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Wed, 21 Dec 2005 11:00:59 +0100Wed, 21 Dec 2005 11:00:59 +0100Relativistic transport theory of N, Delta and N* (1440) interacting through sigma, omega and pi mesons.
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3048
A self-consistent relativistic integral-di erential equation of the Boltzmann- Uehling-Uhlenbeck-type for the N*(1440) resonance is developed based on an effective Lagrangian of baryons interacting through mesons. The closed time-path Green s function technique and semi-classical, quasi-particle and Born approxima- tions are employed in the derivation. The non-equilibrium RBUU-type equation for the N*(1440) is consistent with that of nucleon s and delta s which we derived before. Thus, we obtain a set of coupled equations for the N,Delta and N*(1440) distribution functions. All the N (1440)-relevant in-medium two-body scattering cross sections within the N,Delta and N*(1440) system are derived from the same effective Lagrangian in addition to the mean field and presented analytically, which can be directly used in the study of relativistic heavy-ion collisions. The theoreticalprediction of the free pp - pp* (1440) cross section is in good agreement with the experimental data. We calculate the in-medium N+N - N+N* , N* +N - N+N and N*+N - N* +N cross sections in cold nuclear matter up to twice the nuclear matter density. The influence of different choices of the N* N* coupling strengths, which can not be obtained through fitting certain experimental data, are discussed. The results show that the density dependence of predicted in-medium cross sections are sensitive to the N* N* coupling strengths used. An evident density dependence will appear when a large scalar coupling strength of g^(sigma) N*N* is assumed. PACS number(s): 24.10.Cn; 25.70.-z; 21.65.+fGuangjun Mao; Ludwig Neise; Horst Stöcker; Walter Greiner; Zhuxia Lipreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3048Wed, 21 Dec 2005 11:00:59 +0100Relativistic transport theory for N, Delta and N*(1440) system
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3074
A self-consistent relativistic Boltzmann-Uehling-Uhlenbeck equation for the N (1440) resonance is developed based on an effective Lagrangian of baryons interacting through mesons. The equation is consistent with that of nucleon s and delta s which we derived before. Thus, we obtain a set of coupled equations for the N, Delta and N (1440) distribution functions. All the N (1440)-relevant in-medium two-body scattering cross sections within the N, Delta and N (1440) system are derived from the same effective Lagrangian in addition to the mean field and presented analytically. Medium effects on the cross sections are discussed.Guangjun Mao; Ludwig Neise; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3074Thu, 15 Dec 2005 11:47:10 +0100Relativistic quantum transport theory of hadronic matter: the coupled nucleon, delta and pion system
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3079
We derive the relativistic quantum transport equation for the pion distribution function based on an effective Lagrangian of the QHD-II model. The closed time-path Green s function technique, the semi-classical, quasiparticle and Born approximation are employed in the derivation. Both the mean field and collision term are derived from the same Lagrangian and presented analytically. The dynamical equation for the pions is consistent with that for the nucleons and deltas which we developed before. Thus, we obtain a relativistic transport model which describes the hadronic matter with N,Delta and pi degrees of freedom simultaneously. Within this approach, we investigate the medium e ects on the pion dispersion relation as well as the pion absorption and pion production channels in cold nuclear matter. In contrast to the results of the non-relativistic model, the pion dispersion relation becomes harder at low momenta and softer at high momenta as compared to the free one, which is mainly caused by the relativistic kinetics. The theoretically predicted free pi*N -> Delta cross section is in agreement with the experimental data. Medium e ects on the pi*N -> Delta cross section and momentum-dependent Delta-decay width are shown to be substantial. PACS number(s): 24.10.Cn; 13.75.Cs; 21.65.+f; 25.70.-zGuangjun Mao; Ludwig Neise; Horst Stöcker; Walter Greinerpreprinthttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3079Wed, 14 Dec 2005 13:38:24 +0100