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Register a new userAngular distribution and asymmetries in the decay of the polarized charmed baryon $Lambda_c^+ to K^- , Delta^{++} to K^- , p , pi^+$
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Angular distribution of the final particles in the decay $Lambda_c^+to K^- , Delta (1232)^{++} to K^- , p , pi^+$ of the polarized charmed baryon is discussed. Asymmetries are proposed which allow for determination of the components of the $Lambda_c^+$ polarization vector. The precession angle of the polarization in the process of baryon channeling in a bent crystal is directly related to these asymmetries. The decay rate and asymmetry parameter for the $Lambda_c^+to K^- , Delta (1232)^{++}$ decay are calculated in the pole model and compared with experiment.
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The polarization properties of the charmed Lambda^+_c baryon are investigated in weak non-leptonic four-body Lambda^+_c -> p + K^- + pi^+ + pi^0 decay. The probability of this decay and the angular distribution of the probability are calculated in the effective quark model with chiral U(3)XU(3) symmetry incorporating Heavy Quark Effective theory (HQET) and the extended Nambu-Jona-Lasinio model with a linear realization of chiral U(3)XU(3) symmetry. The theoretical value of the probability of the decay Lambda^+_c -> p + K^- + pi^+ + pi^0 relative to the probability of the decay Lambda^+_c -> p + K^- + pi^+ does not contain free parameters and fits well experimental data. The application of the obtained results to the analysis of the polarization of the Lambda^+_c produced in the processes of photo and hadroproduction is discussed.
We have searched for the Cabibbo-suppressed decay $Lambda_c^+tophi ppi^0$ in $e^+e^-$ collisions using a data sample corresponding to an integrated luminosity of 915 $rm fb^{-1}$. The data were collected by the Belle experiment at the KEKB $e^+e^-$ asymmetric-energy collider running at or near the $Upsilon(4S)$ and $Upsilon(5S)$ resonances. No significant signal is observed, and we set an upper limit on the branching fraction of $mathcal{B}(Lambda_c^+to phi ppi^0) <15.3times10^{-5}$ at 90% confidence level. The contribution for nonresonant $Lambda_c^+to K^+K^- ppi^0$ decays is found to be consistent with zero and the corresponding upper limit on its branching fraction is set to be $mathcal{B}(Lambda_c^+to K^+K^-ppi^0)_{rm NR} <6.3times10^{-5} $ at 90% confidence level. We also measure the branching fraction for the Cabibbo-favored decay $Lambda_c^+to K^-pi^+ppi^0$; the result is $mathcal{B}(Lambda_c^+to K^-pi^+ppi^0)= (4.42pm0.05, (rm stat.) pm 0.12, (rm syst.) pm 0.16, (mathcal{B}_{rm Norm}))%$, which is the most precise measurement to date. Finally, we have searched for an intermediate hidden-strangeness pentaquark decay $P^+_stophi p$. We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of ${cal B}(Lambda_c^+to P^+_s pi^0)times {cal B}(P^+_stophi p) <8.3times 10^{-5}$ at 90% confidence level.
We search for $CP$ violation in the singly-Cabibbo-suppressed decay $D^{0}rightarrow K^{+}K^{-}pi^{+}pi^{-}$ using data corresponding to an integrated luminosity of $988text{ }{rm fb}^{-1}$ collected by the Belle detector at the KEKB $e^{+}e^{-}$ collider. We measure a set of five kinematically dependent $CP$ asymmetries, of which four asymmetries are measured for the first time. The set of asymmetry measurements can be sensitive to $CP$ violation via interference between the different partial-wave contributions to the decay and performed on other pseudoscalar decays. We find no evidence of $CP$ violation.
We investigate $S=-1$ hyperon production from the $Lambda_c^+to K^-ppi^+$ and $Lambda_c^+to K^0_Sppi^0$ decays within the effective Lagrangian approach. We consider the $Sigma/Lambda$ ground states, $Lambda(1520)$, $Lambda(1670)(J^p=1/2^-)$, $Lambda(1890)(J^p=3/2^+)$; $Lambda/Sigma$-pole contributions from the combined resonances between 1800 MeV and 2100 MeV; and $N/Delta$-pole and $K^ast$-pole contributions, which include the proton, $Delta(1232)$, and $K(892)$. We calculate the Dalitz plot density $(d^2Gamma/dM_{K^-p}dM_{K^-pi^+}$) for the $Lambda_c^+to K^-ppi^+$ decay. The calculated result is in good agreement with experimental data from the Belle Collaboration. Using the parameters from the fit, we present the Dalitz plot density for the $Lambda_c^+to K^0_Sppi^0$ decay. In our calculation, a sharp peak-like structure near 1665 MeV is predicted in the $Lambda_c^+to K^-ppi^+$ decay because of the interference effects between the $Lambda(1670)$ resonance and $eta$-$Lambda$ loop channels. We also demonstrate that we can access direct information regarding the weak couplings of $Lambda(1670)$ and $Sigma(1670)$ from the $Lambda_c^+to K^0_Sppi^0$ decay. Finally, a possible interpretation for the 1665 MeV structure beyond our prediction is briefly discussed.
A search for decay-time-dependent charge-parity ($CP$) asymmetry 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 at a center-of-mass energy of 13TeV, and corresponding to an integrated luminosity of 5.4fb$^{-1}$. The $D^0$ mesons are required to originate from semileptonic decays of $b$ hadrons, such that the charge of the muon identifies the flavor of the neutral $D$ meson at production. The asymmetries in the effective decay widths of $D^0$ and $overline{D}^0$ mesons are determined to be $A_{Gamma}(K^+K^-) = ( -4.3 pm 3.6 pm 0.5 )times 10^{-4}$ and $A_{Gamma}(pi^+pi^-) = ( 2.2 pm 7.0 pm 0.8)times 10^{-4}$, where the uncertainties are statistical and systematic, respectively. The results are consistent with $CP$ symmetry and, when combined with previous LHCb results, yield $A_{Gamma}(K^+K^-) = ( -4.4 pm 2.3 pm 0.6 )times 10^{-4}$ and $A_{Gamma}(pi^+pi^-) = ( 2.5 pm 4.3 pm 0.7)times 10^{-4}$.
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