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

Abstract

Measurements are presented of the lifetimes of the B[superscript 0], B[superscript 0][subscript s], Λ[superscript 0][subscript b], and B[superscript +][superscript c] hadrons using the decay channels B[superscript 0]→J/ψK[superscript ∗](892)[superscript 0], B[superscript 0]→J/ψK[superscript 0][subscript S], B[superscript 0][subscript s]→J/ψπ[superscript +]π[superscript −], B[superscript 0][subscript s]→J/ψϕ(1020), Λ[superscript 0][subscript b]→J/ψΛ[superscript 0], and B[superscript +][subscript c]→J/ψπ[superscript +]. The data sample, corresponding to an integrated luminosity of 19.7 fb[superscript -1], was collected by the CMS detector at the LHC in proton–proton collisions at √s = 8TeV. The B[superscript 0] lifetime is measured to be 453.0±1.6(stat) ± 1.8(syst)μm in J/ψK[superscript ∗](892)[superscript 0] and 457.8±2.7(stat)±2.8(syst)μm in J/ψK[superscript 0][subscript S], which results in a combined measurement of cτ[subscript B[superscript]]=454.1±1.4(stat)±1.7(syst)μm. The effective lifetime of the B[superscript 0][subscript s] meson is measured in two decay modes, with contributions from different amounts of the heavy and light eigenstates. This results in two different measured lifetimes: cτ[subscript B[superscript 0][subscript s]]→J/ψπ[superscript +]π[superscript −]=502.7±10.2(stat)±3.4(syst)μm and cτ[subscript B[superscript 0][subscript s]]→J/ψϕ(1020)=443.9±2.0(stat)±1.5(syst)μm . The Λ[superscript 0][subscript 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[superscript +][subscript c] lifetime, measured with respect to the B[superscript +] to reduce the systematic uncertainty, is 162.3±7.8(stat)±4.2(syst)±0.1(τ[subscript B[superscript +]])μm. All results are in agreement with current world-average values.United States. Department of EnergyNational Science Foundation (U.S.)