Measurement of the parity-violating asymmetry parameter αb and the helicity amplitudes for the decay Λb0 →j /ψ Λ0 with the ATLAS detector

G Aad; T Abajyan; B Abbott; J Abdallah; S Abdel Khalek; O Abdinov; R Aben; B Abi; M Abolins; OS Abouzeid; H Abramowicz; H Abreu; Y Abulaiti; BS Acharya; L Adamczyk; DL Adams; J Adelman; S Adomeit; T Adye; T Agatonovic-Jovin; JA Aguilar-Saavedra; M Agustoni; SP Ahlen; A Ahmad; F Ahmadov; G Aielli; TPA Åkesson; G Akimoto; AV Akimov; J Albert; S Albrand; MJ Alconada Verzini; M Aleksa; IN Aleksandrov; C Alexa; G Alexander; G Alexandre; T Alexopoulos; M Alhroob; G Alimonti; L Alio; J Alison; BMM Allbrooke; LJ Allison; PP Allport; SE Allwood-Spiers; J Almond; A Aloisio; R Alon; A Alonso; F Alonso; C Alpigiani; A Altheimer; B Alvarez Gonzalez; MG Alviggi; K Amako; Y Amaral Coutinho; C Amelung; D Amidei; VV Ammosov; SP Amor Dos Santos; A Amorim; S Amoroso; N Amram; G Amundsen; C Anastopoulos; LS Ancu; N Andari; T Andeen; CF Anders; G Anders; KJ Anderson; A Andreazza; V Andrei; XS Anduaga; S Angelidakis; P Anger; A Angerami; F Anghinolfi; AV Anisenkov; N Anjos; A Annovi; A Antonaki; M Antonelli; A Antonov; J Antos; F Anulli; M Aoki; L Aperio Bella; R Apolle; G Arabidze; I Aracena; Y Arai; JP Araque; ATH Arce; JF Arguin; S Argyropoulos; M Arik; AJ Armbruster; O Arnaez

Journal article

Measurement of the parity-violating asymmetry parameter αb and the helicity amplitudes for the decay Λb0 →j /ψ Λ0 with the ATLAS detector

G Aad, T Abajyan, B Abbott, J Abdallah, S Abdel Khalek, O Abdinov, R Aben, B Abi, M Abolins, OS Abouzeid, H Abramowicz, H Abreu, Y Abulaiti, BS Acharya, L Adamczyk, DL Adams, J Adelman, S Adomeit, T Adye, T Agatonovic-Jovin Show all

Physical Review D Particles Fields Gravitation and Cosmology | Published : 2014

DOI: 10.1103/PhysRevD.89.092009

Abstract

A measurement of the parity-violating decay asymmetry parameter, αb, and the helicity amplitudes for the decay Λb0→J/ψ(μ+μ-)Λ0(pπ-) is reported. The analysis is based on 1400 Λb0 and Λ¯b0 baryons selected in 4.6 fb-1 of proton-proton collision data with a center-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. By combining the Λb0 and Λ¯b0 samples under the assumption of CP conservation, the value of αb is measured to be 0.30±0.16(stat)±0.06(syst). This measurement provides a test of theoretical models based on perturbative QCD or heavy-quark effective theory.

University of Melbourne Researchers

Federico Scutti Author

Elisabetta Barberio Author

Matteo Volpi Author

G. N. Taylor Author

Related Projects (1)

ARC CENTRE OF EXCELLENCE FOR PARTICLE PHYSICS AT THE TERA-SCALE

The Large Hadron Collider, a gigantic particle accelerator at the CERN laboratory in Europe, has commenced operation. It will discover how p..

Grants

Awarded by European Commission

Funding Acknowledgements

We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWF and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC, and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST, and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR, and VSC CR, Czech Republic; DNRF, DNSRC, and Lundbeck Foundation, Denmark; EPLANET, ERC, and NSRF, European Union; IN2P3- CNRS, CEA- DSM/ IRFU, France; GNSF, Georgia; BMBF, DFG, HGF, MPG, and AvH Foundation, Germany; GSRT and NSRF, Greece; ISF, MINERVA, GIF, I- CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; BRF and RCN, Norway; MNiSW and NCN, Poland; GRICES and FCT, Portugal; MNE/ IFA, Romania; MES of Russia and ROSATOM, Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia; ARRS and MIZS, Slovenia; DST/ NRF, South Africa; MINECO, Spain; SRC andWallenberg Foundation, Sweden; SER, SNSF, and Cantons of Bern and Geneva, Switzerland; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States of America. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular, from CERN and the ATLAS Tier- 1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC- IN2P3 (France), KIT/ GridKA (Germany), INFN- CNAF (Italy), NL- T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK), and BNL (USA) and in the Tier- 2 facilities worldwide.