Abstract
The time-dependent CP asymmetries of B0→ π+π− and {B}_s^0 → K+K− decays are measured using a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. The results areCππ=−0.311±0.045±0.015,Sππ=−0.706±0.042±0.013,CKK=0.123±0.034±0.015,SKK=0.164±0.034±0.014,AKKΔΓ=−0.83±0.05±0.09,\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ {\\displaystyle \\begin{array}{c}{C}_{\\pi \\pi}=-0.311\\pm 0.045\\pm 0.015,\\\\ {}{S}_{\\pi \\pi}=-0.706\\pm 0.042\\pm 0.013,\\\\ {}{C}_{KK}=0.123\\pm 0.034\\pm 0.015,\\\\ {}{S}_{KK}=0.164\\pm 0.034\\pm 0.014,\\\\ {}{\\mathcal{A}}_{KK}^{\\Delta \\varGamma }=-0.83\\pm 0.05\\pm 0.09,\\end{array}} $$\\end{document}where the first uncertainties are statistical and the second systematic. The same data sample is used to measure the time-integrated CP asymmetries of B0→ K + π− and {B}_s^0 →K−π+ decays and the results areACPB0=−0.0824±0.0033±0.0033,ACPBs0=0.236±0.013±0.011.\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ {\\displaystyle \\begin{array}{c}{A}_{CP}^{B^0}=-0.0824\\pm 0.0033\\pm 0.0033,\\\\ {}{A}_{CP}^{B_s^0}=0.236\\pm 0.013\\pm 0.011.\\end{array}} $$\\end{document}All results are consistent with earlier measurements. A combination of LHCb measurements provides the first observation of time-dependent CP violation in {B}_s^0 decays.
Highlights
Charge-parity (CP ) asymmetries of charmless B(0s)-meson decays to two-body charged final states are important inputs to the validation of the Cabibbo-Kobayashi-Maskawa (CKM)mechanism [1, 2], which models CP violation in charged-current quark transitions
The time-dependent CP asymmetries of B0 → π+π− and Bs0 → K+K− decays are measured using a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV
The CP asymmetry in the B0 → π+π− decay is a fundamental input to the isospin analysis of B → ππ decays that allows the determination of the CKM angle α [10,11,12]
Summary
Charge-parity (CP ) asymmetries of charmless B(0s)-meson decays to two-body charged final states are important inputs to the validation of the Cabibbo-Kobayashi-Maskawa (CKM). The analysis is based on a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb−1, collected with the LHCb detector at a centre-ofmass energy of 13 TeV during 2015 and 2016 These results are combined with previous LHCb results, published in ref. In decays of B(0s) mesons to a final state f , where f is a CP eigenstate (f = f ), CP violation originates from the interference between the decay and The latter can be modelled by an effective Hamiltonian whose mass eigenstates are linear combinations of the two flavour eigenstates, p|B(0s). The time-integrated CP asymmetry for a B(0s) decay to a flavour-specific final state f , such as B0 → K+π− and Bs0 → K−π+, is defined as. The interaction of the generated particles with the detector, and its response, are implemented using the Geant toolkit [49, 50] as described in ref. [51]
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