Conformal field theory of a rotating dyon.
A conformal field theory representing a four-dimensional classical solution of heterotic string theory is presented. The low-energy limit of this solution has U(1) electric and magnetic charges, and also nontrivial axion and dilaton fields. The low-energy metric contains mass, NUT, and rotation parameters. We demonstrate that this solution corresponds to part of an extremal limit of the Kerr-Taub-NUT dyon solution. This limit displays interesting ``remnant'' behavior in that asymptotically far away from the dyon the angular momentum vanishes, but far down the infinite throat in the neighborhood of the horizon (described by our CFT) there is a nonzero angular velocity. A further natural generalization of the CFT to include an additional parameter is presented, but the full physical interpretation of its role in the resulting low energy solution is unclear.

title: Global Currents, Phase Transitions, and Chiral Symmetry Breaking in Large N_c Gauge Theory
abstract: We study, using a gravity dual, the finite temperature dynamics of $SU(N_c)$ gauge theory for large $N_c$, with fundamental quark flavours in a quenched approximation, in the presence of a fixed R--charge under a global R--current. We observe several notable phenomena. There is a first order phase transition where the quark condensate jumps discontinuously at finite quark mass, generalizing similar transitions seen at zero charge. Our tool in these studies is holography, the string dual of the gauge theory being the geometry of $N_c$ spinning D3--branes at finite temperature, probed by a D7--brane.

title: String Theory Without Branes
abstract: We present a class of solvable models that resemble string theories in many respects but have a strikingly different non-perturbative sector. In particular, there are no exponentially small contributions to perturbation theory in the string coupling, which normally are associated with branes and related objects. Perturbation theory is no longer an asymptotic expansion, and so can be completely re-summed to yield all the non-perturbative physics. We examine a number of other properties of the theories, for example constructing and examining the physics of loop operators, which can be computed exactly, and gain considerable understanding of the difference between these new theories and the more familiar ones, including the possibility of how to interpolate between the two types. Interestingly, the models we exhibit contain a family of zeros of the partition function which suggest a novel phase structure. The theories are defined naturally by starting with models that yield well-understood string theories and allowing a flux-like background parameter to take half-integer rather than integer values. The family of models thus obtained are seeded by functions that are intimately related to the classic rational solutions of the Painleve II equation, and a family of generalisations.

title: String theory and water waves
abstract: We uncover a remarkable role that an infinite hierarchy of nonlinear differential equations plays in organizing and connecting certain string theories non-perturbatively. We are able to embed the type 0A and 0B (A, A) minimal string theories into this single framework. The string theories arise as special limits of a rich system of equations underpinned by an integrable system known as the dispersive water wave hierarchy. We observe that there are several other string-like limits of the system, and conjecture that some of them are type IIA and IIB (A, D) minimal string backgrounds. We explain how these and several string-like special points arise and are connected. In some cases, the framework endows the theories with a non-perturbative definition for the first time. Notably, we discover that the Painlev? IV equation plays a key role in organizing the string theory physics, joining its siblings, Painlev? I and II, whose roles have previously been identified in this minimal string context.

title: Holography, thermodynamics, and fluctuations of charged AdS black holes
abstract: The physical properties of Reissner-Nordstrom black holes in (n11)-dimensional anti-de Sitter spacetime are related, by a holographic map, to the physics of a class of n-dimensional field theories coupled to a background global current. Motivated by that fact, and the recent observations of the striking similarity between the thermodynamic phase structure of these black holes ~in the canonical ensemble! and that of the van der Waals-Maxwell liquid-gas system, we explore the physics in more detail. We study fluctuations and stability within the equilibrium thermodynamics, examining the specific heats and electrical permittivity of the holes, and consider the analogue of the Clayperon equation at the phase boundaries. Consequently, we refine the phase diagrams in the canonical and grand canonical ensembles. We study the interesting physics in the neighborhood of the critical point in the canonical ensemble. There is a second order phase transition found there, and that region is characterized by a Landau-Ginzburg model with A3 potential. The holographically dual field theories provide the description of the microscopic degrees of freedom which underlie all of the thermodynamics, as can be seen by examining the form of the microscopic fluctuations. @S0556-2821~99!06820-4#

title: Is string theory a theory of strings
abstract: Recently a great deal of evidence has been found indicating that type IIA string theory compactified on K 3 is equivalent to heterotic string theory compactified on T 4 . Under the transformation which relates the two theories, the roles of fundamental and solitonic string solutions are interchanged. We show that there exists a solitonic membrane solution of the heterotic string theory which becomes a singular solution of the type IIA theory, and should therefore be interpreted as a fundamental membrane in the latter theory. We speculate upon the implications that the complete type IIA theory is a theory of membranes, as well as strings.

title: Constraints on bag formation from the scalar sector.

title: Aspects of the chiral quark model.
abstract: We point out intriguing connections between the chiral quark model in which the nucleon is treated as a soliton and the ordinary potential-binding quark model. The axial-vector coupling comes out near the value (5/3 rather than around 0.7 as in the Skyrme description and can be easily ''fine-tuned'' to its experimental value. A ''linear potential'' in some sense is generated as a collective effect of the ''meson cloud.'' Contact with QCD is made by introducing a gluonium field so as to satisfy the trace-anomaly equation. In the simplest treatment of this field one predicts a scalar-isoscalar state at 900 MeV in agreement with a recent analysis of experiments. The model is used to discuss how a ''nontrivial winding number'' emerges for the meson fields. A number of additional features of the model are treated.

title: Reexamining the Fritzsch-Stech SO(10) model of quarks and leptons.
abstract: In a rather predictive model of the quark and lepton mass matrices we discuss restrictions on the quark and lepton mixings implied by two different phenomena: (1) the Mikheyev-Smirnov-Wolfenstein explanation of the solar-neutrino problem and (2) the recent ARGUS measurements of BB-bar mixing and of charmless B decays involving baryons. We conclude that the model allows for neutrino masses and mixings which may account for matter oscillations of either of the two types ..nu../sub e/ to ..nu../sub ..mu../ or ..nu../sub e/ to ..nu../sub tau/. In the quark sector the phenomenology of the model is identical to that of the Fritzsch quark matrix. Within our scheme the simplest interpretation of the recent ARGUS results suggests a large value of m/sub t/ around 80 GeV. The model predicts chemically bondU/sub u//sub b/chemically bond to be around 0.0032

title: Strongly coupled quarks in the standard model.
abstract: For sufficiently strong Yukawa couplings the standard model goes over to the linear sigma model. We point out that the associated heavy quarks may behave like strongly interacting low-energy u and d quarks so one cannot argue that very-heavy-quark systems will provide an easy test of QCD. An upper-quark-mass bound of about 1.5 TeV is found. This should also apply to techniquarks.) Experimental confirmation of the scheme might come from the observation of very tightly bound baryons made from three heavy quarks.

title: Low-energy technicolor Lagrangian with vector mesons.
abstract: We apply techniques used in QCD and the implied chiral symmetry to motivate a low-energy Lagrangian for technicolor theories. This allows one to cleanly introduce the gluon and the weak gauge bosons at the technifermion level. The Higgs mechanism and techni-vector-meson dominance are displayed. The effect of vector dominance on the {ital W} and {ital Z} masses, the techni-{omega} and techni-{rho} couplings, and the sizable enhancement by the latter on {ital W} and {ital Z} production are demonstrated. Differences between our results and some published results are discussed. The incorporation of extended technicolor interactions is also presented.