257,646 research outputs found
On the Algebra of Ghost Fields
We study in detail the algebra of free ghost fields which we realize in a
Hilbert-Fock space with positive metric. The investigation of causality
clarifies the exact reason for the failure of the spin-statistics theorem and
leads to the introduction of the Krein Operator. We study the charge algebra of
the ghost fields which gives a representation of . The
symmetries of the -matrix in ghost space are pointed out.Comment: Plain TeX, 16 page
Ghost D-branes
We define a ghost D-brane in superstring theories as an object that cancels
the effects of an ordinary D-brane. The supergroups U(N|M) and OSp(N|M) arise
as gauge symmetries in the supersymmetric world-volume theory of D-branes and
ghost D-branes. A system with a pair of D-brane and ghost D-brane located at
the same location is physically equivalent to the closed string vacuum. When
they are separated, the system becomes a new brane configuration. We generalize
the type I/heterotic duality by including n ghost D9-branes on the type I side
and by considering the heterotic string whose gauge group is OSp(32+2n|2n).
Motivated by the type IIB S-duality applied to D9- and ghost D9-branes, we also
find type II-like closed superstrings with U(n|n) gauge symmetry.Comment: 49 pages, 6 figures, harvmac. v2: references and acknowledgements
adde
Statefinder diagnosis and the interacting ghost model of dark energy
A new model of dark energy namely "ghost dark energy model" has recently been
suggested to interpret the positive acceleration of cosmic expansion. The
energy density of ghost dark energy is proportional to the hubble parameter. In
this paper we perform the statefinder diagnostic tool for this model both in
flat and non-flat universe. We discuss the dependency of the evolutionary
trajectories in and planes on the interaction parameter between
dark matter and dark energy as well as the spatial curvature parameter of the
universe. Eventually, in the light of SNe+BAO+OHD+CMB observational data, we
plot the evolutionary trajectories in and planes for the best fit
values of the cosmological parameters and compare the interacting ghost model
with other dynamical dark energy models. We show that the evolutionary
trajectory of ghost dark energy in statefinder diagram is similar to
holographic dark energy model. It has been shown that the statefinder location
of CDM is in good agreement with observation and therefore the dark
energy models whose current statefinder values are far from the CDM
point can be ruled out.Comment: 23 pages, 6 figure
General massive gauge theory
The concept of perturbative gauge invariance formulated exclusively by means
of asymptotic fields is used to construct massive gauge theories. We consider
the interactions of massive and massless gauge fields together with
fermionic ghost and anti-ghost fields. First order gauge invariance
requires the introduction of unphysical scalars (Goldstone bosons) and fixes
their trilinear couplings. At second order additional physical scalars (Higgs
fields) are necessary, their coupling is further restricted at third order. In
case of one physical scalar all couplings are determined by gauge invariance,
including the Higgs potential. For three massive and one massless gauge field
the electroweak theory comes out as the unique solution.Comment: 20 pages, latex, no figure
Heritage destruction and videogames:a pervasive relation
This paper examines the history of the National and University Library in Sarajevo, and particularly the destruction of the site and how it has been represented with different meanings across various media. The second part of the paper will analyse the representation of the library (post-reconstruction) in the videogame Sniper: Ghost Warrior 2âs Act 2 (called âGhost of Sarajevoâ), in order to raise issues about the ethical representation of a heritage site that has not only been destroyed and reconstructed, but that it is part of a national heritage
Veneziano Ghost Versus Isospin Breaking
It is argued that an account for the Veneziano ghost pole, appearing in
resolving the U(1) problem, is necessary for understanding an isospin violation
in the system. By virtue of a perturbative expansion
around the ( ) symmetric Veneziano solution, we
find that the ghost considerably suppresses isospin breaking gluon and s-quark
matrix elements. We speculate further on a few cases where the proposed
mechanism can play an essential role. We discuss the isospin violation in
meson-nucleon couplings and its relevance to the problem of charge asymmetric
nuclear forces and possible breaking of the Bjorken sum rule. It is shown that
the ghost pole could yield the isospin violation of order 2 \% for the couplings and 20 \% for the
Bjorken sum rule.Comment: 16 pages , Preprint TAUP-2127-9
Schwinger-Dyson operator of Yang-Mills matrix models with ghosts and derivations of the graded shuffle algebra
We consider large-N multi-matrix models whose action closely mimics that of
Yang-Mills theory, including gauge-fixing and ghost terms. We show that the
factorized Schwinger-Dyson loop equations, expressed in terms of the generating
series of gluon and ghost correlations G(xi), are quadratic equations S^i G = G
xi^i G in concatenation of correlations. The Schwinger-Dyson operator S^i is
built from the left annihilation operator, which does not satisfy the Leibnitz
rule with respect to concatenation. So the loop equations are not differential
equations. We show that left annihilation is a derivation of the graded shuffle
product of gluon and ghost correlations. The shuffle product is the point-wise
product of Wilson loops, expressed in terms of correlations. So in the limit
where concatenation is approximated by shuffle products, the loop equations
become differential equations. Remarkably, the Schwinger-Dyson operator as a
whole is also a derivation of the graded shuffle product. This allows us to
turn the loop equations into linear equations for the shuffle reciprocal, which
might serve as a starting point for an approximation scheme.Comment: 13 pages, added discussion & references, title changed, minor
corrections, published versio
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