4,952 research outputs found
Lectures on Gauged Supergravity and Flux Compactifications
The low-energy effective theories describing string compactifications in the
presence of fluxes are so-called gauged supergravities: deformations of the
standard abelian supergravity theories. The deformation parameters can be
identified with the various possible (geometric and non-geometric) flux
components. In these lecture notes we review the construction of gauged
supergravities in a manifestly duality covariant way and illustrate the
construction in several examples.Comment: 48 pages, lectures given at the RTN Winter School on Strings,
Supergravity and Gauge Theories, CERN, January 200
Unified Maxwell-Einstein and Yang-Mills-Einstein Supergravity Theories in Five Dimensions
Unified N=2 Maxwell-Einstein supergravity theories (MESGTs) are supergravity
theories in which all the vector fields, including the graviphoton, transform
in an irreducible representation of a simple global symmetry group of the
Lagrangian. As was established long time ago, in five dimensions there exist
only four unified Maxwell-Einstein supergravity theories whose target manifolds
are symmetric spaces. These theories are defined by the four simple Euclidean
Jordan algebras of degree three. In this paper, we show that, in addition to
these four unified MESGTs with symmetric target spaces, there exist three
infinite families of unified MESGTs as well as another exceptional one. These
novel unified MESGTs are defined by non-compact (Minkowskian) Jordan algebras,
and their target spaces are in general neither symmetric nor homogeneous. The
members of one of these three infinite families can be gauged in such a way as
to obtain an infinite family of unified N=2 Yang-Mills-Einstein supergravity
theories, in which all vector fields transform in the adjoint representation of
a simple gauge group of the type SU(N,1). The corresponding gaugings in the
other two infinite families lead to Yang-Mills-Einstein supergravity theories
coupled to tensor multiplets.Comment: Latex 2e, 28 pages. v2: reference added, footnote 14 enlarge
Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared
The TRAPPIST-1 planetary system is a favorable target for the atmospheric
characterization of temperate earth-sized exoplanets by means of transmission
spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible
obstacle to this technique could come from the photospheric heterogeneity of
the host star that could affect planetary signatures in the transit
transmission spectra. To constrain further this possibility, we gathered an
extensive photometric data set of 25 TRAPPIST-1 transits observed in the
near-IR J band (1.2 m) with the UKIRT and the AAT, and in the NB2090 band
(2.1 m) with the VLT during the period 2015-2018. In our analysis of these
data, we used a special strategy aiming to ensure uniformity in our
measurements and robustness in our conclusions. We reach a photometric
precision of (RMS of the residuals), and we detect no significant
temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the
period of three years. The few transit depths measured for planets d and f hint
towards some level of variability, but more measurements will be required for
confirmation. Our depth measurements for planets b and c disagree with the
stellar contamination spectra originating from the possible existence of bright
spots of temperature 4500 K. We report updated transmission spectra for the six
inner planets of the system which are globally flat for planets b and g and
some structures are seen for planets c, d, e, and f.Comment: accepted for publication in MNRA
Supergravity, Supermembrane and M(atrix) model on PP-Waves
In the first part of this paper, we study the back-reaction of large-N light
cone momentum on the maximally supersymmetric anti-pp-wave background. This
gives the type IIA geometry of large-N D0-branes on curved space with fluxes.
By taking an appropriate decoupling limit, we conjecture a new duality between
string theory on that background and dual field theory on D0-branes which we
derive by calculating linear coupling terms. Agreement of decoupling
quantities, SO(3) \times SO(6) isometry and Higgs branch on both theories are
shown. Also we find whenever dual field theory is weakly coupled, the curvature
of the geometry is large. In the second part of this paper, we derive the
supermembrane action on a general pp-wave background only through the
properties of null Killing vector and through this, derive the Matrix model.Comment: 19 pages, LaTeX. v2: corrected interpretation of supergravity
solutio
Symmetry properties of the metric energy-momentum tensor in classical field theories and gravity
We derive a generic identity which holds for the metric (i.e. variational)
energy-momentum tensor under any field transformation in any generally
covariant classical Lagrangian field theory. The identity determines the
conditions under which a symmetry of the Lagrangian is also a symmetry of the
energy-momentum tensor. It turns out that the stress tensor acquires the
symmetry if the Lagrangian has the symmetry in a generic curved spacetime. In
this sense a field theory in flat spacetime is not self-contained. When the
identity is applied to the gauge invariant spin-two field in Minkowski space,
we obtain an alternative and direct derivation of a known no-go theorem: a
linear gauge invariant spin-2 field, which is dynamically equivalent to
linearized General Relativity, cannot have a gauge invariant metric
energy-momentum tensor. This implies that attempts to define the notion of
gravitational energy density in terms of the metric energy--momentum tensor in
a field-theoretical formulation of gravity must fail.Comment: Revised version to match the published version in Class. Quantum Gra
Orbifolds and Flows from Gauged Supergravity
We examine orbifolds of the IIB string via gauged supergravity. For the
gravity duals of the A_{n-1} quiver gauge theories, we extract the massless
degrees of freedom and assemble them into multiplets of N=4 gauged supergravity
in five dimensions. We examine the embedding of the gauge group into the
isometry group of the scalar manifold, as well as the symmetries of the scalar
potential. From this we find that there is a large SU(1,n) symmetry group which
relates different RG flows in the dual quiver gauge theory. We find that this
symmetry implies an extension of the usual duality between ten-dimensional IIB
solutions which involves exchanging geometric moduli with background fluxes.Comment: 37 pages, harvma
Renormalization Group Invariance of Exact Results in Supersymmetric Gauge Theories
We clarify the notion of Wilsonian renormalization group (RG) invariance in
supersymmetric gauge theories, which states that the low-energy physics can be
kept fixed when one changes the ultraviolet cutoff, provided appropriate
changes are made to the bare coupling constants in the Lagrangian. We first
pose a puzzle on how a quantum modified constraint (such as Pf(Q^i Q^j) =
\Lambda^{2(N+1)} in SP(N) theories with N+1 flavors) can be RG invariant, since
the bare fields Q^i receive wave function renormalization when one changes the
ultraviolet cutoff, while we naively regard the scale \Lambda as RG invariant.
The resolution is that \Lambda is not RG invariant if one sticks to canonical
normalization for the bare fields as is conventionally done in field theory. We
derive a formula for how \Lambda must be changed when one changes the
ultraviolet cutoff. We then compare our formula to known exact results and show
that their consistency requires the change in \Lambda we have found. Finally,
we apply our result to models of supersymmetry breaking due to quantum modified
constraints. The RG invariance helps us to determine the effective potential
along the classical flat directions found in these theories. In particular, the
inverted hierarchy mechanism does not occur in the original version of these
models.Comment: LaTeX, 26 page
Universal contributions to scalar masses from five dimensional supergravity
We compute the effective Kahler potential for matter fields in warped
compactifications, starting from five dimensional gauged supergravity, as a
function of the matter fields localization. We show that truncation to zero
modes is inconsistent and the tree-level exchange of the massive gravitational
multiplet is needed for consistency of the four-dimensional theory. In addition
to the standard Kahler coming from dimensional reduction, we find the quartic
correction coming from integrating out the gravity multiplet. We apply our
result to the computation of scalar masses, by assuming that the SUSY breaking
field is a bulk hypermultiplet. In the limit of extreme opposite localization
of the matter and the spurion fields, we find zero scalar masses, consistent
with sequestering arguments. Surprisingly enough, for all the other cases the
scalar masses are tachyonic. This suggests the holographic interpretation that
a CFT sector always generates operators contributing in a tachyonic way to
scalar masses. Viability of warped su- persymmetric compactifications
necessarily asks then for additional contributions. We discuss the case of
additional bulk vector multiplets with mixed boundary conditions, which is a
partic- ularly simple and attractive way to generate large positive scalar
masses. We show that in this case successful fermion mass matrices implies
highly degenerate scalar masses for the first two generations of squarks and
sleptons.Comment: 23 pages. v2: References added, new section on effect of additional
bulk vector multiplets and phenomenolog
Local well-posedness for membranes in the light cone gauge
In this paper we consider the classical initial value problem for the bosonic
membrane in light cone gauge. A Hamiltonian reduction gives a system with one
constraint, the area preserving constraint. The Hamiltonian evolution equations
corresponding to this system, however, fail to be hyperbolic. Making use of the
area preserving constraint, an equivalent system of evolution equations is
found, which is hyperbolic and has a well-posed initial value problem. We are
thus able to solve the initial value problem for the Hamiltonian evolution
equations by means of this equivalent system. We furthermore obtain a blowup
criterion for the membrane evolution equations, and show, making use of the
constraint, that one may achieve improved regularity estimates.Comment: 29 page
Matrix Black Holes
Four and five dimensional extremal black holes with nonzero entropy have
simple presentations in M-theory as gravitational waves bound to configurations
of intersecting M-branes. We discuss realizations of these objects in matrix
models of M-theory, investigate the properties of zero-brane probes, and
propose a measure of their internal density. A scenario for black hole dynamics
is presented.Comment: 26 pages, harvmac; a few more references and additional comment
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