2,723 research outputs found
Some Observations on Non-covariant Gauges and the epsilon-term
We consider the Lagrangian path-integrals in Minkowski space for gauges with
a residual gauge-invariance. From rather elementary considerations, we
demonstrate the necessity of inclusion of an epsilon-term (even) in the formal
treatments, without which one may reach incorrect conclusions. We show,
further, that the epsilon-term can contribute to the BRST WT-identities in a
nontrivial way (even as epsilon-->0). We also show that the (expectation value
of the) correct epsilon-term satisfies an algebraic condition. We show by
considering (a commonly used) example of a simple local quadratic epsilon
-term, that they lead to additional constraints on Green's function that are
not normally taken into account in the BRST formalism that ignores the
epsilon-term, and that they are characteristic of the way the singularities in
propagators are handled. We argue that for a subclass of these gauges, the
Minkowski path-integral could not be obtained by a Wick rotation from a
Euclidean path-integral.Comment: 12 pages, LaTeX2
A superspace formulation of an "asymptotic" OSp(3,1|2) invariance of Yang-Mills theories
We formulate a superspace field theory which is shown to be equivalent to the
symmetric BRS/Anti-BRS invariant Yang-Mills action. The theory uses
a 6-dimensional superspace and one OSp(3,1|2) vector multiplet of unconstrained
superfields. We establish a superspace WT identity and show that the
formulation has an asymptotic OSp(3,1|2) invariance as the gauge parameter goes
to infinity. We give a physical interpretation of this asymptotic OSp(3,1|2)
invariance as a symmetry transformation among the longitudinal/time like
degrees of freedom of and the ghost degrees of freedom.Comment: Latex, 20pages, No fig
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
Augmented Superfield Approach To Exact Nilpotent Symmetries For Matter Fields In Non-Abelian Theory
We derive the nilpotent (anti-)BRST symmetry transformations for the Dirac
(matter) fields of an interacting four (3+1)-dimensional 1-form non-Abelian
gauge theory by applying the theoretical arsenal of augmented superfield
formalism where (i) the horizontality condition, and (ii) the equality of a
gauge invariant quantity, on the six (4, 2)-dimensional supermanifold, are
exploited together. The above supermanifold is parameterized by four bosonic
spacetime coordinates x^\mu (with \mu = 0,1,2,3) and a couple of Grassmannian
variables \theta and \bar{\theta}. The on-shell nilpotent BRST symmetry
transformations for all the fields of the theory are derived by considering the
chiral superfields on the five (4, 1)-dimensional super sub-manifold and the
off-shell nilpotent symmetry transformations emerge from the consideration of
the general superfields on the full six (4, 2)-dimensional supermanifold.
Geometrical interpretations for all the above nilpotent symmetry
transformations are also discussed in the framework of augmented superfield
formalism.Comment: LaTeX file, 19 pages, journal-versio
Relating the generating functionals in field/antifield formulation through finite field dependent BRST transformation
We study the field/antifield formulation of pure Yang Mills theory in the
framework of finite field dependent BRST transformation. We show that the
generating functionals corresponding to different solutions of quantum master
equation are connected through the finite field dependent BRST transformations.
We establish this result with the help of several explicit examples.Comment: Revtex4, 18 pages, No figs, Accepted in Eur. Phys. J
Relating Green's Functions in Axial and Lorentz Gauges using Finite Field-Dependent BRS Transformations
We use finite field-dependent BRS transformations (FFBRS) to connect the
Green functions in a set of two otherwise unrelated gauge choices. We choose
the Lorentz and the axial gauges as examples. We show how the Green functions
in axial gauge can be written as a series in terms of those in Lorentz gauges.
Our method also applies to operator Green's functions. We show that this
process involves another set of related FFBRS transfomations that is derivable
from infinitesimal FBRS. We suggest possible applications.Comment: 20 pages, LaTex, Section 4 expanded, typos corrected; last 2
references modified; (this) revised version to appear in J. Math. Phy
Possible Detection of Causality Violation in a Non-local Scalar Model
We consider the possibility that there may be causality violation detectable
at higher energies. We take a scalar nonlocal theory containing a mass scale
as a model example and make a preliminary study of how the causality
violation can be observed. We show how to formulate an observable whose
detection would signal causality violation. We study the range of energies
(relative to ) and couplings to which the observable can be used.Comment: Latex, 30 page
Can insurance reduce catastrophic out-of-pocket health expenditure?
In India, the out-of-pocket health expenditure by households accounts for around 70 percent of the total expenditure on health. Large out-of-pocket payments may reduce consumption expenditure on other goods and services and push households into poverty. Recently, health insurance has been considered as one of the possible instruments in reducing impoverishing effects of large out-of-pocket health expenditure. In India, health insurance has limited coverage and the present paper studies whether it has been effective so far. Literature defines out-of-pocket health expenditure as catastrophic if its share in the household budget is more than some arbitrary threshold level. In the present paper, we argue that for households below poverty line any expenditure on health is catastrophic as they are unable to attain the subsistence level of consumption. Thus, we take zero percent as a threshold level to define catastrophic health expenditure and examine the impact of health insurance on probability of incurring catastrophic health expenditure.Out-of-pocket health expenditure, Catastrophic health expenditure, Health insurance
A superspace formulation of Abelian antisymmetric tensor gauge theory
We apply a superspace formulation to the four-dimensional gauge theory of a
massless Abelian antisymmetric tensor field of rank 2. The theory is formulated
in a six-dimensional superspace using rank-2 tensor, vector and scalar
superfields and their associated supersources. It is shown that BRS
transformation rules of fields are realized as Euler-Lagrange equations without
assuming the so-called horizontality condition and that a generating functional
constracted in the superspace reduces to that for the ordinary gauge
theory of Abelian rank-2 antisymmetric tensor field. The WT identity for this
theory is derived by making use of the superspace formulation and is expressed
in a neat and compact form .Comment: Latex, 19pages, No fig
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