Daughter Pole Hypothesis of N * (1400) and Phase Shift Analysis of P 11 ?- N Scattering

Abstract

The Roper resonance, N_1/2^*(1400), is assumed to be the second daughter of the nucleon trajectory and the low energy P₁₁ π-N phase shift is analysed by applying Khuri's threshold formula to the direct channel nucleon Regge pole and its daughter. The obtained phase shift starts off negative at threshold and changes its sign at T_π≃250 MeV, a behavior not in disagreement with experiment. This fact is indeed the consequence of the daughter when the parent trajectory contains a stable particle.