5,121,807 research outputs found
Lattice QCD Study of the Pentaquark Baryons
We study the spin hadronic state in quenched lattice QCD to search
for a possible pentaquark resonance. Simulations are carried out on
, , and lattices
at =5.7 at the quenched level with the standard plaquette gauge action
and Wilson quark action. We adopt two independent operators with I=0 and
to construct a correlation matrix. After the
diagonalization of the correlation matrix, we successfully obtain the energies
of the ground-state and the 1st excited-state in this channel. The volume
dependence of the energies suggests the existence of a possible resonance state
slightly above the NK threshold in I=0 and channel.Comment: Talk given at the International Workshop on PENTAQUARK04, SPring-8,
Japan, 20-23 July 2004; 7 pages, 3 figure
Perturbative Confinement
A Procedure is outlined that may be used as a starting point for a
perturbative treatment of theories with permanent confinement. By using a
counter term in the Lagrangian that renormalizes the infrared divergence in the
Coulomb potential, it is achieved that the perturbation expansion at a finite
value of the strong coupling constant may yield reasonably accurate properties
of hadrons, and an expression for the string constant as a function of the QCD
Lambda parameter.Comment: Presented at QCD'02, Montpellier, July 2002. 12 pages LaTeX, 8
Figures PostScript, uses gthstyle.sty Reprt-no: ITF-2002/39; SPIN-2002/2
Exact one-loop results for in 3-3-1 models
We investigate the decays , with
in a general class of 3-3-1 models with heavy exotic leptons with arbitrary
electric charges. We present full and exact analytical results keeping external
lepton masses. As a by product, we perform numerical comparisons between exact
results and approximate ones where the external lepton masses are neglected. As
expected, we found that branching fractions can reach the current experimental
limits if mixings and mass differences of the exotic leptons are large enough.
We also found unexpectedly that, depending on the parameter values, there can
be huge destructive interference between the gauge and Higgs contributions when
the gauge bosons connecting the Standard Model leptons to the exotic leptons
are light enough. This mechanism should be taken into account when using
experimental constraints on the branching fractions to exclude the parameter
space of the model.Comment: 27 pages, 5 figures, 4 tables; additional explanation on input
parameters; matches journal versio
Aspects of warm-flat directions
Considering the mechanism of dissipative slow-roll that has been used in warm
inflation scenario, we show that dissipation may alter usual cosmological
scenarios associated with SUSY-flat directions. We mainly consider SUSY-flat
directions that have strong interactions with non-flat directions and may cause
strong dissipation both in thermal and non-thermal backgrounds. An example is
the Affleck-Dine mechanism in which dissipation may create significant (both
qualitative and quantitative) discrepancies between the conventional scenario
and the dissipative one. We also discuss several mechanisms of generating
curvature perturbations in which the dissipative field, which is distinguished
from the inflaton field, can be used as the source of cosmological
perturbations. Considering the Morikawa-Sasaki dissipative coefficient, the
damping caused by the dissipation may be significant for many MSSM flat
directions even if the dissipation is far from thermal equilibrium.Comment: 22 pages, accepted for publication in International Journal of Modern
Physics
Computer-aided design of large-scale integrated circuits - A concept
Circuit design and mask development sequence are improved by using general purpose computer with interactive graphics capability establishing efficient two way communications link between design engineer and system. Interactive graphics capability places design engineer in direct control of circuit development
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