Measurement of CP violation and the B-s(0) meson decay width difference with B-s(0) -> J/psi K+K- and B-s(0) -> J/psi pi(+) pi(-)decays (original) (raw)

Measurement of Lifetime and Decay-Width Difference in Bs0→J/ψϕ Decays

Physical Review Letters, 2008

We measure the mean lifetime, τ = 2/(ΓL + ΓH), and the decay-width difference, ∆Γ = ΓL − ΓH , of the light and heavy mass eigenstates of the B 0 s meson, B 0 sL and B 0 sH , in B 0 s → J/ψ φ decays using 1.7 fb −1 of data collected with the CDF II detector at the Fermilab Tevatron pp collider. Assuming CP conservation, a good approximation for the B 0 s system in the standard model, we obtain ∆Γ = 0.076 +0.059 −0.063 (stat.) ± 0.006(syst.) ps −1 and τ = 1.52 ± 0.04(stat.) ± 0.02(syst.) ps, the most precise measurements to date. Our constraints on the weak phase and ∆Γ are consistent with CP conservation.

Updated measurement of time-dependent CP$$-violating observables in {{B} ^0_{s}} \rightarrow J/\psi K^+ K^-$$ decays

The European Physical Journal C, 2019

The decay-time-dependent CP asymmetry in B 0 s → J/ψ K + K − decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 1.9 fb −1 , collected with the LHCb detector at a centre-ofmass energy of 13 TeV in 2015 and 2016. Using a sample of approximately 117 000 signal decays with an invariant K + K − mass in the vicinity of the φ(1020) resonance, the CP-violating phase φ s is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B 0 s-B 0 s system, s. The difference of the average B 0 s and B 0 meson decay widths, s − d , is determined using in addition a sample of B 0 → J/ψ K + π − decays. The values obtained are φ s = −0.083 ± 0.041 ± 0.006 rad, s = 0.077 ± 0.008 ± 0.003 ps −1 and s − d = −0.0041 ± 0.0024 ± 0.0015 ps −1 , where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of these quantities to date and are consistent with expectations based on the Standard Model and with a previous LHCb analysis of this decay using data recorded at centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with recent results from B 0 s → J/ψ π + π − decays obtained using the same dataset as this analysis, and with previous independent LHCb results.

Measurement of CP violation in B0→J/ψK0S and B0→ψ(2S)K0S decays

Journal of High Energy Physics, 2017

A measurement is presented of decay-time-dependent CP violation in the decays B 0 → J/ψ K 0 S and B 0 → ψ(2S)K 0 S , 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 C B 0 → J/ψ K 0 S = 0.12 ± 0.07 ± 0.02 , S B 0 → J/ψ K 0 S = 0.83 ± 0.08 ± 0.01 , C B 0 → ψ(2S)K 0 S = − 0.05 ± 0.10 ± 0.01 , S B 0 → ψ(2S)K 0 S = 0.84 ± 0.10 ± 0.01 , 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 B 0-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 B 0 → J/ψ K 0 S decays, where the J/ψ meson was reconstructed from two muons. The averages of all three sets of LHCb results are C(B 0 → [cc]K 0 S) = −0.017 ± 0.029 , S(B 0 → [cc]K 0 S) = 0.760 ± 0.034 , under the assumption that higher-order contributions to the decay amplitudes are negligible. The uncertainties include statistical and systematic contributions.

Measurement of Time-Dependent CP-Violating Parameters in B0→KS0KS0 Decays

Physical Review Letters, 2008

We report a measurement of the CP -violating parameters in B 0 → K 0 S K 0 S decays based on a data sample of 657×10 6 BB pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. In this study, one neutral B meson is fully reconstructed in the B 0 → K 0 S K 0 S decay mode, and the flavor of the accompanying B meson is identified by its decay products. The CP -violating parameters are measured from the asymmetry in the distributions of the proper-time interval between the two B decays: S K 0

Measurement of CP observables for the decays B±→DCP0K±

Physical Review D, 2006

We present a study of the decay B − →D 0 (CP ) K − and its charge conjugate, where D 0 (CP ) is reconstructed in CP -even, CP -odd, and non-CP flavor eigenstates, based on a sample of 232 million Υ (4S)→BB decays collected with the BABAR detector at the PEP-II e + e − storage ring. We measure the partial-rate charge asymmetries ACP ± and the ratios RCP ± of the B→D 0 K decay branching fractions as measured in CP ± and non-CP D 0 decays: ACP+ = 0.35 ± 0.13(stat) ± 0.04(syst), ACP− = −0.06 ± 0.13(stat) ± 0.04(syst), RCP + = 0.90 ± 0.12(stat) ± 0.04(syst), RCP − = 0.86 ± 0.10(stat) ± 0.05(syst).