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Eric Gimon

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Papers by Eric Gimon

Black holes in supergravity: the non-BPS branch

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Oct 25, 2007

We construct extremal, spherically symmetric black hole solutions to 4D supergravity with charge ... more We construct extremal, spherically symmetric black hole solutions to 4D supergravity with charge assignments that preclude BPS-saturation. In particular, we determine the ground state energy as a function of charges and moduli. We find that the mass of the non-BPS black hole remains that of a marginal bound state of four basic constituents throughout the entire moduli space and that there is always a non-zero gap above the BPS bound.

Black ring deconstruction

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 22, 2007

We present a sample microstate for a black ring in four and five dimensional language. The micros... more We present a sample microstate for a black ring in four and five dimensional language. The microstate consists of a black string microstate with an additional D6-brane. We show that with an appropriate choice of parameters the piece involving the black string microstate falls down a long AdS throat, whose M-theory lift is AdS 3 × S 2. We wrap a spinning dipole M2-brane on the S 2 in the probe approximation. In IIA, this corresponds to a dielectric D2-brane carrying only D0-charge. We conjecture this is the first approximation to a cloud of D0-branes blowing up due to their non-abelian degrees of freedom and the Myers effect.

Evidence for a gravitational Myers effect

Annals of Physics, Oct 1, 2004

An indication for the existence of a collective Myers solution in the non-abelian D0-brane Born-I... more An indication for the existence of a collective Myers solution in the non-abelian D0-brane Born-Infeld action is the presence of a tachyonic mode in fluctuations around the standard diagonal background. We show that this computation for non-abelian D0-branes in curved space has the geometric interpretation of computing the eigenvalues of the geodesic deviation operator for U(N)-valued coordinates. On general grounds one therefore expects a geometric Myers effect in regions of sufficiently negative curvature. We confirm this by explicit computations for nonabelian D0-branes on a sphere and a hyperboloid. For the former the diagonal solution is stable, but not so for the latter. We conclude by showing that near the horizon of a Schwarzschild black hole one also finds a tachyonic mode in the fluctuation spectrum, signaling the possibility of a near-horizon gravitationally induced Myers effect.

Hybrid Resources: Challenges, Implications, Opportunities, and Innovation

IEEE Power & Energy Magazine, Nov 1, 2021

The electric power system has historically been designed to provide reliable energy to loads by u... more The electric power system has historically been designed to provide reliable energy to loads by using a relatively small number of well-understood generators. The distinction between load, generation, and transmission resources has been quite clear. Most of the responsibility for planning and operating a system—building a highly reliable network from less reliable parts—has been with the system manager, whether that be a utility, a regional market operator, or some similar entity. Given this historical context, many experts were initially perplexed by the rapidly growing popularity of hybrid resources, which combine multiple technologies into a single entity. Rather than depending on a system operator to provide instructions to individual technologies, hybrid resources intentionally take on more operational responsibility by optimizing and scheduling their combined functions. Interconnection queues in many regions reveal a large and growing interest in hybrids, suggesting that project developers and investors see them as providing advantages.

The operator spectrum of the six-dimensional (1,0) theory

Journal of High Energy Physics, Apr 20, 1999

We study the large N operator spectrum of the (1,0) superconformal chiral six-dimensional theory ... more We study the large N operator spectrum of the (1,0) superconformal chiral six-dimensional theory with E 8 global symmetry. This spectrum is dual to the Kaluza-Klein spectrum of supergravity on AdS 7 × S 4 /Z 2 with a tendimensional E 8 theory at its singular locus. We identify those operators in short multiplets of OSp (6, 2| 2), whose dimensions are exact for any N. We also discuss more general issues concerning AdS/CFT duality on orbifold supergravity backgrounds.

Geometry of non-supersymmetric three-charge bound states

Journal of High Energy Physics, Aug 20, 2007

We study the smooth non-supersymmetric three-charge microstates of Jejjala, Madden, Ross and Titc... more We study the smooth non-supersymmetric three-charge microstates of Jejjala, Madden, Ross and Titchener [1] using Kaluza-Klein reductions of the solutions to five and four dimensions. Our aim is to improve our understanding of the relation between these non-supersymmetric solutions and the well-studied supersymmetric cases. We find some surprising qualitative differences. In the five-dimensional description, the solution has orbifold fixed points which break supersymmetry locally, so the geometries cannot be thought of as made up of separate half-BPS centers. In the four-dimensional description, the two singularities in the geometry are connected by a conical singularity, which makes it impossible to treat them independently and assign unambiguous brane charges to these centers.

Four-dimensional conformal supergravity from AdS space

Physical review, Apr 12, 2001

Exploring the role of conformal theories of gravity in string theory, we show that the minimal (N... more Exploring the role of conformal theories of gravity in string theory, we show that the minimal (N = 2) gauged supergravities in five dimensions induce the multiplets and transformations of N = 1 four dimensional conformal supergravity on the spacetime boundary. N = 1 Poincaré supergravity can be induced by explicitly breaking the conformal invariance via a radial cutoff in the 5d space. The AdS/CFT correspondence relates the maximal gauged supergravity in five dimensions to N = 4 super Yang-Mills on the 4d spacetime boundary. In this context we show that the conformal anomaly of the gauge theory induces conformal gravity on the boundary of the space and that this theory, via the renormalization group, encapsulates the gravitational dynamics of the skin of asymptotically AdS spacetimes. Our results have several applications to the AdS/CFT correspondence and the Randall-Sundrum scenario.

Strings on orbifold lines

Journal of High Energy Physics, May 9, 2001

The orbifold lines IIA/I 8 and IIB/I 8 (−1) F L possess BPS discrete torsion variants which carry... more The orbifold lines IIA/I 8 and IIB/I 8 (−1) F L possess BPS discrete torsion variants which carry fundamental string (NSNS) charge. We show that these variants are actually classified by an integral electric field F from the twisted RR sector, and compute their tension and NSNS charge as a function of F. The analysis employs equivariant K-theory and the string creation phenomenon. The K-theory results demonstrate the corrections to cohomology in the case of torsion; it is found that 8 units of F are invisible at transverse infinity for IIA, and correspondingly 16 units for IIB.

Black Holes in Gödel Universes andppWaves

Physical Review Letters, Jul 11, 2003

We find exact rotating and non-rotating neutral black hole solutions in the Gödel universe of the... more We find exact rotating and non-rotating neutral black hole solutions in the Gödel universe of the five dimensional minimal supergravity theory. We also describe the embedding of this solution in M-theory. After dimensional reduction and T-duality, we obtain a supergravity solution corresponding to placing a black string in a pp-wave background.

Consistency conditions for holographic duality

Journal of High Energy Physics, May 4, 2000

We show that if the beta functions of a field theory are given by the gradient of a certain poten... more We show that if the beta functions of a field theory are given by the gradient of a certain potential on the space of couplings, a gravitational background in one more dimension can express the renormalization group (RG) flow of the theory. The field theory beta functions and the gradient flow constraint together reconstruct the second order spacetime equations of motion. The RG equation reduces to the conventional gravitational computation of the spacetime quasilocal stress tensor, and a c-theorem holds true as a consequence of the Raychaudhuri equation. Conversely, under certain conditions, if the RG evolution of a field theory possesses a monotonic c-function, the flow of couplings can be expressed in terms of a higher dimensional gravitational background.

Multiple realisations of N = 1 vacua in six dimensions

Nuclear Physics B, Nov 1, 1996

A while ago, examples of N =1 vacua in D=6 were constructed as orientifolds of Type IIB string th... more A while ago, examples of N =1 vacua in D=6 were constructed as orientifolds of Type IIB string theory compactified on the K3 surface. Among the interesting features of those models was the presence of D5-branes behaving like small instantons, and the appearance of extra tensor multiplets. These are both non-perturbative phenomena from the point of view of Heterotic string theory. Although the orientifold models are a natural setting in which to study these non-perturbative Heterotic string phenomena, it is interesting and instructive to explore how such vacua are realised in Heterotic string theory, M-theory and F-theory, and consider the relations between them. In particular, we consider models of M-theory compactified on K3×S 1 /Z 2 with fivebranes present on the interval. There is a family of such models which yields the same spectra as a subfamily of the orientifold models. By further compactifying on T 2 to four dimensions we relate them to Heterotic string spectra. We then use Heterotic/Type IIA duality to deduce the existence of Calabi-Yau 3-folds which should yield the original six dimensional orientifold spectra if we use them to compactify F-theory. Finally, we show in detail how to take a limit of such an F-theory compactification which returns us to the Type IIB orientifold models.

Constituent model of extremal non-BPS black holes

Journal of High Energy Physics, Jul 15, 2009

We interpret extremal non-BPS black holes in four dimensions as threshold bound states of four 1/... more We interpret extremal non-BPS black holes in four dimensions as threshold bound states of four 1/2-BPS constituents. We verify the no-force condition for each of the primitive constituents in the probe approximation. Our computations are for a seed solution with D0 − D4 charges and equal B-fields, but symmetries extend the result to any U-dual frame. We make the constituent model for the D0 − D6 system explicit, and also discuss a duality frame where the constituents are D3 branes at angles. We demonstrate stability of the constituent model in the weak coupling description of the constituent D-branes. We discuss the relation between the BPS and non-BPS branches of configuration space.

Orientifolds, RR torsion, and K-theory

Journal of High Energy Physics, May 24, 2001

We analyze the role of RR fluxes in orientifold backgrounds from the point of view of K-theory, a... more We analyze the role of RR fluxes in orientifold backgrounds from the point of view of K-theory, and demonstrate some physical implications of describing these fluxes in K-theory rather than cohomology. In particular, we show that certain fractional shifts in RR charge quantization due to discrete RR fluxes are naturally explained in K-theory. We also show that some orientifold backgrounds, which are considered distinct in the cohomology classification, become equivalent in the K-theory description, while others become unphysical. Contents 1. Introduction 1 2. Review of orientifolds 4 2.1 Basics 4 2.2 Cohomology torsion variants 4 2.3 Brane realization of torsion 6 3. Orientifolds in K-theory 7 3.1 Real K-theory 8 3.2 RR fields in orientifold backgrounds 9 3.3 Comparing with cohomology 4. Applications 13 4.1 Charge quantization 4.2 Equivalent orientifolds 4.3 Unphysical orientifolds 5. The orientifold 6-plane 18 5.1 K-theory 5.2 Anomalies 5.3 Components of Type I vacuua 6. Conclusions and open questions 23 A. AHSS in complex and real K-theory 24 A.1 Defining the Associated Graded Complex A.2 Computing GrK using a spectral sequence A.3 Extending the AHSS to K-theories with freely acting involutions A.4 Illustrative Example: KR(S 6,0) and KH(S 6,0

Astrophysical violations of the Kerr bound as a possible signature of string theory

Physics Letters B, Feb 1, 2009

In 4D general relativity, the angular momentum of a black hole is limited by the Kerr bound. We s... more In 4D general relativity, the angular momentum of a black hole is limited by the Kerr bound. We suggest that in string theory, this bound can be breached and compact black-hole-like objects can spin faster. Near such "superspinars," the efficiency of energy transfer from the accreting matter to radiation can reach 100%, compared to the maximum efficiency of 42% of the extremal Kerr (or 6% of the Schwarzschild) black hole. Finding such superspinning objects as active galactic nuclei, GBHCs, or sources of gamma ray bursts, could be viewed as experimental support for string theory.

Consistency conditions for orientifolds and D-manifolds

Physical review, Jul 15, 1996

We study superstrings with orientifold projections and with generalized open string boundary cond... more We study superstrings with orientifold projections and with generalized open string boundary conditions (D-branes). We find two types of consistency condition, one related to the algebra of Chan-Paton factors and the other to cancellation of divergences. One consequence is that the Dirichlet 5-branes of the Type I theory carry a symplectic gauge group, as required by string duality. As another application we study the Type I theory on a K3 Z 2 orbifold, finding a family of consistent theories with various unitary and symplectic subgroups of U (16) × U (16). We argue that the K3 orbifold with spin connection embedded in gauge connection corresponds to an interacting conformal field theory in the Type I theory.

Black ring deconstruction

Journal of High Energy Physics, Apr 29, 2008

We present a sample microstate for a black ring in four and five dimensional language. The micros... more We present a sample microstate for a black ring in four and five dimensional language. The microstate consists of a black string microstate with an additional D6-brane. We show that with an appropriate choice of parameters the piece involving the black string microstate falls down a long AdS throat, whose M-theory lift is AdS 3 × S 2. We wrap a spinning dipole M2-brane on the S 2 in the probe approximation. In IIA, this corresponds to a dielectric D2-brane carrying only D0-charge. We conjecture this is the first approximation to a cloud of D0-branes blowing up due to their non-abelian degrees of freedom and the Myers effect.

On the complementarity of F-theory, orientifolds, and heterotic strings

Nuclear Physics B, Aug 1, 1998

We study F-theory duals of six dimensional heterotic vacua in extreme regions of moduli space whe... more We study F-theory duals of six dimensional heterotic vacua in extreme regions of moduli space where the heterotic string is very strongly coupled. We demonstrate how to use orientifold limits of these F-theory duals to regain a perturbative string description. As an example, we reproduce the spectrum of a T 4 /Z Z 4 orientifold as an F-theory vacuum with a singular K3 fibration. We relate this vacuum to previously studied heterotic E 8 × E 8 compactifications on K3.

A New Approach to Capabilities Markets: Seeding Solutions for the Future

The Electricity Journal, Jul 1, 2013

The 'Staircase Capabilities Market' is a novel mechanism for building markets to support sustaine... more The 'Staircase Capabilities Market' is a novel mechanism for building markets to support sustained investment in solutions that address long-term issues identified in current grid planning processes. A Staircase Capabilities Market is an iterated sequence of long-term, small-volume requests for proposals for new capabilities to match anticipated system needs.

Brane transfer operations and T-duality of non-BPS states

Journal of High Energy Physics, Apr 11, 1999

Using the relation between D-brane charges and K-theory, we study non-BPS D-branes and their beha... more Using the relation between D-brane charges and K-theory, we study non-BPS D-branes and their behavior under T-duality. We point out that in general compactifications, D-brane charges are classified by relative K-theory groups. T-duality is found to act as a symmetry between the relative K-theory groups in Type II and Type I/IA theories. We also study Type IA theory (which contains an O8 − plane and an O8 + plane), using K-theory and T-duality to identify its stable D-branes. Comparison with string theory constructions reveals two interesting effects. One of them involves the transfer of branes between Oplanes, while in the other, a D-brane charge which seems conserved near one O-plane in fact decays due to the presence of another type of O-plane.

Black holes in supergravity: the non-BPS branch

Journal of High Energy Physics, Jan 16, 2008

We construct extremal, spherically symmetric black hole solutions to 4D supergravity with charge ... more We construct extremal, spherically symmetric black hole solutions to 4D supergravity with charge assignments that preclude BPS-saturation. In particular, we determine the ground state energy as a function of charges and moduli. We find that the mass of the non-BPS black hole remains that of a marginal bound state of four basic constituents throughout the entire moduli space and that there is always a non-zero gap above the BPS bound.