5,936 research outputs found
Absence of Nonlocal Counter-terms in the Gauge Boson Propagator in Axial -type Gauges
We study the two-point function for the gauge boson in the axial-type gauges.
We use the exact treatment of the axial gauges recently proposed that is
intrinsically compatible with the Lorentz type gauges in the path-integral
formulation and has been arrived at from this connection and which is a
``one-vector'' treatment. We find that in this treatment, we can evaluate the
two-point functions without imposing any additional interpretation on the axial
gauge 1/(n.q)^p-type poles. The calculations are as easy as the other
treatments based on other known prescriptions. Unlike the
``uniform-prescription'' /L-M prescription, we note, here, the absence of any
non-local divergences in the 2-point proper vertex. We correlate our
calculation with that for the Cauchy Principal Value prescription and find from
this comparison that the 2-point proper vertex differs from the CPV calculation
only by finite terms. For simplicity of treatment, the divergences have been
calculated here with n^2>0 and these have a smooth light cone limit.Comment: 17 pages; 3 figures drawn using feyn.st
Gluon Condensates, Chiral Symmetry Breaking and Pion Wave Function
We consider here chiral symmetry breaking in quantum chromodynamics arising
from gluon condensates in vacuum. Through coherent states of gluons simulating
a mean field type of approximation, we show that the off-shell gluon
condensates of vacuum generate a mass-like contribution for the quarks, giving
rise to chiral symmetry breaking. We next note that spontaneous breaking of
global chiral symmetry links the four component quark field operator to the
pion wave function. This in turn yields many hadronic properties in the light
quark sector in agreement with experiments, leading to the conclusion that low
energy hadron properties are primarily driven by the vacuum structure of
quantum chromodynamics.Comment: 25 pages, IP/BBSR/92-76, revte
A Variational Approach to Bound States in Quantum Field Theory
We consider here in a toy model an approach to bound state problem in a
nonperturbative manner using equal time algebra for the interacting field
operators. Potential is replaced by offshell bosonic quanta inside the bound
state of nonrelativistic particles. The bosonic dressing is determined through
energy minimisation, and mass renormalisation is carried out in a
nonperturbative manner. Since the interaction is through a scalar field, it
does not include spin effects. The model however nicely incorporates an
intuitive picture of hadronic bound states in which the gluon fields dress the
quarks providing the binding between them and also simulate the gluonic content
of hadrons in deep inelastic collisions.Comment: latex, revtex, 22 page
SUSY Search in Future Collider and Dark Matter Experiments
The lightest superparticle in the MSSM is expected to be a Bino, Higgsino or
Wino. We consider the dark matter abundance constraint on these LSP scenarios
in the minimal SUGRA and AMSB models. We discuss the resulting collider signals
for the Bino LSP at LHC and the Higgsino and Wino LSP at CLIC. The Bino,
Higgsino and Wino LSP signals in dark matter experiments are also discussed
briefly. We conclude with a discussion of these LSP scenarios in nonminimal
SUSY models.Comment: 12 pages pdf file, To appear in Proc 2nd Intl Workshop on Theoretical
High Energy Physics, Roorkee, India, AIP Press (2007
Dust ion-acoustic shocks in quantum dusty pair-ion plasmas
The formation of dust ion-acoustic shocks (DIASs) in a four-component quantum
plasma whose constituents are electrons, both positive and negative ions and
immobile charged dust grains, is studied. The effects of both the dissipation
due to kinematic viscosity and the dispersion caused by the charge separation
as well as the quantum tunneling due to the Bohm potential are taken into
account. The propagation of small but finite amplitude dust ion-acoustic waves
(DIAWs) is governed by the Korteweg-de Vries-Burger (KdVB) equation which
exhibits both oscillatory and monotonic shocks depending not only on the
viscosity parameters, but also on the quantum parameter H (the ratio of the
electron plasmon to the electron Fermi energy) and the positive to negative ion
density ratio. Large amplitude stationary shocks are recovered for a Mach
number exceeding its critical value. Unlike the small amplitude shocks, quite a
smaller value of the viscosity parameter, H and the density ratio may lead to
the large amplitude monotonic shock strucutres. The results could be of
importance in astrophysical and laser produced plasmas.Comment: 15 pages, 5 figure
- …