Related papers: The Delta-Hole model at Finite Temperature
We apply the $\delta$-expansion perturbation scheme to the $\lambda \phi^{4}$ self-interacting scalar field theory in 3+1 D at finite temperature. In the $\delta$-expansion the interaction term is written as $\lambda (\phi^{2})^{ 1 +…
Exact and approximate expressions for thermodynamic characteristics of heated matter, which consists of particles with finite mass-widths, are constructed. They are expressed in terms of Fermi/Bose distributions and spectral functions,…
We present measurements of the pion transverse momentum (p_t) spectra in central Si-nucleus collisions in the rapidity range 2.0<y<5.0 for p_t down to and including p_t=0. The data exhibit an enhanced pion yield at low p_t compared to what…
We study the behavior of the $\pi^0$ width as a function of temperature and density. We provide simple expressions for the neutral pion width in a hot and dense medium based on a renormalized version of the microscopic Nambu Jona Lasinio…
We calculate the nucleonic and pionic dispersion relations at finite temperature T and non-vanishing chemical potentials $(\mu_f)$ in the context of an effective chiral theory that describes the strong and electromagnetic interactions for…
The 2H(p,n) charge exchange reaction at T_p=790 MeV is used to study the Delta(1232)-nucleon interaction in the Delta resonance excitation energy region. For the Delta-N potential, a meson exchange model is adopted where pi, rho, omega, and…
We have investigated the properties of a model of 1D anyons interacting through a $\delta$-function repulsive potential. The structure of the quasi-periodic boundary conditions for the anyonic field operators and the many-anyon…
We present a study of the $\pi\pi$ scattering amplitude in the $\sigma$ and $\rho$ channels at finite temperature and nuclear density within a chiral unitary framework. Meson resonances are dynamically generated in our approach, which…
The mass shift, width broadening, and spectral density for the $\omega$ meson in a heat bath of nucleons and pions is calculated using a general formula which relates the self-energy to the forward scattering amplitude. We use experimental…
The mass shift $\Delta m_N$ of a nucleon in the finite temperature pion gas is calculated in the case of an arbitrary nucleon momentum. A general formula is used which relates the in-medium mass shift $\Delta m(E)$ of a particle to the real…
We examine the role of the Delta-Delta intermediate state in low energy NN scattering using effective field theory. Theories both with and without pions are discussed. They are regulated with dimensional regularization and MSbar…
Thermodynamical properties of an interacting system of scalar bosons at finite temperatures are studied within the framework of a field-theoretical model containing the attractive and repulsive self-interaction terms. Self-consistency…
We study the effect of thermal width of $\pi$ on the spectral function of $\sigma$ applying a resummation technique called optimized perturbation theory at finite temperature ($T$) to ${\cal O}(4)$ linear sigma model. In order to take into…
The dynamics in quantum magnets can often be described by effective models with bosonic excitations obeying a hard-core constraint. Such models can be systematically derived by renormalization schemes such as continuous unitary…
We study the behavior of the pion dispersion relation in a pion medium at finite density and temperature, introducing a chemical potential to describe the finite pion number density. Such description is particularly important during the…
We study the strong couplings of the nucleon and delta resonances in a collective model. In the ensuing algebraic treatment we derive closed expressions for decay widths which are used to analyze the experimental data for strong decays into…
We develop a relativistic covariant and unitary description of the pion-nucleon interaction in a hadron-exchange model. The model is based on the solution of a dimensionally reduced (quasipotential) Bethe-Salpeter equation for the…
Pion-nucleus elastic scattering at energies above the Delta(1232) resonance is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The present data provide an opportunity to study the interaction of pions with nuclei at…
The large variety of experimental data around the pion-production threshold are compared with a meson-exchange isobar model which includes the pion-nucleon interaction in s-- and p-waves. Theoretical results obtained with two different NN…
Predictions of the existence of well-defined deeply bound pionic atom states for heavy nuclei and the eventual observation of such states by the (d,3He) reaction have revived interest in the pion-nucleus interaction at threshold and in its…