Related papers: Solving the four-dimensional $NN-\pi NN$ equations…
A general form of multi-channel Bethe-Salpeter equation is considered. In contradistinction to the hitherto applied approaches, our coupled system of equations leads to the simultaneous solutions for all relativistic four-point Green…
The cross sections of the scalar meson $f_0(980)$, $a_0(980)$ and $\sigma(600)$ production in collision of electron and positron beams were calculated. The two-photon decays of the scalar mesons, obtained in the framework of the…
In this work, expanding on previous analyses, we employ an effective Lagrangian approach to investigate the mass spectrum of scalar and pseudoscalar mesons at finite temperature, above the (pseudo-)critical temperature $T_c$, in a…
A numerical analysis to the scalar form-factor in the $\pi\pi$ and KK coupled--channel system is made by solving the coupled-channel dispersive integral equations, using the iteration method. The solutions are found not unique. Physical…
Quantum fluctuations of a scalar field and its derivatives are calculated when the field is confined between two parallel plates satisfying Dirichlet or Neumann boundary conditions. After regulation these fluctuations diverge in general…
We employ an effective Lagrangian approach to investigate double $\phi$ production in the $\bar{p}p$ reaction near the threshold and describe a notable violation of the Okubo-Zweig-Iizuka (OZI) rule in this reaction process through hadronic…
To solve the spinor-spinor Bethe-Salpeter equation in Euclidean space we propose a novel method related to the use of hyperspherical harmonics. We suggest an appropriate extension to form a new basis of spin-angular harmonics that is…
Motivated by the success of models based on chiral symmetry in NN interactions we investigate self-interacting scalar, pseudoscalar and vector meson fields and their impact for NN forces. We parametrize the corresponding nonlinear field…
We discuss a recent extraction of the $\pi N$ $\sigma$ term $\sigma_{\pi N}$ from a large-scale fit of pionic-atom strong-interaction data across the periodic table. The value thus derived, $\sigma_{\pi N}^{\rm FG}=57\pm 7$ MeV, is directly…
A description of the NN scattering is constructed starting from the $\pi, \eta, \eta'$ pseudoscalar-, the $\rho, \phi, \omega$ vector-, and the $\varepsilon(600), a_0, f_0(1400)$ scalar - meson-nucleon coupling constants, which we obtain…
We study the nucleon-nucleon interaction in the isoscalar-scalar channel using t he chiral unitary approach. The $t$-matrix of the pion-pion scattering in this c hannel is summed up to all orders using the B-S equation. We find that the…
We propose a new way of looking at the Navier-Stokes equation (N-S) in dimensions two and three. We consider its regular approximations in which the -P Delta operator is replaced with the fractional power. The 3-D N-S equation is…
In this work, the $\eta^\prime$ meson photoproduction near threshold is studied in the quark model framework. A pseudovector effective Lagrangian is introduced for the $\eta^\prime NN$ coupling and the newly published data from the SAPHIR…
A $NN\to NN^{\ast}(1440)$ transition potential, based on an effective quark-quark interaction and a constituent quark cluster model for baryons, is derived in the Born-Oppenheimer approach. The potential shows significant differences with…
It has been suggested in arXiv:1010.1415 that certain derivatively coupled non-renormalizable scalar field theories might restore the perturbative unitarity of high energy hard scatterings by classicalization, i.e. formation of…
We report a project to study scalar particles by lattice QCD simulations. After a brief introduction of the current situation of lattice study of the sigma meson, we describe our numerical simulations of scalar mesons, $\sigma$ and…
Finite volume multiple-particle interaction is studied in a two-dimensional complex $\phi^4$ lattice model. The existence of analytical solutions to the $\phi^4$ model in two-dimensional space and time makes it a perfect model for the…
The s-wave meson-nucleon interaction in the $S = -1$ sector is studied by means of coupled-channel Lippmann Schwinger equations, using the lowest order chiral Lagrangian and a cut off to regularize the loop integrals. The method reproduces…
Effects of non-resonant photoproductions arising from two different $\pi NN$ couplings are investigated in the $\gamma N\to\pi\pi N$ reaction. We find that the pseudoscalar (PS) $\pi NN$ coupling is generally preferable to the pseudovector…
Within the framework of dispersion theory, we study the the processes $e^+e^-\to \phi(2170) \to \phi \pi\pi(K\bar{K})$. The strong pion-pion final-state interactions, especially the $K\bar{K}$ coupled channel in the $S$-wave, are taken into…