# SEMINAR

The antifield formalism and BRST Cohomology
*Dr. Filipe Freire*
(**Universiteit Leiden**)

**Sala P7, IST, Edifício Pós-Graduação**

**Tuesday, October 19th, 2004 at 04:00 PM**

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**Abstract**
`
Following a brief introduction to the quantisation of constrained systems in the Hamiltonian formalism, we move
to a Lagrangean language suitable to a path integral representation and present a construction of the Batalin-Vilkovisky antifield formalism and show how BRST cohomology emerges naturally from this formalism. We show how the identification of observables, anomalies and counter-terms can be gathered into a cohomology problem.
Several applications of the formalism are discussed in the lectures or presented in problem sheets. In particular, we explain the method of consistent deformations of gauge invariant actions and the distinction between gauge independent and gauge fixed BRST cohomology. We aim at ending with an outlook to topical applications in topological field theories and string theory.`

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