Abstract
The decay Z→bb¯ is reconstructed in pp collision data, corresponding to 2 fb−1 of integrated luminosity, collected by the LHCb experiment at a centre-of-mass energy of s=8 TeV. The product of the Z production cross-section and the Z→bb¯ branching fraction is measured for candidates in the fiducial region defined by two particle-level b-quark jets with pseudorapidities in the range 2.2<η<4.2, with transverse momenta pT>20 GeV and dijet invariant mass in the range 45<mjj<165 GeV. From a signal yield of 5462±763 Z→bb¯ events, where the uncertainty is statistical, a production cross-section times branching fraction of 332±46±59 pb is obtained, where the first uncertainty is statistical and the second systematic. The measured significance of the signal yield is 6.0 standard deviations. This measurement represents the first observation of the Z→bb¯ production in the forward region of pp collisions.
Original language | English |
---|---|
Pages (from-to) | 430-439 |
Number of pages | 10 |
Journal | Physics Letters. Section B, Nuclear, Elementary Particle and High-Energy Physics |
Volume | 776 |
DOIs | |
Publication status | Published - 10 Jan 2018 |
Funding
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 (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). We acknowledge the computing resources that are provided by CERN , IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (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 AvH Foundation (Germany), EPLANET , Marie Skłodowska-Curie Actions and ERC (European Union), ANR , Labex P2IO , ENIGMASS and OCEVU , and Région Auvergne-Rhône-Alpes (France), RFBR and Yandex LLC (Russia), GVA , XuntaGal and GENCAT (Spain), Herchel Smith Fund , the Royal Society , the English-Speaking Union and the Leverhulme Trust (United Kingdom). 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 (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (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 AvH Foundation (Germany), EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union), ANR, Labex P2IO, ENIGMASS and OCEVU, and Région Auvergne-Rhône-Alpes (France), RFBR and Yandex LLC (Russia), GVA, XuntaGal and GENCAT (Spain), Herchel Smith Fund, the Royal Society, the English-Speaking Union and the Leverhulme Trust (United Kingdom).
Funders | Funder number |
---|---|
Not added | 1681016, 1796908, ST/H006737/1, ST/N000463/1, ST/N000242/1 |
EPLANET | |
Herchel Smith Fund | |
MinES | |
OCEVU | |
Yandex LLC | |
National Science Foundation | |
Alexander von Humboldt-Stiftung | |
Office of Strategic Coordination | |
California Department of Fish and Wildlife | |
Ministry of Science and Technology | |
Poultry Industry Council | |
Karlsruher Institut für Technologie | |
School of Energy Resources, University of Wyoming | |
H2020 Marie Skłodowska-Curie Actions | |
CERN | |
Science and Technology Facilities Council | ST/J004332/1, ST/N000250/1, 1641747, ST/K003410/1, LHCb, ST/N000331/1, GRIDPP, LHCb Upgrades |
Leverhulme Trust | |
Royal Society | |
English-Speaking Union | |
European Commission | |
European Research Council | |
Deutsches Elektronen-Synchrotron | |
Deutsche Forschungsgemeinschaft | |
Agence Nationale de la Recherche | |
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung | 172637, 166208 |
National Natural Science Foundation of China | |
Russian Foundation for Basic Research | |
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |
Bundesministerium für Bildung und Forschung | |
Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
Ministerio de Economía y Competitividad | |
Generalitat Valenciana | |
Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
Instituto Nazionale di Fisica Nucleare | |
Max-Planck-Gesellschaft | |
Narodowe Centrum Nauki | |
Narodowym Centrum Nauki | |
Ministerstwo Nauki i Szkolnictwa Wyższego | |
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
Ministry of Science and Technology, Taiwan | |
National Academy of Sciences of Ukraine | |
Centre National de la Recherche Scientifique | |
Financiadora de Estudos e Projetos | |
Bundesministerium für Bildung und Frauen | |
Région Auvergne-Rhône-Alpes | |
Institut national de physique nucléaire et de physique des particules | |
Federal Agency for Scientific Organizations | |
Sociedad Española de Reumatología |