Related papers: Cancellation of the sigma meson in thermal models
We calculate the pressure of the interacting pion gas using the Beth-Uhlenbeck approach to the relativistic virial expansion with Breit-Wigner phase shifts for the $\sigma$- and $\varrho$- meson resonances. The repulsive phase shift…
We discuss why the scalar-isoscalar resonance $f_{0}(500)$ should in practice not be included in thermal models describing the freeze-out of heavy-ion collisions. Its contribution into pion multiplicities is in principle relevant because it…
An important role of the scalar isoscalar sigma-meson in the low-energy physics is discussed. The behavior of the sigma-meson in the hot and dense medium is studied. It is shown that in the vicinity of critical values of temperature(T) and…
A separable potential model of three coupled channels (pion-pion, kaon-antikaon and an effective four pion) has been constructed and applied in the analysis of the isoscalar S-wave pion-pion and kaon-antikaon phase shifts and inelasticities…
Scalar-isoscalar mesons are studied using an unitary model in three channels: pi-pi, K-anti K and an effective 2pi-2pi. All the solutions, fitted to the pi-pi and K-anti K data, exhibit a wide f0(500), a narrow f0(980) and two relatively…
The meson meson interaction in the scalar isoscalar channel at finite baryonic density is studied in the framework of a chiral unitary approach which generates the f0 and sigma resonances and reproduces well the meson meson phase shifts in…
Properties of scalar-isoscalar mesons are analysed using separable interactions in three decay channels: pion-pion, kaon-antikaon and an effective 2pion-2pion. We obtain different solutions by fitting various data on the pion-pion and…
The quark-level linear sigma model is revisited, in particular concerning the identification of the f_0(400-1200) (or \sigma(600)) scalar meson as the chiral partner of the pion. We demonstrate the predictive power of the linear sigma model…
In this work the nature of the \sigma or f_0(600) resonance is discussed by evaluating its quadratic scalar radius, \la r^2\ra_s^\sigma. This allows one to have a quantitative estimate for the size of this resonance. We obtain that the…
We first discuss the theoretical and phenomenological significance of the sigma meson ($\sigma$) in QCD. It is indicated that if the collective modes with the mass 500-600 MeV exists in the $I=J=0$ channel, various empirical facts in hadron…
We evaluate the $a_1(1260) \to \pi \sigma (f_0(500))$ decay width from the perspective that the $a_1(1260)$ resonance is dynamically generated from the pseudoscalar-vector interaction and the $\sigma$ arises from the…
Resonance pole positions of the $f_0(500)$ alias $\sigma(500)$ meson are computed and plotted as a continuous function of pion mass in the framework of a unitary and analytic coupled-channel model for scalar mesons as dynamical $q\bar{q}$…
Using constituent quarks coupled to a linear sigma model at nonzero temperature, I show that many anomalous mesonic amplitudes, such as $\pi^0 \rightarrow \gamma \gamma$, vanish in a chirally symmetric phase. Processes which are allowed,…
The effect of scalar and vector meson mixing on the dilepton radiation from hot and dense hadronic matter is estimated in different isospin channels. In particular, we study the effect of $\sigma$-$\omega$ and $\rho-a_0$ mixing and…
We study the reaction $e^+e^-\to\pi^0\gamma$ based on a dispersive representation of the underlying $\pi^0\to\gamma\gamma^*$ transition form factor. As a first application, we evaluate the contribution of the $\pi^0\gamma$ channel to the…
The Hidden Local Symmetry Lagrangian is used to study the interactions of phi mesons with other pseudoscalar and vector mesons in a hadronic gas at finite temperature. We have found a significantly small phi mean free path (less than 2.4 fm…
Changes in the properties of the vector mesons in hot and dense hadronic matter, as produced in heavy ion collisions, lead to the intriguing possibility of the opening of the decay channel $\omega \ra \rho \pi$, for the omega meson, which…
Detailed information on decay channel probabilities is absent for many high mass resonances, which are typically included in thermal models. In these cases, the sum over all known decay branching probabilities is smaller than 1. Due to this…
The pion scalar form factor along with all existing S-wave iso-scalar $\pi\pi$-scattering phase shift data in the elastic region up to $1 {\rm GeV}^2$ are applied for a determination of the $f_0(500)$ and $f_0(980)$ meson parameters…
Yields, rapidity and transverse momentum spectra of $\Delta^{++}(1232)$, $\Lambda(1520)$, $\Sigma^\pm(1385)$ and the meson resonances $K^0(892)$, $\Phi$, $\rho^0$ and $f_0(980)$ are predicted. Hadronic rescattering leads to a suppression of…