arXiv subjects

H. J. Schnitzer

Publications and source records attributed to H. J. Schnitzer.

At least 19 recordsLinked to original sources

arXiv2013

Wilson line approach to gravity in the high energy limit

We examine the high energy (Regge) limit of gravitational scattering using a Wilson line approach previously used in the context of non-Abelian gauge theories. Our aim is to clarify the nature of the Reggeization of the graviton and the interplay between this Reggeization and the so-called eikonal phase which determines the spectrum of gravitational bound states. Furthermore, we discuss finite corrections to this picture. Our results are of relevance to various supergravity theories, and also help to clarify the relationship between gauge and gravity theories.

hep-th↗

arXiv2004

Improved matrix-model calculation of the N=2 prepotential

We present a matrix-model expression for the sum of instanton contributions to the prepotential of an N=2 supersymmetric U(N) gauge theory, with matter in various representations. This expression is derived by combining the renormalization-group approach to the gauge theory prepotential with matrix-model methods. This result can be evaluated order-by-order in matrix-model perturbation theory to obtain the instanton corrections to the prepotential. We also show, using this expression, that the one-instanton prepotential assumes a universal form.

hep-th↗

arXiv2004

Matrix models and N=2 gauge theory

We describe how the ingredients and results of the Seiberg-Witten solution to N=2 supersymmetric U(N) gauge theory may be obtained from a matrix model.

hep-th↗

arXiv2003

Matrix-model description of N=2 gauge theories with non-hyperelliptic Seiberg-Witten curves

Using matrix-model methods we study three different N=2 models: U(N) x U(N) with matter in the bifundamental representation, U(N) with matter in the symmetric representation, and U(N) with matter in the antisymmetric representation. We find that the (singular) cubic Seiberg-Witten curves (and associated Seiberg-Witten differentials) implied by the matrix models, although of a different form from the ones previously proposed using M-theory, can be transformed into the latter and are thus physically equivalent. We also calculate the one-instanton corrections to the gauge-coupling matrix using the perturbative expansion of the matrix model. For the U(N) theories with symmetric or antisymmetric matter we use the modified matrix-model prescription for the gauge-coupling matrix discussed in ref. [hep-th/0303268]. Moreover, in the matrix model for the U(N) theory with antisymmetric matter, one is required to expand around a different vacuum than one would naively have anticipated. With these modifications of the matrix-model prescription, the results of this paper are in complete agreement with those of Seiberg-Witten theory obtained using M-theory methods.

hep-th↗

arXiv2003

Cubic curves from matrix models and generalized Konishi anomalies

We study the matrix model/gauge theory connection for three different N=1 models: U(N) x U(N) with matter in bifundamental representations, U(N) with matter in the symmetric representation, and U(N) with matter in the antisymmetric representation. Using Ward identities, we explicitly show that the loop equations of the matrix models lead to cubic algebraic curves. We then establish the equivalence of the matrix model and gauge theory descriptions in two ways. First, we derive generalized Konishi anomaly equations in the gauge theories, showing that they are identical to the matrix-model equations. Second, we use a perturbative superspace analysis to establish the relation between the gauge theories and the matrix models. We find that the gauge coupling matrix for U(N) with matter in the symmetric or antisymmetric representations is_not_ given by the second derivative of the matrix-model free energy. However, the matrix-model prescription can be modified to give the gauge coupling matrix.

hep-th↗

arXiv2003

One-instanton predictions of Seiberg-Witten curves for product groups

One-instanton predictions for the prepotential are obtained from the Seiberg-Witten curve for the Coulomb branch of N=2 supersymmetric gauge theory for the product group \prod_{n=1}^{m} SU(N_n) with a massless matter hypermultiplet in the bifundamental representation (N_n,\bar N_{n+1}) of SU(N_n) x SU(N_{n+1}) for n=1 to m-1, together with N_0 and N_{m+1} matter hypermultiplets in the fundamental representations of SU(N_1) and SU(N_m) respectively. The derivation uses a generalization of the systematic perturbation expansion about a hyperelliptic curve developed by us in earlier work.

hep-th↗

arXiv2000

Elliptic models and M-theory

We give a unified analysis of four-dimensional elliptic models with N=2 supersymmetry and a simple gauge group, and their relation to M-theory. Explicit calculations of the Seiberg-Witten curves and the resulting one-instanton prepotential are presented. The remarkable regularities that emerge are emphasized. In addition, we calculate the prepotential in the Coulomb phase of the (asymptotically-free) Sp(2N) gauge theory with N_f fundamental hypermultiplets of arbitrary mass.

hep-th↗

arXiv1999

Tests of M-Theory from N=2 Seiberg-Witten Theory

Methods are reviewed for computing the instanton expansion of the prepotential for N=2 Seiberg-Witten (SW) theory with non-hyperelliptic curves. These results, if compared with the instanton expansion obtained from the microscopic Lagrangian, will provide detailed tests of M-theory. We observe group-theoretic regularities of the one-instanton prepotential which allow us to "reverse engineer" a SW curve for SU(N) gauge theory with two hypermultiplets in the antisymmetric representation and $N_f\leq 3$ hypermultiplets in the fundamental representations, a result not yet available by other methods. Consistency with M-theory requires a curve of infinite order, which we identify as a decompactified version of elliptic models of the type described by Donagi and Witten, Uranga, and others. This leads us to a brief discussion of some elliptic models that relate to our work.

hep-th↗

arXiv1998

Magnon modes and magnon-vortex scattering in two-dimensional easy-plane ferromagnets

We calculate the magnon modes in the presence of a vortex in a circular system, combining analytical calculations in the continuum limit with a numerical diagonalization of the discrete system. The magnon modes are expressed by the S-matrix for magnon-vortex scattering, as a function of the parameters and the size of the system and for different boundary conditions. Certain quasi-local translational modes are identified with the frequencies which appear in the trajectory X(t) of the vortex center in recent Molecular Dynamics simulations of the full many-spin model. Using these quasi-local modes we calculate the two parameters of a 3rd-order quation of motion for X(t). This equation was recently derived by a collective variable theory and describes very well the trajectories observed in the simulations. Both parameters, the vortex mass and a factor on the third time derivative of X(t), depend strongly on the boundary conditions.

cond-mat.mtrl-sci↗

arXiv1997

Superconformal Coset Equivalence from Level-Rank Duality

We construct a one-to-one map between the primary fields of the N=2 superconformal Kazama-Suzuki models G(m,n,k) and G(k,n,m) based on complex Grassmannian cosets, using level-rank duality of Wess-Zumino-Witten models. We then show that conformal weights, superconformal U(1) charges, modular transformation matrices, and fusion rules are preserved under this map, providing strong evidence for the equivalence of these coset models.

hep-th↗

arXiv1997

A Note on the Picard-Fuchs Equations for N=2 Seiberg-Witten Theories

A concise presentation of the PF equations for N=2 Seiberg-Witten theories for the classical groups of rank r with N_f massless hypermultiplets in the fundamental representation is provided. For N_f=0, all r PF equations can be given in a generic form. For certain cases with N_f\neq zero, not all equations are generic. However, in all cases there are at least r-2 generic PF equations. For these cases the classical part of the equations is generic, while the quantum part can be formulated using a method described in a previous paper by the authors, which is well suited to symbolic computer calculations.

hep-th↗

arXiv1996

Field Strength Correlators For 2D Yang-Mills Over Riemann Surfaces

The path integral computation of field strength correlation functions for two dimensional Yang-Mills theories over Riemann surfaces is studied. The calculation is carried out by abelianization, which leads to correlators that are topological. They are nontrivial as a result of the topological obstructions to the abelianization. It is shown in the large N limit on the sphere that the correlators undergo second order phase transitions at the critical point. Our results are applied to a computation of contractible Wilson loops.

hep-th↗

arXiv1996

A New Derivation of the Picard-Fuchs Equations for Effective $N = 2$ Super Yang-Mills Theories

A new method to obtain the Picard-Fuchs equations of effective $N = 2$ supersymmetric gauge theories in 4 dimensions is developed. It includes both pure super Yang-Mills and supersymmetric gauge theories with massless matter hypermultiplets. It applies to all classical gauge groups, and directly produces a decoupled set of second-order, partial differential equations satisfied by the period integrals of the Seiberg-Witten differential along the 1-cycles of the algebraic curves describing the vacuum structure of the corresponding $N = 2$ theory.

hep-th↗

arXiv1996

Evaluation of the Free Energy of Two-Dimensional Yang-Mills Theory

The free energy in the weak-coupling phase of two-dimensional Yang-Mills theory on a sphere for SO(N) and Sp(N) is evaluated in the 1/N expansion using the techniques of Gross and Matytsin. Many features of Yang-Mills theory are universal among different gauge groups in the large N limit, but significant differences arise in subleading order in 1/N.

hep-th↗

arXiv1995

The Master Field For 2D QCD On The Sphere

We continue our analysis of the field strength correlation functions of two-dimensional QCD on Riemann surfaces by studying the large $N$ limit of these correlation functions on the sphere for gauge group $U(N)$. Our results allow us to exhibit an explicit master field for the field strength $F_{μν}$ in a ``topological gauge'', given by a single master matrix in the Lie algebra of the maximal torus of the gauge group. Field correlators are obtained from traces of products of the master field. We also obtain a master field for the gauge potential $A_μ$ on the sphere, consistent with the master field for the field strength.

hep-th↗

arXiv1995

BF Theories and Group-Level Duality

It is known that the partition function and correlators of the two-dimensional topological field theory $G_K(N)/ G_K(N)$ on the Riemann surface $Σ_{g,s}$ is given by Verlinde numbers, dim($V_{g,s,K}$) and that the large $K$ limit of dim($V_{g,s,K}$) gives Vol(${\cal M}_s$), the volume of the moduli space of flat connections of gauge group $G(N)$ on $Σ_{g,s}$, up to a power of $K$. Given this relationship, we complete the computation of Vol(${\cal M}_s$) using only algebraic results from conformal field theory. The group-level duality of $G(N)_K$ is used to show that if $G(N)$ is a classical group, then $\displaystyle \lim_{N\rightarrow \infty} G_K(N) / G_K(N)$ is a BF theory with gauge group $G(K)$. Therefore this limit computes Vol(${\cal M}^\prime_s$), the volume of the moduli space of flat connections of gauge group $G(K)$.

hep-th↗

arXiv1995

Large-N Universality of the Two-Dimensional Yang-Mills String

We exhibit the gauge-group independence (``universality'') of all normalized non-intersecting Wilson loop expectation values in the large N limit of two-dimensional Yang-Mills theory. This universality is most easily understood via the string theory reformulation of these gauge theories. By constructing an isomorphism between the string maps contributing to normalized Wilson loop expectation values in the different theories, we prove the large N universality of these observables on any surface. The string calculation of the Wilson loop expectation value on the sphere also leads to an indication of the large N phase transition separating strong- and weak-coupling phases.

hep-th↗

arXiv1993

Two-dimensional Yang-Mills Theories Are String Theories

We show that two-dimensional SO(N) and Sp(N) Yang-Mills theories without fermions can be interpreted as closed string theories. The terms in the 1/N expansion of the partition function on an orientable or nonorientable manifold M can be associated with maps from a string worldsheet onto M. These maps are unbranched and branched covers of M with an arbitrary number of infinitesimal worldsheet cross-caps mapped to points in M. These string theories differ from SU(N) Yang-Mills string theory in that they involve odd powers of 1/N and require both orientable and nonorientable worldsheets.

hep-th↗