23 research outputs found
The Schwinger Mechanism in (Anti) de Sitter Spacetimes
We present a short and novel derivation of the Schwinger mechanism for
particle pair production in dimensional de Sitter and Anti de Sitter
spacetimes. We work directly in the flat embedding space and derive the pair
production rates in these spacetimes via instanton methods. The derivation is
manifestly coordinate independent, and also lends support to the possible deep
connection between two conceptually disparate quantum phenomena - Schwinger
effect and the Davies-Unruh effect.Comment: 9 pages. References added, typos corrected and expanded conclusio
Rindler-AdS/CFT
In anti-de Sitter space a highly accelerating observer perceives a Rindler
horizon. The two Rindler wedges in AdS_{d+1} are holographically dual to an
entangled conformal field theory that lives on two boundaries with geometry R x
H_{d-1}. For AdS_3, the holographic duality is especially tractable, allowing
quantum-gravitational aspects of Rindler horizons to be probed. We recover the
thermodynamics of Rindler-AdS space directly from the boundary conformal field
theory. We derive the temperature from the two-point function and obtain the
Rindler entropy density precisely, including numerical factors, using the Cardy
formula. We also probe the causal structure of the spacetime, and find from the
behavior of the one-point function that the CFT "knows" when a source has
fallen across the Rindler horizon. This is so even though, from the bulk point
of view, there are no local signifiers of the presence of the horizon. Finally,
we discuss an alternate foliation of Rindler-AdS which is dual to a CFT living
in de Sitter space.Comment: 29 Pages, 4 Figures, citations adde
Rotating Rindler-AdS Space
If the Hamiltonian of a quantum field theory is taken to be a timelike
isometry, the vacuum state remains empty for all time. We search for such
stationary vacua in anti-de Sitter space. By considering conjugacy classes of
the Lorentz group, we find interesting one-parameter families of stationary
vacua in three-dimensional anti-de Sitter space. In particular, there exists a
family of rotating Rindler vacua, labeled by the rotation parameter beta, which
are related to the usual Rindler vacuum by non-trivial Bogolubov
transformations. Rotating Rindler-AdS space possesses not only an
observer-dependent event horizon but even an observer-dependent ergosphere. We
also find rotating vacua in global AdS provided a certain region of spacetime
is excluded.Comment: 14 pages, LaTe
Time Evolution of Temperature Fluctuation in a Non-Equilibrated System
The evolution equation for inhomogeneous and anisotropic temperature
fluctuation inside a medium is derived within the ambit of Boltzmann Transport
Equation (BTE) for a hot gas of massless particles. Also, specializing to a
situation created after heavy-ion collision (HIC), we analyze the Fourier space
variation of temperature fluctuation of the medium using its temperature
profile. The effect of viscosity on the variation of fluctuations in the latter
case is investigated and possible implications for early universe cosmology,
and its connection with HICs are also explored.Comment: 5 pages, 5 figures, Minor changes in the tex
Revisiting Vacuum Energy in Compact Spacetimes
We revisit the calculation of vacuum energy density in compact space times.
By explicitly computing the effective action through the heat kernel method, we
compute vacuum energy density for the general case of compact spatial
dimensions in dimensional Minkowski space time. Additionally, we use this
formalism to calculate the Casimir force on a piston placed in such space
times, and note the deviations from previously reported results in the
literature.Comment: 21 Pages, 4 Figure