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تسجيل مستخدم جديدDirect CP violation in $D^+ to K^0(bar K^0) pi^+$ decays as a probe for new physics
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In this paper we investigate CP violation in charged decays of $D$ meson. Particularly, we study the direct CP asymmetry of the Cabibbo favored non-leptonic $D^+ rightarrow bar K^0 pi^+$ and the doubly Cabibbo-suppressed decay mode $D^+ rightarrow K^0 pi^+$ within standard model, two Higgs doublet model with generic Yukawa structure and left right symmetric models. In the standard model, we first derive the contributions from box and di-penguin diagrams contributing to their amplitudes which are relevant to the generation of the weak phases essential for non-vanishing direct CP violation. Then, we show that these phases are so tiny leading to a direct CP asymmetry of order $10^{-11}$ in both decay modes. Regarding the two Higgs doublet model with generic Yukawa structure and after taking into account all constraints on the parameter space of the model, we show that the enhanced direct CP asymmetries can be 6 and 7 orders of magnitudes larger than the standard model prediction for $D^+ rightarrow bar K^0 pi^+$ and $D^+ rightarrow K^0 pi^+$ respectively. Finally, within left right symmetric models, we find that sizable direct CP asymmetry of ${mathcal O } (10^{-3})$ can be obtained for the decay mode $D^+ rightarrow bar K^0 pi^+$ after respecting all relevant constraints.
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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.
A search for time-dependent violation of the charge-parity symmetry 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 from 2015 to 2018 at a centre-of-mass energy of 13 T
eV, corresponding to an integrated luminosity of 6 fb$^{-1}$. The $D^0$ meson is required to originate from a $D^*(2010)^+ to D^0 pi^+$ decay, such that its flavour at production is identified by the charge of the accompanying pion. The slope of the time-dependent asymmetry of the decay rates of $D^0$ and $bar{D}^0$ mesons into the final states under consideration is measured to be $Delta Y_{K^+ K^-} = (-2.3 pm 1.5 pm 0.3) times 10^{-4}$, $Delta Y_{pi^+ pi^-} = (-4.0 pm 2.8 pm 0.4)times 10^{-4}$, where the first uncertainties are statistical and the second are systematic. These results are compatible with the conservation of the $CP$ symmetry at the level of 2 standard deviations and improve the precision by nearly a factor of two.
In this paper, we study the Cabibbo favored non-leptonic $D^0$ decays into $K^- pi^+$ decays. First we show that, within the Standard Model, the corresponding CP asymmetry is strongly suppressed and out of the experimental range even taking into acco
unt the large strong phases coming from final state Interactions. We show also that although new physics models with extra sequential generation can enhance the CP asymmetry by few orders of magnitude however the resulting CP asymmetry is still far from experimental range. The most sensitive New Physics Models to this CP asymmetry comes from no-manifest Left-Right models where a CP asymmetry up to 10% can be reached and general two Higgs models extension of SM where a CP asymmetry of order $10^{-2}$ can be obtained without being in contradiction with the experimental constraints on these models.
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