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Martin Cederwall

Publications and source records attributed to Martin Cederwall.

103 records · Page 6Linked to original sources
arXiv1996

Monopole and Dyon Spectra in N=2 SYM with Higher Rank Gauge Groups

We derive parts of the monopole and dyon spectra for N=2 super-Yang--Mills theories in four dimensions with gauge groups G of rank r>1 and matter multiplets. Special emphasis is put on G=SU(3) and those matter contents that yield perturbatively finite theories. There is no direct interpretation of the soliton spectra in terms of naive selfduality under strong--weak coupling and exchange of electric and magnetic charges. We argue that, in general, the standard procedure of finding the dyon spectrum will not give results that support a conventional selfduality hypothesis --- the SU(2) theory with four fundamental hypermultiplets seems to be an exception. Possible interpretations of the results are discussed.

hep-th↗
arXiv1995

Deformations in Closed String Theory -- Canonical Formulation and Regularization

We study deformations of closed string theory by primary fields of conformal weight $(1,1)$, using conformal techniques on the complex plane. A canonical surface integral formalism for computing commutators in a non-holomorphic theory is constructed, and explicit formulæfor deformations of operators are given. We identify the unique regularization of the arising divergences that respects conformal invariance, and consider the corresponding parallel transport. The associated connection is metric compatible and carries no curvature.

hep-th↗
arXiv1995

Low Energy Dynamics of Monopoles in N=2 SYM with Matter

We derive, for $N\is2$ super-Yang--Mills with gauge group $SU(2)$ and massless matter, the supersymmetric quantum mechanical models describing the time evolution of multi-monopole configurations in the low energy approximation. This is a first step towards identifying the solitonic states mapped to fundamental excitations by duality in the model with four hypermultiplets in the fundamental representation.

hep-th↗
arXiv1994

Why Don't We Have a Covariant Superstring Field Theory?

This talk deals with the old problem of formulatingn a covariant quantum theory of superstrings, ``covariant'' here meaning having manifest Lorentz symmetry and supersymmetry. The advantages and disadvantages of several quantization methods are reviewed. Special emphasis is put on the approaches using twistorial variables, and the algebraic structures of these. Some unsolved problems are identified.

hep-th↗
arXiv1994

Schwinger Terms and Cohomology of Pseudodifferential Operators

We study the cohomology of the Schwinger term arising in second quantization of the class of observables belonging to the restricted general linear algebra. We prove that, for all pseudodifferential operators in 3+1 dimensions of this type, the Schwinger term is equivalent to the ``twisted'' Radul cocycle, a modified version of the Radul cocycle arising in non-commutative differential geometry. In the process we also show how the ordinary Radul cocycle for any pair of pseudodifferential operators in any dimension can be written as the phase space integral of the star commutator of their symbols projected to the appropriate asymptotic component.

hep-th↗
arXiv1994

Towards a Complete Twistorization of the Heterotic String

In $D=3,4,6$ and 10 space--time dimensions considered is a string model invariant under transformations of $N=1$ space--time supersymmetry and $n=D-2$ local worldsheet supersymmetry with the both Virasoro constraints solved in the twistor form. The twistor solution survives in a modified form even in the presence of the heterotic fermions.

hep-th↗
arXiv1994

$S^7$ Current Algebras

We present $S^7$-algebras as generalized Kac-Moody algebras. A number of free-field representations is found. We construct the octonionic projective spaces $ØP^N$.

hep-th↗
arXiv1993

A Note on the Relation between Different Forms of Superparticle Dynamics'

A formulation of $D\is 10$ superparticle dynamics is given that contain space-time and twistor variables. The set of constraints is entirely first class, and gauge conditions may be imposed that reduces the system to a Casalbuoni-Brink-Schwarz superparticle, a spinning particle or a twistor particle.

hep-th↗
arXiv1993

Introduction to Division Algebras, Sphere Algebras and Twistors

A very basic introduction is given to the rôles of division algebras and the related sphere algebras concerning the structure of space-time in the dimensionalities $D\is 3,4,6$ and $10$, with special emphasis on twistors transformations for light-likeness conditions and Hopf maps, together with some outlook for particle and string theory.

hep-th↗
arXiv1993

The Seven-sphere and its Kac-Moody Algebra

We investigate the seven-sphere as a group-like manifold and its extension to a Kac-Moody-like algebra. Covariance properties and tensorial composition of spinors under $S^7$ are defined. The relation to Malcev algebras is established. The consequences for octonionic projective spaces are examined. Current algebras are formulated and their anomalies are derived, and shown to be unique (even regarding numerical coefficients) up to redefinitions of the currents. Nilpotency of the BRST operator is consistent with one particular expression in the class of (field-dependent) anomalies. A Sugawara construction is given.

hep-th↗
arXiv1993

$N\!=\!8$ Superconformal Algebra and the Superstring

The superstring in $D\!=\!3,4$ and 6 is invariant under an $N\!=\!D\!-\!2$ superconformal algebra based on $\widehat{S^{D-3}}$. There is a direct relationship between this (world-sheet) symmetry and the super-Poincaré (target space) symmetry. We establish this relationship using the light-cone gauge, show how the statement generalizes to $D\!=\!10$ and examine the properties of the $N\!=\!8$ superconformal algebra and the possible implications of its existence.

hep-th↗
arXiv1992

Quaternionic Superconformal Field Theory

We develop a superfield formalism for N=4 superconformal two-dimensional field theory. A list is presented of minimal free superfields, i.e. of multiplets containing four bosons and four fermions. We show that the super-Poincaré algebra of the six-dimensional superstring in the light-cone gauge is essentially equivalent to a local N=4 superconformal symmetry, and outline the construction of octonionic superconformal field theory.

hep-th↗