17,451 research outputs found
Duality Symmetries and G^{+++} Theories
We show that the non-linear realisations of all the very extended algebras
G^{+++}, except the B and C series which we do not consider, contain fields
corresponding to all possible duality symmetries of the on-shell degrees of
freedom of these theories. This result also holds for G_2^{+++} and we argue
that the non-linear realisation of this algebra accounts precisely for the form
fields present in the corresponding supersymmetric theory. We also find a
simple necessary condition for the roots to belong to a G^{+++} algebra.Comment: 35 pages. v2: 2 appendices added, other minor corrections. v3: tables
corrected, other minor changes, one appendix added, refs. added. Version
published in Class. Quant. Gra
On Holomorphic Effective Actions of Hypermultiplets Coupled to External Gauge Superfields
We study the structure of holomorphic effective action for hypermultiplet
models interacting with background super Yang-Mills fields. A general form of
holomorphic effective action is found for hypermultiplet belonging to arbitrary
representation of any semisimple compact Lie group spontaneously broken to its
maximal abelian subgroup. The applications of obtained results to
hypermultiplets in fundamental and adjoint representations of the SU(n), SO(n),
Sp(n) groups are considered.Comment: 8 pages, no figure
Generalised Space-time and Gauge Transformations
We consider the generalised space-time introduced by the author in 2003 in
the context of the non-linear realisation of the semi-direct product of E11 and
its first fundamental representation. For all the fields we propose gauge
transformations which are compatible with the underlying E11 structure. A
crucial role is played by the generalised vielbein that the generalised
space-time possess. We work out the explicit form of the gauge transformations,
at low levels, in four, five and eleven dimensions.Comment: 33 page
E11, generalised space-time and equations of motion in four dimensions
We construct the non-linear realisation of the semi-direct product of E11 and
its first fundamental representation at low levels in four dimensions. We
include the fields for gravity, the scalars and the gauge fields as well as the
duals of these fields. The generalised space-time, upon which the fields
depend, consists of the usual coordinates of four dimensional space-time and
Lorentz scalar coordinates which belong to the 56-dimensional representation of
E7. We demand that the equations of motion are first order in derivatives of
the generalised space-time and then show that they are essentially uniquely
determined by the properties of the E11 Kac-Moody algebra and its first
fundamental representation. The two lowest equations correctly describe the
equations of motion of the scalars and the gauge fields once one takes the
fields to depend only on the usual four dimensional space-time
Generalised geometry, eleven dimensions and E11
We construct the non-linear realisation of E11 and its first fundamental
representation in eleven dimensions at low levels. The fields depend on the
usual coordinates of space-time as well as two form and five form coordinates.
We derive the terms in the dynamics that contain the three form and six form
fields and show that when we restricted their field dependence to be only on
the usual space-time we recover the correct self-duality relation. Should this
result generalise to the gravity fields then the non-linear realisation is an
extension of the maximal supergravity theory, as previously conjectured. We
also comment on the connections between the different approaches to generalised
geometry.Comment: 17 pages, Trivial typos corrected in version one and a substantial
note added which gives the equation of motion relating the gravity field to
its dua
Kac-Moody Symmetries of Ten-dimensional Non-maximal Supergravity Theories
A description of the bosonic sector of ten-dimensional N=1 supergravity as a
non-linear realisation is given. We show that if a suitable extension of this
theory were invariant under a Kac-Moody algebra, then this algebra would have
to contain a rank eleven Kac-Moody algebra, that can be identified to be a
particular real form of very-extended D_8. We also describe the extension of
N=1 supergravity coupled to an abelian vector gauge field as a non-linear
realisation, and find the Kac-Moody algebra governing the symmetries of this
theory to be very-extended B_8. Finally, we discuss the related points for the
N=1 supergravity coupled to an arbitrary number of abelian vector gauge fields
Worldsheet Matter Superfields on Half-Shell
In this paper we discuss some of the effects of using "unidexterous"
worldsheet superfields, which satisfy worldsheet differential constraints and
so are partly on-shell, i.e., on half-shell. Most notably, this results in a
stratification of the field space that reminds of "brane-world" geometries.
Linear dependence on such superfields provides a worldsheet generalization of
the super-Zeeman effect. In turn, non-linear dependence yields additional
left-right asymmetric dynamical constraints on the propagating fields, again in
a stratified fashion.Comment: 15 pages, 2 figures; minor algebraic correction
Multiloop calculations in supersymmetric theories with the higher covariant derivative regularization
Most calculations of quantum corrections in supersymmetric theories are made
with the dimensional reduction, which is a modification of the dimensional
regularization. However, it is well known that the dimensional reduction is not
self-consistent. A consistent regularization, which does not break the
supersymmetry, is the higher covariant derivative regularization. However, the
integrals obtained with this regularization can not be usually calculated
analytically. We discuss application of this regularization to the calculations
in supersymmetric theories. In particular, it is demonstrated that integrals
defining the beta-function are possibly integrals of total derivatives. This
feature allows to explain the origin of the exact NSVZ beta-function, relating
the beta-function with the anomalous dimensions of the matter superfields.
However, integrals for the anomalous dimension should be calculated
numerically.Comment: 8 pages, contribution to ACAT 2011 proceeding
Saprolegnia diclina IIIA and S. parasitica employ different infection strategies when colonizing eggs of Atlantic salmon, Salmo salar L.
Acknowledgements The work has been funded by the European Commission through the EU Marie Curie ITN project SAPRO (238550) (MMS, AW). We would also like to acknowledge support from the BBSRC and the University of Aberdeen (PvW) and Landcatch and AquaGen for providing salmon eggs. Elin Rolen's assistance with sequencing of the strains is highly appreciated.Peer reviewedPublisher PD
E_{11} origin of Brane charges and U-duality multiplets
We derive general equations which determine the decomposition of the G^{+++}
multiplet of brane charges into the sub-algebras that arise when the
non-linearly realised G^{+++} theory is dimensionally reduced on a torus. We
apply this to calculate the low level E_8 multiplets of brane charges that
arise when the E_{8}^{+++}, or E_{11}, non-linearly realised theory is
dimensionally reduced to three dimensions on an eight dimensional torus. We
find precise agreement with the U-duality multiplet of brane charges previously
calculated, thus providing a natural eleven dimensional origin for the
"mysterious" brane charges found that do not occur as central charges in the
supersymmetry algebra. We also discuss the brane charges in nine dimensions and
how they arise from the IIA and IIB theories.Comment: 30 pages, plain te
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