POINCARÉ GAUGE THEORY WITH COUPLED EVEN AND ODD PARITY DYNAMIC SPIN-0 MODES: DYNAMICAL EQUATIONS FOR ISOTROPIC BIANCHI COSMOLOGIES

2011 ◽  
Vol 20 (11) ◽  
pp. 2125-2138 ◽  
Author(s):  
FEI-HUNG HO ◽  
JAMES M. NESTER
Keyword(s):  
Gauge Theory ◽  
Cross Coupling ◽  
Lagrange Equations ◽  
Dynamical Equations ◽  
First Order ◽  
Class A ◽  
Effective Lagrangian ◽  
Dynamic Spin ◽  
Bianchi Cosmologies ◽  
Gauge Theory Of Gravity

We are investigating the dynamics of a new Poincaré gauge theory of gravity model, which has cross coupling between the spin-0+ and spin-0- modes. To this end we here consider a very appropriate situation — homogeneous-isotropic cosmologies — which is relatively simple, and yet all the modes have nontrivial dynamics which reveals physically interesting and possibly observable results. More specifically we consider manifestly isotropic Bianchi class A cosmologies; for this case we find an effective Lagrangian and Hamiltonian for the dynamical system. The Lagrange equations for these models lead to a set of first-order equations that are compatible with those found for the FLRW models and provide a foundation for further investigations. Typical numerical evolution of these equations shows the expected effects of the cross parity coupling.

scholarly journals ON COSMOLOGICAL-TYPE SOLUTIONS IN MULTI-DIMENSIONAL MODEL WITH GAUSS–BONNET TERM

2010 ◽  
Vol 07 (05) ◽  
pp. 797-819 ◽  
Author(s):  
V. D. IVASHCHUK
Keyword(s):  
Exact Solutions ◽  
Power Law ◽  
Equations Of Motion ◽  
Exponential Dependence ◽  
Dimensional Model ◽  
Lagrange Equations ◽  
First Order ◽  
Scale Factors ◽  
Effective Lagrangian ◽  
Bonnet Term

A (n + 1)-dimensional Einstein–Gauss–Bonnet (EGB) model is considered. For diagonal cosmological-type metrics, the equations of motion are reduced to a set of Lagrange equations. The effective Lagrangian contains two "minisuperspace" metrics on ℝn. The first one is the well-known 2-metric of pseudo-Euclidean signature and the second one is the Finslerian 4-metric that is proportional to n-dimensional Berwald–Moor 4-metric. When a "synchronous-like" time gauge is considered, the equations of motion are reduced to an autonomous system of first-order differential equations. For the case of the "pure" Gauss–Bonnet model, two exact solutions with power-law and exponential dependence of scale factors (with respect to "synchronous-like" variable) are obtained. (In the cosmological case, the power-law solution was considered earlier in papers of N. Deruelle, A. Toporensky, P. Tretyakov and S. Pavluchenko.) A generalization of the effective Lagrangian to the Lowelock case is conjectured. This hypothesis implies existence of exact solutions with power-law and exponential dependence of scale factors for the "pure" Lowelock model of mth order.

PERTURBATIVE EXPANSION FOR THE t-J MODEL CONSTRUCTED FROM THE GENERATORS OF THE SUPERSYMMETRIC HUBBARD ALGEBRA

2009 ◽  
Vol 23 (14) ◽  
pp. 3159-3177
Author(s):  
CARLOS E. REPETTO ◽  
OSCAR P. ZANDRON
Keyword(s):  
Perturbative Expansion ◽  
Lagrangian Formalism ◽  
Graded Algebra ◽  
Integral Formalism ◽  
Generating Functional ◽  
First Order ◽  
Effective Lagrangian ◽  
Supersymmetric Version ◽  
Present Formalism ◽  
Ghost Field

By using the Hubbard [Formula: see text]-operators as field variables along with the supersymmetric version of the Faddeev–Jackiw symplectic formalism, a family of first-order constrained Lagrangians for the t-J model is found. In order to satisfy the Hubbard [Formula: see text]-operator commutation rules satisfying the graded algebra spl(2,1), the number and kind of constraints that must be included in a classical first-order Lagrangian formalism for this model are presented. The model is also analyzed via path-integral formalism, where the correlation-generating functional and the effective Lagrangian are constructed. In this context, the introduction of a proper ghost field is needed to render the model renormalizable. The perturbative Lagrangian formalism is developed and it is shown how propagators and vertices can be renormalized to each order. In particular, the renormalized ferromagnetic magnon propagator arising in the present formalism is discussed. As an example, the thermal softening of the magnon frequency is computed.

scholarly journals A CHERN–SIMONS E8 GAUGE THEORY OF GRAVITY IN D = 15, GRAND UNIFICATION AND GENERALIZED GRAVITY IN CLIFFORD SPACES

2007 ◽  
Vol 04 (08) ◽  
pp. 1239-1257 ◽  
Author(s):  
CARLOS CASTRO
Keyword(s):  
Gauge Theory ◽  
Grand Unification ◽  
De Sitter ◽  
Sitter Group ◽  
Yang Mills ◽  
Theory Of Gravity ◽  
M Theory ◽  
Chern Simons ◽  
Topological Part ◽  
Gauge Theory Of Gravity

A novel Chern–Simons E8 gauge theory of gravity in D = 15 based on an octicE8 invariant expression in D = 16 (recently constructed by Cederwall and Palmkvist) is developed. A grand unification model of gravity with the other forces is very plausible within the framework of a supersymmetric extension (to incorporate spacetime fermions) of this Chern–Simons E8 gauge theory. We review the construction showing why the ordinary 11D Chern–Simons gravity theory (based on the Anti de Sitter group) can be embedded into a Clifford-algebra valued gauge theory and that an E8 Yang–Mills field theory is a small sector of a Clifford (16) algebra gauge theory. An E8 gauge bundle formulation was instrumental in understanding the topological part of the 11-dim M-theory partition function. The nature of this 11-dim E8 gauge theory remains unknown. We hope that the Chern–Simons E8 gauge theory of gravity in D = 15 advanced in this work may shed some light into solving this problem after a dimensional reduction.

CAN TORSION BE TREATED AS JUST ANOTHER TENSOR FIELD?

2012 ◽  
Vol 07 ◽  
pp. 158-164 ◽  
Author(s):  
JAMES M. NESTER ◽  
CHIH-HUNG WANG
Keyword(s):  
Gauge Theory ◽  
Tensor Field ◽  
Affine Connection ◽  
Cartan Geometry ◽  
Civita Connection ◽  
Levi Civita Connection ◽  
Alternative Gravity Theories ◽  
Theory Of Gravity ◽  
Gauge Theory Of Gravity ◽  
Alternative Gravity

Many alternative gravity theories use an independent connection which leads to torsion in addition to curvature. Some have argued that there is no physical need to use such connections, that one can always use the Levi-Civita connection and just treat torsion as another tensor field. We explore this issue here in the context of the Poincaré Gauge theory of gravity, which is usually formulated in terms of an affine connection for a Riemann-Cartan geometry (torsion and curvature). We compare the equations obtained by taking as the independent dynamical variables: (i) the orthonormal coframe and the connection and (ii) the orthonormal coframe and the torsion (contortion), and we also consider the coupling to a source. From this analysis we conclude that, at least for this class of theories, torsion should not be considered as just another tensor field.

scholarly journals Cosmology from a new nonconservative gravity

2018 ◽  
Vol 27 (06) ◽  
pp. 1841006 ◽  
Author(s):  
Júlio C. Fabris ◽  
Hermano Velten ◽  
Thiago R. P. Caramês ◽  
Matheus J. Lazo ◽  
Gastão S. F. Frederico
Keyword(s):  
Fluid Model ◽  
Gravitational Theory ◽  
Dissipative Process ◽  
The Novel ◽  
Least Action Principle ◽  
Dynamical Equations ◽  
First Order ◽  
Least Action ◽  
Dissipative Effects ◽  
Cosmic Background

In this paper, we present a cosmological model arising from a nonconservative gravitational theory proposed in [M. J. Lazo, J. Paiva, J. T. S. Amaral and G. S. F. Frederico, Phys. Rev. D 95 (2017) 101501.] The novel feature where comparing with previous implementations of dissipative effects in gravity is the possible arising of such phenomena from a least action principle, so they are of a purely geometric nature. We derive the dynamical equations describing the behavior of the cosmic background, considering a single fluid model composed by pressureles matter, whereas the dark energy is conceived as an outcome of the “geometric” dissipative process emerging in the model. Besides, adopting the synchronous gauge, we obtain the first-order perturbative equations which shall describe the evolution of the matter perturbations within the linear regime.

scholarly journals Radiative corrections in 2 + 1 dimensional supergravity

2018 ◽  
Vol 96 (12) ◽  
pp. 1409-1412 ◽  
Author(s):  
D.G.C. McKeon
Keyword(s):  
Gauge Theory ◽  
Radiative Correction ◽  
Effective Action ◽  
Spin Connection ◽  
Dynamical Generation ◽  
Effective Lagrangian ◽  
Majorana Spinor ◽  
The One ◽  
Brst Invariance ◽  
Topological Mass

Supergravity in 2 + 1 dimensions has a set of first-class constraints that result in two bosonic and one fermionic gauge invariances. When one uses Faddeev–Popov quantization, these gauge invariances result in four fermionic scalar ghosts and two bosonic Majorana spinor ghosts. The BRST invariance of the effective Lagrangian is found. As an example of a radiative correction, we compute the phase of the one-loop effective action in the presence of a background spin connection, and show that it vanishes. This indicates that unlike a spinor coupled to a gauge field in 2 + 1 dimensions, there is no dynamical generation of a topological mass in this model. An additional example of how a BRST invariant effective action can arise in a gauge theory is provided in Appendix B where the BRST effective action for the classical Palatini action in 1 + 1 dimensions is examined.

scholarly journals Maxwell-affine gauge theory of gravity

2015 ◽  
Vol 751 ◽  
pp. 131-134 ◽  
Author(s):  
O. Cebecioğlu ◽  
S. Kibaroğlu
Keyword(s):  
Gauge Theory ◽  
Theory Of Gravity ◽  
Gauge Theory Of Gravity
Sign in / Sign up

Export Citation Format

Share Document