Measurement of the ratio of the production cross sections times branching fractions of Bc ±→ J/ψπ± and B± → J/ψK± and (Formula presented.) in pp collisions at (Formula presented.) TeV

Khachatryan, V. and Sirunyan, A. M. and Tumasyan, A. and Adam, W. and Bergauer, T. and Filipovic, Nicolas and Bencze, György and Hajdú, Csaba and Hidas, Pál and Horváth, Dezső and Siklér, Ferenc and Veszprémi, Viktor and Vesztergombi, György and Zsigmond, Anna Júlia and Karancsi, János and Molnár, József and Pálinkás, József and Trócsányi, Zoltán and Ujvári, Balázs and Veres, Gábor (2015) Measurement of the ratio of the production cross sections times branching fractions of Bc ±→ J/ψπ± and B± → J/ψK± and (Formula presented.) in pp collisions at (Formula presented.) TeV. JOURNAL OF HIGH ENERGY PHYSICS (1). ISSN 1126-6708

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Abstract

The ratio of the production cross sections times branching fractions(σ(B± c )B(B± c → J/ψπ±))/(σ(B±)B(B± → J/ψK±)) is studied in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector at the LHC. The kinematic region investigated requires B± c and B± mesons with transverse momentum pT > 15 GeV and rapidity |y| < 1.6. The data sample corre- sponds to an integrated luminosity of 5.1 fb−1. The ratio is determined to be [0.48 ± 0.05 (stat) ± 0.03 (syst) ± 0.05 (τBc )]%. The B± c → J/ψπ±π±π∓ decay is also observed in the same data sample. Using a model-independent method developed to measure the efficiency given the presence of resonant behaviour in the three-pion system, the ratio of the branching fractions B(B± c → J/ψπ±π±π∓)/B(B± c → J/ψπ±) is measured to be 2.55 ± 0.80 (stat) ± 0.33 (syst)+0.04 −0.01 (τBc ), consistent with the previous LHCb result.

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