Five-quark picture of Lambda(1405) in anisotropic lattice QCD

TL;DR

This study investigates the five-quark structure of Lambda(1405) using lattice QCD with boundary conditions to distinguish states, finding it likely a mixed state of three- and five-quark configurations.

Contribution

It introduces a lattice QCD approach with hybrid boundary conditions to analyze the five-quark nature of Lambda(1405), suggesting a mixed state rather than a pure three- or five-quark state.

Findings

The five-quark mass is around 1.89 GeV, too heavy for Lambda(1405).

Lambda(1405) is likely a mixed state of 3Q and 5Q configurations.

Abstract

Five-quark (5Q) picture of Lambda(1405) is studied using quenched lattice QCD with an exotic 5Q operator of N\bar{K} type. To discreminate mere N\bar{K} and \Sigma\pi scattering states, Hybrid Boundary Condition (HBC), a flavor-dependent boundary condition, is imposed on the quark fields along spatial direction. 5Q mass m_{5Q}\simeq 1.89 GeV is obtained after the chiral extrapolation to the physical quark mass region, which is too heavy to be identified with Lambda(1405). Then, Lambda(1405) seems neither a pure 3Q state nor a pure 5Q state, and therefore we present an interesting possibility that Lambda(1405) is a mixed state of 3Q and 5Q states.