1,550 research outputs found
Gauge Consistent Wilson Renormalization Group II: Non-Abelian Case
We give a wilsonian formulation of non-abelian gauge theories explicitly
consistent with axial gauge Ward identitities. The issues of unitarity and
dependence on the quantization direction are carefully investigated. A
wilsonian computation of the one-loop QCD beta function is performed.Comment: 34 pages, 1 eps figure, latex2e. Minor changes, version to appear in
Int. J. Mod. Phy
Renormalizing a BRST-invariant composite operator of mass dimension 2 in Yang-Mills theory
We discuss the renormalization of a BRST and anti-BRST invariant composite
operator of mass dimension 2 in Yang-Mills theory with the general BRST and
anti-BRST invariant gauge fixing term of the Lorentz type. The interest of this
study stems from a recent claim that the non-vanishing vacuum condensate of the
composite operator in question can be an origin of mass gap and quark
confinement in any manifestly covariant gauge, as proposed by one of the
authors. First, we obtain the renormalization group flow of the Yang-Mills
theory. Next, we show the multiplicative renormalizability of the composite
operator and that the BRST and anti-BRST invariance of the bare composite
operator is preserved under the renormalization. Third, we perform the operator
product expansion of the gluon and ghost propagators and obtain the Wilson
coefficient corresponding to the vacuum condensate of mass dimension 2.
Finally, we discuss the connection of this work with the previous works and
argue the physical implications of the obtained results.Comment: 49 pages, 35 eps-files, A number of typographic errors are corrected.
A paragraph is added in the beginning of section 5.3. Two equations (7.1) and
(7.2) are added. A version to be published in Phys. Rev.
Reducible Gauge Algebra of BRST-Invariant Constraints
We show that it is possible to formulate the most general first-class gauge
algebra of the operator formalism by only using BRST-invariant constraints. In
particular, we extend a previous construction for irreducible gauge algebras to
the reducible case. The gauge algebra induces two nilpotent, Grassmann-odd,
mutually anticommuting BRST operators that bear structural similarities with
BRST/anti-BRST theories but with shifted ghost number assignments. In both
cases we show how the extended BRST algebra can be encoded into an operator
master equation. A unitarizing Hamiltonian that respects the two BRST
symmetries is constructed with the help of a gauge-fixing Boson. Abelian
reducible theories are shown explicitly in full detail, while non-Abelian
theories are worked out for the lowest reducibility stages and ghost momentum
ranks.Comment: 42 pages, LaTeX. v2: New material added to Sec. 3.9-3.10, Sec. 6 and
App. E. v3: Version published in Nuclear Physics B. v4: Grant number adde
Thermal Bogoliubov transformation in nuclear structure theory
Thermal Bogoliubov transformation is an essential ingredient of the thermo
field dynamics -- the real time formalism in quantum field and many-body
theories at finite temperatures developed by H. Umezawa and coworkers. The
approach to study properties of hot nuclei which is based on the extension of
the well-known Quasiparticle-Phonon Model to finite temperatures employing the
TFD formalism is presented. A distinctive feature of the QPM-TFD combination is
a possibility to go beyond the standard approximations like the thermal
Hartree-Fock or the thermal RPA ones.Comment: 8 pages, Proceedings of the International Bogolyubov Conference
"Problems of Theoretical and Mathematical Physics", August 23 -- 27, 2009,
Dubna, Russi
On ghost condensation, mass generation and Abelian dominance in the Maximal Abelian Gauge
Recent work claimed that the off-diagonal gluons (and ghosts) in pure
Yang-Mills theories, with Maximal Abelian gauge fixing (MAG), attain a
dynamical mass through an off-diagonal ghost condensate. This condensation
takes place due to a quartic ghost interaction, unavoidably present in MAG for
renormalizability purposes. The off-diagonal mass can be seen as evidence for
Abelian dominance. We discuss why ghost condensation of the type discussed in
those works cannot be the reason for the off-diagonal mass and Abelian
dominance, since it results in a tachyonic mass. We also point out what the
full mechanism behind the generation of a real mass might look like.Comment: 7 pages; uses revtex
Nonequilibrium Steady States and Fano-Kondo Resonances in an AB Ring with a Quantum Dot
Electron transport through a strongly correlated quantum dot (QD) embedded in
an Aharonov-Bohm (AB) ring is investigated with the aid of the finite-U
slave-boson mean-field (SBMF) approach extended to nonequilibrium regime. A
nonequilibrium steady state (NESS) of the mean-field Hamiltonian is constructed
with the aid of the C*-algebraic approach for studying infinitely extended
systems. In the linear response regime, the Fano-Kondo resonances and AB
oscillations of the conductance obtained from the SBMF approach are in good
agreement with those from the numerical renormalization group technique (NRG)
by Hofstetter et al. by using twice larger Coulomb interaction. At zero
temperature and finite bias voltage, the resonance peaks of the differential
conductance tend to split into two. At low bias voltage, the split of the
asymmetric resonance can be observed as an increase of the conductance plateau.
We also found that the differential conductance has zero-bias maximum or
minimum depending on the background transmission via direct tunneling between
the electrodes.Comment: 24 pages,17 figure
THERMAL EFFECTS ON THE CATALYSIS BY A MAGNETIC FIELD
We show that the formation of condensates in the presence of a constant
magnetic field in 2+1 dimensions is extremely unstable. It disappears as soon
as a heat bath is introduced with or without a chemical potential. We point out
some new nonanalytic behavior that develops in this system at finite
temperature.Comment: 10 pages, plain Te
The Northern Eurasia Earth Science Partnership: An Example of Science Applied to Societal Needs
Northern Eurasia, the largest landmass in the northern extratropics, accounts for ~20% of the global land area. However, little is known about how the biogeochemical cycles, energy and water cycles, and human activities specific to this carbon-rich, cold region interact with global climate. A major concern is that changes in the distribution of land-based life, as well as its interactions with the environment, may lead to a self-reinforcing cycle of accelerated regional and global warming. With this as its motivation, the Northern Eurasian Earth Science Partnership Initiative (NEESPI) was formed in 2004 to better understand and quantify feedbacks between northern Eurasian and global climates. The first group of NEESPI projects has mostly focused on assembling regional databases, organizing improved environmental monitoring of the region, and studying individual environmental processes. That was a starting point to addressing emerging challenges in the region related to rapidly and simultaneously changing climate, environmental, and societal systems. More recently, the NEESPI research focus has been moving toward integrative studies, including the development of modeling capabilities to project the future state of climate, environment, and societies in the NEESPI domain. This effort will require a high level of integration of observation programs, process studies, and modeling across disciplines
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