42 research outputs found
Supersymmetry algebra in N = 1 chiral supergravity
We consider the supersymmetry (SUSY) transformations in the chiral Lagrangian
for supergravity (SUGRA) with the complex tetrad following the method
used in the usual SUGRA, and present the explicit form of the SUSY
trasformations in the first-order form. The SUSY transformations are generated
by two independent Majorana spinor parameters, which are apparently different
from the constrained parameters employed in the method of the 2-form gravity.
We also calculate the commutator algebra of the SUSY transformations on-shell.Comment: 10 pages, late
A simple approach to counterterms in N=8 supergravity
We present a simple systematic method to study candidate counterterms in N=8
supergravity. Complicated details of the counterterm operators are avoided
because we work with the on-shell matrix elements they produce. All n-point
matrix elements of an independent SUSY invariant operator of the form D^{2k}
R^n +... must be local and satisfy SUSY Ward identities. These are strong
constraints, and we test directly whether or not matrix elements with these
properties can be constructed. If not, then the operator does not have a
supersymmetrization, and it is excluded as a potential counterterm. For n>4, we
find that R^n, D^2 R^n, D^4 R^n, and D^6 R^n are excluded as counterterms of
MHV amplitudes, while only R^n and D^2 R^n are excluded at the NMHV level. As a
consequence, for loop order L<7, there are no independent D^{2k}R^n
counterterms with n>4. If an operator is not ruled out, our method constructs
an explicit superamplitude for its matrix elements. This is done for the 7-loop
D^4 R^6 operator at the NMHV level and in other cases. We also initiate the
study of counterterms without leading pure-graviton matrix elements, which can
occur beyond the MHV level. The landscape of excluded/allowed candidate
counterterms is summarized in a colorful chart.Comment: 25 pages, 1 figure, published versio
Supergravity with cosmological constant and the AdS group
It is shown that the supersymmetric extension of the Stelle-West formalism
permits the construction of an action for -dimensional N=1 supergravity
with cosmological constant genuinely invariant under the Since the
action is invariant under the supersymmetric extension of the group, the
supersymmetry algebra closes off shell without the need for auxiliary fields.
The limit case , i.e. -dimensional N=1 supergravity invariant
under the Poincar\'{e} supergroup is also discussed.Comment: 10 page
New Formulations of D=10 Supersymmetry and D8-O8 Domain Walls
We discuss a generalized form of IIA/IIB supergravity depending on all R-R
potentials C^(p) (p=0,1,...,9) as the effective field theory of Type IIA/IIB
superstring theory. For the IIA case we explicitly break this R-R democracy to
either p=5 which allows us to write a new bulk action that can be
coupled to N=1 supersymmetric brane actions.
The case of 8-branes is studied in detail using the new bulk & brane action.
The supersymmetric negative tension branes without matter excitations can be
viewed as orientifolds in the effective action. These D8-branes and O8-planes
are fundamental in Type I' string theory. A BPS 8-brane solution is given which
satisfies the jump conditions on the wall. It implies a quantization of the
mass parameter in string units. Also we find a maximal distance between the two
walls, depending on the string coupling and the mass parameter. We derive the
same results via supersymmetric flow equations.Comment: 30 pages, 2nd version: reference adde
Quantum Aspects of Massive Gravity II: Non-Pauli-Fierz Theory
We investigate the non-Pauli-Fierz(nPF) theory, a linearized massive gravity
with a generic graviton mass term, which has been ignored due to a ghost in its
spectrum and the resultant loss of unitarity. We first show that it is possible
to use the Lee-Wick mechanism, a unitarization through the decay of a ghost, in
order to handle the sixth mode ghost of nPF, and then check for the quantum
consistency. Once proven to be consistent, nPF could become a viable candidate
for a large distance modification of gravity, because it naturally solves the
intrinsic problems that most dark energy/modified gravity models suffer from:
It smoothly converges to general relativity at short distances, and the small
graviton mass necessary to modify gravity at large scales can be stable under
the radiative corrections from the minimal gravity-to-matter coupling.Comment: 1+16pp, accepted for JHE
Quantum Cosmology and Higher-Order Lagrangian Theories
In this paper the quantum cosmological consequences of introducing a term
cubic in the Ricci curvature scalar into the Einstein--Hilbert action are
investigated. It is argued that this term represents a more generic
perturbation to the action than the quadratic correction usually considered. A
qualitative argument suggests that there exists a region of parameter space in
which neither the tunneling nor the no-boundary boundary conditions predict an
epoch of inflation that can solve the horizon and flatness problems of the big
bang model. This is in contrast to the --theory.Comment: 13 pages, LaTeX, preprint FERMILAB-Pub-94/XXX-A, March 199
A Search for Non-Perturbative Dualities of Local Yang--Mills Theories from Calabi--Yau Threefolds
The generalisation of the rigid special geometry of the vector multiplet
quantum moduli space to the case of supergravity is discussed through the
notion of a dynamical Calabi--Yau threefold. Duality symmetries of this
manifold are connected with the analogous dualities associated with the
dynamical Riemann surface of the rigid theory. N=2 rigid gauge theories are
reviewed in a framework ready for comparison with the local case. As a
byproduct we give in general the full duality group (quantum monodromy) for an
arbitrary rigid gauge theory, extending previous explicit
constructions for the cases. In the coupling to gravity, R--symmetry
and monodromy groups of the dynamical Riemann surface, whose structure we
discuss in detail, are embedded into the symplectic duality group
associated with the moduli space of the dynamical Calabi--Yau threefold.Comment: Latex. Version of previous paper with enlarged and revised appendix
35 pages, plain LaTe
Projective Invariance and One-Loop Effective Action in Affine-Metric Gravity Interacting with Scalar Field
We investigate the influence of the projective invariance on the
renormalization properties of the theory. One-loop counterterms are calculated
in the most general case of interaction of gravity with scalar field.Comment: 10 pages, LATE
Particle creation, renormalizability conditions and the mass-energy spectrum in gravity theories of quadratic Lagrangians
Massive scalar particle production, due to the anisotropic evolution of a
five-dimensional spacetime, is considered in the context of a quadratic
Lagrangian theory of gravity. Those particles, corresponding to field modes
with non-vanishing momentum component along the fifth dimension, are created
mostly in the neighbourhood of a singular epoch where only their high-frequency
behaviour is of considerable importance. At the 1-loop approximation level,
general renormalizability conditions on the physical quantities relevant to
particle production are derived and discussed. Exact solutions of the resulting
Klein-Gordon field equation are obtained and the mass-energy spectrum
attributed to the scalar field due to the cosmological evolution is being
investigated further. Finally, analytic expressions regarding the number and
the energy density of the created particles at late times, are also derived and
discussed.Comment: LaTeX file, 23 page
Holographic c-theorems in arbitrary dimensions
We re-examine holographic versions of the c-theorem and entanglement entropy
in the context of higher curvature gravity and the AdS/CFT correspondence. We
select the gravity theories by tuning the gravitational couplings to eliminate
non-unitary operators in the boundary theory and demonstrate that all of these
theories obey a holographic c-theorem. In cases where the dual CFT is
even-dimensional, we show that the quantity that flows is the central charge
associated with the A-type trace anomaly. Here, unlike in conventional
holographic constructions with Einstein gravity, we are able to distinguish
this quantity from other central charges or the leading coefficient in the
entropy density of a thermal bath. In general, we are also able to identify
this quantity with the coefficient of a universal contribution to the
entanglement entropy in a particular construction. Our results suggest that
these coefficients appearing in entanglement entropy play the role of central
charges in odd-dimensional CFT's. We conjecture a new c-theorem on the space of
odd-dimensional field theories, which extends Cardy's proposal for even
dimensions. Beyond holography, we were able to show that for any
even-dimensional CFT, the universal coefficient appearing the entanglement
entropy which we calculate is precisely the A-type central charge.Comment: 62 pages, 4 figures, few typo's correcte