https://doi.org/10.1140/epjc/s10052-017-4610-6
Regular Article - Experimental Physics
Observation of 
and 
decays
1
Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
2
Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
3
Center for High Energy Physics, Tsinghua University, Beijing, China
4
LAPP, Université Savoie Mont-Blanc, CNRS/IN2P3, Annecy-Le-Vieux, France
5
Clermont Université, Université Blaise Pascal, CNRS/IN2P3, LPC, Clermont-Ferrand, France
6
CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France
7
LAL, Université Paris-Sud, CNRS/IN2P3, Orsay, France
8
LPNHE, Université Pierre et Marie Curie, Université Paris Diderot, CNRS/IN2P3, Paris, France
9
I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
10
Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
11
Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
12
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
13
School of Physics, University College Dublin, Dublin, Ireland
14
Sezione INFN di Bari, Bari, Italy
15
Sezione INFN di Bologna, Bologna, Italy
16
Sezione INFN di Cagliari, Cagliari, Italy
17
Sezione INFN di Ferrara, Ferrara, Italy
18
Sezione INFN di Firenze, Florence, Italy
19
Laboratori Nazionali dell’INFN di Frascati, Frascati, Italy
20
Sezione INFN di Genova, Genova, Italy
21
Sezione INFN di Milano Bicocca, Milan, Italy
22
Sezione INFN di Milano, Milan, Italy
23
Sezione INFN di Padova, Padova, Italy
24
Sezione INFN di Pisa, Pisa, Italy
25
Sezione INFN di Roma Tor Vergata, Rome, Italy
26
Sezione INFN di Roma La Sapienza, Rome, Italy
27
Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
28
Faculty of Physics and Applied Computer Science, AGH, University of Science and Technology, Kraków, Poland
29
National Center for Nuclear Research (NCBJ), Warsaw, Poland
30
Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania
31
Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia
32
Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia
33
Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia
34
Institute for Nuclear Research of the Russian Academy of Sciences (INR RAN), Moscow, Russia
35
Yandex School of Data Analysis, Moscow, Russia
36
Budker Institute of Nuclear Physics (BINP SB RAS), Novosibirsk, Russia
37
Institute for High Energy Physics (IHEP), Protvino, Russia
38
ICCUB, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
39
Universitat de Barcelona, Barcelona, Spain
40
European Organization for Nuclear Research (CERN), Geneva, Switzerland
41
Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
42
Physik-Institut, Universität Zürich, Zurich, Switzerland
43
Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands
44
Nikhef National Institute for Subatomic Physics, VU University Amsterdam, Amsterdam, The Netherlands
45
NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
46
Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine
47
University of Birmingham, Birmingham, UK
48
H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
49
Cavendish Laboratory, University of Cambridge, Cambridge, UK
50
Department of Physics, University of Warwick, Coventry, UK
51
STFC Rutherford Appleton Laboratory, Didcot, UK
52
School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
53
School of Physics and Astronomy, University of Glasgow, Glasgow, UK
54
Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK
55
Imperial College London, London, UK
56
School of Physics and Astronomy, University of Manchester, Manchester, UK
57
Department of Physics, University of Oxford, Oxford, UK
58
Massachusetts Institute of Technology, Cambridge, MA, USA
59
University of Cincinnati, Cincinnati, OH, USA
60
University of Maryland, College Park, MD, USA
61
Syracuse University, Syracuse, NY, USA
62
Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil
63
University of Chinese Academy of Sciences, Beijing, China
64
Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China
65
Departamento de Fisica, Universidad Nacional de Colombia, Bogotá, Colombia
66
Institut für Physik, Universität Rostock, Rostock, Germany
67
National Research Centre Kurchatov Institute, Moscow, Russia
68
Instituto de Fisica Corpuscular (IFIC), Universitat de Valencia-CSIC, Valencia, Spain
69
Van Swinderen Institute, University of Groningen, Groningen, The Netherlands
* e-mail: Ivan.Belyaev@itep.ru
Received:
6
October
2016
Accepted:
7
January
2017
Published online:
6
February
2017
The decays and are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb
, collected by the LHCb experiment in proton–proton collisions at the centre-of-mass energies of 7 and 8
. The branching fractions relative to that of 
are measured to be 
where the first uncertainties are statistical and the second are systematic.
© CERN for the benefit of the LHCb collaboration, 2017
