14,653 research outputs found
Generalized Density Matrix Revisited: Microscopic Approach to Collective Dynamics in Soft Spherical Nuclei
The generalized density matrix (GDM) method is used to calculate
microscopically the parameters of the collective Hamiltonian. Higher order
anharmonicities are obtained consistently with the lowest order results, the
mean field [Hartree-Fock-Bogoliubov (HFB) equation] and the harmonic potential
[quasiparticle random phase approximation (QRPA)]. The method is applied to
soft spherical nuclei, where the anharmonicities are essential for restoring
the stability of the system, as the harmonic potential becomes small or
negative. The approach is tested in three models of increasing complexity: the
Lipkin model, model with factorizable forces, and the quadrupole plus pairing
model.Comment: submitted to Physical Review C on 08 May, 201
Rigid supersymmetry with boundaries
We construct rigidly supersymmetric bulk-plus-boundary actions, both in
-space and in superspace. For each standard supersymmetric bulk action a
minimal supersymmetric bulk-plus-boundary action follows from an extended -
or -term formula. Additional separately supersymmetric boundary actions can
be systematically constructed using co-dimension one multiplets (boundary
superfields). We also discuss the orbit of boundary conditions which follow
from the Euler-Lagrange variational principle.Comment: 28 pages, JHEP clas
Hexadecapole Interaction and the Delta I=4 Staggering Effect in Rotational Bands
A role of the multipole interaction in the description of the =4
staggering phenomenon is investigated in a model consisting of a single-
shell filled by identical nucleons. Exact diagonalization of the
quadrupole-plus-hexadecapole Hamiltonian shows that the
hexadecapole-hexadecapole interaction can produce a =4 periodicity
in the yrast sequence.Comment: revised version with technical changes only, to be published in
Physica Scripta, latex, 4 pages, 3 PostScript figures available on request
from [email protected], preprint No. IFT/18/9
Magnetic Moments of Heavy Baryons in Light Cone QCD Sum Rules
The magnetic moments of heavy baryons containing a single charm or
bottom quark are calculated in the framework of light cone QCD sum rules
method. A comparison of our results with the predictions of the quark models is
presented.Comment: 26 Pages, 8 Figures and 1 Tabl
-pair Production in the Littlest Higgs Model with T parity in next-to-leading order QCD at LHC
In the framework of the littlest Higgs model with parity, we study the
-pair production at the CERN Large Hadron Collider up to the QCD
next-to-leading order (NLO). The kinematic distributions of final decay
products and the theoretical dependence of the cross section on the
factorization/renormalization scale are analyzed. We adopt the PROSPINO scheme
in the QCD NLO calculations to avoid double counting and keep the convergence
of the perturbative QCD description. Our numerical results show that the QCD
NLO corrections significantly reduce the scale uncertainty, and enhance the
leading order integrated cross section with a -factor in the range of
() with the symmetry breaking scale varying from
() to () at the LHC.
We find that it is possible to select the signal events of the -pair
production from the
background with high ratio of signature over background by taking proper lower
limits on transverse momenta, invariant mass of the final charged leptons and
the missing transverse momentum.Comment: 34 pages, 14 figures, 4 table
Single top quarks at the Fermilab Tevatron
We present a calculation of the single top quark cross section for
proton-antiproton interactions with sqrt(s) = 1.8 TeV at the Fermilab Tevatron
collider. We examine the effects of top mass, parton distribution functions,
QCD scale, and collision energy, on each of the component production
mechanisms, and study the kinematic distributions for standard model
electroweak production. At the upgraded Tevatron with sqrt(s) = 2.0 TeV and
high luminosity, it will be possible to test the nature of the Wtb coupling
using single top production. We estimate the sensitivity to measure the single
top cross section, and thus to directly measure V_tb and the top quark partial
width. We show what happens to the V_tb measurement when an anomalous (V+A)
component is added to the Wtb coupling, and how the top quark polarization
affects the kinematic distributions.Comment: 31 pages including 11 figure
E6SSM vs MSSM gluino phenomenology
The E6SSM is a promising model based on the group E6, assumed to be broken at
the GUT scale, leading to the group SU(3)\times SU(2)\times U(1)\times U(1)' at
the TeV scale. It gives a solution to the MSSM {\mu}-problem without
introducing massless axions, gauge anomalies or cosmological domain walls. The
model contains three families of complete 27s of E6, giving a richer
phenomenology than the MSSM. The E6SSM generically predicts gluino cascade
decay chains which are about 2 steps longer than the MSSM's due to the presence
of several light neutralino states. This implies less missing (and more
visible) transverse momentum in collider experiments and kinematical
distributions such as M_eff are different. Scans of parameter space and MC
analysis suggest that current SUSY search strategies and exclusion limits have
to be reconsidered.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011),
Paris, France, November 14-18 2011, 3 pages, 7 figure
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