Measurement of b hadron lifetimes in pp collisions at root s=8TeV

Sirunyan, A.M. and Tumasyan, A. and Adam, W. and Ambrogi, F. and Asilar, E. and Csanád, Máté and Filipovic, Nicolas and Pásztor, Gabriella and Veres, Gábor and Bencze, György and Hajdú, Csaba and Horváth, Dezső and Siklér, Ferenc and Veszprémi, Viktor and Zsigmond, Anna Júlia and Béni, Noémi Tekla and Karancsi, János and Makovec, Alajos and Molnár, József and Szillási, Zoltán and Bartók, Márton and Trócsányi, Zoltán and Ujvári, Balázs (2018) Measurement of b hadron lifetimes in pp collisions at root s=8TeV. EUROPEAN PHYSICAL JOURNAL C, 78 (6). ISSN 1434-6044

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Abstract

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-EP-2017-244 2018/06/19 CMS-BPH-13-008 Measurement of b hadron lifetimes in pp collisions at√s = 8 TeV The CMS Collaboration∗ Abstract Measurements are presented of the lifetimes of the B0, B0 s , Λ0 b, and B+ c hadrons using the decay channels B0 → J/ψK∗(892)0, B0 → J/ψK0 S, B0 s → J/ψπ+π−, B0 s → J/ψφ(1020), Λ0 b → J/ψΛ0, and B+ c → J/ψπ+. The data sample, corresponding to an integrated luminosity of 19.7 fb−1, was collected by the CMS detector at the LHC in proton- proton collisions at √s = 8 TeV. The B0 lifetime is measured to be 453.0 ± 1.6 (stat) ± 1.8 (syst) μm in J/ψK∗(892)0and 457.8 ± 2.7 (stat) ± 2.8 (syst) μm in J/ψK0 S, which re- sults in a combined measurement of cτB0 = 454.1 ± 1.4 (stat) ± 1.7 (syst) μm. The effective lifetime of the B0 s meson is measured in two decay modes, with contri- butions from different amounts of the heavy and light eigenstates. This results in two different measured lifetimes: cτB0 s →J/ψπ+ π− = 502.7 ± 10.2 (stat) ± 3.4 (syst) μm and cτB0 s →J/ψφ(1020) = 443.9 ± 2.0 (stat) ± 1.5 (syst) μm. The Λ0 b lifetime is found to be 442.9 ± 8.2 (stat) ± 2.8 (syst) μm. The precision from each of these channels is as good as or better than previous measurements. The B+ c lifetime, measured with re- spect to the B+ to reduce the systematic uncertainty, is 162.3 ± 7.8 (stat) ± 4.2 (syst) ± 0.1 (τB+ ) μm. All results are in agreement with current world-average values.

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