Journal of High Energy Physics > 2017 > 2017 > 11 > 1-18
Measurement of CP violation in B0 → J/ψKS0 and B0 → ψ(2S)KS0 decays
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Abstract
A measurement is presented of decay-time-dependent CP violation in the decays B0 → J/ψ KS0 and B0 → ψ(2S)KS0, where the J/ψ is reconstructed from two electrons and the ψ(2S) from two muons. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1. The CP -violation observables are measured to be CB0→J/ψKS0=0.12±0.07±0.02,SB0→J/ψKS0=0.83±0.08±0.01,CB0→ψ2SKS0=−0.05±0.10±0.01,SB0→ψ2SKS0=0.84±0.10±0.01, $$ \begin{array}{l}C\left({B}^0\to J/\psi \kern0.5em {K}_{\mathrm{S}}^0\right)=0.12\pm 0.07\pm 0.02,\\ {}S\left({B}^0\to J/\psi \kern0.5em {K}_{\mathrm{S}}^0\right)=0.83\pm 0.08\pm 0.01,\\ {}C\left({B}^0\to \psi (2S){K}_{\mathrm{S}}^0\right)=-0.05\pm 0.10\pm 0.01,\\ {}S\left({B}^0\to \psi (2S){K}_{\mathrm{S}}^0\right)=0.84\pm 0.10\pm 0.01,\end{array} $$ where C describes CP violation in the direct decay, and S describes CP violation in the interference between the amplitudes for the direct decay and for the decay after B0−B¯0 $$ {B}^0-{\overline{B}}^0 $$ oscillation. The first uncertainties are statistical and the second are systematic. The two sets of results are compatible with the previous LHCb measurement using B0 → J/ψ KS0 decays, where the J/ψ meson was reconstructed from two muons. The averages of all three sets of LHCb results are CB0→cc¯KS0=−0.017±0.029,SB0→cc¯KS0=0.760±0.034, $$ \begin{array}{l}C\left({B}^0\to \left[c\overline{c}\right]{K}_{\mathrm{S}}^0\right)=-0.017\pm 0.029,\\ {}S\left({B}^0\to \left[c\overline{c}\right]{K}_{\mathrm{S}}^0\right)=0.760\pm 0.034,\end{array} $$ under the assumption that higher-order contributions to the decay amplitudes are negligible. The uncertainties include statistical and systematic contributions.
Identifiers
journal e-ISSN : | 1029-8479 |
DOI | 10.1007/JHEP11(2017)170 |