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Jeffrey A. Harvey

Publications and source records attributed to Jeffrey A. Harvey.

67 records · Page 4Linked to original sources
arXiv2000

D-Branes as Unstable Lumps in Bosonic Open String Field Theory

We construct Dp-branes in bosonic string theory as unstable lumps in a truncated string field theory of open strings on a D25-brane. We find that the lowest level truncation gives good quantitative agreement with the predicted D-brane tension and low-lying spectrum of the D-brane for sufficiently large p and study the effect of the next level corrections for p=24. We show that a U(1) gauge field zero mode on the D-brane arises through a mechanism reminiscent of the Randall-Sundrum mechanism for gravity.

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arXiv2000

D-Sphalerons and the Topology of String Configuration Space

We show that unstable D-branes play the role of ``D-sphalerons'' in string theory. Their existence implies that the configuration space of Type II string theory has a complicated homotopy structure, similar to that of an infinite Grassmannian. In particular, the configuration space of Type IIA (IIB) string theory on $\R^{10}$ has non-trivial homotopy groups $π_k$ for all $k$ even (odd).

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arXiv1998

String Duality and Non-supersymmetric Strings

In recent work Kachru, Kumar and Silverstein introduced a special class of non-supersymmetric type II string theories in which the cosmological constant vanishes at the first two orders of perturbation theory. Heuristic arguments suggest the cosmological constant may vanish in these theories to all orders in perturbation theory leading to a flat potential for the dilaton. A slight variant of their model can be described in terms of a dual heterotic theory. The dual theory has a non-zero cosmological constant which is non-perturbative in the coupling of the original type II theory. The dual theory also predicts a mismatch between Bose and Fermi degrees of freedom in the non-perturbative D-brane spectrum of the type II theory.

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arXiv1997

Spin Dependence of D0-brane Interactions

The long-range, spin-dependent forces between D0-branes are related to long-range fundamental string interactions using duality. These interactions can then be computed by taking the long distance non-relativistic expansion of string four-point amplitudes. The results are in accord with the general constraints of Matrix Theory.

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arXiv1997

Unwinding strings and T-duality of Kaluza-Klein and H-Monopoles

A fundamental string with non-zero winding number can unwind in the presence of a Kaluza-Klein monopole. We use this fact to deduce the presence of a zero mode for the Kaluza-Klein monopole corresponding to excitations carrying H electric charge and we study the coupling of this zero mode to fundamental strings. We also a describe a T-dual process in which the momentum of a fundamental string ``unwinds'' in the presence of a H monopole. We use the coupling of string winding modes to the dyon collective coordinate of the Kaluza-Klein monopole to argue that there are stringy corrections to the Kaluza-Klein monopole which are in accordance with T-duality.

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arXiv1997

On the algebras of BPS states

We define an algebra on the space of BPS states in theories with extended supersymmetry. We show that the algebra of perturbative BPS states in toroidal compactification of the heterotic string is closely related to a generalized Kac-Moody algebra. We use D-brane theory to compare the formulation of RR-charged BPS algebras in type II compactification with the requirements of string/string duality and find that the RR charged BPS states should be regarded as cohomology classes on moduli spaces of coherent sheaves. The equivalence of the algebra of BPS states in heterotic/IIA dual pairs elucidates certain results and conjectures of Nakajima and Gritsenko & Nikulin, on geometrically defined algebras and furthermore suggests nontrivial generalizations of these algebras. In particular, to any Calabi-Yau 3-fold there are two canonically associated algebras exchanged by mirror symmetry.

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arXiv1996

Exact Gravitational Threshold Correction in the FHSV Model

We consider the automorphic forms which govern the gravitational threshold correction $F_1$ in models of heterotic/IIA duality with N=2 supersymmetry in four dimensions. In particular we derive the full nonperturbative formula for $F_1$ for the dual pair originally considered by Ferrara, Harvey, Strominger and Vafa (FHSV). The answer involves an interesting automorphic product constructed by Borcherds which is associated to the ``fake Monster Lie superalgebra.'' As an application of this result we rederive a result of Jorgenson & Todorov on determinants of $\bar \partial$ operators on $K3$ surfaces.

hep-th↗
arXiv1996

Fivebrane Instantons and $R^2$ couplings in $N=4$ String Theory

We compute the gravitational coupling $F_1$ for IIA string theory on $K3 \times T^2$ and use string-string duality to deduce the corresponding term for heterotic string on $T^6$. The latter is an infinite sum of gravitational instanton effects which we associate with the effects of Euclidean fivebranes wrapped on $T^6$. These fivebranes are the neutral fivebranes or zero size instantons of heterotic string theory.

hep-th↗
arXiv1996

Magnetic Monopoles, Duality, and Supersymmetry

These notes present a pedagogical introduction to magnetic monopoles and exact electromagnetic duality in supersymmetric gauge theories. They are based on lectures given at the 1995 Trieste Summer School in High Energy Physics and Cosmology and at the 1995 Busstepp Summer School at Cosener's House.

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arXiv1996

I-Brane Inflow and Anomalous Couplings on D-Branes

We show that the anomalous couplings of $D$-brane gauge and gravitational fields to Ramond-Ramond tensor potentials can be deduced by a simple anomaly inflow argument applied to intersecting $D$-branes and use this to determine the eight-form gravitational coupling.

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arXiv1993

Anomaly Inflow for Gauge Defects

Topological defects constructed out of scalar fields and possessing chiral fermion zero modes are known to exhibit an anomaly inflow mechanism which cancels the anomaly in the effective theory of the zero modes through an inflow of current from the space in which the defect is embedded. We investigate the analog of this mechanism for defects constructed out of gauge fields in higher dimensions. In particular we analyze this mechanism for string (one-brane) defects in six dimensions and for fivebranes in ten dimensions.}

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arXiv1992

Magnetic Monopoles in String Theory

Magnetic monopole solutions to heterotic string theory are discussed in toroidal compactifications to four spacetime dimensions. Particular emphasis is placed on the relation to previously studied fivebrane solutions in ten dimensions and on the possibility of constructing exact monopole solutions related to symmetric fivebranes.

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