. M. Berkey ⁷⁰, R. Bernet ⁵³, A. Bertolin ³⁴, F. Betti ²⁶, J. Bex ⁵⁸, O. Bezshyyko ⁸⁸, S. Bhattacharya ⁸¹, M. S. Bieker ¹⁹, N. V. Biesuz ²⁷, A. Biolchini ³⁹, M. Birch ⁶⁴, F. C. R. Bishop ¹¹, A. Bitadze ⁶⁵, A. Bizzeti ^28,d, T. Blake ^59,e, F. Blanc ⁵², J. E. Blank ²⁰, S. Blusk ⁷¹, J. A. Boelhauve ²⁰, O. Boente Garcia ⁵¹, T. Boettcher ⁹⁰, A. Bohare ⁶¹, C. Bolognani ²⁰, R. B. Bonacci ¹, A. Bordelius ⁵¹, F. Borgato ^34,51, S. Borghi ⁶⁵, M. Borsato ^32,c, J. T. Borsuk ⁸⁶, E. Bottalico ⁶³, S. A. Bouchiba ⁵², M. Bovill ⁶⁶, T. J. V. Bowcock ⁶³, A. Boyer ⁵¹, C. Bozzi ²⁷, J. D. Brandenburg ⁹¹, A. Brea Rodriguez ⁵², N. Breer ²⁰, C. Breitfeld ²⁰, J. Brodzicka ⁴³, J. Brown ⁶³, E. Buchanan ⁶¹, M. Burgos Marcos ⁴¹, C. Burr ⁵¹, C. Buti ²⁸, J. S. Butter ⁵⁸, J. Buytaert ⁵¹, W. Byczynski ⁵¹, S. Cadeddu ³³, H. Cai ⁷⁶, Y. Cai ⁵, A. Caillet ¹⁷, R. Calabrese ^27,f, L. Calefice ⁴⁷, M. Calvi ^32,c, M. Calvo Gomez ⁴⁸, P. Camargo Magalhaes ^2,g, J. I. Cambon Bouzas ⁴⁹, P. Campana ²⁹, D. H. Campora Perez ⁴¹, A. C. Campos ³, A. F. Campoverde Quezada ⁷, Y. Cao⁶, S. Capelli ^32,c, M. Caporale ²⁶, L. Capriotti ³⁴, R. Caravaca-Mora ¹⁰, A. Carbone ^26,h, L. Carcedo Salgado ⁴⁹, R. Cardinale ^30,i, A. Cardini ³³, P. Carniti ³², L. Carus ²³, A. Casais Vidal ⁶⁷, R. Caspary ²³, G. Casse ⁶³, M. Cattaneo ⁵¹, G. Cavallero ²⁷, V. Cavallini ^27,f, S. Celani ⁵¹, I. Celestino ^36,j, S. Cesare ^51,k, A. J. Chadwick ⁶³, I. Chahrour ⁸⁹, M. Charles ¹⁷, Ph. Charpentier ⁵¹, E. Chatzianagnostou ³⁹, R. Cheaib ⁸¹, M. Chefdeville ¹¹, C. Chen ⁵⁹, J. Chen ⁵², S. Chen ⁵, Z. Chen ⁷, A. Chen Hu ⁶⁴, M. Cherif ¹³, S. Chernyshenko ⁵⁵, X. Chiotopoulos ⁴¹, G. Chizhik ¹, V. Chobanova ⁴⁶, A. Christakakis ¹, M. Chrzaszcz ⁴³, V. Chulikov ^29,51,37, P. Ciambrone ²⁹, X. Cid Vidal ⁴⁹, P. Cifra ⁵¹, P. E. L. Clarke ⁶¹, M. Clemencic ⁵¹, H. V. Cliff ⁵⁸, J. Closier ⁵¹, C. Cocha Toapaxi ²³, V. Coco ⁵¹, J. Cogan ¹⁴, E. Cogneras ¹², L. Cojocariu ⁴⁵, S. Collaviti ⁵², P. Collins ⁵¹, T. Colombo ⁵¹, M. Colonna ²⁰, A. Comerma-Montells ⁴⁷, L. Congedo ²⁵, J. Connaughton ⁵⁹, A. Contu ³³, N. Cooke ⁶², G. Cordova ^36,j, C. Coronel ⁶⁸, I. Corredoira ¹³, A. Correia ¹⁷, G. Corti ⁵¹, G. C. Costantino ⁶³, J. Cottee Meldrum ⁵⁷, B. Couturier ⁵¹, D. C. Craik ⁵³, N. Crepet ¹⁵, M. Cruz Torres ^2,l, M. Cubero Campos ¹⁰, E. Curras Rivera ⁵², R. Currie ⁶¹, C. L. Da Silva ⁷⁰, X. Dai ⁴, J. Dalseno ⁴⁶, C. D’Ambrosio ⁶⁴, G. Darze ³, A. Davidson ⁵⁹, J. E. Davies ⁶⁵, O. De Aguiar Francisco ⁶⁵, C. De Angelis ³³, F. De Benedetti ⁵¹, J. de Boer ³⁹, K. De Bruyn ⁸⁴, S. De Capua ⁶⁵, M. De Cian ⁶⁵, U. De Freitas Carneiro Da Graca ², E. De Lucia ²⁹, J. M. De Miranda ², L. De Paula ³, M. De Serio ^25,m, P. De Simone ²⁹, F. De Vellis ²⁰, J. A. de Vries ⁴¹, F. Debernardis ²⁵, D. Decamp ¹¹, S. Dekkers ¹, L. Del Buono ¹⁷, B. Delaney ⁶⁷, J. Deng ⁹, V. Denysenko ⁵³, O. Deschamps ¹², F. Dettori ^33,n, B. Dey ⁸¹, P. Di Nezza ²⁹, S. Ding ⁷¹, Y. Ding ⁵², L. Dittmann ²³, A. D. Docheva ⁶², A. Doheny ⁵⁹, C. Dong ⁴, F. Dordei ³³, A. C. dos Reis ², J. Dos Santos Oliveira², A. D. Dowling ⁷¹, L. Dreyfus ¹⁴, W. Duan ⁷⁵, P. Duda ⁸⁶, L. Dufour ⁵², V. Duk ³⁵, P. Durante ⁵¹, M. M. Duras ⁸⁶, J. M. Durham ⁷⁰, O. D. Durmus ⁸¹, K. Duwe ⁵¹, A. Dziurda ⁴³, S. Easo ⁶⁰, E. Eckstein ¹⁹, U. Egede ¹, S. Eisenhardt ⁶¹, E. Ejopu ⁶³, L. Eklund ⁸⁷, M. Elashri ⁶⁸, D. Elizondo Blanco ¹⁰, J. Ellbracht ²⁰, S. Ely ⁶⁴, A. Ene ⁴⁵, T. Evans ³⁹, F. Fabiano ¹⁵, S. Faghih ⁶⁸, L. N. Falcao ^32,c, B. Fang ⁷, R. Fantechi ³⁶, L. Fantini ^35,o, M. Faria ⁵², K. Farmer ⁶¹, F. Fassin ^84,39, D. Fazzini ^32,c, L. Felkowski ⁸⁶, C. Feng⁶, M. Feng ^5,7, A. Fernandez Casani ⁵⁰, M. Fernandez Gomez ⁴⁹, A. D. Fernez ⁶⁹, F. Ferrari ^26,h, F. Ferreira Rodrigues ³, M. Ferro-Luzzi ⁵¹, R. A. Fini ²⁵, M. Fiorini ^27,f, M. Firlej ⁴², D. S. Fitzgerald ⁸⁹, C. Fitzpatrick ⁶⁵, T. Fiutowski ⁴², F. Fleuret ¹⁶, A. Fomin ⁵⁴, M. Fontana ^26,51, M. Fontes Vaz⁷², L. A. Foreman ⁶⁵, R. Forty ⁵¹, D. Foulds-Holt ⁶¹, V. Franco Lima ³, M. Franco Sevilla ⁶⁹, M. Frank ⁵¹, E. Franzoso ^27,f, G. Frau ⁶⁵, C. Frei ⁵¹, D. A. Friday ^65,51, J. Fu ⁷, Y. Fu⁵, Q. Führing ^20,58,b, T. Fulghesu ¹⁴, G. Galati ^25,m, M. D. Galati ³⁹, A. Gallas Torreira ⁴⁹, D. Galli ^26,h, S. Gambetta ⁶¹, M. Gandelman ³, P. Gandini ³¹, B. Ganie ⁶⁵, H. Gao ⁷, R. Gao ⁶⁶, T. Q. Gao ⁵⁸, Y. Gao ⁹, Y. Gao ⁶, Y. Gao ⁹, L. M. Garcia Martin ⁵², P. Garcia Moreno ⁴⁷, J. García Pardiñas⁶⁷, P. Gardner ⁶⁹, L. Garrido ⁴⁷, C. Gaspar ⁵¹, A. Gavrikov ³⁴, E. Gersabeck ²¹, M. Gersabeck ²¹, T. Gershon ⁵⁹, S. Ghizzo ^30,i, Z. Ghorbanimoghaddam ⁵⁷, F. I. Giasemis ^17,p, V. Gibson ⁵⁸, H. K. Giemza ⁴⁴, A. L. Gilman ⁶⁸, M. Giovannetti ²⁹, A. Gioventù ⁴⁹, L. Girardey ^65,60, M. A. Giza ⁴³, F. C. Glaser ²³, V. V. Gligorov ¹⁷, C. Göbel ⁷², L. Golinka-Bezshyyko ⁸⁸, E. Golobardes ⁴⁸, A. Golutvin ^64,51, S. Gomez Fernandez ⁴⁷, W. Gomulka ⁴², F. Goncalves Abrantes ⁶⁶, I. Gonçales Vaz ⁵¹, M. Goncerz ⁴³, G. Gong ^4,q, J. A. Gooding ²⁰, C. Gotti ³², E. Govorkova ⁶⁷, J. P. Grabowski ³¹, L. A. Granado Cardoso ⁵¹, R. Grande Quartieri ², E. Graugés ⁴⁷, E. Graverini ^36,52,r, L. Grazette ⁵⁹, G. Graziani ²⁸, A. T. Grecu ⁴⁵, N. A. Grieser ⁶⁸, L. Grillo ⁶², C. Gu ¹⁶, M. Guarise ²⁷, L. Guerry ¹², A.-K. Guseinov ⁵², Y. Guz ⁶, T. Gys ⁵¹, K. Habermann ¹⁹, T. Hadavizadeh ¹, C. Hadjivasiliou ⁶⁹, G. Haefeli ⁵², C. Haen ⁵¹, S. Haken ⁵⁸, G. Hallett ⁵⁹, P. M. Hamilton ⁶⁹, Q. Han ³⁴, S. Han ⁷, X. Han ^23,51, S. Hansmann-Menzemer ²³, N. Harnew ⁶⁶, T. J. Harris ¹, L. Hartman ⁵², M. Hartmann ¹⁵, S. Hashmi ⁴², J. He ^7,s, N. Heatley ¹⁵, A. Hedes ⁶⁵, F. Hemmer ⁵¹, C. Henderson ⁶⁸, R. Henderson ¹⁵, R. D. L. Henderson ¹, A. M. Hennequin ⁵¹, K. Hennessy ⁶³, J. Herd ⁶⁴, P. Herrero Gascon ²³, J. Heuel ¹⁸, A. Heyn ¹⁴, A. Hicheur ³, G. Hijano Mendizabal ⁵³, J. Horswill ⁶⁵, R. Hou ⁹, Y. Hou ¹², D. C. Houston ⁶², N. Howarth ⁶³, W. Hu ^7,s, X. Hu ⁴, W. Huang ⁷, W. Hulsbergen ³⁹, R. J. Hunter ⁵⁹, D. Hutchcroft ⁶³, M. Idzik ⁴², P. Ilten ⁶⁸, A. Iohner ¹¹, H. Jage ¹⁸, S. J. Jaimes Elles ^78,50,51, S. Jakobsen ⁵¹, T. Jakoubek ⁷⁹, E. Jans ³⁹, A. Jawahery ⁶⁹, C. Jayaweera ⁵⁶, A. Jelavic ¹, V. Jevtic ²⁰, Z. Jia ¹⁷, E. Jiang ⁶⁹, X. Jiang ^5,7, Y. Jiang ⁷, Y. J. Jiang ⁶, E. Jimenez Moya ¹⁰, N. Jindal ⁹¹, M. John ⁶⁶, A. John Rubesh Rajan ²⁴, D. Johnson ⁵⁶, C. R. Jones ⁵⁸, S. Joshi ⁴⁴, B. Jost ⁵¹, J. Juan Castella ⁵⁸, N. Jurik ⁵¹, I. Juszczak ⁴³, K. Kalecinska⁴², D. Kaminaris ⁵², S. Kandybei ⁵⁴, M. Kane ⁶¹, Y. Kang ^4,q, C. Kar ¹², M. Karacson ⁵¹, A. Kauniskangas ⁵², J. W. Kautz ⁶⁸, M. K. Kazanecki ⁴³, F. Keizer ⁵¹, M. Kenzie ⁵⁸, T. Ketel ³⁹, B. Khanji ⁷¹, S. Kholodenko ^64,51, G. Khreich ¹⁵, F. Kiraz¹⁵, T. Kirn ¹⁸, V. S. Kirsebom ^32,c, N. Kleijne ^36,j, A. Kleimenova ⁵², D. K. Klekots ⁸⁸, K. Klimaszewski ⁴⁴, M. R. Kmiec ⁴⁴, T. Knospe ²⁰, R. Kolb ²³, S. Koliiev ⁵⁵, L. Kolk ²⁰, A. Konoplyannikov ⁶, P. Kopciewicz ⁵¹, P. Koppenburg ³⁹, A. 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Liu ⁶⁴, G. Loachamin Ordonez ⁷², I. Lobo ¹, A. Lobo Salvia ¹¹, A. Loi ³³, T. Long ⁵⁸, F. C. L. Lopes ^2,g, J. H. Lopes ³, A. Lopez Huertas ⁴⁷, C. Lopez Iribarnegaray ⁴⁹, Q. Lu ¹⁶, C. Lucarelli ⁵¹, D. Lucchesi ^34,t, M. Lucio Martinez ⁵⁰, Y. Luo ⁶, A. Lupato ^34,u, M. Lupberger ²¹, E. Luppi ^27,f, K. Lynch ²⁴, S. Lyu⁶, X.-R. Lyu ⁷, H. Ma ⁷⁴, S. Maccolini ⁵¹, F. Machefert ¹⁵, F. Maciuc ⁴⁵, B. Mack ⁷¹, I. Mackay ⁶⁶, L. M. Mackey ⁷¹, L. R. Madhan Mohan ⁵⁸, M. J. Madurai ⁵⁶, D. Magdalinski ³⁹, J. J. Malczewski ⁴³, S. Malde ⁶⁶, L. Malentacca ⁵¹, G. Manca ^33,n, G. Mancinelli ¹⁴, C. Mancuso ¹⁵, R. Manera Escalero ⁴⁷, A. Mangalasseri ⁸¹, F. M. Manganella ³⁸, D. Manuzzi ²⁶, S. Mao ⁷, D. Marangotto ^31,k, J. F. Marchand ¹¹, R. Marchevski ⁵², U. Marconi ²⁶, E. Mariani ¹⁷, S. Mariani ^51,28, C. Marin Benito ⁴⁷, J. Marks ²³, A. M. Marshall ⁵⁷, L. Martel ⁶⁶, G. Martelli ²⁰, G. Martellotti ³⁷, L. Martinazzoli ⁵¹, M. Martinelli ^32,c, C. Martinez ³, D. Martinez Gomez ⁸⁴, D. Martinez Santos ⁴⁶, F. 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Mulder ²⁰, K. Müller ⁵³, F. Muñoz-Rojas ¹⁰, V. Mytrochenko ⁵⁴, P. Naik ⁶³, T. Nakada ⁵², R. Nandakumar ⁶⁰, G. Napoletano ⁵², I. Nasteva ³, M. Needham ⁶¹, N. Neri ^31,k, S. Neubert ¹⁹, N. Neufeld ⁵¹, J. Nicolini ⁵¹, D. Nicotra ⁴¹, E. M. Niel ¹⁶, L. Nisi ²⁰, Q. Niu ⁸, B. K. Njoki ⁵¹, P. Nogarolli ³, P. Nogga ¹⁹, J. Nombela Royo ⁶⁵, C. Normand ⁴⁹, J. Novoa Fernandez ⁴⁹, G. Nowak ⁶⁸, H. N. Nur ⁶², A. Oblakowska-Mucha ⁴², T. Oeser ¹⁸, O. Okhrimenko ⁵⁵, R. Oldeman ^33,n, F. Oliva ^61,51, E. Olivart Pino ⁴⁷, M. Olocco ²⁰, C. J. G. Onderwater ⁴¹, R. H. O’Neil ⁵¹, J. S. Ordonez Soto ¹², D. Osthues ²⁰, J. M. Otalora Goicochea ³, P. Owen ⁵³, A. Oyanguren ⁵⁰, O. Ozcelik ⁵¹, F. Paciolla ^36,v, A. Padee ⁴⁴, K. O. Padeken ¹⁹, B. Pagare ⁴⁹, T. Pajero ⁵¹, A. Palano ²⁵, L. Palini ³¹, M. Palutan ²⁹, C. Pan ⁷⁶, X. Pan ^4,q, S. Panebianco ¹³, S. Paniskaki ⁵¹, L. Paolucci ⁶⁵, A. Papanestis ⁶⁰, M. Pappagallo ^25,m, L. L. Pappalardo ²⁷, C. Pappenheimer ⁶⁸, C. Parkes ⁶⁵, D. Parmar ⁸⁰, G. Passaleva ²⁸, D. 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Sarpis ⁸², C. Satriano ³⁷, A. Satta ³⁸, M. Saur ⁸, H. Sazak ¹⁸, F. Sborzacchi ^51,29, A. Scarabotto ²⁰, S. Schael ¹⁸, S. Scherl ⁶³, M. Schiller ²³, H. Schindler ⁵¹, M. Schmelling ²², B. Schmidt ⁵¹, N. Schmidt ⁷⁰, S. Schmitt ⁶⁷, H. Schmitz¹⁹, O. Schneider ⁵², A. Schopper ⁶⁴, N. Schulte ²⁰, H. Schumacher¹⁹, M. H. Schune ¹⁵, G. Schwering ¹⁸, B. Sciascia ²⁹, A. Sciuccati ⁵¹, G. Scriven ⁴¹, I. Segal ⁸⁰, S. Sellam ⁴⁹, M. Senghi Soares ⁴⁰, A. Sergi ^30,i, N. Serra ⁵³, L. Sestini ²⁸, B. Sevilla Sanjuan ⁴⁸, Y. Shang ⁶, D. M. Shangase ⁸⁹, R. S. Sharma ⁷¹, L. Shchutska ⁵², T. Shears ⁶³, J. Shen⁶, Z. Shen ³⁹, S. Sheng ⁵², B. Shi ⁷, J. Shi ⁵⁸, Q. Shi ⁷, W. S. Shi ⁷⁵, E. Shmanin ²⁶, R. Silva Coutinho ², G. Simi ^34,t, S. Simone ^25,m, M. Singha ⁸¹, I. Siral ⁵², N. Skidmore ⁵⁹, T. Skwarnicki ⁷¹, M. W. Slater ⁵⁶, E. Smith ⁶⁷, M. Smith ⁶⁴, L. Soares Lavra ⁶¹, M. D. Sokoloff ⁶⁸, F. J. P. Soler ⁶², A. Solomin ⁵⁷, K. Solovieva ²¹, N. S. Sommerfeld ¹⁹, R. Song ¹, Y. Song ⁵², Y. Song ^4,q, Y. S. Song ⁶, F. L. Souza De Almeida ⁴⁷, G. Souza De Castro⁷², B. Souza De Paula ³, K. M. Sowa ⁴², E. Spadaro Norella ^30,i, E. Spedicato ²⁶, J. G. Speer ²⁰, P. Spradlin ⁶², F. Stagni ⁵¹, M. Stahl ⁸⁰, S. Stahl ⁵¹, S. Stanislaus ⁶⁶, M. Stefaniak ⁹¹, O. Steinkamp ⁵³, F. Suljik ⁶⁶, J. Sun ⁶⁵, L. Sun ⁷⁶, M. Sun⁶, D. Sundfeld ², W. Sutcliffe ⁵³, P. Svihra ⁷⁹, V. Svintozelskyi ⁵⁰, K. Swientek ⁴², F. Swystun ⁵⁸, A. Szabelski ⁴⁴, T. Szumlak ⁴², Y. Tan ⁷, Y. Tang ⁷⁶, Y. T. Tang ⁷, M. D. Tat ²³, J. A. Teijeiro Jimenez ⁴⁹, F. Terzuoli ^36,v, F. Teubert ⁵¹, E. Thomas ⁵¹, D. J. D. Thompson ⁵⁶, A. R. Thomson-Strong ⁶¹, H. Tilquin ⁶⁴, V. Tisserand ¹², S. T’Jampens ¹¹, M. Tobin ^5,51, T. T. Todorov ²¹, L. Tomassetti ^27,f, G. Tonani ³¹, X. Tong ⁶, T. Tork ³¹, L. Toscano ²⁰, D. Y. Tou ^4,q, C. Trippl ⁴⁸, G. Tuci ²³, N. Tuning ³⁹, L. H. Uecker ²³, A. Ukleja ⁴², A. Upadhyay ⁵¹, B. Urbach ⁶¹, A. Usachov ³⁹, U. Uwer ²³, V. Vagnoni ^26,51, A. Vaitkevicius ⁸², V. Valcarce Cadenas ⁴⁹, G. Valenti ²⁶, N. Valls Canudas ⁵¹, J. van Eldik ⁵¹, H. Van Hecke ⁷⁰, E. van Herwijnen ⁶⁴, C. B. Van Hulse ^49,w, R. Van Laak ⁵², M. van Veghel ⁴¹, G. Vasquez ⁵³, R. Vazquez Gomez ⁴⁷, P. Vazquez Regueiro ⁴⁹, C. Vázquez Sierra ⁴⁶, S. Vecchi ²⁷, J. Velilla Serna ⁵⁰, J. J. Velthuis ⁵⁷, M. Veltri ^28,x, A. Venkateswaran ⁵², M. Verdoglia ³³, M. Vesterinen ⁵⁹, W. Vetens ⁷¹, D. Vico Benet ⁶⁶, P. Vidrier Villalba ⁴⁷, M. Vieites Diaz ⁴⁹, X. Vilasis-Cardona ⁴⁸, E. Vilella Figueras ⁶³, A. Villa ⁵², P. Vincent ¹⁷, B. Vivacqua ³, F. C. Volle ⁵⁶, D. vom Bruch ¹⁴, K. Vos ⁴¹, C. Vrahas ⁶¹, J. Wagner ²⁰, J. Walsh ³⁶, N. Walter⁵¹, E. J. Walton ¹, G. Wan ⁶, A. Wang ⁷, B. Wang ⁵, C. Wang ²³, G. Wang ⁹, H. Wang ⁸, J. Wang ⁷, J. Wang ⁵, J. Wang ^4,q, J. Wang ⁷⁶, M. Wang ⁵¹, N. W. Wang ⁷, R. Wang ⁵⁷, X. Wang ⁴, X. Wang ⁹, X. Wang ⁷⁵, X. W. Wang ⁶⁴, Y. Wang ⁷⁷, Y. Wang ⁶, Y. H. Wang ⁸, Z. Wang ¹⁵, Z. Wang ³¹, J. A. Ward ^59,1, A. Wasili ^63,y, M. Waterlaat ³⁹, N. K. Watson ⁵⁶, D. Websdale ⁶⁴, Y. Wei ⁶, Z. Weida ⁷, J. Wendel ⁴⁶, B. D. C. Westhenry ⁵⁷, C. White ⁵⁸, M. Whitehead ⁶², E. Whiter ⁵⁶, A. R. Wiederhold ⁶⁵, D. Wiedner ²⁰, M. A. Wiegertjes ³⁹, C. Wild ⁶⁶, G. Wilkinson ⁶⁶, M. K. Wilkinson ⁶⁸, M. Williams ⁶⁷, M. J. Williams ⁵¹, M. R. J. Williams ⁶¹, R. Williams ⁵⁸, S. Williams ⁵⁷, Z. Williams ⁵⁷, F. F. Wilson ⁶⁰, M. Winn ¹³, W. Wislicki ⁴⁴, M. Witek ⁴³, L. Witola ²⁰, T. Wolf ²³, E. Wood ⁵⁸, G. Wormser ¹⁵, S. A. Wotton ⁵⁸, H. Wu ⁷¹, J. Wu ⁹, X. Wu ⁷⁶, Y. Wu ^6,58, Z. Wu ⁷, K. Wyllie ⁵¹, S. Xian ⁷⁵, Z. Xiang ⁵, Y. Xie ⁹, T. X. Xing ³¹, A. Xu ^36,j, L. Xu ^4,q, M. Xu ⁵¹, R. Xu⁸⁹, Z. Xu ⁹³, Z. Xu ⁹², Z. Xu ⁷, Z. Xu ⁵, S. Yadav ²⁷, K. Yang ⁶⁴, X. Yang ⁶, Y. Yang ⁸¹, Y. Yang ⁷, Z. Yang ⁶, Z. Yang ⁴, Z. Yang ⁶⁹, H. Yeung ⁶⁵, H. Yin ⁹, X. Yin ⁷, C. Y. Yu ⁶, J. Yu ⁷⁴, K. Yu ⁸, X. Yuan ⁵, Y Yuan^5,7, J. A. Zamora Saa ⁷³, M. Zavertyaev ²², M. Zdybal ⁴³, F. Zenesini ²⁶, C. Zeng ^5,7, M. Zeng ^4,q, S. H Zeng⁵⁷, C. Zhang ⁶³, C. Zhang⁶, D. Zhang ⁹, J. Zhang ⁴⁴, L. Zhang ^4,q, Q. Z. Zhang ⁷, R. Zhang ⁹, S. Zhang ⁶⁶, S. L. Zhang ⁷⁴, Y. Zhang ⁶, Z. Zhang ^4,q, J. Zhao ⁷, Y. Zhao ²³, A. Zhelezov ²³, S. Z. Zheng ⁶, X. Z. Zheng ^4,q, Y. Zheng ⁷, T. Zhou ⁴³, X. Zhou ⁹, V. Zhovkovska ⁵⁹, L. Z. Zhu ⁶¹, X. Zhu ^4,q, X. Zhu ⁹, Y. Zhu ¹⁸, V. Zhukov ¹⁸, J. Zhuo ⁵⁰, D. Zuliani ^34,t, G. Zunica ²⁹, and X. Zuo ⁵² (LHCb Collaboration)

¹School of Physics and Astronomy, Monash University, Melbourne, Australia
²Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
³Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
⁴Department of Engineering Physics, Tsinghua University, Beijing, China
⁵Institute of High Energy Physics (IHEP), Beijing, China
⁶School of Physics State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
⁷University of Chinese Academy of Sciences, Beijing, China
⁸Lanzhou University, Lanzhou, China
⁹Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China
¹⁰Consejo Nacional de Rectores (CONARE), San Jose, Costa Rica
¹¹Université Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France
¹²Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
¹³Université Paris-Saclay, Centre d’Etudes de Saclay (CEA), IRFU, Gif-Sur-Yvette, France
¹⁴Aix Marseille Université, CNRS/IN2P3, CPPM, Marseille, France
¹⁵Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
¹⁶Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France
¹⁷Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Sorbonne Université, CNRS/IN2P3, Paris, France
¹⁸I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
¹⁹Universität Bonn—Helmholtz-Institut für Strahlen und Kernphysik, Bonn, Germany
²⁰Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
²¹Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
²²Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
²³Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
²⁴School of Physics, University College Dublin, Dublin, Ireland
²⁵INFN Sezione di Bari, Bari, Italy
²⁶INFN Sezione di Bologna, Bologna, Italy
²⁷INFN Sezione di Ferrara, Ferrara, Italy
²⁸INFN Sezione di Firenze, Firenze, Italy
²⁹INFN Laboratori Nazionali di Frascati, Frascati, Italy
³⁰INFN Sezione di Genova, Genova, Italy
³¹INFN Sezione di Milano, Milano, Italy
³²INFN Sezione di Milano-Bicocca, Milano, Italy
³³INFN Sezione di Cagliari, Monserrato, Italy
³⁴INFN Sezione di Padova, Padova, Italy
³⁵INFN Sezione di Perugia, Perugia, Italy
³⁶INFN Sezione di Pisa, Pisa, Italy
³⁷INFN Sezione di Roma La Sapienza, Roma, Italy
³⁸INFN Sezione di Roma Tor Vergata, Roma, Italy
³⁹Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands
⁴⁰Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, Netherlands
⁴¹Universiteit Maastricht, Maastricht, Netherlands
⁴²AGH—University of Krakow, Faculty of Physics and Applied Computer Science, Kraków, Poland
⁴³Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
⁴⁴National Center for Nuclear Research (NCBJ), Warsaw, Poland
⁴⁵Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania
⁴⁶Universidade da Coruña, A Coruña, Spain
⁴⁷ICCUB, Universitat de Barcelona, Barcelona, Spain
⁴⁸La Salle, Universitat Ramon Llull, Barcelona, Spain
⁴⁹Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
⁵⁰Instituto de Fisica Corpuscular, Centro Mixto Universidad de Valencia—CSIC, Valencia, Spain
⁵¹European Organization for Nuclear Research (CERN), Geneva, Switzerland
⁵²Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
⁵³Physik-Institut, Universität Zürich, Zürich, Switzerland
⁵⁴NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
⁵⁵Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine
⁵⁶School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom
⁵⁷H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom
⁵⁸Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
⁵⁹Department of Physics, University of Warwick, Coventry, United Kingdom
⁶⁰STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
⁶¹School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
⁶²School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom
⁶³Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom
⁶⁴Imperial College London, London, United Kingdom
⁶⁵Department of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
⁶⁶Department of Physics, University of Oxford, Oxford, United Kingdom
⁶⁷Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
⁶⁸University of Cincinnati, Cincinnati, Ohio, USA
⁶⁹University of Maryland, College Park, Maryland, USA
⁷⁰Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, USA
⁷¹Syracuse University, Syracuse, New York, USA
⁷²Pontifícia 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)
⁷³Universidad Andres Bello, Santiago, Chile (associated with Physik-Institut, Universität Zürich, Zürich, Switzerland)
⁷⁴School of Physics and Electronics, Hunan University, Changsha City, China (associated with Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China)
⁷⁵State Key Laboratory of Nuclear Physics and Technology, South China Normal University, Guangzhou, China (associated with Department of Engineering Physics, Tsinghua University, Beijing, China)
⁷⁶School of Physics and Technology, Wuhan University, Wuhan, China (associated with Department of Engineering Physics, Tsinghua University, Beijing, China)
⁷⁷Henan Normal University, Xinxiang, China (associated with Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China)
⁷⁸Departamento de Fisica, Universidad Nacional de Colombia, Bogota, Colombia (associated with Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Sorbonne Université, CNRS/IN2P3, Paris, France)
⁷⁹Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic (associated with Department of Physics and Astronomy, University of Manchester, Manchester, United Kingdom)
⁸⁰Ruhr Universitaet Bochum, Fakultaet für Physik und Astronomie, Bochum, Germany (associated with Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany)
⁸¹Eotvos Lorand University, Budapest, Hungary (associated with European Organization for Nuclear Research (CERN), Geneva, Switzerland)
⁸²Faculty of Physics, Vilnius University, Vilnius, Lithuania (associated with Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany)
⁸³Institute of Physics and Technology, Mongolian Academy of Sciences, Ulan Bator, Mongolia (associated with Institute of High Energy Physics (IHEP), Beijing, China)
⁸⁴Van Swinderen Institute, University of Groningen, Groningen, Netherlands (associated with Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands)
⁸⁵Universidad de Ingeniería y Tecnología (UTEC), Lima, Peru (associated with Massachusetts Institute of Technology, Cambridge, Massachusetts, USA)
⁸⁶Tadeusz Kosciuszko Cracow University of Technology, Cracow, Poland (associated with Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland)
⁸⁷Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden (associated with School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom)
⁸⁸Taras Schevchenko University of Kyiv, Faculty of Physics, Kyiv, Ukraine (associated with Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France)
⁸⁹University of Michigan, Ann Arbor, Michigan, USA (associated with Syracuse University, Syracuse, New York, USA)
⁹⁰Indiana University, Bloomington, Indiana, USA (associated with Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, USA)
⁹¹Ohio State University, Columbus, Ohio, USA (associated with Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, USA)
⁹²Kent State University Physics Department, Kent, Ohio, USA (associated with Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, USA)
⁹³University of Science and Technology of China, Hefei, China

^*Full author list given at the end of the Letter.
^aDeceased.
^bAlso at Lamarr Institute for Machine Learning and Artificial Intelligence, Dortmund, Germany.
^cAlso at Università degli Studi di Milano-Bicocca, Milano, Italy.
^dAlso at Università di Modena e Reggio Emilia, Modena, Italy.
^eAlso at Department of Physics and Astronomy, University of Victoria, Victoria, Canada.
^fAlso at Università di Ferrara, Ferrara, Italy.
^gAlso at Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil.
^hAlso at Università di Bologna, Bologna, Italy.
ⁱAlso at Università di Genova, Genova, Italy.
^jAlso at Scuola Normale Superiore, Pisa, Italy.
^kAlso at Università degli Studi di Milano, Milano, Italy.
^lAlso at Universidad Nacional Autónoma de Honduras, Tegucigalpa, Honduras.
^mAlso at Università di Bari, Bari, Italy.
ⁿAlso at Università di Cagliari, Cagliari, Italy.
^oAlso at Università di Perugia, Perugia, Italy.
^pAlso at LIP6, Sorbonne Université, Paris, France.
^qAlso at Center for High Energy Physics, Tsinghua University, Beijing, China.
^rAlso at Università di Pisa, Pisa, Italy.
^sAlso at Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China.
^tAlso at Università di Padova, Padova, Italy.
^uAlso at Università di Bergamo, Bergamo, Italy.
^vAlso at Università di Siena, Siena, Italy.
^wAlso at Universidad de Alcalá, Alcalá de Henares, Spain.
^xAlso at Università di Urbino, Urbino, Italy.
^yAlso at Department of Physical Sciences, Physics Division, College of Science, Jazan University, Jazan, Kingdom of Saudi Arabia.

PDF

Phys. Rev. Lett. 137, 141801 – Published 1 October, 2026

DOI: https://doi.org/10.1103/13fb-1gc2

Abstract

A measurement of the ratio of semileptonic branching fractions $R (J / ψ)$ , defined as $R (J / ψ) \equiv B (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) / B (B_{c}^{+} \to J / ψ μ^{+} ν_{μ})$ , is reported using a sample of proton-proton collision data corresponding to an integrated luminosity of $5.4 {fb}^{- 1}$ recorded by the LHCb experiment in 2016–2018 at a center-of-mass energy of 13 TeV. The measured value is found to be $R (J / ψ) = 0.51 \pm 0.12 (stat) \pm 0.08 (syst)$ , which is within 1.8 standard deviations of the predictions from the standard model assuming lepton flavor universality.

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (33)

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Phys. Rev. Lett. 137, 141801– Published 1 October, 2026

Vol. 137, Iss. 14 — 2 October 2026

Received 10 June 2026
Accepted 9 September 2026

DOI: https://doi.org/10.1103/13fb-1gc2

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Measurement of the Ratio of Branching Fractions $B (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) / B (B_{c}^{+} \to J / ψ μ^{+} ν_{μ})$

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Measurement of the Ratio of Branching Fractions B(Bc+→J/ψτ+ντ)/B(Bc+→J/ψμ+νμ)

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Measurement of the Ratio of Branching Fractions $B (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) / B (B_{c}^{+} \to J / ψ μ^{+} ν_{μ})$