Delta degrees of freedom in antisymmetrized molecular dynamics and (p,p') reactions in the Delta region.

Delta degrees of freedom are introduced into antisymmetrized molecular dynamics (AMD). This is done by increasing the number of basic states in the AMD wave function, introducing a Skyrme-type delta-nucleon potential, and including NN ↔ N∆ reactions in the collision description. As a test of the delta dynamics, the extended AMD is applied to (p,p′) recations at Elab = 800 MeV for a 12C target. It is found that the ratio and the absolute values for delta peak and quasielastic peak (QEP) in the 12C(p,p′) reaction are reproduced for angles Θlab ∼ 40◦, pointing to a correct treatment of the delta dynamics in the extended AMD. For forward angles the QEP is overestimated, but in generally the agreement between AMD calculations and experimental data is good. The results of the AMD calculations are compared to one-step Monte Carlo (OSMC) calculations and a detailed analysis of multi-step and delta potential effects is given. Along this analysis a decompostion of the cross section into various reaction channels is presented and the reaction dynamics is discussed in detail. As important side results we present a way to apply a Gallilei invariant theory for (N,N′) reactions up to Elab ≈ 800 MeV which ensures approximate Lorentz invariance and we discuss how to fix the width parameter ν of the single particle momentum distribution for outgoing nucleons in the AMD calculation. 25.40.Ep, 24.10.Cn, 14.20.Gk Typeset using REVTEX ∗Present address: Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki-ken 319-11, Japan. †Present address: Cyclotron Laboratory, Institute of Physical and Chemical Research (RIKEN), Hirosawa, Wako-shi, Saitama-ken 351-01, Japan.