Holography and SL(2,ℝ) symmetry in 2D Rindler space–time

It is shown that it is possible to define quantum field theory of a massless scalar free field on the Killing horizon of a 2D Rindler space–time. Free quantum field theory on the horizon enjoys diffeomorphism invariance and turns out to be unitarily and algebraically equivalent to the analogous theory of a scalar field propagating inside Rindler space–time, no matter the value of the mass of the field in the bulk. More precisely, there exists a unitary transformation that realizes the bulk-boundary correspondence upon an appropriate choice for Fock representation spaces. Second, the found correspondence is a subcase of an analogous algebraic correspondence described by injective  * -homomorphisms of the abstract algebras of observables generated by abstract quantum free-field operators. These field operators are smeared with suitable test functions in the bulk and exact one-forms on the horizon. In this sense the correspondence is independent from the chosen vacua. It is proven that, under that correspondence, the “hidden” SL(2,ℝ) quantum symmetry found in a previous work gets a clear geometric meaning, it being associated with a group of diffeomorphisms of the horizon itself.