Enhancement of pionic modes in the quasielastic region

We report an evidence for the precursor phenomena of the pion condensation, which is found in the enhancement of the spin longitudinal cross sections ID q of the quasielastic 12C, \(^{40} Ca(\vec p, \vec n)\), reactions at the incident energy 494 and 346 MeV around the momentum transfer q ≈ q c , the critical momentum of the pion condensation. We utilized the distorted wave impulse approximation incorporated with the continuum random phase approximation. We adjusted the Landau-Migdal parameters, g′ NN and g′ NΔ, and obtained g′ NN ≈ 0.6–0.7 and g′ N Δ ≈ 0.3–0.4, which are consistent with those obtained from the energy of the Gamov-Teller giant resonance and the quenching factor of the Gamov-Teller sum rule.