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Register a new userProbing CP violation in $B^0_s rightarrow K^{0}_{rm S} pi^{+}pi^{-}$ decays
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The three-body charmless hadronic decay $B^0_s rightarrow K^{0}_{rm S} pi^{+}pi^{-}$ provides a number of novel possibilities to search for CP violation effects and test the Standard Model of particle physics. These include fits to the Dalitz-plot distributions of the decay-time-integrated final state, decay-time-dependent (but without initial state flavour tagging) fits to the Dalitz-plot distribution, as well as full decay-time-dependent and flavour tagged fits. The relative sensitivities of these different approaches are investigated.
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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.
The decays $K^{ast}(892)rightarrow K_{S,L}^{0}pi$ can be used to study CP violation and CPT violation. The $K^{ast}(892)$ meson can be produced via $J/psi$ decays at BESIII. In this paper, we study CP violation and CPT violation in $K^{ast}(892)rightarrow K_{S,L}^{0}pi$ decays at BESIII. Basing on two cases: the samples of $10^{10}$ and $10^{12}$ $J/psi$ events, we calculate the expected numbers of the observed signal events on the CP violation in $J/psi$ decays with $K^{ast}(892)$ meson in the final states, we find that the BESIII experiment may be able to unambiguously observe CP violation for each of these two cases. Under the assumption that the observed event on CPT violation is absent, we discuss the upper limits on the absolute value of the CPT violation parameter $Re(z)$ in $J/psi$ decays involving $K^{ast}(892)$ meson in the final states with $10^{10}$ $J/psi$ events and $10^{12}$ $J/psi$ events, respectively. By using the accumulated $10^{10}$ $J/psi$ events, the upper limits on $left|Re(z)right|$ can be obtained at the $90%$ confidence level of $10^{-4}-10^{-5}$, which is competitive with the current best result, if the detection efficiency $varepsilon_{K^0_{L}}$ is assumed to be at the level of $8times 10^{-3}$ at BESIII. And besides, the upper limits on $left|Re(z)right|$ will be improved by about two orders of magnitude compared with the current best result with $10^{12}$ $J/psi$ events.
Measurements of the effective lifetimes in the $B_{s}^{0} rightarrow K^{+}K^{-}$, $B^{0} rightarrow K^{+}pi^{-}$ and $B_{s}^{0} rightarrow pi^{+}K^{-}$ decays are presented using $1.0~mathrm{fb^{-1}}$ of $pp$ collision data collected at a centre-of-mass energy of 7 TeV by the LHCb experiment. The analysis uses a data-driven approach to correct for the decay time acceptance. The measured effective lifetimes are $tau_{B_{s}^{0} rightarrow K^{+}K^{-}}$ = $1.407~pm~0.016~pm~0.007~mathrm{ps}$, $tau_{B^{0} rightarrow K^{+}pi^{-}}$ = $1.524~pm~0.011~pm~0.004~mathrm{ps}$, $tau_{B_{s}^{0} rightarrow pi^{+}K^{-}}$ = $1.60~pm~0.06~pm~0.01~mathrm{ps}$. This is the most precise determination to date of the effective lifetime in the $B_{s}^{0} rightarrow K^{+}K^{-}$ decay and provides constraints on contributions from physics beyond the Standard Model to the $B_{s}^{0}$ mixing phase and the width difference $DeltaGamma_{s}$.
Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ and $overline{B}{}^0$ mesons to the $J/psi K^0_S$ final state. The data sample corresponds to an integrated luminosity of $3.0,text{fb}^{-1}$ collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8,text{TeV}$. The analysis of the time evolution of $41500$ $B^0$ and $overline{B}{}^0$ decays yields $S = 0.731 pm 0.035 , text{(stat)} pm 0.020 ,text{(syst)}$ and $C = -0.038 pm 0.032 , text{(stat)} pm 0.005,text{(syst)}$. In the Standard Model, $S$ equals $sin(2beta)$ to a good level of precision. The values are consistent with the current world averages and with the Standard Model expectations.
In this paper we study the direct CP asymmetry of the doubly Cabibbo-suppressed decay mode $D^0 to K^+ pi^- $ within standard model and two Higgs doublet model with generic Yukawa structure. In the standard model we derive the corrections to the tree level amplitude, generated from the box and di-penguin diagrams, required for generating the weak CP violating phases. We show that these phases are so tiny leading to a direct CP asymmetry of order $10^{-9}$. Regarding the two Higgs doublet model with generic Yukawa structure we derive the Wilson coefficients relevant to $D^0 to K^+ pi^- $. After taking into account all constraints on the parameter space of the model we show that charged Higgs couplings to quarks can lead to a direct CP asymmetry of order $10^{-3}$ which is $6$ orders of magnitude larger than the standard model prediction.
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