arXiv subjects
Publications and source records attributed to Hiroyuki Kamano.
We present a proper off-mass-shell extension of the chiral reduction formula (CHRF) proposed by Yamagishi and Zaned. This is achieved by rewriting the CHRF in a manifestly consistent form with the conventional LSZ reduction formula.
We study the pi N -> pi pi N reaction around the N(1440) mass-shell energy. Considering the total cross sections and invariant mass distributions, we discuss the role of N(1440) and its decay processes. The calculation is performed by extending our previous approach [Phys. Rev. C 69, 025206 (2004)] to this reaction, in which only the nucleon and Delta(1232) were considered as intermediate baryon states. The characteristics observed in the recent data for the pi- p -> pi0 pi0 n reaction obtained by Crystal Ball Collaboration (CBC), can be understood as a strong interference between the two decay processes: N(1440) -> pi Delta(1232) and N(1440) -> N(pi pi)_S. It is also found that the scalar-isoscalar pi pi rescattering effect in the NN*(pi pi)_S vertex, which corresponds to the propagation of sigma meson, seems to be necessary for explain ing the several observables of the pi N -> pi pi N reaction: the large asymmetric shape in the pi0-pi0 invariant mass distributions of the pi- p -> pi0 pi0 n reaction and the pi+ p -> pi+ pi+ n total cross section.
The contribution of Delta(1232) to the piN -> pipiN reaction is examined by making use of the chiral reduction formula developed by Yamagishi and Zahed. The influence of the pi-Delta-Delta and rho-N-Delta interactions on this reaction, which has not been regarded as important so far, is considered for all channels with the initial pi^{+ -}p states. The total cross sections are calculated to tree level for the energy up to T_{pi}=400 MeV. Although the pi-Delta-Delta and rho-N-Delta interactions give a small effect on the pi^{+}p -> pi^{+}pi^{+}n, pi^{-}p -> pi^{+}pi^{-}n and pi^{-}p -> pi^{0}pi^{0}p channels, the pi^{+ -}p -> pi^{+ -}pi^{0}p channels are found to be sensitive to these interactions.