We study a pentaquark model of the negative parity hyperon Λ(1405). We choose a specific quark configuration for trial, and use the perturbative chiral quark model extended to four quarks and one anti-quark system. We calculate a σ-term and a scalar form factor of the hyperon and demonstrate their usefulness to study the nature of the hyperon.

COSY with a maximum beam momentum of ∼ 3.65 GeV/c allows the production of ground state (Λ and Σ) and excited hyperons (Λ(1405), Σ(1385) and Λ(1520) ) in elementary NN interactions. The existing data base in this field is rather poor. A systematic study of the hyperon production at COSY will result in an improvement of our understanding concerning topics like hyperon–nucleon interaction, kaon–n...

Recently several experimental groups analysed data on πp → ηπp and πp → ηπn reactions with exotic 1 P -wave and found a conflicting evidence for an exotic meson I = 11(1405). High statistics data on these reactions are presently analysed by BNL E852 Collaboration. All these analyses are based on the crucial assumption that the production amplitudes do not depend on nucleon spin. This assumption...

We have carried a theoretical study of the Kp → MBγ reaction with MB = Kp, K̄0n, π−Σ+, π+Σ−, π0Σ0, π0Λ, for K lab. momenta between 200 and 500 MeV/c, using a chiral unitary approach for the strong Kp interaction with its coupled channels. The Λ(1405) resonance, which is generated dynamically in this approach, shows up clearly in the dσ/dMI spectrum, providing new tests for chiral symmetry and th...

In this article, we construct the six-quark currents with $$J^P=0^+$$ , $$0^-$$ $$1^+$$ and $$1^-$$ to study $$\Lambda _c$$ dibaryon $${\bar{\Lambda }}_c$$ baryonium states via QCD sum rules. We consider vacuum condensates up dimension 16 truncation of order $${\mathcal {O}}(\alpha _s^k )$$ $$k\le 3$$ . The predicted masses are $$5.11_{-0.12}^{+0.15}$$ GeV, $$4.66_{-0.06}^{+0.10}$$ $$4.99_{-0.0...