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John F. Wheater

Publications and source records attributed to John F. Wheater.

34 records · Page 2Linked to original sources
arXiv2001

Convergent Yang-Mills Matrix Theories

We consider the partition function and correlation functions in the bosonic and supersymmetric Yang-Mills matrix models with compact semi-simple gauge group. In the supersymmetric case, we show that the partition function converges when $D=4,6$ and 10, and that correlation functions of degree $k< k_c=2(D-3)$ are convergent independently of the group. In the bosonic case we show that the partition function is convergent when $D \geq D_c$, and that correlation functions of degree $k < k_c$ are convergent, and calculate $D_c$ and $k_c$ for each group, thus extending our previous results for SU(N). As a special case these results establish that the partition function and a set of correlation functions in the IKKT IIB string matrix model are convergent.

hep-th↗
arXiv2001

Modular transformation and boundary states in logarithmic conformal field theory

We study the $c=-2$ model of logarithmic conformal field theory in the presence of a boundary using symplectic fermions. We find boundary states with consistent modular properties. A peculiar feature of this model is that the vacuum representation corresponding to the identity operator is a sub-representation of a ``reducible but indecomposable'' larger representation. This leads to unusual properties, such as the failure of the Verlinde formula. Despite such complexities in the structure of modules, our results suggest that logarithmic conformal field theories admit bona fide boundary states.

hep-th↗
arXiv2001

The Convergence of Yang-Mills Integrals

We prove that SU(N) bosonic Yang-Mills matrix integrals are convergent for dimension (number of matrices) $D\ge D_c$. It is already known that $D_c=5$ for N=2; we prove that $D_c=4$ for N=3 and that $D_c=3$ for $N\ge 4$. These results are consistent with the numerical evaluations of the integrals by Krauth and Staudacher.

hep-th↗
arXiv2000

Peeling and Multi-critical Matter Coupled to Quantum Gravity

We show how to determine the unknown functions arising when the peeling decomposition is applied to multi-critical matter coupled to two-dimensional quantum gravity and compute the loop-loop correlation functions. The results that $η=2+2/(2K-3)$ and $ν=1-3/2K$ agree with the slicing decomposition, and satisfy Fisher scaling.

hep-th↗
arXiv2000

Boundary Logarithmic Conformal Field Theory

We discuss the effect of boundaries in boundary logarithmic conformal field theory and show, with reference to both $c=-2$ and $c=0$ models, how they produce new features even in bulk correlation functions which are not present in the corresponding models without boundaries. We discuss the modification of Cardy's relation between boundary states and bulk quantities.

hep-th↗
arXiv2000

Bottleneck Surfaces and Worldsheet Geometry of Higher-Curvature Quantum Gravity

We describe a simple lattice model of higher-curvature quantum gravity in two dimensions and study the phase structure of the theory as a function of the curvature coupling. It is shown that the ensemble of flat graphs is entropically unstable to the formation of baby universes. In these simplified models the growth in graphs exhibits a branched polymer behaviour in the phase directly before the flattening transition.

hep-th↗
arXiv1999

What does E_8 know about 11 dimensions ?

We discuss some possible relationships in gauge theories, string theory and M theory in the light of some recent results obtained in gauge invariant supersymmetric quantum mechanics. In particular this reveals a new relationship between the gauge group E_8 and 11-dimensional space.

hep-th↗
arXiv1998

The Hausdorff dimension in polymerized quantum gravity

We calculate the Hausdorff dimension, $d_H$, and the correlation function exponent, $η$, for polymerized two dimensional quantum gravity models. If the non-polymerized model has correlation function exponent $η_0 >3$ then $d_H=γ^{-1}$ where $γ$ is the susceptibility exponent. This suggests that these models may be in the same universality class as certain non-generic branched polymer models.

hep-th↗
arXiv1997

Branched polymers, complex spins and the freezing transition

We show that by coupling complex three-state systems to branched-polymer like ensembles we can obtain models with gamma-string different from one half. It is also possible to study the interpolation between dynamical and crystalline graphs for these models; we find that only when geometry fluctuations are completely forbidden is there a crystalline phase.

hep-lat↗
arXiv1997

ND Tadpoles as New String States and Quantum Mechanical Particle-Wave Duality from World-Sheet T-Duality

We consider new objects in bosonic open string theory -- ND tadpoles, which have N(euman) boundary conditions at one end of the world-sheet and D(irichlet) at the other, must exist due to s-t duality in a string theory with both NN strings and D-branes. We demonstrate how to interpolate between N and D boundary conditions. In the case of mixed boundary conditions the action for a quantum particle is induced on the boundary. Quantum-mechanical particle-wave duality, a dual description of a quantum particle in either the coordinate or the momentum representation, is induced by world-sheet T-duality. The famous relation between compactification radii is equivalent to the quantization of the phase space area of a Planck cell. We also introduce a boundary operator - a ``Zipper'' which changes the boundary condition from N into D and vice versa.

hep-th↗
arXiv1996

Curvature Matrix Models for Dynamical Triangulations and the Itzykson-DiFrancesco Formula

We study the large-N limit of a class of matrix models for dually weighted triangulated random surfaces using character expansion techniques. We show that for various choices of the weights of vertices of the dynamical triangulation the model can be solved by resumming the Itzykson-Di Francesco formula over congruence classes of Young tableau weights modulo three. From this we show that the large-N limit implies a non-trivial correspondence with models of random surfaces weighted with only even coordination number vertices. We examine the critical behaviour and evaluation of observables and discuss their interrelationships in all models. We obtain explicit solutions of the model for simple choices of vertex weightings and use them to show how the matrix model reproduces features of the random surface sum. We also discuss some general properties of the large-N character expansion approach as well as potential physical applications of our results.

hep-th↗
arXiv1996

D-Brane Recoil and Logarithmic Operators

We construct the pair of logarithmic operators associated with the recoil of a $D$-brane. This construction establishes a connection between a translation in time and a world-sheet rescaling. The problem of measuring the centre of mass coordinate of the $D$-brane is considered and the relation between the string uncertainty principle and the logarithmic operators is discussed.

hep-th↗