Gauge-Unfixed Hamiltonian Casimir and Static Torsionful Sector in the Katanaev-Volovich Model

Abstract

Hamiltonian analysis of the first-order Katanaev-Volovich model of two-dimensional gravity with torsion. The first-order action already singles out natural canonical pairs: the auxiliary Lorentz scalars are conjugate to the spatial connection and zweibein. An extended Dirac-Bergmann embedding isolates an auxiliary second-class sector whose elimination recovers the canonical structure encoded in the first-order action and leaves the first-class constraints generating the local gauge symmetries. An independent Faddeev-Jackiw reduction yields the same reduced brackets. The Katanaev/Poisson-Sigma Casimir is then recovered, up to normalization, directly from the reduced Dirac-Bergmann first-class constraint ideal, before imposing any gauge condition. This identifies the Casimir as a global label of the reduced canonical sectors; after the static normalization is chosen, it supplies the Hamiltonian parameter of the torsionful branch. The same normalization is applied to that branch in dilaton gauge, whose field equations are verified on shell. In this static sector the Casimir-normalized radial field does not coincide with the metric Killing norm: the diagonal representative satisfies \(NB=e^{4βr}\). Consequently, torsion modifies the Killing temperature through the normalization of the Killing time, while the horizon entropy retains its standard two-dimensional dilaton value and the Casimir-normalized first law holds.