Conserved current for the Cotton tensor, black hole entropy and equivariant Pontryagin forms

Roberto Ferreiro Pérez (1)

1 Departamento de Economa Financiera y Contabilidad I Facultad de Ciencias Económicas y Empresariales

The Chern-Simons lagrangian density in the space of metrics of a 3-dimensional manifold M is not invariant under the action of diffeomorphisms on M. However, its Euler-Lagrange operator can be identified with the Cotton tensor, which is invariant under diffeomorphims. As the lagrangian is not invariant, Noether Theorem cannot be applied to obtain conserved currents. We show that it is possible to obtain an equivariant conserved current for the Cotton tensor by using the first equivariant Pontryagin form on the bundle of metrics. Finally we define a hamiltonian current which gives the contribution of the Chern-Simons term to the black hole entropy, energy and angular momentum.

Mots clés: Chern-Simons Lagrangian; Cotton tensor; conserved current; equivariant Pontryagin form; black hole entropy 2

Roberto Ferreiro Pérez. Conserved current for the Cotton tensor, black hole entropy and equivariant Pontryagin forms. Classical and Quantum Gravity, 2010, 27 (13), pp.135015. ⟨10.1088/0264-9381/27/13/135015⟩. ⟨hal-00606653⟩