0000000001033080
AUTHOR
T. Hyodo
Lambda(1405) production in the pi-p -> K-0 pi Sigma reaction
We discuss the mechanisms that lead to Lambda(1405) production in the pi(-)p-->K(0)piSigma reaction. The problem has gained renewed interest after different works converge to the conclusion that there are two resonances around the region of 1400 MeV, rather than one, and that they couple differently to the piSigma and (K) over barN channels. We look at the dynamics of that reaction and find two mechanisms which eventually filter each one of the resonances, leading to very different shapes of the piSigma invariant mass distributions. The combination of the two mechanisms leads to a shape of this distribution compatible with the experimental measurements.
A narrow $DNN$ quasi-bound state
The energies and widths of $DNN$ quasi-bound states with isospin I=1/2 are evaluated in two methods, the fixed center approximation to the Faddeev equation and the variational method approach to the effective one-channel Hamiltonian. The $DN$ interactions are constructed so that they dynamically generate the $\Lambda_c(2595)$ (I=0, $J^{\pi} =1/2^-$) resonance state. We find that the system is bound by about 250 MeV from the $DNN$ threshold, $\sqrt{s} \sim 3500$ MeV. Its width including both the mesonic decay and the $D$ absorption, is estimated to be about 20-40 MeV. The I=0 $DN$ pair in the $DNN$ system is found to form a cluster that is similar to the $\Lambda_c(2595)$.
Coupling of (K)over-bar(*)N to the Lambda(1520)
We study the coupling of the Λ(1520)≡Λ* resonance to the K* vector meson and nucleon. This coupling is not directly measured from the resonance decay, but is expected to be important in hyperon production reactions, in particular for the exotic Θ+ production. We compute the coupling in two different schemes, one in the chiral unitary model where the Λ* is dominated by the quasibound state of mesons and baryons, and the other in the quark model where the resonance is a p-wave excitation in the three valence quarks. Although it is possible to construct both models such that they reproduce the KN and πΣ decays, there is a significant difference between the Λ*K*N couplings in the two models. In…
Energy And Width Of A Narrow I=1/2 Dnn Quasibound State
The energies and widths of DNN quasibound states with isospin I = 1/2 are evaluated in two methods, the fixed center approximation to the Faddeev equation and the variational method approach to the effective one-channel Hamiltonian. The DN interactions are constructed so they dynamically generate the Lambda(c)(2595) (I = 0, J(pi) = 1/2(-)) resonance state. We find that the system is bound by about 250 MeV from the DNN threshold, root s similar to 3500 MeV. Its width, including both the mesonic decay and the D absorption, is estimated to be about 20-40 MeV. The I = 0 DN pair in the DNN system is found to form a cluster that is similar to the Lambda(c)(2595).
Weak decay of Lambda_c^+ for the study of Lambda(1405) and Lambda(1670)
We study the Lambda_c decay process to pi^+ and the meson-baryon final state for the analysis of Lambda resonances. Considering the Cabibbo-Kobayashi-Maskawa matrix, color suppression, diquark correlation and the kinematical condition, we show that the final meson-baryon state should be in a pure I=0 combination, when the meson-baryon invariant mass is small. Because the I=1 contamination usually makes it difficult to analyze Lambda resonances directly from experiments, the Lambda_c decay is an ideal process to study Lambda resonances. Calculating the final state interaction by chiral unitary approaches, we find that the piSigma invariant mass distributions have the same peak structure in t…
Photoproduction of $K^*$ for the study of $\Lambda(1405)$
The photo-induced $K^*$ vector meson production is investigated for the study of the $\Lambda(1405)$ resonance. This reaction is particularly suited to the isolation of the second pole in the $\Lambda(1405)$ region which couples dominantly to the $\bar K N$ channel. We obtain the mass distribution of the $\Lambda(1405)$ which peaks at 1420 MeV, and differs from the nominal one. Combined with several other reactions, like the $\pi^- p \to K^0 \pi \Sigma$ which favours the first pole, this detailed study will reveal a novel structure of the $\Lambda(1405)$ state.