Related papers: Cross sections for meson-meson nonresonant reactio…
The $\pi^-p \to e^+e^- n$ and $\pi^+n \to e^+e^- p$ reaction cross sections are calculated below and in the vicinity of the vector meson ($\rho^0$, $\omega$) production threshold. These processes are largely responsible for the emission of…
We have shown that the lowest order QCD amplitude, i.e. the quark exchange contribution, to the forward production of a pair of longitudinally polarized rmesons in the scattering of two virtual photons gamma (Q1) gamma (Q2) rho rho…
We report the measurements of the transverse momentum spectra and invariant mass distributions of $\Delta$(1232)$\to \pi p$, $K^*$(892)$^{0,\pm} \to \pi K$ and $\rho$(770)$^{0} \to \pi^{+} \pi^{-}$ in Au+Au and p+p collisions at…
The backgrounds due to the direct diffractive dissociation of the photon into the $\pi^+\pi^-$ as well as $K^+K^-$ pairs to the "elastic" diffractive $\rho '$ and $\phi $ mesons production in electron-proton collisions are calculated. It is…
Kaon production in pion-nucleon collisions in nuclear matter is studied in the resonance model. To evaluate the in-medium modification of the reaction amplitude as a function of the baryonic density we introduce relativistic, mean-field…
We discuss the non-relativistic multichannel quark model and describe the techniques developed to solve the resulting equations. We then investigate some simple solutions to demonstrate how the model unifies meson-meson scattering with…
Exploring the mass modifications of $\phi$ mesons in nuclei provides insights into the nature of strongly interacting matter. Specifically, $\phi$ meson mass shifts can be related to the in-medium modification of the strange quark…
The effect of possible in-medium modifications of nucleon-nucleon ($NN$) cross sections on particle production is investigated in heavy ion collisions ($HIC$) at intermediate energies. In particular, using a fully covariant relativistic…
The interference of the $\rho^0$ and $\omega$ mesons has been studied in the hadronic and leptonic decay channels, i.e., dipion and dilepton decay channels respectively, but this interference is not studied yet in the semihadronic or…
Heavy meson production in nucleon-nucleon collisions is discussed within a meson exchange model of hadronic interactions, paying special attention to the basic dynamics that determine the behavior of the cross sections near the threshold…
The novel point of this analysis is a direct use of reggeon exchange technique for the description of the reactions $\pi N\to two mesons + N$ at large energies of the initial pion. This approach allows us to describe simultaneously…
The influence of nonvanishing quark masses on the total cross section in electron positron collisions and on the $Z$ decay rate is calculated. The corrections are expanded in $m^2/s$ and $\as$. Methods similar to those applied for the…
Cross sections for photon production in hadronic scattering processes have been calculated according to an effective chiral field theory. For $\pi + \rho \to \pi + \gamma$ and $\pi + \pi \to \rho + \gamma$ processes, these cross sections…
Recent heavy ion experiments indicate modifications of the $\rho-$meson mass in medium. In the CERES experiments $\rho-$mesons are produced at $\sim$ normal nuclear matter density, where hadrons are more appropriate constituents than…
We explore the role of a scalar meson exchange interaction between quarks in a semirelativistic constituent quark model where the quarks are subject to a linear confinement. We search for a variational solution and show that the gap between…
Azimuthal distributions of pi+, K+ and K- mesons have been measured in Au+Au reactions at 1.5 AGeV and Ni+Ni reactions at 1.93 AGeV. In semi-central collisions at midrapidity, pi+ and K+ mesons are emitted preferentially perpendicular to…
We study electromagnetic as well as strong isospin breaking effects in the isospin mass splittings of light pseudoscalar and vector mesons. To this end we employ a coupled system of quark Dyson-Schwinger and meson Bethe-Salpeter equations…
A kaon decaying into three pions is an example of a weak process. However, since the quarks are confined into mesons, the strong interaction also plays an important part. The reaction is a low-energy one, meaning that it takes place in the…
We discuss a few, apparently different (but actually, tightly related) problems: 1. The relation between QCD and valence quark model, 2. The asymptotic behavior of the nonperturbative pion wave function $\psi(\k, x)$ at $x\rightarrow 0,~1,…
A combined analysis of the reactions $\pi^-p\rightarrow K^0\Lambda$ and $\eta n$ is carried out with a chiral quark model. The data in the center-of-mass (c.m.) energy range from threshold up to $W\simeq 1.8$ GeV are reasonably described.…