共查询到20条相似文献,搜索用时 31 毫秒
1.
Marc Henneaux Bernard Knaepen Christiane Schomblond 《Communications in Mathematical Physics》1997,186(1):137-165
The characteristic cohomologyH
k
char(d) for an arbitrary set of freep-form gauge fields is explicitly worked out in all form degreesk < n — 1, wheren is the spacetime dimension. It is shown that this cohomology is finite-dimensional and completely generated by the forms
dual to the field strengths. The gauge invariant characteristic cohomology is also computed. The results are extended to interactingp-form gauge theories with gauge invariant interactions. Implications for the BRST cohomology are mentioned. 相似文献
2.
3.
Sunil Mukhi 《Pramana》2000,54(4):543-559
In addition to being a prime candidate for a fundamental unified theory of all interactions in nature, string theory provides
a natural setting to understand gauge field theories. This is linked to the concept of ‘D-branes’: extended, solitonic excitations of string theory which can be studied using techniques of string theory and which
support gauge fields localized along their world-volumes. It follows that the techniques of string theory can be very useful
even for those particle physicists who are not specifically interested in unification and/or quantum gravity. In this talk
I attempt to review how strings help us to understand fields. The discussion is restricted to 3+1 spacetime dimensions. 相似文献
4.
R. Cartas-Fuentevilla A. Escalante-Hernandez J. A. Lopez-Osio J. M. Solano-Altamirano J. F. Tlapanco-Limon J. Berra-Montiel P. Enriquez-Silverio 《General Relativity and Gravitation》2011,43(5):1365-1390
We prove that some basic aspects of gravity commonly attributed to the modern connection-based approaches, can be reached
naturally within the usual Riemannian geometry-based approach, by assuming the independence between the metric and the connection
of the background manifold. These aspects are: 1) the BF-like field theory structure of the Einstein–Hilbert action, of the
cosmological term, and of the corresponding equations of motion; 2) the formulation of Maxwellian field theories using only
the Riemannian connection and its corresponding curvature tensor, and the subsequent unification of gravity and gauge interactions
in a four dimensional field theory; 3) the construction of four and three dimensional geometrical invariants in terms of the
Riemann tensor and its traces, particularly the formulation of an anomalous Chern–Simons topological model where the action of diffeomorphisms is identified with the action of a gauge symmetry, close
to Witten’s formulation of three-dimensional gravity as a Chern–Simon gauge theory. 4) Tordions as propagating and non-propagating fields are also formulated in this approach. This new formulation collapses to the usual
one when the metric connection is invoked, and certain geometrical structures very known in the traditional literature can
be identified as remanent structures in this collapse. 相似文献
5.
A. H. Khater D. K. Callebaut S. M. Sayed 《International Journal of Theoretical Physics》2006,45(6):1021-1028
In this paper, we found a new representation for self-duality . In addition, exact solution class of the classical SU(2) Yang–Mills field in four-dimensional Euclidean space and two exact solution classes for SU(2) Yang–Mills when ρ is a complex analytic function are also obtained.
PACS numbers: 11.15.-q Gauge field theories, 11.15.Kc Semiclassical theories in gauge fields, 12.10.-g, 12.15.-y Yang–Mills fields 相似文献
6.
Christian Fleischhack 《Communications in Mathematical Physics》2003,234(3):423-454
The bundle structure of the space of Ashtekar's generalized connections is investigated in the compact case. It is proven that every stratum is a locally trivial
fibre bundle. The only stratum being a principal fibre bundle is the generic stratum. Its structure group equals the space
of all generalized gauge transforms modulo the constant center-valued gauge transforms. For abelian gauge theories the generic
stratum is globally trivial and equals the total space . However, for a certain class of non-abelian gauge theories – e.g., all SU(N) theories – the generic stratum is nontrivial. This means, there are no global gauge fixings – the so-called Gribov problem.
Nevertheless, for many physical measures there is a covering of the generic stratum by trivializations each having total measure
1. Finally, possible physical consequences and the relation between fundamental modular domains and Gribov horizons are discussed.
Received: 4 March 2002 / Accepted: 20 August 2002 Published online: 30 January 2003
Communicated by H. Nicolai 相似文献
7.
Supergravity provides the effective field theories for string compactifications. The deformation of the maximal supergravities
by non-abelian gauge interactions is only possible for a restricted class of charges. Generically these ‘gaugings’ involve
a hierarchy of p-form fields which belong to specific representations of the duality group. The group-theoretical structure of this p-form hierarchy exhibits many interesting features. In the case of maximal supergravity the class of allowed deformations
has intriguing connections with M/string theory.
This study is based on a talk presented at Quantum gravity: challenges and perspectives, Heraeus Seminar, Bad Honnef, 14–16
April 2008. 相似文献
8.
Ali H. Chamseddine 《Communications in Mathematical Physics》2001,218(2):283-292
The presence of a constant background antisymmetric tensor for open strings or D-branes forces the space-time coordinates
to be noncommutative. This effect is equivalent to replacing ordinary products in the effective theory by the deformed star
product. An immediate consequence of this is that all fields get complexified. The only possible noncommutative Yang–Mills
theory is the one with U(N) gauge symmetry. By applying this idea to gravity one discovers that the metric becomes complex. We show in this article
that this procedure is completely consistent and one can obtain complexified gravity by gauging the symmetry U(1,D−1) instead of the usual SO(1,D−1). The final theory depends on a Hermitian tensor containing both the symmetric metric and antisymmetric tensor. In contrast
to other theories of nonsymmetric gravity the action is both unique and gauge invariant. The results are then generalized
to noncommutative spaces.
Received: 1 June 2000 / Accepted: 27 November 2000 相似文献
9.
We consider the relation between higher spin gauge fields and real Kac–Moody Lie algebras. These algebras are obtained by double and triple extensions of real forms \mathfrakg0{\mathfrak{g}_0} of the finite-dimensional simple algebras \mathfrakg{\mathfrak{g}} arising in dimensional reductions of gravity and supergravity theories. Besides providing an exhaustive list of all such algebras, together with their associated involutions and restricted root diagrams, we are able to prove general properties of their spectrum of generators with respect to a decomposition of the triple extension of \mathfrakg0{\mathfrak{g}_0} under its gravity subalgebra \mathfrakgl(D,\mathbb R){\mathfrak{gl}(D,\mathbb {R})} . These results are then combined with known consistent models of higher spin gauge theory to prove that all but finitely many generators correspond to non-propagating fields and there are no higher spin fields contained in the Kac–Moody algebra. 相似文献
10.
General field theories are considered, within the functional differential formalism of quantum field theory, with interaction Lagrangian densities L
I
(x;λ), with λ a generic coupling constant, such that the following expression ∂
L
I
(x;λ)/∂
λ may be expressed as quadratic functions in dependent fields but may, in general, be arbitrary functions of independent fields. These necessarily include, as special cases, present renormalizable gauge theories. It is shown, in a unified manner,
that the vacuum-to-vacuum transition amplitude (the generating functional) may be explicitly derived in functional differential
form which, in general, leads to modifications to computational rules by including such factors as Faddeev–Popov ones and
modifications thereof which are explicitly obtained. The derivation is given in the presence of external sources and does not rely on any symmetry and invariance arguments as is often done in gauge theories and no
appeal is made to path integrals. 相似文献
11.
Shahar Hod 《General Relativity and Gravitation》2009,41(10):2295-2299
The anti-de Sitter/conformal field theory (AdS/CFT) correspondence implies that small perturbations of a black hole correspond
to small deviations from thermodynamic equilibrium in a dual field theory. For gauge theories with an Einstein gravity dual,
the AdS/CFT correspondence predicts a universal value for the ratio of the shear viscosity to the entropy density, η/s = 1/4π. It was conjectured recently that all fluids conform to the lower bound η/s ≥ 1/4π. This conjectured bound has been the focus of much recent attention. However, despite the flurry of research in this field we still lack a
proof for the general validity of the bound. In this essay we show that this mysterious bound is actually a direct outcome
of the interplay between gravity, quantum theory, and thermodynamics. 相似文献
12.
Ben Heidenreich Matthew Reece Tom Rudelius 《The European Physical Journal C - Particles and Fields》2018,78(4):337
We study ultraviolet cutoffs associated with the Weak Gravity Conjecture (WGC) and Sublattice Weak Gravity Conjecture (sLWGC). There is a magnetic WGC cutoff at the energy scale \(e G_N^{-1/2}\) with an associated sLWGC tower of charged particles. A more fundamental cutoff is the scale at which gravity becomes strong and field theory breaks down entirely. By clarifying the nature of the sLWGC for nonabelian gauge groups we derive a parametric upper bound on this strong gravity scale for arbitrary gauge theories. Intriguingly, we show that in theories approximately saturating the sLWGC, the scales at which loop corrections from the tower of charged particles to the gauge boson and graviton propagators become important are parametrically identical. This suggests a picture in which gauge fields emerge from the quantum gravity scale by integrating out a tower of charged matter fields. We derive a converse statement: if a gauge theory becomes strongly coupled at or below the quantum gravity scale, the WGC follows. We sketch some phenomenological consequences of the UV cutoffs we derive. 相似文献
13.
D.V. Vassilevich R. Fresneda D.M. Gitman 《The European Physical Journal C - Particles and Fields》2006,47(1):235-240
We start with a non-commutative version of the Jackiw–Teitelboim gravity in two dimensions which has a linear potential for
the dilaton fields. We study whether it is possible to deform this model by adding quadratic terms to the potential but preserving
the number of gauge symmetries. We find that no such deformation exists (provided one does not twist the gauge symmetries). 相似文献
14.
Giorgio Papini 《General Relativity and Gravitation》2008,40(6):1117-1144
External gravitational fields induce phase factors in the wave functions of particles. The phases are exact to first order
in the background gravitational field, are manifestly covariant and gauge invariant and provide a useful tool for the study
of spin–gravity coupling and of the optics of particles in gravitational or inertial fields. We discuss the role that spin–gravity
coupling plays in particular problems. 相似文献
15.
We analyze locally anisotropic configurations modeled by anholonomic frames with associated nonlinear connections in general relativity, affine–Poincarè and/or de Sitter gauge gravity and Kaluza–Klein theories. A suitable geometrical formalism for theories with higher order anisotropies and non compactified extra dimensions is introduced. We give a mostly self–containing review of some aspects of gauge models of gravity and discuss their anholonomic generalizations and the conditions of equivalence with the Einstein gravity in arbitrary dimensions. New classes of cosmological solutions describing Friedmann–Robertson–Walker like universes with resolution ellipsoid or torus symmetry. 相似文献
16.
R.P. Malik 《The European Physical Journal C - Particles and Fields》2007,51(1):169-177
We provide an alternative to the gauge covariant horizontality condition, which is responsible for the derivation of the nilpotent (anti-) BRST symmetry transformations for
the gauge and (anti-) ghost fields of a (3+1)-dimensional (4D) interacting 1-form non-Abelian gauge theory in the framework
of the usual superfield approach to the Becchi–Rouet–Stora–Tyutin (BRST) formalism. The above covariant horizontality condition
is replaced by a gauge invariant restriction on the (4,2)-dimensional supermanifold, parameterised by a set of four spacetime coordinates, xμ(μ=0,1,2,3), and a pair of Grassmannian variables, θ and θ̄. The latter condition enables us to derive the nilpotent (anti-)
BRST symmetry transformations for all the fields of an interacting 1-form 4D non-Abelian gauge theory in which there is an explicit coupling between the gauge
field and the Dirac fields. The key differences and the striking similarities between the above two conditions are pointed
out clearly.
PACS 11.15.-q; 12.20.-m; 03.70.+k 相似文献
17.
We investigate the dual superconductor hypothesis in finite-temperature SU(2) lattice gluodynamics in the spatial maximal Abelian gauge. This gauge is more physical than the ordinary maximal Abelian gauge due to absence of nonlocalities
in the temporal direction. We show numerically that in the spatial maximal Abelian gauge the probability distribution of the
Abelian monopole field is consistent with the dual superconductor mechanism of confinement: the Abelian condensate vanishes
in the deconfinement phase and is nonzero in the confinement phase.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 3, 166–170 (10 February 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
18.
R.P. Malik 《The European Physical Journal C - Particles and Fields》2006,48(3):825-834
The derivation of the exact and unique nilpotent Becchi–Rouet–Stora–Tyutin (BRST) and anti-BRST symmetries for the matter
fields, present in any arbitrary interacting gauge theory, has been a long-standing problem in the framework of the superfield
approach to the BRST formalism. These nilpotent symmetry transformations are deduced for the four (3+1)-dimensional (4D) complex
scalar fields, coupled to the U(1) gauge field, in the framework of an augmented superfield formalism. This interacting gauge
theory (i.e. QED) is considered on a six (4,2)-dimensional supermanifold parametrized by four even spacetime coordinates and a couple of odd elements of the Grassmann algebra. In addition to the horizontality condition (that is responsible for the derivation of
the exact nilpotent symmetries for the gauge field and the (anti-)ghost fields), a new restriction on the supermanifold, owing
its origin to the (super) covariant derivatives, has been invoked for the derivation of the exact nilpotent symmetry transformations
for the matter fields. The geometrical interpretations for all the above nilpotent symmetries are discussed, too.
PACS 11.15.-q, 12.20.-m, 03.70.+k 相似文献
19.
The nonlocal interaction between electrons and electromagnetic fields is considered. It is shown that different contraction
forms of interacting fields are equivalent to different nonlocal theories where nonlocality is connected to either the photon
field or the electron field, or to both these fields simultaneously. The nonlocal theory where the electron carries nonlocality
is studied in detail. The gauge invariance of this model is achieved by using thed-operation applying the perturbation theory. Primitive Feynman diagrams of the nonlocal theory are investigated and a restriction
on the “size”l of the electron is obtained. From low-energy experimental data from tests of local quantum electrodynamics it follows thatl≦10−15 cm. 相似文献
20.
Diego Julio Cirilo-Lombardo 《International Journal of Theoretical Physics》2011,50(6):1699-1708
The space-time structure of the new Unified Field Theory presented in previous reference (Int. J. Theor. Phys. 49:1288–1301,
2010) is analyzed from its SL(2C) underlying structure in order to make precise the notion of minimal coupling. To this end, the
framework is the language of tensors and particularly differential forms and the condition a priory of the existence of a
potential for the torsion is relaxed. We shown trough exact cosmological solutions from this model, where the geometry is
Euclidean R⊗O
3∼R⊗SU(2), the relation between the space-time geometry and the structure of the gauge group. Precisely this relation is directly
connected with the relation of the spin and torsion fields. The solution of this model is explicitly compared with our previous
ones and we find that: (i) the torsion is not identified directly with the Yang Mills type strength field, (ii) there exists
a compatibility condition connected with the identification of the gauge group with the geometric structure of the space-time:
this fact lead the identification between derivatives of the scale factor a(τ) with the components of the torsion in order to allows the Hosoya-Ogura ansatz (namely, the alignment of the isospin with
the frame geometry of the space-time), (iii) this compatibility condition precisely mark the fact that local gauge covariance,
coordinate independence and arbitrary space time geometries are harmonious concepts and (iv) of two possible structures of
the torsion the “tratorial” form (the only one studied here) forbids wormhole configurations, leading only, cosmological instanton
space-time in eternal expansion. 相似文献