Search for CP violation in $D^{+} to K^{-}K^{+}pi^{+}$ decays

A model-independent search for direct CP violation in the Cabibbo suppressed decay $D^+ to K^- K^+pi^+$ in a sample of approximately 370,000 decays is carried out. The data were collected by the LHCb experiment in 2010 and correspond to an integrated luminosity of 35 pb$^{-1}$. The normalized Dalitz plot distributions for $D^+$ and $D^-$ are compared using four different binning schemes that are sensitive to different manifestations of CP violation. No evidence for CP asymmetry is found.

Evidence for CP violation in $B^+to p overline p K^+$ decays

Three-body $B^+to p overline p K^+$ and $B^+to p overline p pi^+$ decays are studied using a data sample corresponding to an integrated luminosity of 3.0 $fb^{-1}$ collected by the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8$ TeV. Evidence of CP violation in the $B^+to p overline p K^+$ decay is found in regions of the phase space, representing the first measurement of this kind for a final state containing baryons. Measurements of the forward-backward asymmetry of the light meson in the $poverline p$ rest frame yield $A_{mathrm{FB}}(p overline p K^+,~m_{poverline p}<2.85mathrm{,Gekern -0.1em V!/}c^2)=0.495pm0.012~(mathrm{stat})pm0.007~(mathrm{syst})$ and $A_{mathrm{FB}}(poverline p pi^+,~m_{poverline p}<2.85mathrm{,Gekern -0.1em V!/}c^2)=-0.409pm0.033~(mathrm{stat})pm0.006~(mathrm{syst})$. In addition, the branching fraction of the decay $B^+tokern 0.1emoverline{kern -0.1emLambda}(1520)p$ is measured to be $mathcal{B}(B^+ to kern 0.1emoverline{kern -0.1emLambda}(1520)p)=(3.15pm0.48~(mathrm{stat})pm0.07~(mathrm{syst})pm0.26~(mathrm{BF}))times 10^{-7}$, where BF denotes the uncertainty on secondary branching fractions.

Search for direct CP-violation in singly-Cabibbo suppressed D+- --> K+ K- pi+- decays

We report on a search for direct CP asymmetry in the singly Cabibbo-suppressed decay D+- --> K+ K- pi+- using a data sample of 476 fb-1 accumulated with the BaBar detector running at and just below the Y(4S) resonance. The CP-violating decay rate asymmetry A_CP is determined to be (0.35 +- 0.30 +- 0.15)%. Model-dependent and model-independent Dalitz plot analysis techniques are used to search for CP-violating asymmetries in the various intermediate states.

Search for $CP$ violation using $T$-odd correlations in $D^0 to K^+K^-pi^+pi^-$ decays

A search for $CP$ violation using $T$-odd correlations is performed using the four-body $D^0 to K^+K^-pi^+pi^-$ decay, selected from semileptonic $B$ decays. The data sample corresponds to integrated luminosities of $1.0,text{fb}^{-1}$ and $2.0,text{fb}^{-1}$ recorded at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. The $CP$-violating asymmetry $a_{CP}^{Ttext{-odd}}$ is measured to be $(0.18pm 0.29text{(stat)}pm 0.04text{(syst)})%$. Searches for $CP$ violation in different regions of phase space of the four-body decay, and as a function of the $D^0$ decay time, are also presented. No significant deviation from the $CP$ conservation hypothesis is found.

Search for time-dependent $CP$ violation in $D^0 to K^+ K^-$ and $D^0 to pi^+ pi^-$ decays

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 TeV, 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.