Douglas Singleton

Hawking temperature in the tunneling picture

Abstract We examine Hawking radiation from a Schwarzschild black hole in several reference frames using the quasi-classical tunneling picture. It is shown that when one uses, Γ ∝ exp ( Im [ ∮ p d r ] ) , rather than, Γ ∝ exp ( 2 Im [ ∫ p d r ] ) , for the tunneling probability/decay rate one obtains twice the original Hawking temperature. The former expression for Γ is argued to be correct since ∮ p d r is invariant under canonical transformations, while ∫ p d r is not. Thus, either the tunneling methods of calculating Hawking radiation are suspect or the Hawking temperature is twice that originally calculated.

Temporal contribution to gravitational WKB-like calculations

Abstract Recently, it has been shown that the radiation arising from quantum fields placed in a gravitational background (e.g. Hawking radiation) can be derived using a quasi-classical calculation. Here we show that this method has a previously overlooked temporal contribution to the quasi-classical amplitude. The source of this temporal contribution lies in different character of time in general relativity versus quantum mechanics. Only when one takes into account this temporal contribution does one obtain the canonical temperature for the radiation. Although in this Letter the specific example of radiation in de Sitter space–time is used, the temporal contribution is a general contribution to the radiation given off by any gravitational background where the time coordinate changes its signature upon crossing a horizon. Thus, the quasi-classical method for gravitational backgrounds contains subtleties not found in the usual quantum mechanical tunneling problem.

Subtleties in the quasi-classical calculation of Hawking radiation

The quasi-classical method of deriving Hawking radiation is investigated. In order to recover the original Hawking temperature one must take into account a previously ignored contribution coming from the temporal part of the action. This contribution plus a contribution coming from the spatial part of the action gives the correct temperature.

6D thick branes from interacting scalar fields

A thick brane in six dimensions is constructed using two scalar fields. The field equations for 6D gravity plus the scalar fields are solved numerically. This thick brane solution shares some features with previously studied analytic solutions, but has the advantage that the energy-momentum tensor which forms the thick brane comes from the scalar fields rather than being put in by hand. Additionally the scalar fields which form the brane also provide a universal, nongravitational trapping mechanism for test fields of various spins.

Brane in 6D with an increasing gravitational trapping potential

A new solution to the Einstein equations in

Nonsingular increasing gravitational potential for the brane in 6D

1+5

Hawking radiation, Unruh radiation, and the equivalence principle.

spacetime with an embedded

Ellipsoidal, cylindrical, bipolar and toroidal wormholes in 5D gravity

1+3

A two measure model of dark energy and dark matter

brane is given. This solution localizes the zero modes of all kinds of matter fields and four-gravity on the (1+3) brane by an increasing, transverse gravitational potential. This localization occurs despite the fact that the gravitational potential is not a decreasing exponential, and asymptotically approaches a finite value rather than zero.

Exact Schwarzschild-like solution for Yang-Mills theories

Abstract We present a new (1+3)-brane solution to Einstein equations in (1+5)-space. As distinct from previous models this solution is free of singularities in the full 6-dimensional space–time. The gravitational potential transverse to the brane is an increasing (but not exponentially) function and asymptotically approaches a finite value. The solution localizes the zero modes of all kinds of matter fields and Newtonian gravity on the brane. An essential feature of the model is that different kind of matter fields have different localization radii.