2,053 research outputs found
Complete one-loop corrections to the mass spectrum of charginos and neutralinos in the MSSM
The mass spectrum of the chargino--neutralino sector in the minimal
supersymmetric standard model (MSSM) is calculated at the one-loop level, based
on the complete set of one-loop diagrams. On-shell renormalization conditions
are applied to determine the counterterms for the gaugino-mass-parameters and the Higgsino-mass parameter . The input is fixed in terms of
three pole masses (two charginos and one neutralino); the other pole masses
receive a shift with respect to the tree-level masses, which can amount to
several GeV. The detailed evaluation shows that both the fermionic/sfermionic
loop contributions and the non-(s)fermionic loop contributions are of the same
order of magnitude and are thus relevant for precision studies at future
colliders.Comment: 19 pages, including 3 figures; corrected some typo
Correlated EoM and Distributions for A=6 Nuclei
Energy spectra and electromagnetic transitions of nuclei are strongly
depending from the correlations of the bound nucleons. Two particle
correlations are responsible for the scattering of model particles either to
low momentum- or to high momentum-states. The low momentum states form the
model space while the high momentum states are used to calculate the G-matrix.
The three and higher order particle correlations do not play a role in the
latter calculation especially if the correlations induced by the scattering
operator are of sufficient short range. They modify however, via the long tail
of the nuclear potential, the Slater determinant of the A particles by
generating excited Slater's determinants. In this work the influence of the
correlations on the level structure and ground state distributions of even open
shell nuclei is analyzed via the boson dynamic correlation model BDCM. The
model is based on the unitary operator ({\it S} is the correlation
operator) formalism which in this paper is presented within a non perturbative
approximation. The low lying spectrum calculated for Li reproduce very well
the experimental spectrum while for He a charge radius slightly larger than
that obtained within the isotopic-shift (IS) theory has been calculated. Good
agreement between theoretical and experimental results has been obtained
without the introduction of a genuine three body force.Comment: 25 pages 4 figures. To be published in the Progress Theoretical
Physic
Extended Cluster Model for Light, and Medium Nuclei
The structures, the electromagnetic transitions, and the beta decay strengths
of exotic nuclei are investigated within an extended cluster model. We start by
deriving an effective nuclear Hamiltonian within the correlation
operator. Tensor forces are introduced in a perturbative expansion which
includes up to the second order terms. Within this Hamiltonian we calculate the
distributions and the radii of A=3,~4 nuclei. For exotic nuclei characterized
by n valence protons/neutrons we excite the structure of the closed shell
nuclei via mixed modes formed by considering correlations operators of higher
order. Good results have been obtained for the calculated transitions and for
the beta decay transition probabilities.Comment: 8-pages, 5-figure
Monte-Carlo approach to calculate the proton stopping in warm dense matter within particle-in-cell simulations
A Monte-Carlo approach to proton stopping in warm dense matter is implemented
into an existing particle-in-cell code. The model is based on multiple
binary-collisions among electron-electron, electron-ion and ion-ion, taking
into account contributions from both free and bound electrons, and allows to
calculate particle stopping in much more natural manner. At low temperature
limit, when ``all'' electron are bounded at the nucleus, the stopping power
converges to the predictions of Bethe-Bloch theory, which shows good
consistency with data provided by the NIST. With the rising of temperatures,
more and more bound electron are ionized, thus giving rise to an increased
stopping power to cold matter, which is consistent with the report of a
recently experimental measurement [Phys. Rev. Lett. 114, 215002 (2015)]. When
temperature is further increased, with ionizations reaching the maximum,
lowered stopping power is observed, which is due to the suppression of
collision frequency between projected proton beam and hot plasmas in the
target.Comment: 6 pages, 4 figure
Monte-Carlo approach to calculate the ionization of warm dense matter within particle-in-cell simulations
A physical model based on a Monte-Carlo approach is proposed to calculate the
ionization dynam- ics of warm dense matters (WDM) within particle-in-cell
simulations, and where the impact (col- lision) ionization (CI), electron-ion
recombination (RE) and ionization potential depression (IPD) by surrounding
plasmas are taken into consideration self-consistently. When compared with
other models, which are applied in the literature for plasmas near thermal
equilibrium, the temporal re- laxation of ionization dynamics can also be
simulated by the proposed model. Besides, this model is general and can be
applied for both single elements and alloys with quite different composi-
tions. The proposed model is implemented into a particle-in-cell (PIC) code,
with (final) ionization equilibriums sustained by competitions between CI and
its inverse process (i.e., RE). Comparisons between the full model and model
without IPD or RE are performed. Our results indicate that for bulk aluminium
in the WDM regime, i) the averaged ionization degree increases by including
IPD; while ii) the averaged ionization degree is significantly over estimated
when the RE is neglected. A direct comparison from the PIC code is made with
the existing models for the dependence of averaged ionization degree on thermal
equilibrium temperatures, and shows good agreements with that generated from
Saha-Boltzmann model or/and FLYCHK code.Comment: 7 pages, 4 figure
The Implementation of the Renormalized Complex MSSM in FeynArts and FormCalc
We describe the implementation of the renormalized complex MSSM (cMSSM) in
the diagram generator FeynArts and the calculational tool FormCalc. This
extension allows to perform UV-finite one-loop calculations of cMSSM processes
almost fully automatically. The Feynman rules for the cMSSM with counterterms
are available as a new model file for FeynArts. Also included are default
definitions of the renormalization constants; this fixes the renormalization
scheme. Beyond that all model parameters are generic, e.g. we do not impose any
relations to restrict the number of input parameters. The model file has been
tested extensively for several non-trivial decays and scattering reactions. Our
renormalization scheme has been shown to give stable results over large parts
of the cMSSM parameter space.Comment: 29 pages, extended chargino/neutralino and sfermion renormalization
schemes, version accepted for publication in Comp. Phys. Commu
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