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A microscopic model for the $N\bar N\to\pi\pi$ process is presented in the meson exchange framework, which in the pseudophysical region agrees with available quasiempirical information. The scalar ($\sigma$) and vector ($\rho$) piece of…

Nuclear Theory · Physics 2009-09-25 C. Schütz , J. W. Durso , K. Holinde , B. C. Pearce , J. Speth

We derive the equation of state of symmetric nuclear matter in a relativistic theory with $\sigma$ and $\omega$ exchange. We take a chiral version of this model which insures all the chiral constraints. Going beyond the mean field approach…

Nuclear Theory · Physics 2008-11-26 G. Chanfray , M. Ericson

We present theoretical results for (gamma,pi0 pi0) and (gamma,pi+- pi0) production on nucleons and nuclei in the kinematical region where the scalar isoscalar pi pi amplitude is influenced by the sigma pole. The final state interaction of…

Nuclear Theory · Physics 2009-11-07 L. Roca , E. Oset , M. J. Vicente Vacas

We investigate the influence of medium corrections to the pion dispersion relation on the pion dynamics in intermediate energy heavy ion collisions. To do so a pion potential is extracted from the in-medium dispersion relation and used in…

Nuclear Theory · Physics 2008-11-26 C. Fuchs , L. Sehn , E. Lehmann , J. Zipprich , Amand Faessler

First, it is pointed out that hadron/nuclear physics based on QCD should be regarded as ``condensed matter physics'' of the QCD vacuum. We indicate that phase shift analyses which respect chiral symmetry (ChS), analyticity and crossing…

Nuclear Theory · Physics 2014-11-18 Teiji Kunihiro

The chiral nonlinear ($\sigma,\pi,\omega$) mean-field model is an extension of the conserving nonlinear (nonchiral) $\sigma$-$\omega$ hadronic mean-field model which is thermodynamically consistent, relativistic and Lorentz-covariant…

Nuclear Theory · Physics 2010-11-24 Schun T. Uechi , Hiroshi Uechi

We analyse the interplay between nucleon-nucleon potentials deduced from chiral perturbation theory and a coarse grained representation of the short distance interactions by delta-shells potentials below a certain cut-off distance. While we…

Nuclear Theory · Physics 2013-01-30 Rodrigo Navarro Perez , J. E. Amaro , E. Ruiz Arriola

The role played by nucleon-nucleon short-range correlations in photon- and electron-nucleus reactions is analyzed with a model which includes all the diagrams containing a single correlation function. The excitation of low-lying high-spin…

Nuclear Theory · Physics 2007-05-23 Antonio M. Lallena , Marta Anguiano , Giampaolo Co'

The axial-vector coupling constant in nuclear medium is systematically studied using chiral perturbation theory. For normal nuclear matter, the first non-trivial corrections are estimated based on the independent particle approximation…

Nuclear Theory · Physics 2009-10-30 Tae-Sun Park , Hong Jung , Dong-Pil Min

We evaluate the contribution of second order terms to the pion-nucleus s-wave optical potential of pionic atoms generated by short range nuclear correlation. The corrections are sizeable because they involve the isoscalar s-wave $\pi N$…

Nuclear Theory · Physics 2009-10-28 L. L. Salcedo , K. Holinde , E. Oset , C. Schütz

We discuss a relativistic chiral theory of nuclear matter with $\sigma$ and $\omega$ exchange using a formulation of the $\sigma$ model in which all the chiral constraints are automatically fulfilled. We establish a relation between the…

Nuclear Theory · Physics 2008-11-26 M. Ericson , G. Chanfray

Medium modifications of the pion-omega-rho vertex are analyzed in context of the omega -> pi gamma* and rho -> pi gamma* decays in nuclear matter. A relativistic hadronic model with mesons, nucleons, and Delta(1232)isobars is applied. A…

Nuclear Theory · Physics 2017-08-23 Anna Baran , Agnieszka Bieniek , Wojciech Broniowski

We investigate the role of the pion in Covariant Density Functional Theory. Starting from conventional Relativistic Mean Field (RMF) theory with a non-linear coupling of the $\sigma$-meson and without exchange terms we add pions with a…

Nuclear Theory · Physics 2009-11-06 G. A. Lalazissis , S. Karatzikos , M. Serra , T. Otsuka , P. Ring

The light-front formalism for a covariant description of the European Muon Collaboration (EMC) effect, already applied to $^3$He, is formally extended to any nucleus, and used for actually calculating the $^3$H and $^4$He cases. The…

Correlations of two like charged pions emitted from a hot and charged spherically expanding nuclear system are investigated. The motion of the pions is described quantum mechanically using the Klein-Gordon equation which includes Coulomb…

Nuclear Theory · Physics 2009-10-31 H. W. Barz

We present a microscopic model for coherent pion production off nuclei induced by neutrinos. This model is built upon a model for single nucleon processes that goes beyond the usual Delta dominance by including non resonant background…

Nuclear Theory · Physics 2010-01-15 M. Valverde , J. E. Amaro , E. Hernandez , J. Nieves

The impact of relativistic pionic correlations and meson-exchange currents on the response functions for electromagnetic quasielastic electron scattering from nuclei is studied in detail. Results in first-order perturbation theory are…

Nuclear Theory · Physics 2008-11-26 J. E. Amaro , M. B. Barbaro , J. A. Caballero , T. W. Donnelly , A. Molinari

The influence of a dropping sigma-meson mass on previously calculated in-medium pion-pion correlations in the J=I=0 (sigma-meson) channel is investigated. It is found that the invariant-mass distribution around the vacuum threshold…

Nuclear Theory · Physics 2009-10-31 Z. Aouissat , G. Chanfray , P. Schuck , J. Wambach

Recent results concerning the use of the Correlated Basis Function to investigate the ground state properties of medium-heavy doubly magic nuclei with microscopic interactions are presented. The calculations have been done by considering a…

Nuclear Theory · Physics 2007-05-23 Giampaolo Co'

Elastic pion-nucleon scattering is analyzed in the framework of chiral perturbation theory up to fourth order within the heavy-baryon expansion and a covariant approach based on an extended on-mass-shell renormalization scheme. We discuss…

Nuclear Theory · Physics 2016-08-03 D. Siemens , V. Bernard , E. Epelbaum , A. Gasparyan , H. Krebs , Ulf-G. Meißner