Superheavies: Theoretical incitements and predictions

It is well known that in fusion reactions one may get only neutron deficient superheavy nuclei located far from the island of stability. The multi-nucleon transfer reactions allow one to produce more neutron enriched new heavy nuclei but the corresponding cross sections are rather low. Neutron capture process is considered here as alternative method for production of long-lived neutron rich superheavy nuclei. Strong neutron fluxes might be provided by nuclear reactors and nuclear explosions in laboratory frame and by supernova explosions in nature. All these cases are discussed in the paper.Comment: 7 FIGURE

Van der Waals excluded volume model for Lorentz contracted rigid spheres

Conventional cluster and virial expansions are generalized to momentum dependent interparticle potentials. The model with Lorentz contracted hard core potentials is considered, e.g. as hadron gas model. A Van der Waals-type model with a temperature dependent excluded volume is derived. Lorentz contraction effects at given temperature are stronger for light particles and make their effective excluded volume smaller than that of heavy ones

Properties of dense strange hadronic matter with quark degrees of freedom

The properties of strange hadronic matter are studied in the context of the modified quark-meson coupling model using two substantially di erent sets of hyperon-hyperon (Y Y ) interactions. The first set is based on the Nijmegen hard core potential model D with slightly attractive Y Y interactions. The second potential set is based on the recent SU(3) extension of the Nijmegen soft-core potential NSC97 with strongly attractive Y Y interactions which may allow for deeply bound hypernuclear matter. The results show that, for the first potential set, the hyperon does not appear at all in the bulk at any baryon density and for all strangeness fractions. The binding energy curves of the resulting N system vary smoothly with density and the system is stable (or metastable if we include the weak force). However, the situation is drastically changed when using the second set where the hyperons appear in the system at large baryon densities above a critical strangeness fraction. We find strange hadronic matter undergoes a first order phase transition from a N system to a N for strangeness fractions fS > 1.2 and baryonic densities exceeding twice ordinary nuclear matter density. Furthermore, it is found that the system built of N is deeply bound. This phase transition a ects significantly the equation of state which becomes much softer and a substantial drop in energy density and pressure are detected as the phase transition takes place. PACS:21.65.+f, 24.85.+p, 12.39B

Motor proteins traffic regulation by supply-demand balance of resources

In cells and in vitro assays the number of motor proteins involved in biological transport processes is far from being unlimited. The cytoskeletal binding sites are in contact with the same finite reservoir of motors (either the cytosol or the flow chamber) and hence compete for recruiting the available motors, potentially depleting the reservoir and affecting cytoskeletal transport. In this work we provide a theoretical framework to study, analytically and numerically, how motor density profiles and crowding along cytoskeletal filaments depend on the competition of motors for their binding sites. We propose two models in which finite processive motor proteins actively advance along cytoskeletal filaments and are continuously exchanged with the motor pool. We first look at homogeneous reservoirs and then examine the effects of free motor diffusion in the surrounding medium. We consider as a reference situation recent in vitro experimental setups of kinesin-8 motors binding and moving along microtubule filaments in a flow chamber. We investigate how the crowding of linear motor proteins moving on a filament can be regulated by the balance between supply (concentration of motor proteins in the flow chamber) and demand (total number of polymerised tubulin heterodimers). We present analytical results for the density profiles of bound motors, the reservoir depletion, and propose novel phase diagrams that present the formation of jams of motor proteins on the filament as a function of two tuneable experimental parameters: the motor protein concentration and the concentration of tubulins polymerized into cytoskeletal filaments. Extensive numerical simulations corroborate the analytical results for parameters in the experimental range and also address the effects of diffusion of motor proteins in the reservoir.Comment: 31 pages, 10 figure

Transverse Meissner Physics of Planar Superconductors with Columnar Pins

The statistical mechanics of thermally excited vortex lines with columnar defects can be mapped onto the physics of interacting quantum particles with quenched random disorder in one less dimension. The destruction of the Bose glass phase in Type II superconductors, when the external magnetic field is tilted sufficiently far from the column direction, is described by a poorly understood non-Hermitian quantum phase transition. We present here exact results for this transition in (1+1)-dimensions, obtained by mapping the problem in the hard core limit onto one-dimensional fermions described by a non-Hermitian tight binding model. Both site randomness and the relatively unexplored case of bond randomness are considered. Analysis near the mobility edge and near the band center in the latter case is facilitated by a real space renormalization group procedure used previously for Hermitian quantum problems with quenched randomness in one dimension.Comment: 23 pages, 22 figure

Neutron star properties in the quark-meson coupling model

The effects of internal quark structure of baryons on the composition and structure of neutron star matter with hyperons are investigated in the quark- meson coupling (QMC) model. The QMC model is based on mean-field description of nonoverlapping spherical bags bound by self-consistent exchange of scalar and vector mesons. The predictions of this model are compared with quantum hadrodynamic (QHD) model calibrated to reproduce identical nuclear matter saturation properties. By employing a density dependent bag constant through direct coupling to the scalar field, the QMC model is found to exhibit identical properties as QHD near saturation density. Furthermore, this modified QMC model provides well-behaved and continuous solutions at high densities relevant to the core of neutron stars. Two additional strange mesons are introduced which couple only to the strange quark in the QMC model and to the hyperons in the QHD model. The constitution and structure of stars with hyperons in the QMC and QHD models reveal interesting di erences. This suggests the importance of quark structure e ects in the baryons at high densities. PACS number(s): 26.60.+c, 21.65.+f, 12.39.Ba, 24.85.+

A self-consistent equation of state for nuclear matter

The authors formulate a phenomenological extension of the mean-field theory approach and define a class of thermodynamically self-consistent equations of state for nuclear matter. A new equation of state of this class is suggested and examined in detail

Hot hypernuclear matter in the modified quark meson coupling model

Hot hypernuclear matter is investigated in an explicit SU(3) quark model based on a mean field description of nonoverlapping baryon bags bound by the self-consistent exchange of scalar sigma, zeta and vector omega,phi mesons. The sigma, omega mean fields are assumed to couple to the u, d-quarks while the zeta ,phi mean fields are coupled to the s-quark. The coupling constants of the mean fields with the quarks are assumed to satisfy SU(6) symmetry. The calculations take into account the medium dependence of the bag parameter on the scalar fields sigma, zeta. We consider only the octet baryons N,Lambda,Sigma, Xi in hypernuclear matter. An ideal gas of the strange mesons K and K is introduced to keep zero net strangeness density. Our results for symmetric hypernuclear matter show that a phase transition takes place at a critical temperature around 180 MeV in which the scalar mean fields sigma, zeta take nonzero values at zero baryon density. Furthermore, the bag contants of the baryons decrease significantly at and above this critical temperature indicating the onset of quark deconfinement. The present results imply that the onset of quark deconfinement in SU(3) hypernuclear matter is much stronger than in SU(2) nuclear matter. PACS:21.65.+f, 24.85.+p, 12.39B

Decoherence and Entanglement Dynamics in Fluctuating Fields

We study pure phase damping of two qubits due to fluctuating fields. As frequently employed, decoherence is thus described in terms of random unitary (RU) dynamics, i.e., a convex mixture of unitary transformations. Based on a separation of the dynamics into an average Hamiltonian and a noise channel, we are able to analytically determine the evolution of both entanglement and purity. This enables us to characterize the dynamics in a concurrence-purity (CP) diagram: we find that RU phase damping dynamics sets constraints on accessible regions in the CP plane. We show that initial state and dynamics contribute to final entanglement independently.Comment: 10 pages, 5 figures, added minor changes in order to match published versio