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Register a new userSearch for $CP$ violation in $Xi_c^+rightarrow pK^-pi^+$ decays using model-independent techniques
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A first search for $CP$ violation in the Cabibbo-suppressed $Xi_c^+rightarrow pK^-pi^+$ decay is performed using both a binned and an unbinned model-independent technique in the Dalitz plot. The studies are based on a sample of proton-proton collision data, corresponding to an integrated luminosity of $3.0~{rm fb^{-1}}$, and collected by the LHCb experiment at centre-of-mass energies of $7$ and $8~rm TeV$. The data are consistent with the hypothesis of no $CP$ violation.
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A search for CP violation in the phase-space structures of D0 and D0bar decays to the final states K-K+pi-pi+ and pi-pi+pi+pi- is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0fb^-1 collected in 2011 by the LHCb experiment in $pp$ collisions at a centre-of-mass energy of 7TeV. For the K-K+pi-pi+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the pi-pi+pi+pi- final state is partitioned into 128 bins, each bin with approximately 2500 decays. The $p$-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity.
A search for $C$P and $P$ violation using triple-product asymmetries is performed with $Lambda^{0}_{b}to pK^{-}pi^{+}pi^{-}$, $Lambda^{0}_{b}to pK^{-}K^{+}K^{-}$ and $Xi^{0}_{b}to pK^{-}K^{-}pi^{+}$ decays. The data sample corresponds to integrated luminosities of 1.0fb$^{-1}$ and 2.0fb$^{-1}$, recorded with the LHCb detector at centre-of-mass energies of 7TeV and 8TeV, respectively. The $CP$- and $P$-violating asymmetries are measured both integrating over all phase space and in specific phase-space regions. No significant deviation from $CP$ or $P$ symmetry is found. The first observation of $Lambda^{0}_{b}to pK^{-}chi_{c0}(1P)(topi^{+}pi^{-}, K^{+}K^{-})$ decay is also reported.
Searches for $CP$ violation in the two-body decays $D_{(s)}^{+}rightarrow h^{+}pi^{0}$ and $D_{(s)}^{+} rightarrow h^{+}eta$ (where $h^{+}$ denotes a $pi^{+}$ or $K^{+}$ meson) are performed using $pp$ collision data collected by the LHCb experiment corresponding to either 9 fb$^{-1}$ or 6 fb$^{-1}$ of integrated luminosity. The $pi^{0}$ and $eta$ mesons are reconstructed using the $e^{+}e^{-}gamma$ final state, which can proceed as three-body decays $pi^{0}rightarrow e^{+}e^{-}gamma$ and $eta rightarrow e^{+}e^{-}gamma$, or via the two-body decays $pi^{0}rightarrow gammagamma$ and $etarightarrowgammagamma$ followed by a photon conversion. The measurements are made relative to the control modes $D_{(s)}^{+}rightarrow K_{S}^{0} h^{+}$ to cancel the production and detection asymmetries. The $CP$ asymmetries are measured to be begin{align} mathcal{A}_{CP}(D^{+}rightarrow pi^{+}pi^{0}) &= (-1.3 pm 0.9 pm 0.6 )%, end{align} begin{align} mathcal{A}_{CP}(D^{+}rightarrow K^{+}pi^{0}) &= (-3.2 pm 4.7 pm 2.1 )%, end{align} begin{align} mathcal{A}_{CP}(D^{+}rightarrow pi^{+}eta) &= (-0.2 pm 0.8 pm 0.4 )%, end{align} begin{align} mathcal{A}_{CP}(D^{+}rightarrow K^{+}eta) &= (-6 pm 10 pm 4 )%, end{align} begin{align} mathcal{A}_{CP}(D_{s}^{+}rightarrow K^{+}pi^{0}) &= (-0.8 pm 3.9 pm 1.2 )%, end{align} begin{align} mathcal{A}_{CP}(D_{s}^{+}rightarrow pi^{+}eta) &= (0.8 pm 0.7 pm 0.5 )%, end{align} begin{align} mathcal{A}_{CP}(D_{s}^{+}rightarrow K^{+}eta) &= (0.9 pm 3.7 pm 1.1 )%, end{align} where the first uncertainties are statistical and the second systematic. These results are consistent with no $CP$ violation and mostly constitute the most precise measurements of $mathcal{A}_{CP}$ in these decay modes to date.
A search for $CP$ violation in the Cabibbo-suppressed $D^0 rightarrow K^+ K^- pi^+ pi^-$ decay mode is performed using an amplitude analysis. The measurement uses a sample of $pp$ collisions recorded by the LHCb experiment during 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $D^0$ mesons are reconstructed from semileptonic $b$-hadron decays into $D^0mu^- X$ final states. The selected sample contains more than 160000 signal decays, allowing the most precise amplitude modelling of this $D^0$ decay to date. The obtained amplitude model is used to perform the search for $CP$ violation. The result is compatible with $CP$ symmetry, with a sensitivity ranging from 1% to 15% depending on the amplitude considered.
We search for CP violation in neutral charm meson decays using a data sample with an integrated luminosity of 966 fb^-1 collected with the Belle detector at the KEKB e+e- asymmetric-energy collider. The asymmetry obtained in the rate of D^0 and D^0-bar decays to the pi^0 pi^0 final state, [-0.03+-0.64(stat)+-0.10(syst)]%, is consistent with no CP violation. This constitutes an order of magnitude improvement over the existing result. We also present an updated measurement of the CP asymmetry in the D^0 -> K_S pi^0 decay: A_{CP}(D^0 -> K_S pi^0) = [-0.21+-0.16(stat)+-0.07(syst)]%.
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