Jaume Gomis

Gauge theory at large N and new G_2 holonomy metrics

We find a one-parameter family of new G_2 holonomy metrics and demonstrate that it can be extended to a two-parameter family. These metrics play an important role as the supergravity dual of the large N limit of four-dimensional supersymmetric Yang–Mills. We show that these G_2 holonomy metrics describe the M theory lift of the supergravity solution describing a collection of D6-branes wrapping the supersymmetric three-cycle of the deformed conifold geometry for any value of the string coupling constant.

Penrose Limit of N = 1 Gauge Theories

We find a Penrose limit of AdS_5 × T^(1,1) which gives the pp-wave geometry identical to the one that appears in the Penrose limit of AdS_5 × S^5. This leads us to conjecture that there is a subsector of the corresponding N = 1 gauge theory which has enhanced N = 4 supersymmetry. We identify operators in the N = 1 gauge theory with stringy excitations in the pp-wave geometry and discuss how the gauge theory operators fall into N = 4 supersymmetry multiplets. We find similar enhancement of symmetry in some other models, but there are also examples in which there is no supersymmetry enhancement in the Penrose limit.

Nonrelativistic closed string theory

We construct a Galilean invariant nongravitational closed string theory whose excitations satisfy a nonrelativistic dispersion relation. This theory can be obtained by taking a consistent low energy limit of any of the conventional string theories, including the heterotic string. We give a finite first order worldsheet Hamiltonian for this theory and show that this string theory has a sensible perturbative expansion, interesting high energy behavior of scattering amplitudes and a Hagedorn transition of the thermal ensemble. The strong coupling duals of the Galilean superstring theories are considered and are shown to be described by an eleven-dimensional Galilean invariant theory of light membrane fluctuations. A new class of Galilean invariant nongravitational theories of light-brane excitations are obtained. We exhibit dual formulations of the strong coupling limits of these Galilean invariant theories and show that they exhibit many of the conventional dualities of M theory in a nonrelativistic setting.

SYM description of SFT Hamiltonian in a pp-wave background

Abstract We compute string field theory Hamiltonian matrix elements and compare them with matrix elements of the dilatation operator in gauge theory. We get precise agreement between the string field theory and gauge theory computations once the correct cubic Hamiltonian matrix elements in string field theory and a particular basis of states in gauge theory are used. We proceed to compute the matrix elements of the dilatation operator to order g 2 2 in this same basis. This calculation makes a prediction for string field theory Hamiltonian matrix elements to order g 2 2 , which have not yet been computed. However, our gauge theory results precisely match the results of the recent computation by Pearson et al. of the order g 2 2 Hamiltonian matrix elements of the string bit model.

PP-wave/CFT_2 duality

We investigate the pp-wave limit of the AdS_3 × S^3 × K3 compactification of type-IIB string theory from the point of view of the dual Sym_N(K3) CFT. It is proposed that a fundamental string in this pp-wave geometry is dual to the c = 6 effective string of the Sym_N(K3) CFT, with the string bits of the latter being composed of twist operators. The massive fundamental string oscillators correspond to certain twisted Virasoro generators in the effective string. It is shown that both the ground states and the genus expansion parameter (at least in the orbifold limit of the CFT) coincide. Surprisingly the latter scales like J^2/N rather than the J^4/N^2 which might have been expected. We demonstrate a leading-order agreement between the pp-wave and CFT particle spectra. For a degenerate special case (one NS 5-brane) an intriguing complete agreement is found.

Noncommutative gauge dynamics from the string worldsheet

We show how string theory can be used to reproduce the one-loop two-point photon amplitude in non-commutative U(1) gauge theory. Using a simple realization of the gauge theory in bosonic string theory, we extract from a string cylinder computation in the decoupling limit the exact one loop field theory result. The result is obtained entirely from the region of moduli space where massless open strings dominate. Our computation indicates that the unusual IR/UV singularities of non-commutative field theory do not come from closed string modes in any simple way.

Two-dimensional unoriented strings and matrix models

We investigate unoriented strings and superstrings in two dimensions and their dual matrix quantum mechanics. Most of the models we study have a tachyon tadpole coming from the RP2 worldsheet which needs to be cancelled by a renormalization of the worldsheet theory. We find evidence that the dual matrix models describe the renormalized theory. The singlet sector of the matrix models is integrable and can be formulated in terms of fermions moving in an external potential and interacting via the Calogero-Moser potential. We show that in the double-scaling limit the latter system exhibits particle-hole duality and interpret it in terms of the dual string theory. We also show that oriented string theories in two dimensions can be continuously deformed into unoriented ones by turning on non-local interactions on the worldsheet. We find two unoriented superstring models for which only oriented worldsheets contribute to the S-matrix. A simple explanation for this is found in the dual matrix model.

D = 2+1 N = 2 Yang-Mills Theory From Wrapped Branes

We find a new solution of type-IIB supergravity which represents a collection of D5-branes wrapped on the topologically non-trivial S^3 of the deformed conifold geometry T*S^3. The type-IIB solution is obtained by lifting a new solution of D = 7 SU(2)_L × SU(2)_R gauged supergravity to ten dimensions in which SU(2)_D gauge fields in the diagonal subgroup are turned on. The supergravity solution describes a slice of the Coulomb branch in the large-N limit of

On SUSY breaking and χSB from string duals

Abstract We find regular string duals of three-dimensional N =1 SYM with a Chern–Simons interaction at level k for SO and Sp gauge groups. Using the string dual we exactly reproduce the conjectured pattern of supersymmetry breaking proposed by Witten by showing that there is dynamical supersymmetry breaking for k N =1 SYM for SO and Sp gauge groups and exactly reproduce the expected pattern of chiral symmetry breaking Z2h→Z2 by analyzing the symmetries of the string solution.