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Register a new userMeasurement of CP asymmetries in $B^0 to K^0pi^0$ decays
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We report measurements of CP violation parameters in $B^0 to K^0 pi^0$ decays based on a data sample of $657 times 10^6 Bbar{B}$ pairs collected with the Belle detector at the KEKB $e^+ e^-$ asymmetric-energy collider. We use $B^0 to K^0_S pi^0$ decays for both mixing-induced and direct $CP$ violating asymmetry measurements and $B^0 to K^0_L pi^0$ decays for the direct CP violation measurement. The CP violation parameters obtained are $sin 2 phi_1^{rm eff} = +0.67 pm 0.31{(stat)} pm 0.08 {(syst)}$ and $mathcal{A}_{K^0 pi^0} = +0.14 pm 0.13{(stat)} pm 0.06 {(syst)}$. The branching fraction of $B^0 to K^0 pi^0$ decay is measured to be $mathcal{B}(B^0 to K^0 pi^0) = (8.7pm0.5 (rm{stat.})pm0.6 (rm{syst.}))times 10^{-6}$. The observed $mathcal{A}_{K^0 pi^0}$ value differs by 1.9 standard deviations from the value expected from an isospin sum rule.
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We report a measurement of time-dependent $CP$ violation parameters in ${B^0 to K_S^0 eta gamma}$ decays. The study is based on a data sample, containing ${772 times 10^6 Bbar{B}}$ pairs, that was collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We obtain the $CP$ violation parameters of ${{cal S} = -1.32 pm 0.77 {rm (stat.)} pm 0.36{rm (syst.)}}$ and ${{cal A} = -0.48 pm 0.41 {rm (stat.)} pm 0.07{rm (syst.)}}$ for the invariant mass of the $K_S^0 eta$ system up to 2.1 GeV/$c^2$.
An angular analysis of the decay $B_s^0 rightarrow K^{*0}bar{K}{}^{*0}$ is performed using $pp$ collisions corresponding to an integrated luminosity of $1.0$ ${fb}^{-1}$ collected by the LHCb experiment at a centre-of-mass energy $sqrt{s} = 7$ TeV. A combined angular and mass analysis separates six helicity amplitudes and allows the measurement of the longitudinal polarisation fraction $f_L = 0.201 pm 0.057 {(stat.)} pm 0.040{(syst.)}$ for the $B_s^0 rightarrow K^*(892)^0 bar{K}{}^*(892)^0$ decay. A large scalar contribution from the $K^{*}_{0}(1430)$ and $K^{*}_{0}(800)$ resonances is found, allowing the determination of additional $CP$ asymmetries. Triple product and direct $CP$ asymmetries are determined to be compatible with the Standard Model expectations. The branching fraction $mathcal{B}(B_s^0 rightarrow K^*(892)^0 bar{K}{}^*(892)^0)$ is measured to be $(10.8 pm 2.1 { rm (stat.)} pm 1.4 { rm (syst.)} pm 0.6 (f_d/f_s) ) times 10^{-6}$.
An angular analysis of the decay $B^0 to phi K^*(892)^0$ is reported based on a $pp$ collision data sample, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected at a centre-of-mass energy of $sqrt{s} = 7$ TeV with the LHCb detector. The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave $K^+ pi^-$ and $K^+K^-$ contributions are taken into account and found to be significant. A comparison of the $B^0 to phi K^*(892)^0$ and $bar{B}^0 to phi bar{K}^*(892)^0$ results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.
We report a measurement of time-dependent $CP$ violation in $B^0 to K^0_S pi^0 pi^0$ decays using a data sample of $772 times 10^6$ $Bbar{B}$ pairs collected by the Belle experiment runnin g at the $Upsilon (4S)$ resonance at the KEKB $e^+ e^-$ collider. This decay proceeds mainly via a $bto sdbar{d}$ penguin amplitude. The results are $sin 2phi^{rm eff}_1 = 0.92^{+0.27}_{-0.31}~$ (stat.) $pm 0.11$ (syst.) and $mathcal{A} = 0.28 pm 0.21$ (stat.) $pm 0.04$ (syst.), which are the most precise measurements of $CP$ violati on in this decay mode to date. The value for the $CP$-violating parameter $sin 2phi^{rm eff}_1$ is consistent with that obtained using decay modes proceeding via a $bto cbar{c}s$ tree amplitude.
A search for decay-time-dependent charge-parity ($CP$) asymmetry in $D^0 to K^+K^-$ and $D^0 to pi^+pi^-$ decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13TeV, and corresponding to an integrated luminosity of 5.4fb$^{-1}$. The $D^0$ mesons are required to originate from semileptonic decays of $b$ hadrons, such that the charge of the muon identifies the flavor of the neutral $D$ meson at production. The asymmetries in the effective decay widths of $D^0$ and $overline{D}^0$ mesons are determined to be $A_{Gamma}(K^+K^-) = ( -4.3 pm 3.6 pm 0.5 )times 10^{-4}$ and $A_{Gamma}(pi^+pi^-) = ( 2.2 pm 7.0 pm 0.8)times 10^{-4}$, where the uncertainties are statistical and systematic, respectively. The results are consistent with $CP$ symmetry and, when combined with previous LHCb results, yield $A_{Gamma}(K^+K^-) = ( -4.4 pm 2.3 pm 0.6 )times 10^{-4}$ and $A_{Gamma}(pi^+pi^-) = ( 2.5 pm 4.3 pm 0.7)times 10^{-4}$.
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