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Open Access Publications from the University of California

Study of the production of and hadrons in pp collisions and first measurement of the branching fraction* *Supported by CERN and national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG, HGF and MPG (Germany); INFN (Italy); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FANO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). The Tier1 computing centres are supported by IN2P3 (France), KIT and BMBF (Germany), INFN (Italy), NWO and SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom). Individual groups or members have received support from EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union), Conseil général de Haute-Savoie, Labex ENIGMASS and OCEVU, Région Auvergne (France), RFBR (Russia), XuntaGal and GENCAT (Spain), Royal Society and Royal Commission for the Exhibition of 1851 (United Kingdom).

Abstract

The product of the Λ0b(B0) differential production cross-section and the branching fraction of the decay Λ0bJ= pK.. (B0!J= K Λ (892)0) is measured as a function of the beauty hadron transverse momentum, pT, and rapidity, y. The kinematic region of the measurements is pT >20 GeV=c and 2:0>y>4:5. The measurements use a data sample corresponding to an integrated luminosity of 3fb..1 collected by the LHCb detector in pp collisions at centre-of-mass energies ps = 7 TeV in 2011 and ps = 8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio, fΛ0 b =fd, the branching fraction of the decay Λ0 b!J= pK.. is measured to be B(Λ0 bJ= pK..)=(3:17±0:04±0:07±0:34+0:45 ..0:28 )10..4 ; where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B0J= K Λ (892)0, and the fourth is due to the knowledge of fΛ0 b =fd. The sum of the asymmetries in the production and decay between Λ0 b and Λ 0 b is also measured as a function of pT and y. The previously published branching fraction of Λ0 b ! J= p.., relative to that of Λ0 b ! J= pK.., is updated. The branching fractions of Λ0 b!P+ c (!J= p)K.. are determined.

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