$Λ(1405)$ and $\barΛ(1405)$ in $J/ψ$ four-body decays

Abstract

We study the structure of the baryon resonances $Λ(1405)$ and $\barΛ(1405)$ in $J/ψ$ four body decays $J/ψ\to Σ\bar Σππ$ in the framework of a coupled channel chiral unitary approach. With still sufficient freedom for model parameters, the $Λ(1405)$ and $\barΛ(1405)$ resonances are generated by simultaneously taking the meson baryon and meson anti-baryon final state interactions into account. The $πΣ$ ($π\barΣ$) invariant mass distributions peak around 1410 MeV, which favors the assertion that the $Λ(1405)$ ($\barΛ(1405)$) is a superposition of the two $Λ(1405)$ ($\barΛ(1405)$) states which dominantly couple to $\bar K N$ ($K\bar N$) and $πΣ$ ($π\barΣ$), respectively. We also calculate the amplitude for isospin I=1 which gives hints on a possible I=1 baryon resonance in the energy region of the $Λ(1405)$, which up to now has not been observed.

17 pages, 5 figures, version accepted for publication in Phys. Rev. C