arXiv subjects

G. Turan

Publications and source records attributed to G. Turan.

12 recordsLinked to original sources

arXiv2017

Multi-Nucleon Transfer in Central Collisions of $^{238}$U + $^{238}$U

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.

nucl-th↗

arXiv2015

Quantal description of nucleon exchange in stochastic mean-field approach

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.

nucl-th↗

arXiv2009

Finding bipartite subgraphs efficiently

Polynomial algorithms are given for the following two problems: given a graph with $n$ vertices and $m$ edges, where $m \ge 3 n^{3/2}$, find a complete balanced bipartite subgraph with parts about $\ln n/(\ln (n^2/m))$, given a graph with $n$ vertices, find a decomposition of its edges into complete balanced bipartite graphs having altogether $O(n^2 / \ln n)$ vertices. Previous proofs of the existence of such objects, due to Kővári-Sós-Turán, Chung-Erdős-Spencer, Bublitz and Tuza were non-constructive.

math.CO↗

arXiv2008

QCD Sum Rules study of meson-baryon sigma terms

The pion-baryon sigma terms and the strange-quark condensates of the octet and the decuplet baryons are calculated by employing the method of quantum chromodynamics (QCD) sum rules. We evaluate the vacuum-to-vacuum transition matrix elements of two baryon interpolating fields in an external isoscalar-scalar field and use a Monte Carlo-based approach to systematically analyze the sum rules and the uncertainties in the results. We extract the ratios of the sigma terms, which have rather high accuracy and minimal dependence on QCD parameters. We discuss the sources of uncertainties and comment on possible strangeness content of the nucleon and the Delta.

hep-ph↗

arXiv2007

General analysis of the rare Bc->D^*_s l^+ l^- decay beyond the standard model

The general analysis of the rare Bc->D^*_s l^+ l^- decay is presented by using the most general, model independent effective Hamiltonian. The dependencies of the branching ratios, longitudinal, normal and transversal polarization asymmetries for l^- and the combined asymmetries for l^- and l^+ on the new Wilson coefficients are investigated. Our analysis shows that the lepton polarization asymmetries are very sensitive to the scalar and tensor type interactions, which will be very useful in looking for new physics beyond the standard model.

hep-ph↗

arXiv2004

B-> X_d \ell^+\ell^- in a CP softly broken two Higgs doublet model

We study the differential branching ratio, forward-backward asymmetry, CP-violating asymmetry, CP-violating asymmetry in the forward-backward asymmetry and polarization asymmetries of the final lepton in the B-> X_d \ell^+\ell^- decays in the context of a CP softly broken two Higgs doublet model. We analyze the dependencies of these observables on the model parameters by paying a special attention to the effects of neutral Higgs boson (NHB) exchanges and possible CP violating effects. We find that NHB effects are quite significant for the τmode. The above-mentioned observables seems to be promising as a testing ground for new physics beyond the SM, especially for the existence of the CP-violating phase in the theory.

hep-ph↗

arXiv2004

A General analysis of the lepton polarizations in Bs ->γ\ell^+ \ell^- decays

We present a general analysis of the lepton polarizations in the rare Bs ->γ\ell^+ \ell^- decays by using the most general model independent form of the effective Hamiltonian. The sensitivity of the longitudinal, transverse and normal polarizations of final state leptons, as well as lepton-antilepton combined asymmetries, on the new Wilson coefficients are investigated. It has been shown that all these physical observables are very sensitive to the existence of new physics beyond the standard model and their experimental measurements can give valuable information about it.

hep-ph↗

arXiv2003

New physics effects in the rare B_s --> γ\ell^+ \ell^- decays with polarized photon

Using the most general model independent form of the effective Hamiltonian, the rare B_s --> γ\ell^+ \ell^- decays are studied by taking into account the polarization of the photon. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are presented. Dependence of these observables on the new Wilson coefficients are studied. It is also investigated the sensitivity of "photon polarization asymmetry" in B_s --> γ\ell^+ \ell^- decays to the new Wilson coefficients. It has been shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.

hep-ph↗

arXiv2001

B --> K^* τ^+ τ^- decay in the general two Higgs doublet model including the neutral Higgs boson effects

We study the CP violating asymmetry, the forward-backward asymmetry of the lepton pair and the CP asymmetry in the forward backward asymmetry for the exclusive decay $B --> K^* τ^+ τ^- in the general two Higgs doublet model including the neutral Higgs boson effects. We analyse the dependencies of these quantities on the model III parameters. We found that the physical parameters studied above are at the order of the magnitude 1% and neutral Higgs boson effects are detectable for large values of the coupling \barξ_{N,ττ}^D.

hep-ph↗

arXiv2001

b --> s τ^+ τ^- decay in the two Higgs doublet model with flavor changing neutral currents

We study the decay width and forward-backward asymmetry of the lepton pair for the inclusive decay b --> s τ^+ τ^- in the two Higgs doublet model with three level flavor changing neutral currents (model III) and analyse the dependencies of these quantities on the model III parameters, including the leading order QCD corrections. We found that there is a considerable enhancement in the decay width and neutral Higgs effects are detectable for large values of the parameter \barξ_{N,ττ}^D.

hep-ph↗

arXiv2000

B_s -> \tau^+ \tau^- decay in the general two Higgs Doublet model

We study the exclusive decay B_s -> \tau^+ \tau^-$ in the general two Higgs doublet model. We analyse the dependencies of the branching ratio on the model parameters, including the leading order QCD corrections. We found that there is an enhancement in the branching ratio, especially for r_{tb}=\frac{\bar{\xi}_{N,tt}^U}{\bar{\xi}_{N,bb}^D}>1 case. Further, the neutral Higgs effects are detectable for large values of the parameter \bar{\xi}_{N,\tau\tau}^D.

hep-ph↗

arXiv1999

Rare Radiative B -> τ^+ τ^- γdecay in the two Higgs doublet Model

The radiative B ->τ^+ τ^- γdecay is investigated in the framework of the two Higgs doublet model . The dependence of the differential branching ratio on the photon energy and the branching ratio on the two Higgs doublet model parameters, m_{H^\pm} and \tan β, are studied. It is shown that there is an enhancement in the predictions of the two Higgs doublet model compared to the Standard model case. We also observe that contributions of neutral Higgs bosons to the decay are sizable when \tanβis large.

hep-ph↗