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This work aims to show that the quantal diffusion approach based on the stochastic mean field (SMF) theory is capable of explaining the reaction dynamics observed in MNT reactions. Primary product mass distributions in $^{48}$Ca+$^{244}$Pu reaction at E$_\text{{c.m.}}= $ 203.2 MeV and $^{86}$Kr+$^{198}$Pt reaction at E$_\text{{c.m.}} = $ 324.2 MeV are calculated and compared with the available experimental data., Comment: 10 pages, 6 figures

Multinucleon transfer mechanism in collision of ${}^{160}\mathrm{Gd}+{}^{186}\mathrm{W}$ system is investigated in the framework of quantal transport description, based on the stochastic mean-field (SMF) theory. The SMF theory provides a microscopic approach for nuclear dynamics beyond the time-dependent Hartree-Fock (TDHF) approach by including mean-field fluctuations. Cross-sections for the primary fragment production are determined in the quantal transport description and compared with the available data., Comment: 15 pages, 10 figures

Production cross-sections of heavy neutron-rich isotopes are calculated by employing quantal transport description in ${}^{250}\text{Cf}+{}^{232}\text{Th}$ collisions. This quantal transport description is based on the stochastic mean-field (SMF) approach, and it provides a microscopic approach beyond time-dependent Hartree-Fock (TDHF) theory to include mean-field fluctuations. De-excitation of primary fragments is determined by employing the statistical GEMINI++ code. Calculations provide predictions for production cross-sections of neutron rich transfermium isotopes without any adjustable parameters., Comment: 15 pages, 10 figures

As an extension of previous work, we calculate the production cross-section of heavy neutron-rich isotopes by employing the quantal diffusion description to ${}^{48} \text{Ca} + {}^{238} \text{U}$ collisions. The quantal diffusion is deduced from stochastic mean-field approach, and transport properties are determined in terms of time-dependent single-particle wave functions of the time-dependent Hartree-Fock (TDHF) theory. As a result, the approach allows for prediction of production cross-sections without any adjustable parameters. The secondary cross-sections by particle emission are calculated with the help of the statistical GEMINI++ code., Comment: 9 pages, six figures

Multinucleon transfer mechanism in the collision of ${}^{238}\text{U}+{}^{238}\text{U}$ system is investigated at $E_\text{c.m.} =833$ MeV in the framework of the quantal diffusion description based on the stochastic mean-field approach (SMF). Double cross-sections $\sigma(N,Z)$ as a function of the neutron and proton numbers, the cross-sections $\sigma(Z)$ and $\sigma(A)$ as a function of the atomic numbers and the mass numbers are calculated for production of the primary fragments. The calculation indicates the ${}^{238} \text{U}+{}^{238} \text{U}$ system may be located at an unstable equilibrium state at the potential energy surface with a slightly negative curvature along the beta stability line on the $(N,Z)-$plane. This behavior may lead to rather large diffusion along the beta stability direction., Comment: 10 pages, 10 figures. arXiv admin note: text overlap with arXiv:1904.09619

Employing the quantal diffusion mechanism for multi-nucleon transfer, the double differential cross-sections are calculated for production of primary projectile-like and target-like fragments in collisions of ${}^{136}\text{Xe}+{}^{208}\text{Pb}$ system at $E_\text{c.m.} =514$ MeV. Including de-excitation due to neutron emission, the cross-section for production of ${}^{210}\text{Po}$, ${}^{222}\text{Rn}$ and ${}^{224}\text{Ra}$ isotopes are estimated and compared with data., Comment: 7 pages, 3 figures, 2 tables

Employing a quantal diffusion description based on the stochastic mean-field (SMF) approach, we analyze the mass distribution of the primary fragments in the collisions of ${}^{136} \text{Xe}+{}^{208} \text{Pb}$ system at the bombarding energy $E_\text{c.m.} =526$~MeV. This quantal approach provides a good description of the primary fragment distribution without any adjustable parameter, including the effects of shell structure., Comment: 11 pages, 8 figures. arXiv admin note: text overlap with arXiv:1802.05564

Employing the stochastic mean-field (SMF) approach, we develop a quantal diffusion description of the multi-nucleon transfer in heavy-ion collisions at finite impact parameters. The quantal transport coefficients are determined by the occupied single-particle wave functions of the time-dependent Hartree-Fock equations. As a result, the primary fragment mass and charge distribution functions are determined entirely in terms of the mean-field properties. This powerful description does not involve any adjustable parameter, includes the effects of shell structure and is consistent with the fluctuation-dissipation theorem of the non-equilibrium statistical mechanics. As a first application of the approach, we analyze the fragment mass distribution in $^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ collisions at the bombarding energy $E_{\text{c.m.}}=193$ MeV and compare the calculations with the experimental data., Comment: 15 pages, 8 figures, 2 tables. arXiv admin note: text overlap with arXiv:1706.03563

Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of $^{238}$U + $^{238}$U in the framework of the stochastic mean-field (SMF) approach. For bombarding energies considered in this work, the di-nuclear structure is maintained during the collision. Hence, it is possible to describe nucleon exchange as a diffusion process for mass and charge asymmetry. Quantal neutron and proton diffusion coefficients, including memory effects, are extracted from the SMF approach and the primary fragment distributions are calculated., Comment: 9 pages, 6 figures

Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of several symmetric heavy-ion collisions in the framework of the Stochastic Mean-Field (SMF) approach. Since at bombarding energies below the fusion barrier, di-nuclear structure is maintained, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Quantal diffusion coefficients, including memory effects, for proton and neutron exchanges are extracted microscopically employing the SMF approach. The quantal calculations of neutron and proton variances are compared with the semi-classical results., Comment: 9 pages, 4 figures

Nucleon exchange mechanism is investigated in the central collisions of ${}^{40}$Ca + ${}^{238}$U and ${}^{48}$Ca + ${}^{238}$U systems near the quasi-fission regime in the framework of the Stochastic Mean-Field (SMF) approach. Sufficiently below the fusion barrier, di-nuclear structure in the collisions is maintained to a large extend. Consequently, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Diffusion coefficients for proton and neutron exchange are determined from the microscopic basis of the SMF approach in the semi-classical framework. Calculations show that after a fast charge equilibration the system drifts toward symmetry over a very long interaction time. Large dispersions of proton and neutron distributions of the produced fragments indicate that diffusion mechanism may help to populate heavy trans-uranium elements near the quasi-fission regime in these collisions.

As an extension of our previous work, the growth of density fluctuations in the spinodal region of charge asymmetric nuclear matter is investigated in the basis of the stochastic mean-field approach in the non-relativistic framework. A complete treatment of density correlation functions are presented by including collective modes and non-collective modes as well., Comment: 20 pages, 6 figures, Accepted by Physical Review C

Nucleon exchange mechanism is investigated in central collisions of symmetric heavy-ions in the basis of the stochastic mean-field approach. Quantal diffusion coefficients for nucleon exchange are calculated by including non-Markovian effects and shell structure. Variances of fragment mass distributions are calculated in central collisions of ${}^{40}$Ca + ${}^{40}$Ca, ${}^{48}$Ca + ${}^{48}$Ca and ${}^{56}$Ni + ${}^{56}$Ni systems.

Early growth of density fluctuations of nuclear matter in spinodal region is investigated employing the stochastic mean-field approach. In contrast to the earlier treatments in which only collective modes were included in the calculations, in the present work non-collective modes are also included, thus providing a complete treatment of the density correlation functions. Calculations are carried out for symmetric matter in non-relativistic framework using a semi-classical approximation., Comment: 19 pages, 10 figures

Nucleon exchange mechanism is investigated in deep-inelastic symmetric heavy-ion collisions in the basis of the Stochastic Mean-Field approach. By extending the previous work to off-central collisions, analytical expression is deduced for diffusion coefficient of nucleon exchange mechanism. Numerical calculations are carried out for ${}^{40}$Ca + ${}^{40}$Ca and ${}^{90}$Zr + ${}^{90}$Zr systems and the results are compared with the phenomenological nucleon exchange model. Also, calculations are compared with the available experimental results of deep-inelastic collisions between calcium nuclei., Comment: 8 pages, 7 figures

Spinodal instabilities and early growth of baryon density fluctuations in symmetric nuclear matter are investigated in the basis of stochastic extension of relativistic mean-field approach in the semi-classical approximation. Calculations are compared with the results of non-relativistic calculations based on Skyrme-type effective interactions under similar conditions. A qualitative difference appears in the unstable response of the system: the system exhibits most unstable behavior at higher baryon densities around $\rho_{b}=0.4 ~\rho_{0}$ in the relativistic approach while most unstable behavior occurs at lower baryon densities around $\rho_{b}=0.2 ~\rho_{0}$ in the non-relativistic calculations, Comment: 18 pages, 7 figures

Quantal effects on growth of spinodal instabilities in charge asymmetric nuclear matter are investigated in the framework of a stochastic mean field approach. Due to quantal effects, in both symmetric and asymmetric matter, dominant unstable modes shift towards longer wavelengths and modes with wave numbers larger than the Fermi momentum are strongly suppressed. As a result of quantum statistical effects, in particular at lower temperatures, magnitude of density fluctuations grows larger than those calculated in semi-classical approximation., Comment: 19 pages, 7 figures submitted to Nucl. Phys. A

We study the radiative $\phi\to K^0\bar{K}^0\gamma$ decay within a phenomenological framework by considering the contributions of the $f_{0}(980)$ and $a_{0}(980)$ scalar resonances. We calculate the branching ratio $B(\phi\to K^0\bar{K}^0\gamma)$ by employing the coupling constants $g_{f_0K^{+}K^{-}}$ and $g_{a_0K^{+}K^{-}}$ as determined by different experimental groups., Comment: 10 pages, 3 figures

We investigate the quantized magnetic flux through the electronic orbits of Dirac hydrogen atom in the absence of an external magnetic field. The sources of the magnetic fields are taken to be that of proton's magnetic moment $\mu _{p}$ and electron's magnetic moment $\mu_{e}$ (or $\mu_{j}$) which has two components namely the orbital part $\mu_{l}$ and the spinning part $\mu_{s}$ >.We show that the quantized magnetic fluxes through the electronic orbits corresponding to the ($n,l=n-1,m_{j}$) eigenstates of Dirac hydrogen atom take the forms: $\Phi (n,l,m_{j})=[ n-l-m_{j}] \Phi_{0}$, where $\Phi _{0}=\frac{h}{| e|}$ is the flux quanta. The application of the present result to the selection rules for the optical transitions of hydrogen atom gives access to the spin flip-floppings. The present result is believed to serve a significant help for understanding the recent observations of spin relaxation in excitonic transitions (such as 1s -> 2p or 2p -> 3d) in nanostructures., Comment: 18 pages

In order to describe the fusion of two very heavy nuclei at near barrier energies, a generalized Langevin approach is proposed, which incorporates the quantum statistical fluctuations in accordance with the fluctuation and dissipation theorem. It is illustrated that the quantum statistical effects introduce an enhancement of the formation of compound nucleus, though the quantum enhancement is somewhat less pronounced as indicated in the previous calculations., Comment: 17 pages, 6 figures

We investigate f_0-sigma mixing in the framework of light cone QCD sum rules and by employing the experimental results about the decay widths and the masses of these scalar mesons we estimate the scalar mixing angle by using sigma meson data and f_0 meson data. The two values we thus obtain of the scalar mixing angle are not entirely consistent with each other, possibly indicating that the structure of these mesons cannot be simple quark-antiquark states., Comment: 10 pages, Latex, 2 figures

We investigate the $a_0K^+K^-$-vertex in the framework of light cone QCD sum rules. We estimate the coupling constant g$_{a_0K^+K^-}$ which is an essential ingredient in the analysis of physical processes involving $a_0(980)$ meson. Our result is somewhat larger than the previous determinations of this coupling constant., Comment: 8 pages, 1 figure

We calculate the branching ratio of omega --> pi^+ pi^- gamma decay in a phenomenological framework in which the contributions of VMD, chiral loops, sigma-meson intermediate state amplitudes and the effects of omega-rho mixing are considered. We conclude that the sigma-meson intermediate state amplitude and omega-rho mixing make substantial contribution to the branching ratio., Comment: 10 pages RevTex, 4 Figures, to be published in Acta Phys. Pol. B

In an attempt to explain the latest experimental result about the branching ratio of $\omega\to \pi^0\pi^0\gamma$ decay we reexamine the decay mechanism of this decay in a phenomenological framework in which the contributions of VMD, chiral loops, $\sigma$-meson intermediate state amplitudes and the effects of $\omega-\rho$ mixing are considered. We conclude that in order to obtain the experimental value of the branching ratio $B(\omega\to \pi^0\pi^0\gamma)$ $\sigma$-meson amplitude which makes a substantial contribution should be included into the reaction mechanism and the effects of $\omega-\rho$ mixing should be taken into account. We also estimate the coupling constant $g_{\omega\sigma\gamma}$ as $g_{\omega\sigma\gamma}=0.11$ which is much smaller than the values suggested by light cone QCD sum rules calculations., Comment: to be published in Phys. Rev. D

We study the radiative $\rho^0\to \pi^+\pi^-\gamma$ and $\rho^0\to \pi^0\pi^0\gamma$ decays and we calculate their branching ratios using a phenomenological approach by adding to the amplitude calculated within the framework of chiral perturbation theory and vector meson dominance the amplitude of $\sigma$-meson intermediate state. Our results for the branching ratios are in good agreement with the experimental values., Comment: to be published in Phys. Rev. D

The dipole response function of nuclear matter at zero and finite temperatures is investigated by employing the linearized version of the extended TDHF theory with a non-Markovian binary collision term. Calculations are carried out for nuclear dipole vibrations by employing the Steinwedel-Jensen model and compared with experimental results for $^{120}Sn$ and $^{208}Pb$., Comment: 14 pages, RevTex, 3 PS figures

We study the radiative decay $\phi\to\pi^{0}\eta\gamma$ within the framework of a phenomenological approach in which the contributions of $\rho$-meson, chiral loop and $a_0$-meson are considered. We analyze the interference effects between different contributions and utilizing the experimental branching ratio and invariant $\pi^0\eta$ mass spectrum for $\phi\to\pi^{0}\eta\gamma$ decay we estimate the branching ratio of $\phi\to a_0\gamma$ decay., Comment: 18 pages, RevTeX, 6 PS figures. A rounding-off error in printing the horizontal axes of figures resulting from the computer program Grapher is corrected. Journal Ref.: J. Phys. G: Nucl. Part. Phys. 28 (2002) 2783-2793

We investigate the $\omega\sigma\gamma$-vertex and estimate the coupling constant g$_{\omega\sigma\gamma}$ in the framework of the light cone QCD sum rules. We compare our result with the values of this coupling constant deduced from a phenomenological analysis of $\omega\to\pi\pi\gamma$ decays., Comment: 5 pages, RevTex, 1 Figure

We study $\phi a_0\gamma$- and $\phi\sigma\gamma$-vertices in the framework of the light cone QCD sum rules and we estimate the coupling constants g$_{\phi a_0\gamma}$ and g$_{\phi\sigma\gamma}$ utilizing $\omega\phi$-mixing. We compare our results with the previous estimations of these coupling constants in the literature obtained from phenomenological considerations., Comment: 8 pages, RevTex, 2 figures

The $\omega$-meson photoproduction, $\gamma+p\to p+\omega$, is studied in the framework of a model, containing $\pi$-meson exchange in t-channel and nucleon-exchange in s- and u-channels. Considering both $\omega NN$-coupling constants in the region of time-like meson four momenta as the free parameters, we find different sets of solutions for these constants from the existing data on the t-dependence of the differential cross sections, $d\sigma(\gamma+p\to p+\omega)/dt$, in the near threshold region $E_{\gamma}\leq 2$ GeV. These sets of $\omega NN$-coupling constants, corresponding to destructive and constructive $\pi\bigotimes N$-interference contributions to $d\sigma/dt$ can be well distinguished by measurements of beam asymmetry, induced by linear photon polarization., Comment: 29 pages, RevTex, 6 PS Figures

We investigate the possibility that the process of $\rho^{0}$-meson photoproduction on proton, $\gamma+p\to p+\rho^{0}$, in the near threshold region $E_{\gamma}< 2$ GeV, can be considered in the framework of model with $\pi$-, $\sigma$- and N-exchanges. This suggestion is based on a study of the t-dependence of differential cross section, $d\sigma(\gamma p \to p \rho^{0})/dt$, which has been measured by SAPHIR Collaboration. We find that the suggested model provides a good description of the experimental data with new values of $\rho NN$-coupling constants in the region of the time-like $\rho^{0}$-meson momentum. Our results suggest that such model can be considered as a suitable nonresonant background mechanism for the future discussion of possible role of nucleon resonance contributions. Our predictions for $\rho^{0}$-meson photoproduction on neutron target and for beam asymmetry on both proton and neutron targets are presented., Comment: 21 pages, RevTex, 6 PS figures

We consider the two point correlation function of scalar current in QCD sum rules approach to estimate the overlap amplitude of $a_0$ meson. We then employ QCD sum rules to calculate the coupling constants g$_{\omega a_0\gamma}$ and g$_{\rho a_0\gamma}$ by studying the three point ${a_0\omega\gamma}$- and ${a_0\rho\gamma}$-correlation functions., Comment: 9 pages, 4 figures, RevTex

We study the radiative decay $\phi\to\pi^{0}\pi^{0}\gamma$ within the framework of a phenomenological approach in which the contributions of $\sigma$-meson, $\rho$-meson and $f_0$-meson are considered. We analyze the interference effects between different contributions and utilizing the experimental branching ratio for this decay we estimate the coupling constant $g_{\phi\sigma\gamma}$., Comment: 12 Pages in REVTEX, 5 Figures, to be published in Phys.Rev.D

We employ QCD sum rules to calculate the coupling constant g$_{\rho\sigma\gamma}$ by studying the three point ${\rho\sigma\gamma}$-correlation function. Our results is consistent with the value of this coupling constant obtained using vector meson dominance of the electromagnetic current and the experimental $\rho^0$-photoproduction data., Comment: 10 pages RevTex, 3 postscript figures