On the Concept of Duality and πNScattering

Abstract

463A modified interference model is presented, which relates the direct channel resonance amplitude with the crossed channel Regge pole amplitude. Analyses are made in rcN scattering processes by using this model and then we discuss the relation between the resonance limplitude and background (Regge pole) amplitude in order to clarify the concept of" duality". § l. Introduction It has recently been discussed that a direct channel amplitude and its crossed channel amplitude are not independent but provide two complementary descriptions of a scattering process. 1 > This discussion on the duality concept has been brought about by the investigation of the validity of the interference model. Since the successful analyses of the interference effects in the backward rc-p differential cross section and the difference between total rc-p and rc+ p cross sections by Barger and others, 2 > it has been pursued to explain vadous scattering processes in terms of this model. But Chiu and Stirling 3 ) have shown that there are difficulties in fitting the data of the average of the total n-p and n+p cross section, the n+ p differential cross section and n+ p polarization, although this model is compatible with some other processes.The unified understanding of all cases of nN scattering processes on the basis of the interference model has been disturbed not only on account of nonuniqueness of the quantitative description of the n-p 180° differential cross section but also on account of the larger and constructive contribution of the resonance amplitude in most cases in which the interference model is imcompatible with the experimental results. In particular this model conflicts with the finite energy sum rule on the average of the n±p scattering amplitudes at e = 0, because the imaginary parts of their resonance amplitudes do not oscillate around the background Regge amplitude and always contribute constructively to the background amplitudes.Furthermore the formal suggestion by Schmid 4 ) indicates that the Regge amplitude contains in itself resonance effects, that is to say, the partial wave projection of p-Regge amplitude produces resonance loops on the Argand diagram, and such a loop corresponds to N* resonance, Then it has finally been con-by guest on March 22, 2015 http://ptp.oxfordjournals.org/ Downloaded from

Distortion of the HBT image by mean field interaction

“…We show how the effects of the mean-field interaction, encoded in the phase and attenuation factors of the amplitude, reflect in the interference pattern. By using a semiclassical method to evaluate the amplitude, a modified correlation function has been obtained in a time-independent case [4], and then the framework has been extended to a time-dependent case to take into account the expansion dynamics of the hadron source [5].…”

“…3, we illustrate the distorted HBT images due to the mean-field interactions (see Ref. [4] for details). A repulsive mean-field interaction induces an image elongated along the outward axis, whereas an attractive one induces a stretched image with a longer extension along the sideward axis.…”

“…It has been known as the "RHIC HBT puzzle". This contribution is based on the works [4,5] originally motivated by solving this puzzle. We investigate effects of a mean-field interaction, sketched in Fig.…”

“…We have shown how the modification of a pion amplitude due to a mean-field interaction reflects in a distorted HBT image [4], within a semiclassical framework. We also found a possible improvement of the discrepancies, owing to cooperative effects of attractive and absorptive meanfield interactions.…”

“…We also found a possible improvement of the discrepancies, owing to cooperative effects of attractive and absorptive meanfield interactions. To pursue this possibility, we have constructed a more realistic mean-field interaction on the basis of the pion-pion forward scattering amplitudes [5]. There, we actually obtained attractive and absorptive mean-field interactions following from a strong attraction and attenuation around the momentum regime of the ρ-meson resonance.…”