Regge Pole Model with the Diffractive Correction. I

Abstract

)/(drJ/dt)(rp-fn +n» and the cross section for the n± production with polarized photon are calculated. In the neighbourhood of forward direction, our results fit experiment quite well. pion photoproductionl )~3) are accumulated. The differential cross sections for the n+ photoproduction are extensively measured over a wide energy range and in particular at small four-momentum transfer. The n-/n+ ratio from deuterium as well as the cross section for the charged pion photoproduction with a polarized photon are also measured at intermediate energies. 4 ),5) Many attempts have been made to explain the experimental results on the n± photoproduction in terms of the conspiracy model,6),7) the background model}) the cut mechanism 9 ) and the vector-meson dominance model. lo ) However, we try to explain the above-mentioned experimental results using the evasive Regge pole model with the diffractive corrections, for the following reasons: Although the Regge pole model has succeeded in explaining the two­ body scattering phenomena in a very wide range at high energy, it is difficult to explain high energy phenomena consistently by a simple Regge pole model. ll ),12) Some of the evidences of the discrepancy between the Regge pole model and experimental results are summarized below. i) The first of these dfficulties is related to the Pomeranchuk trajectory. The one is related to the violation of the Froissart bound l3 ) in the multi-Regge model which uses the repeated exchange of the Pomeranchukon. The other is related to the finite slope of the Pomeranchuk trajectory.14) ii) The second is the necessity of the additional Regge poles including a conspirator to explain the polarization and the forward peak.15) iii) The third is the inconsistency between the cross-over phenomenon and the dip in other reactions. We demand the zero for residues of ()) trajectory at t = - 0.15 (Ge V / C)2 to explain the pp and pp cross-over phenomena. Factorization also predicts the dip at the same t value for the reactions dominated by ()) trajec­ tory such as np~pN and rp~nop, but no dip is seen experimentally.