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Register a new userStudy of CP violation in $B^pm$ decays to $overline{D^0}(D^0) K^pm$ at FCCee
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The great progress made recently in the sector of Flavor Physics has enabled to establish CP violation in the B-meson decays. The unitarity triangle derived from the unitarity relation $V_{ub}^* V_{ud} + V_{cb}^* V_{cd} + V_{tb}^* V_{td} = 0$ has been measured very precisely. To further asses our understanding of CP violation, it would be useful to carry out similar measurement of other triangles. In this note, we investigate the triangle derived from the relation $V_{ub}^* V_{us} + V_{cb}^* V_{cs} + V_{tb}^* V_{ts} = 0$. Two angles of this triangle ($alpha_s$ and $beta_s$) could be measured very accurately at FCCee using the decays $B_s(overline{B_s})rightarrow D^pm_sK^mp$ and $B_s(overline{B_s})rightarrow J/psi phi$ respectively, as discussed elsewhere by us. This note concentrates on the measurement of the third angle $gamma_s$ using the modes $B^pm to overline{D^0}(D^0)K^pm$. We show that a direct measurement of the angle $gamma_s$ is possible with some specific $B^pm$ decays with an estimated resolution of the order of 1$^circ$.
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A first study of CP violation in the decay modes $B^pmto [K^0_{rm S} K^pm pi^mp]_D h^pm$ and $B^pmto [K^0_{rm S} K^mp pi^pm]_D h^pm$, where $h$ labels a $K$ or $pi$ meson and $D$ labels a $D^0$ or $overline{D}^0$ meson, is performed. The analysis uses the LHCb data set collected in $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. The analysis is sensitive to the CP-violating CKM phase $gamma$ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of $gamma$ using other decay modes.
Measurements of $CP$ observables in $B^pm rightarrow D^{(*)} K^pm$ and $B^pm rightarrow D^{(*)} pi^pm$ decays are presented, where $D^{(*)}$ indicates a neutral $D$ or $D^*$ meson that is an admixture of $D^{(*)0}$ and $bar{D}^{(*)0}$ states. Decays of the $D^*$ meson to the $Dpi^0$ and $Dgamma$ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the $B$ candidate invariant mass distribution. Decays of the $D$ meson are fully reconstructed in the $K^pm pi^mp$, $K^+ K^-$ and $pi^+ pi^-$ final states. The analysis uses a sample of charged $B$ mesons produced in $pp$ collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb$^{-1}$ taken at centre-of-mass energies of $sqrt{s}$ = 7, 8 and 13 TeV, respectively. The study of $B^{pm} to D^{*} K^{pm}$ and $B^{pm} to D^{*} pi^{pm}$ decays using a partial reconstruction method is the first of its kind, while the measurement of $B^{pm} to D K^{pm}$ and $B^{pm} to D pi^{pm}$ decays is an update of previous LHCb measurements. The $B^{pm} to D K^{pm}$ results are the most precise to date.
A measurement of the $CP$ asymmetries $S_{f}$ and $S_{bar{f}}$ in $B^0to D^{mp}pi^{pm}$ decays is reported. The decays are reconstructed in a dataset collected with the LHCb experiment in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of $3.0 rm{ fb}^{-1}$. The $CP$ asymmetries are measured to be $S_{f} = 0.058 pm 0.020 (rm{stat}) pm 0.011(rm{syst})$ and $S_{bar{f}} = 0.038pm 0.020 (text{stat})pm 0.007 (text{syst})$. These results are in agreement with, and more precise than, previous determinations. They are used to constrain $|sinleft(2beta+gammaright)|$ and $gamma$ to intervals that are consistent with the current world-average values.
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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