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Register a new userOn the polarization properties of the charmed baryon Lambda^+_c in the Lambda^+_c -> p + K^- + pi^+ + pi^0 decay
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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.
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We report the first observation of the decay $Lambda^{+}_{c} rightarrow p K^{+} pi^{-}$ using a 980 $mathrm{fb^{-1}}$ data sample collected by the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. This is the first doubly Cabibbo-suppressed decay of a charmed baryon to be observed. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be $mathcal{B}(Lambda^{+}_{c} rightarrow p K^{+} pi^{-})/mathcal{B}(Lambda^{+}_{c} rightarrow p K^{-} pi^{+})=(2.35pm0.27pm0.21)times10^{-3}$, where the uncertainties are statistical and systematic, respectively.
The $varLambda^0_b to varLambda^+_c K^+ K^- pi^-$ decay is observed for the first time using a data sample of proton-proton collisions at centre-of-mass energies of $sqrt{s}=7$ and 8 $rm{TeV}$ collected by the $mbox{LHCb}$ detector, corresponding to an integrated luminosity of $3{rm{fb}^{-1}}$. The ratio of branching fractions between the $varLambda^0_b to varLambda^+_c K^+ K^- pi^-$ and the $varLambda^{0}_{b}tovarLambda^{+}_{c}D^{-}_{s}$ decays is measured to be begin{equation*} frac{mathcal{B} ( varLambda^0_b to varLambda^+_c K^+ K^- pi^-) } {mathcal{B} ( varLambda^0_b to varLambda^+_c D^-_s)} = (9.26 pm 0.29 pm 0.46 pm 0.26)times10^{-2}, end{equation*} where the first uncertainty is statistical, the second systematic and the third is due to the knowledge of the $D^-_s to K^+ K^- pi^-$ branching fraction. No structure on the invariant mass distribution of the $varLambda^+_c K^+$ system is found, consistent with no open-charm pentaquark signature.
We propose a two component model for charmed baryon production in $pp$ collisions consisting of the conventional parton fusion mechanism and fragmentation plus quarks recombination in which a $ud$ valence diquark from the proton recombines with a $c$-sea quark to produce a $Lambda_c^+$. Our two-component model is compared with the intrinsic charm two-component model and experimental data.
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.
$Lambda^+_c$- and $Lambda_b$-hypernuclei are studied in the quark-meson coupling (QMC) model. Comparisons are made with the results for $Lambda$-hypernuclei studied in the same model previously. Although the scalar and vector potentials felt by the $Lambda$, $Lambda_c^+$ and $Lambda_b$ in the corresponding hypernuclei multiplet which has the same baryon numbers are quite similar, the wave functions obtained, e.g., for $1s_{1/2}$ state, are very different. The $Lambda^+_c$ baryon density distribution in $^{209}_{Lambda^+_c}$Pb is much more pushed away from the center than that for the $Lambda$ in $^{209}_Lambda$Pb due to the Coulomb force. On the contrary, the $Lambda_b$ baryon density distributions in $Lambda_b$-hypernuclei are much larger near the origin than those for the $Lambda$ in the corresponding $Lambda$-hypernuclei due to its heavy mass. It is also found that level spacing for the $Lambda_b$ single-particle energies is much smaller than that for the $Lambda$ and $Lambda^+_c$.
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