1,551 research outputs found
BRST theory without Hamiltonian and Lagrangian
We consider a generic gauge system, whose physical degrees of freedom are
obtained by restriction on a constraint surface followed by factorization with
respect to the action of gauge transformations; in so doing, no Hamiltonian
structure or action principle is supposed to exist. For such a generic gauge
system we construct a consistent BRST formulation, which includes the
conventional BV Lagrangian and BFV Hamiltonian schemes as particular cases. If
the original manifold carries a weak Poisson structure (a bivector field giving
rise to a Poisson bracket on the space of physical observables) the generic
gauge system is shown to admit deformation quantization by means of the
Kontsevich formality theorem. A sigma-model interpretation of this quantization
algorithm is briefly discussed.Comment: 19 pages, minor correction
Consistent interactions and involution
Starting from the concept of involution of field equations, a universal
method is proposed for constructing consistent interactions between the fields.
The method equally well applies to the Lagrangian and non-Lagrangian equations
and it is explicitly covariant. No auxiliary fields are introduced. The
equations may have (or have no) gauge symmetry and/or second class constraints
in Hamiltonian formalism, providing the theory admits a Hamiltonian
description. In every case the method identifies all the consistent
interactions.Comment: Minor misprints corrected, to appear in JHE
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