Traschen, Jennie

Job Title

Professor, Department of Physics

Last Name

Traschen

First Name

Jennie

Discipline

Physics

Expertise

Classical and Quantum Gravity

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Now showing 1 - 10 of 25

Extended First Law for Entanglement Entropy in Lovelock Gravity
(2016-01-01) Kastor, David; Traschen, Jennie; Ray, Sourya
The first law for the holographic entanglement entropy of spheres in a boundary CFT (Conformal Field Theory) with a bulk Lovelock dual is extended to include variations of the bulk Lovelock coupling constants. Such variations in the bulk correspond to perturbations within a family of boundary CFTs. The new contribution to the first law is found to be the product of the variation δa'>δaδa of the “A”-type trace anomaly coefficient for even dimensional CFTs, or more generally its extension δa*'>δa∗δa* to include odd dimensional boundaries, times the ratio S/a*'>S/a∗S/a* . Since a*'>a∗a* is a measure of the number of degrees of freedom N per unit volume of the boundary CFT, this new term has the form μδN'>μδNμδN , where the chemical potential μ is given by the entanglement entropy per degree of freedom.
Pair creation of dilaton black holes
(1994) Dowker, F; Gauntlett, J; Kastor, David; Traschen, Jennie
We consider dilaton gravity theories in four spacetime dimensions parametrized by a constant a, which controls the dilaton coupling, and construct new exact solutions. We first generalize the C metric of Einstein-Maxwell theory (a=0) to solutions corresponding to oppositely charged dilaton black holes undergoing uniform acceleration for general a. We next develop a solution-generating technique which allows us to ‘‘embed’’ the dilaton C metrics in magnetic dilaton Melvin backgrounds, thus generalizing the Ernst metric of Einstein-Maxwell theory. By adjusting the parameters appropriately, it is possible to eliminate the nodal singularities of the dilaton C metrics. For a<1 (but not for a≥1), it is possible to further restrict the parameters so that the dilaton Ernst solutions have a smooth Euclidean section with topology S2×S2-{pt}, corresponding to instantons describing the pair production of dilaton black holes in a magnetic field. A different restriction on the parameters leads to smooth instantons for all values of a with topology S2×openR2.
Overlapping branes in M-theory
(1999) Gauntlett, Jerome; Kastor, David; Traschen, Jennie
We construct new supersymmetric solutions of D = 11 supergravity describing n orthogonally “overlapping” membranes and fivebranes for n = 2,…,8. Overlapping branes arise after separating intersecting branes in a direction transverse to all of the branes. The solutions, which generalize known intersecting brane solutions, preserve at least 2−n of the supersymmetry. Each pairwise overlap involves a membrane overlapping a membrane in a 0-brane, a fivebrane overlapping a fivebrane in a 3-brane or a membrane overlapping a fivebrane in a string. After reducing n overlapping membranes to obtain n overlapping D-2-branes in D = 10, T-duality generates new overlapping D-brane solutions in type IIA and type IIB string theory. Uplifting certain type IIA solutions leads to the D = 11 solutions. Some of the new solutions reduce to dilaton black holes in D = 4. Additionally, we present a D = 10 solution that describes two D-5-branes overlapping in a string. T-duality then generates further D = 10 solutions and uplifting one of the type IIA solutions gives a new D = 11 solution describing two fivebranes overlapping in a string.
Spin of the M2-brane and spin-spin interactions via probe techniques
(1999) Balasubramanian,; Kastor, David; Traschen, Jennie; Win, K.Z.
The 256-dimensional M2-brane multiplet contains solitons of many different intrinsic spins. Using the broken supersymmetry transformations of the M2-brane, we find supergravity solutions which explicitly display these spins. This amounts to quantizing the fermionic zero modes and computing the back reaction on the metric and gauge potential. These spacetime fields are therefore operator valued and acquire a conventional classical meaning only after taking expectations in given BPS states. Our spinning spacetimes are not of the standard Kerr form—there is a nonvanishing gravitino. Nevertheless, the solutions have angular momentum and magnetic dipole moments with a g factor of 2. We use probe techniques to study scattering of spinning BPS M2-branes. The static interactions cancel between like-sign branes at leading order, but there are static spin-spin forces between branes and antibranes. The general probe-background Lagrangian contains gravitational spin-spin and magnetic dipole-dipole forces, as well as gravitino exchanges which allow branes to change fermion number.
A positive energy theorem for asymptotically de Sitter spacetimes
(2002-01-01) Kastor, David; Traschen, Jennie
We construct a set of conserved charges for asymptotically de Sitter spacetimes that correspond to asymptotic conformal isometries. The charges are given by boundary integrals at spatial infinity in the flat cosmological slicing of de Sitter. Using a spinor construction, we show that the charge associated with conformal time translations is necessarily positive and hence may provide a useful definition of energy for these spacetimes. A similar spinor construction shows that the charge associated with the time translation Killing vector of de Sitter in static coordinates has both positive and negative definite contributions. For Schwarzschild–de Sitter the conformal energy we define is given by the mass parameter times the cosmological scale factor. The time dependence of the charge is a consequence of a nonzero flux of the corresponding conserved current at spatial infinity. For small perturbations of de Sitter, the charge is given by the total comoving mass density.
Stresses and strains in the first law for Kaluza-Klein black holes
(2006-01-01) Kastor, David; Traschen, Jennie
We consider how variations in the moduli of the compactification manifold contribute `pdV' type work terms to the first law for Kaluza-Klein black holes. We give a new proof for the S1 case, based on Hamiltonian methods, which demonstrates that the result holds for arbitrary perturbations around a static black hole background. We further apply these methods to derive the first law for black holes in 2-torus compactifications, where there are three real moduli. We find that the result can be simply stated in terms of constructs familiar from the physics of elastic materials, the stress and strain tensors. The strain tensor encodes the change in size and shape of the 2-torus as the moduli are varied. The role of the stress tensor is played by a tension tensor, which generalizes the spacetime tension that enters the first law in the S1 case.
Conserved gravitational charges from Yano tensors
(2004-01-01) Kastor, David; Traschen, Jennie
The defining properties of Yano tensors naturally generalize those of Killing vectors to anti-symmetric tensor fields of arbitrary rank. We show how the Yano tensors of flat spacetime can be used to construct new, conserved gravitational charges for transverse asymptotically flat spacetimes. The relationship of these new charges to Yano tensors parallels that of ordinary ADM conserved charges to Killing vectors. Hence, we call them Y-ADM charges. A rank n Y-ADM charge is given by an integral over a co-dimension n slice of spatial infinity. In particular, a rank (p+1) Y-ADM charge in a p-brane spacetime is given by an integral over only the sphere SD−(p+2) surrounding the brane and may be regarded as an intensive property of the brane.
Do Killing–Yano tensors form a Lie algebra?
(2007-01-01) Kastor, David; Ray, Sourya; Traschen, Jennie
Killing–Yano tensors are natural generalizations of Killing vectors. We investigate whether Killing–Yano tensors form a graded Lie algebra with respect to the Schouten–Nijenhuis bracket. We find that this proposition does not hold in general, but that it does hold for constant curvature spacetimes. We also show that Minkowski and (anti)-deSitter spacetimes have the maximal number of Killing–Yano tensors of each rank and that the algebras of these tensors under the SN bracket are relatively simple extensions of the Poincaré and (A)dS symmetry algebras.
Horizons inside classical lumps
(1992) Kastor, David; Traschen, Jennie
We investigate the possibility of having horizons inside various classical field configurations. Using the implicit function theorem, we show that models satisfying a certian set of criteria allow for (at least) small horizons within extended matter fields. Gauge and global monopoles and Skyrmions satisfy these criteria. Q balls and boson stars are examples which do not and can be shown not to allow for horizons. In examples that do allow for horizons, we show how standard "no hair" arguments are avoided.
Breaking Cosmic Strings without Monopoles
(1995) Eardley, D; Horowitz, G; Kastor, David; Traschen, Jennie
It is shown that topologically stable cosmic strings can, in fact, appear to end or to break, even in theories without monopoles. This can occur whenever the spatial topology of the universe is nontrivial. For the case of Abelian-Higgs strings, we describe the gauge and scalar field configurations necessary for a string to end on a black hole. We give a lower bound for the rate at which a cosmic string will break via black hole pair production, using an instanton calculation based on the Euclidean C-metric.