109 research outputs found
On curvature squared terms in N = 2 supergravity
We present the N = 2 supersymmetric completion of a scalar curvature squared
term in a completely gauge independent form. We also elaborate on its component
structure.Comment: 15 pages; V2: 17 pages, typos corrected, discussion comments and
acknowledgement added; V3: published versio
On massive tensor multiplets
Massive tensor multiplets have recently been scrutinized in hep-th/0410051
and hep-th/0410149, as they appear in orientifold compactifications of type IIB
string theory. Here we formulate several dually equivalent models for massive N
= 1, N=2 tensor multiplets in four space-time dimensions. In the N = 2 case, we
employ harmonic and projective superspace techniques.Comment: 17 pages, LaTeX, no figures; V2: reference adde
Algebraic computing in general relativity and supergravity : space-time embeddings and higher dimensional theories
Imperial Users onl
The Shape of Dark Matter Halos: Dependence on Mass, Redshift, Radius, and Formation
Using six high resolution dissipationless simulations with a varying box size
in a flat LCDM universe, we study the mass and redshift dependence of dark
matter halo shapes for M_vir = 9.0e11 - 2.0e14, over the redshift range z=0-3,
and for two values of sigma_8=0.75 and 0.9. Remarkably, we find that the
redshift, mass, and sigma_8 dependence of the mean smallest-to-largest axis
ratio of halos is well described by the simple power-law relation = (0.54
+- 0.02)(M_vir/M_*)^(-0.050 +- 0.003), where s is measured at 0.3 R_vir and the
z and sigma_8 dependences are governed by the characteristic nonlinear mass,
M_*=M_*(z,sigma_8). We find that the scatter about the mean s is well described
by a Gaussian with sigma ~ 0.1, for all masses and redshifts. We compare our
results to a variety of previous works on halo shapes and find that reported
differences between studies are primarily explained by differences in their
methodologies. We address the evolutionary aspects of individual halo shapes by
following the shapes of the halos through ~100 snapshots in time. We determine
the formation scalefactor a_c as defined by Wechsler et al. (2002) and find
that it can be related to the halo shape at z = 0 and its evolution over time.Comment: 18 pages, 21 figures, submitted to MNRA
N=2 supergravity and supercurrents
We address the problem of classifying all N=2 supercurrent multiplets in four
space-time dimensions. For this purpose we consider the minimal formulation of
N=2 Poincare supergravity with a tensor compensator, and derive its linearized
action in terms of three N=2 off-shell multiplets: an unconstrained scalar
superfield, a vector multiplet, and a tensor multiplet. Such an action was
ruled out to exist in the past. Using the action constructed, one can derive
other models for linearized N=2 supergravity by applying N=2 superfield duality
transformations. The action depends parametrically on a constant non-vanishing
real isotriplet g^{ij}=g^{ji} which originates as an expectation value of the
tensor compensator. Upon reduction to N=1 superfields, we show that the model
describes two dually equivalent formulations for the massless multiplet
(1,3/2)+(3/2,2) depending on a choice of g^{ij}. In the case g^{11}=g^{22}=0,
the action describes (i) new minimal N=1 supergravity; and (ii) the
Fradkin-Vasiliev-de Wit-van Holten gravitino multiplet. In the case g^{12}=0,
on the other hand, the action describes (i) old minimal N=1 supergravity; and
(ii) the Ogievetsky-Sokatchev gravitino multiplet.Comment: 40 pages; v2: added references, some comments, new appendi
Hypermultiplets and Topological Strings
The c-map relates classical hypermultiplet moduli spaces in compactifications
of type II strings on a Calabi-Yau threefold to vector multiplet moduli spaces
via a further compactification on a circle. We give an off-shell description of
the c-map in N=2 superspace. The superspace Lagrangian for the hypermultiplets
is a single function directly related to the prepotential of special geometry,
and can therefore be computed using topological string theory. Similarly, a
class of higher derivative terms for hypermultiplets can be computed from the
higher genus topological string amplitudes. Our results provide a framework for
studying quantum corrections to the hypermultiplet moduli space, as well as for
understanding the black hole wave-function as a function of the hypermultiplet
moduli.Comment: 21 pages, references adde
- …