261 research outputs found
Open-closed homotopy algebra in mathematical physics
In this paper we discuss various aspects of open-closed homotopy algebras
(OCHAs) presented in our previous paper, inspired by Zwiebach's open-closed
string field theory, but that first paper concentrated on the mathematical
aspects. Here we show how an OCHA is obtained by extracting the tree part of
Zwiebach's quantum open-closed string field theory. We clarify the explicit
relation of an OCHA with Kontsevich's deformation quantization and with the
B-models of homological mirror symmetry. An explicit form of the minimal model
for an OCHA is given as well as its relation to the perturbative expansion of
open-closed string field theory. We show that our open-closed homotopy algebra
gives us a general scheme for deformation of open string structures
(-algebras) by closed strings (-algebras).Comment: 38 pages, 4 figures; v2: published versio
Reducing Computational Costs in the Basic Perturbation Lemma
Homological Perturbation Theory [11, 13] is a well-known
general method for computing homology, but its main algorithm, the Basic
Perturbation Lemma, presents, in general, high computational costs.
In this paper, we propose a general strategy in order to reduce the complexity
in some important formulas (those following a specific pattern)
obtained by this algorithm. Then, we show two examples of application
of this methodology.
Batalin-Vilkovisky Integrals in Finite Dimensions
The Batalin-Vilkovisky method (BV) is the most powerful method to analyze
functional integrals with (infinite-dimensional) gauge symmetries presently
known. It has been invented to fix gauges associated with symmetries that do
not close off-shell. Homological Perturbation Theory is introduced and used to
develop the integration theory behind BV and to describe the BV quantization of
a Lagrangian system with symmetries. Localization (illustrated in terms of
Duistermaat-Heckman localization) as well as anomalous symmetries are discussed
in the framework of BV.Comment: 35 page
Irreducible Hamiltonian approach to the Freedman-Townsend model
The irreducible BRST symmetry for the Freedman-Townsend model is derived. The
comparison with the standard reducible approach is also addressed.Comment: 18 pages, LaTeX 2.0
Irreducible Hamiltonian BRST approach to topologically coupled abelian forms
An irreducible Hamiltonian BRST approach to topologically coupled p- and
(p+1)-forms is developed. The irreducible setting is enforced by means of
constructing an irreducible Hamiltonian first-class model that is equivalent
from the BRST point of view to the original redundant theory. The irreducible
path integral can be brought to a manifestly Lorentz covariant form.Comment: 29 pages, LaTeX 2.0
Irreducible Hamiltonian BRST symmetry for reducible first-class systems
An irreducible Hamiltonian BRST quantization method for reducible first-class
systems is proposed. The general theory is illustrated on a two-stage reducible
model, the link with the standard reducible BRST treatment being also
emphasized.Comment: Latex 2.09, 23 pages, to appear in Int. J. Mod. Phys.
A Note on "Irreducible" p-Form Gauge Theories with Stueckelberg Coupling
p-form gauge theories with Stueckelberg coupling are quantized in an
irreducible antifield-BRST way. As a consequence, neither the ghosts of ghosts
nor their antifields appear. Some irreducible gauge conditions are inferred
naturally within our formalism. In the end we briefly discuss the interacting
case.Comment: 10 pag, latex 2.09, no figure
Primary versus delayed repair for bile duct injuries sustained during cholecystectomy: results of a survey of the Association Francaise de Chirurgie
BACKGROUND: Bile duct injuries (BDIs) sustained during a cholecystectomy still remain a major surgical problem, and it is still not clear whether the injury should be repaired immediately or a delayed repair is preferred.
METHODS: A retrospective national French survey was conducted to compare the results of immediate (at time of cholecystectomy), early (within 45 days after a cholecystectomy) and late (beyond 45 days after a cholecystectomy) surgical repair for BDI sustained during a cholecystectomy.
RESULTS: Forty-seven surgical centres provided 640 cases of bile duct injury sustained during a cholecystectomy of which 543 were analysed for the purpose of the present study. The timing of repair was immediate in 194 cases (35.7%), early in 216 cases (39.8%) and late in 133 cases (24.5%). The type of repair was a suture repair in 157 cases (81%), and a bilio-digestive reconstruction in 37 cases (19%) for immediate repair; a suture repair in 119 cases (55.1%) and a bilio-digestive anastomosis in 96 cases (44.9%) for the early repair; and a bilio-digestive reconstruction in 129 cases (97%) and a suture repair in 4 cases (3%) for late repair. A second procedure was required in 110 cases (56.7%) for immediate repair, 80 cases (40.7%) for early repair (P < 0.05) and in 9 cases (6.8%) for late repair (P < 0.001).
CONCLUSION: The timing of surgical repair for a bile duct injury sustained during a cholecystectomy influences significantly the rate of a second procedure and a late repair should be preferred option
Irreducible antifield-BRST approach to reducible gauge theories
An irreducible antifield BRST quantization method for reducible gauge
theories is proposed. The general formalism is illustrated in the case of the
Freedman-Townsend model.Comment: 19 pages, LaTeX 2.0
Invariants from classical field theory
We introduce a method that generates invariant functions from perturbative
classical field theories depending on external parameters. Applying our methods
to several field theories such as abelian BF, Chern-Simons and 2-dimensional
Yang-Mills theory, we obtain, respectively, the linking number for embedded
submanifolds in compact varieties, the Gauss' and the second Milnor's invariant
for links in S^3, and invariants under area-preserving diffeomorphisms for
configurations of immersed planar curves.Comment: 20 pages, 1 figure, to appear in J. Math. Phy
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