14,778 research outputs found
Multi-Nucleon Exchange in Quasi-Fission Reactions
Nucleon exchange mechanism is investigated in the central collisions of
Ca + U and Ca + 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
Nucleon exchange in heavy-ion collisions within stochastic mean-field approach
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 Ca + Ca and Zr +
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 figure
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 Ca +
Ca, Ca + Ca and Ni + Ni systems
The single production of the lightest E6 isosinglet quark at the LHC
We study the jet associated production of the new quarks predicted by the
GUT model at the LHC. Generator level considerations are made for
different mass values of the lightest of the new quarks to investigate its
discovery potential and the prospects for obtaining its mixing angle to the
Standard Model quarks. We find that after 100 fb of data taking, it is
possible to discover the new quark with a significance more than 5 up
to a mass of 1500 GeV. If no discovery is made, it is possible to constrain the
mass vs quark mixing angle plane.Comment: uses axodraw.st
Collisional Damping of Giant Monopole and Quadrupole Resonances
Collisional damping widths of giant monopole and quadrupole excitations for
Sn and Pb at zero and finite temperatures are calculated within
Thomas-Fermi approximation by employing the microscopic in-medium
cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny
forces, and are compared with each other. The results for the collisional
widths of giant monopole and quadrupole vibrations at zero temperature as a
function of the mass number show that the collisional damping of giant monopole
vibrations accounts for about 30-40% of the observed widths at zero
temperature, while for giant quadrupole vibrations it accounts for only 20-30%
of the observed widths of zero temperature.Comment: RevTex, 12 pages, 6 PS figure
Exponential Metric Fields
The Laser Interferometer Space Antenna (LISA) mission will use advanced
technologies to achieve its science goals: the direct detection of
gravitational waves, the observation of signals from compact (small and dense)
stars as they spiral into black holes, the study of the role of massive black
holes in galaxy evolution, the search for gravitational wave emission from the
early Universe. The gravitational red-shift, the advance of the perihelion of
Mercury, deflection of light and the time delay of radar signals are the
classical tests in the first order of General Relativity (GR). However, LISA
can possibly test Einstein's theories in the second order and perhaps, it will
show some particular feature of non-linearity of gravitational interaction. In
the present work we are seeking a method to construct theoretical templates
that limit in the first order the tensorial structure of some metric fields,
thus the non-linear terms are given by exponential functions of gravitational
strength. The Newtonian limit obtained here, in the first order, is equivalent
to GR.Comment: Accepted for publication in Astrophysics and Space Science, 17 page
Non-Linear Realisation of the Pure N=4, D=5 Supergravity
We perform the non-linear realisation or the coset formulation of the pure
N=4, D=5 supergravity. We derive the Lie superalgebra which parameterizes a
coset map whose induced Cartan-Maurer form produces the bosonic field equations
of the pure N=4, D=5 supergravity by canonically satisfying the Cartan-Maurer
equation. We also obtain the first-order field equations of the theory as a
twisted self-duality condition for the Cartan-Maurer form within the
geometrical framework of the coset construction.Comment: 12 page
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