arXiv subjects
Publications and source records attributed to L. Dolan.
We will discuss an integrable structure for weakly coupled superconformal Yang-Mills theories, describe certain equivalences for the Yangian algebra, and fill a technical gap in our previous study of this subject.
These lectures provide an introduction to perturbative string theory and its construction on spaces with background Ramond flux. Traditional covariant quantization of the string and its connection with vertex operators and conformal invariance of the worldsheet theory are reviewed. A supersymmetric covariant quantization of the superstring in six and ten spacetime dimensions is discussed. Correlation functions are computed with these variables. Applications to strings in anti-de Sitter backgrounds with Ramond flux are analyzed. Based on lectures presented at the Theoretical Advanced Study Institute TASI 2001, June 3-29, 2001.
We compute the three-graviton tree amplitude in Type IIB superstring theory compactified to six dimensions using the manifestly (6d) supersymmetric Berkovits-Vafa-Witten worldsheet variables. We consider two cases of background geometry: the flat space example R6xK3, and the curved example AdS3xS3xK3 with Ramond flux, and compute the correlation functions in the bulk.
This review gives results on vertex operators for the Type IIB superstring in an AdS3 x S3 background with Ramond-Ramond flux, which were presented at Strings 2000. Constraint equations for these vertex operators are derived, and their components are shown to satisfy the supergravity linearized equations of motion for the six-dimensional (2,0) theory of a supergravity and tensor multiplet expanded around AdS3 x S3 spacetime.
We show how the gauge symmetry representations of the massless particle content of gauged supergravities that arise in the AdS/CFT correspondences can be derived from symmetric subgroups to be carried by string theory vertex operators in these compactified models, although an explicit vertex operator construction of IIB string and M theories on AdSxS remains elusive. Our symmetry mechanism parallels the construction of representations of the Monster group and affine algebras in terms of twisted conformal field theories, and may serve as a guide to the perturbative description of the IIB string on AdSxS.
The partition function of type IIA and B strings on R^6xK3, in the T^4/Z_2 orbifold limit, is explicitly computed as a modular invariant sum over spin strutures required by perturbative unitarity in order to extend the analysis to include type II strings on R^6 x W4, where W4 is associated with the tube metric conformal field theory, given by the degrees of freedom transverse to the Neveu-Schwarz fivebrane solution. This generates partition functions and perturbative spectra of string theories in six space-time dimensions, associated with the modular invariants of the level k affine SU(2) Kac-Moody algebra. These theories provide a conformal field theory (i.e. perturbative) probe of non-perturbative (fivebrane) vacua. We contrast them with theories whose N=(4,4) sigma-model action contains n_H=k+2 hypermultiplets as well as vector supermultiplets, and where k is the level just mentioned. In Appendix B we also give a D=6, N=(1,1) `free fermion' string model which has a different moduli space of vacua from the 81 parameter space relevant to the above examples.
We present a mechanism to construct four-dimensional charged massless Ramond states using the discrete states of a fivebrane Liouville internal conformal field theory. This conformal field theory has background charge, and admits an inner product which allows positive norm states. A connection among supergravity soliton solutions, Liouville conformal field theory, non-critical string theory and their gauge symmetry properties is given. A generalized construction of the SU(2) super Kac-Moody algebra mixing with the N=1 super Virasoro algebra is analyzed. How these Ramond states evade the DKV no-go theorem is explained.
The role of Kac-Moody algebras in exploiting symmetries of particle physics and string theory is described.
For the closed superstring, spin fields and bi-spinor states are defined directly in four spacetime dimensions. Explicit operator product expansions are given, including those for the internal superconformal field theory, which are consistent with locality and BRST invariance for the string vertices. The most general BRST picture changing for these fields is computed. A covariant notation for the spin decomposition of these states is developed in which non-vanishing polarizations are selected automatically. The kinematics of the three-gluon dual model amplitude in both the Neveu-Schwarz and Ramond sectors in the Lorentz gauges is calculated and contrasted. Modular invariance and enhanced gauge symmetry of four-dimensional models incorporating these states is described.
An account is given of the structure and representations of chiral bosonic meromorphic conformal field theories (CFT's), and, in particular, the conditions under which such a CFT may be extended by a representation to form a new theory. This general approach is illustrated by considering the untwisted and $Z_2$-twisted theories, $H(Λ)$ and $\tilde H(Λ)$ respectively, which may be constructed from a suitable even Euclidean lattice $Λ$. Similarly, one may construct lattices $Λ_C$ and $\tildeΛ_C$ by analogous constructions from a doubly-even binary code $C$. In the case when $C$ is self-dual, the corresponding lattices are also. Similarly, $H(Λ)$ and $\tilde H(Λ)$ are self-dual if and only if $Λ$ is. We show that $H(Λ_C)$ has a natural ``triality'' structure, which induces an isomorphism $H(\tildeΛ_C)\equiv\tilde H(Λ_C)$ and also a triality structure on $\tilde H(\tildeΛ_C)$. For $C$ the Golay code, $\tildeΛ_C$ is the Leech lattice, and the triality on $\tilde H(\tildeΛ_C)$ is the symmetry which extends the natural action of (an extension of) Conway's group on this theory to the Monster, so setting triality and Frenkel, Lepowsky and Meurman's construction of the natural Monster module in a more general context. The results also serve to shed some light on the classification of self-dual CFT's. We find that of the 48 theories $H(Λ)$ and $\tilde H(Λ)$ with central charge 24 that there are 39 distinct ones, and further that all 9 coincidences are accounted for by the isomorphism detailed above, induced by the existence of a doubly-even self-dual binary code.
A distinctive feature of string unification is the possibility of unification by a non-simply-laced group. This occurs most naturally in four dimensional type~II string models where the gauge symmetry is realized by Kac-Moody algebras at different levels. We investigate the running coupling constants and the one-loop thresholds for such general models. As a specific case, we examine a $\rm SU(3)\times U(1)\times U(1)$ model and find that the threshold corrections lead to a small $6\%$ increase in the unification scale.