Abstract
The lifetime is among the fundamental properties of particles and is one of the important observables in heavy hadrons allowing to test the theoretical tools describing their physics. This report presents lifetime measurements of B0, B0s, Λ0b and B+c hadrons performed on data, corresponding to 19.7 fb-1, collected by the CMS experiment at the LHC at a center-of-mass energy of √s = 8 TeV. The B0 lifetime is measured to be 453:0± 1:6 (stat) ± 1:5 (syst) μm in J/ψK0S and 457:8 ± 2:7 (stat) ± 2:7 (syst) μm in J/ψK*(892)0. The B0s meson lifetime is measured in two decay modes with differing contributions from the heavy and light eigenstates, resulting in two different measured lifetimes: 504:3 ± 10:5 (stat) ±3:7 (syst) μm in J/ψπ+π- and 443:9±2:0 (stat) ±1:2 (syst) μm in J/ψϕ(1020) respectively. The lifetime of the Λ0b hadron is found to be 443:1±8:2 (stat) ±2:7 (syst) μm. The B+c lifetime is measured with respect to the B+ lifetime and is found to be 162:3 ± 8:2 (stat) ± 4:7 (syst) ± 0:1 (τB+) μm.
Highlights
Precise lifetime measurements of heavy hadrons play an important role in the study of nonperturbative Quantum Chromodynamics (QCD)
The large production rate of b hadrons at the LHC and the detection capabilities of the CMS detector allow to make precise b hadron lifetime measurements, which in turn make it possible to test these predictions. In this √report the measurement of the B0, B0s, B+c and Λ0b hadrons lifetimes at the center-of-mass energy of s = 8 TeV by the CMS collaboration [2] are discussed
For all channels the lifetime measurement is restricted to events for which the ct of the b hadron is larger than 0.02 cm to avoid reconstruction and resolution effects in the low-ct region
Summary
Precise lifetime measurements of heavy hadrons play an important role in the study of nonperturbative Quantum Chromodynamics (QCD). Model describes the weak decays of hadrons containing a heavy quark and provides accurate estimates of the ratio of their lifetimes [1]. The large production rate of b hadrons at the LHC and the detection capabilities of the CMS detector allow to make precise b hadron lifetime measurements, which in turn make it possible to test these predictions. In this √report the measurement of the B0, B0s, B+c and Λ0b hadrons lifetimes at the center-of-mass energy of s = 8 TeV by the CMS collaboration [2] are discussed. Where M is the world-average value of the b hadron mass [3]
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