Maverick Examples Of Coset Conformal Field Theories

We present coset conformal field theories whose spectrum is not determined by the identification current method. In these ``maverick'' cosets there is a larger symmetry identifying primary fields than under the identification current. We find an A-D-E classification of these mavericks. }Comment: 16pages , reportSWAT-93-0

Advanced Techniques for Multiparton Loop Calculations: A Minireview

We present an overview of techniques developed in recent years for the efficient calculation of one-loop multiparton amplitudes, in particular those relying on unitarity and collinear factorization.Comment: 5 pages, LaTeX/aipproc, presented at DIS '97, Chicago, IL, April 14-18, 199

Identities amongst the Two Loop Partial Amplitudes of Yang-Mills theory

We characterise possible identities among the two-loop partial amplitudes of gluon scattering in Yang-Mills theory. We use known amplitudes in an exhaustive search to identify potential new relations. We find two candidate relations which may extend to all-$n$ amplitudes

Alternative Compactification of Superstring Related Theories

The aim of this work is to consider the recently introduced ten dimensional Superstring theories and, by considering the low energy field theory limit, consider possible compactification schemes where the original ten dimensions split up into four observed space time dimensions and six highly curved, compactified dimensions. We shall attempt to find solutions which satisfy the classical equations of motion and then, using these solutions, we shall try to obtain schemes which give a spectrum of particles which is compatible with the observed spectrum. We shall, by considering situations where we allow nonzero torsion on the compactified 6-D manifold, investigate possibilities other than the Calabi-Yau spaces which are usually considered. In Chapter 0 we give a (very biased) review of particle physics and in Chapter 1 we give a little Superstring formalism. In Chapter 2 we discuss the low energy limit of Superstring theories and decide upon the lagrangian which we shall subsequently use. The two types of internal manifold which we shall consider are group manifolds and Coset spaces. We consider these because they provide a natural ansatz for a non-zero torsion. In Chapter 3 we attempt to find solutions to the equations of motion when the internal manifold is a group space and in Chapter 4 we discuss the consequence of any such solutions. In Chapters 5 and 6 we do the same for Non-Symmetric Coset Spaces and in Chapter 7 we look at Symmetric Coset Spaces. In Chapter 8 we return to the issue of what the low energy field theory should be

Counterterms in type I Supergravities

We compute the one-loop divergences of D=10, N=1 supergravity and of its reduction to D=8. We study the tensor structure of the counterterms appearing in D=8 and D=10 and compare these to expressions previously found in the low energy expansion of string theory. The infinities have the primitive Yang-Mills tree amplitude as a common factor.Comment: 26 pages, Latex, 4 eps figure

Obtaining One-loop Gravity Amplitudes Using Spurious Singularities

The decomposition of a one-loop scattering amplitude into elementary functions with rational coefficients introduces spurious singularities which afflict individual coefficients but cancel in the complete amplitude. These cancellations create a web of interactions between the various terms. We explore the extent to which entire one-loop amplitudes can be determined from these relationships starting with a relatively small input of initial information, typically the coefficients of the scalar integral functions as these are readily determined. In the context of one-loop gravity amplitudes, of which relatively little is known, we find that some amplitudes with a small number of legs can be completely determined from their box coefficients. For increasing numbers of legs, ambiguities appear which can be determined from the physical singularity structure of the amplitude. We illustrate this with the four-point and N=1,4 five-point (super)gravity one-loop amplitudes.Comment: Minor corrections. Appendix adde

Perturbative expansion of N<8 Supergravity

We characterise the one-loop amplitudes for N=6 and N=4 supergravity in four dimensions. For N=6 we find that the one-loop n-point amplitudes can be expanded in terms of scalar box and triangle functions only. This simplification is consistent with a loop momentum power count of n-3, which we would interpret as being n+4 for gravity with a further -7 from the N=6 superalgebra. For N=4 we find that the amplitude is consistent with a loop momentum power count of n, which we would interpret as being n+4 for gravity with a further -4 from the N=4 superalgebra. Specifically the N=4 amplitudes contain non-cut-constructible rational terms.Comment: 13 pages. v2 adds analytic expression for rational parts of 5-pt 1-loop N=4 SUGRA amplitude; v3 normalisations clarifie