19 research outputs found
Quantum cosmology in the models of 2d and 4d dilatonic supergravity with WZ matter
We consider N=1 two-dimensional (2d) dilatonic supergravity (SG), 2d
dilatonic SG obtained by dimensional reduction from N=1 four-dimensional (4d)
SG, N=2 2d dilatonic SG and string-inspired 4d dilatonic SG. For all the
theories, the corresponding action on a bosonic background is constructed and
the interaction with (dilatonic) Wess-Zumino (WZ) multiplets is presented.
Working in the large-N approximation, it is enough to consider the trace
anomaly induced effective action due to dilaton-coupled conformal matter as a
quantum correction (for 2d models s-waves approximation is additionally used).
The equations of motion for all such models with quantum corrections are
written in a form convenient for numerical analysis. Their solutions are
numerically investigated for 2d and 4d Friedmann-Robertson-Walker (FRW) or 4d
Kantowski-Sacks Universes with a time-dependent dilaton via exponential dilaton
coupling. The evolution of the corresponding quantum cosmological models is
given for different choices of initial conditions and theory parameters. In
most cases we find quantum singular Universes. Nevertheless, there are examples
of Universe non-singular at early times. Hence, it looks unlikely that quantum
matter back reaction on dilatonic background (at least in large
approximation) may really help to solve the singularity problem.Comment: LaTeX file of the text (36 pages) and 3 ps files of 14 figures, few
misprints are corrected and references adde
Vacuum energy for the supersymmetric twisted D-brane in constant electromagnetic field
We calculate vacuum energy for twisted SUSY D-brane on toroidal background
with constant magnetic or constant electric field. Its behaviour for toroidal
D-brane (p=2) in constant electric field shows the presence of stable minimum
for twisted versions of the theory. That indicates such a background maybe
reasonable groundstate.Comment: LaTeX, 10 page
(Non) singular Kantowski-Sachs Universe from quantum spherically reduced matter
Using s-wave and large N approximation the one-loop effective action for 2d
dilaton coupled scalars and spinors which are obtained by spherical reduction
of 4d minimal matter is found. Quantum effective equations for reduced Einstein
gravity are written. Their analytical solutions corresponding to 4d
Kantowski-Sachs (KS) Universe are presented. For quantum-corrected Einstein
gravity we get non-singular KS cosmology which represents 1) quantum-corrected
KS cosmology which existed on classical level or 2)purely quantum solution
which had no classical limit. The analogy with Nariai BH is briefly mentioned.
For purely induced gravity (no Einstein term) we found general analytical
solution but all KS cosmologies under discussion are singular. The
corresponding equations of motion are reformulated as classical mechanics
problem of motion of unit mass particle in some potential V.Comment: LaTeX file, 16 pages, a few misprints are correcte
New two-loop contribution to electric dipole moment in supersymmetric theories
We calculate a new type of two-loop contributions to the electric dipole
moments of the electron and neutron in supersymmetric theories. The new
contributions are originated from the potential CP violation in the trilinear
couplings of the Higgs bosons to the scalar-top or the scalar-bottom quarks.
These couplings were previously very weakly constrained. The electric dipole
moments are induced through a mechanism analogous to that due to Barr and Zee.
We find observable effects for a sizeable portion of the parameter space
related to the third generation scalar-quarks in the minimal supersymmetric
standard model which cannot be excluded by earlier considerations.Comment: Erratum appended in the paper: EDM predictions are by a factor 2
larger than those given in the published versio
N = 3 chiral supergravity compatible with the reality condition and higher N chiral Lagrangian density
We obtain N = 3 chiral supergravity (SUGRA) compatible with the reality
condition by applying the prescription of constructing the chiral Lagrangian
density from the usual SUGRA. The chiral Lagrangian density in
first-order form, which leads to the Ashtekar's canonical formulation, is
determined so that it reproduces the second-order Lagrangian density of the
usual SUGRA especially by adding appropriate four-fermion contact terms. We
show that the four-fermion contact terms added in the first-order chiral
Lagrangian density are the non-minimal terms required from the invariance under
first-order supersymmetry transformations. We also discuss the case of higher N
theories, especially for N = 4 and N = 8.Comment: 20 pages, Latex, some more discussions and new references added, some
typos corrected, accepted for publication in Physical Review
Holographic Formulation of Quantum Supergravity
We show that supergravity with a cosmological constant can be
expressed as constrained topological field theory based on the supergroup
. The theory is then extended to include timelike boundaries with
finite spatial area. Consistent boundary conditions are found which induce a
boundary theory based on a supersymmetric Chern-Simons theory. The boundary
state space is constructed from states of the boundary supersymmetric
Chern-Simons theory on the punctured two sphere and naturally satisfies the
Bekenstein bound, where area is measured by the area operator of quantum
supergravity.Comment: 30 pages, no figur
Quantum geometry with intrinsic local causality
The space of states and operators for a large class of background independent
theories of quantum spacetime dynamics is defined. The SU(2) spin networks of
quantum general relativity are replaced by labelled compact two-dimensional
surfaces. The space of states of the theory is the direct sum of the spaces of
invariant tensors of a quantum group G_q over all compact (finite genus)
oriented 2-surfaces. The dynamics is background independent and locally causal.
The dynamics constructs histories with discrete features of spacetime geometry
such as causal structure and multifingered time. For SU(2) the theory satisfies
the Bekenstein bound and the holographic hypothesis is recast in this
formalism.Comment: Latex 33 pages, 7 Figure, epsfi
A Geometric Approach to CP Violation: Applications to the MCPMFV SUSY Model
We analyze the constraints imposed by experimental upper limits on electric
dipole moments (EDMs) within the Maximally CP- and Minimally Flavour-Violating
(MCPMFV) version of the MSSM. Since the MCPMFV scenario has 6 non-standard
CP-violating phases, in addition to the CP-odd QCD vacuum phase \theta_QCD,
cancellations may occur among the CP-violating contributions to the three
measured EDMs, those of the Thallium, neutron and Mercury, leaving open the
possibility of relatively large values of the other CP-violating observables.
We develop a novel geometric method that uses the small-phase approximation as
a starting point, takes the existing EDM constraints into account, and enables
us to find maximal values of other CP-violating observables, such as the EDMs
of the Deuteron and muon, the CP-violating asymmetry in b --> s \gamma decay,
and the B_s mixing phase. We apply this geometric method to provide upper
limits on these observables within specific benchmark supersymmetric scenarios,
including extensions that allow for a non-zero \theta_QCD.Comment: 34 pages, 16 eps figures, to appear in JHE
A candidate for a background independent formulation of M theory
A class of background independent membrane field theories are studied, and
several properties are discovered which suggest that they may play a role in a
background independent form of M theory. The bulk kinematics of these theories
are described in terms of the conformal blocks of an algebra G on all oriented,
finite genus, two-surfaces. The bulk dynamics is described in terms of causal
histories in which time evolution is specified by giving amplitudes to certain
local changes of the states. Holographic observables are defined which live in
finite dimensional states spaces associated with boundaries in spacetime. We
show here that the natural observables in these boundary state spaces are, when
G is chosen to be Spin(D) or a supersymmetric extension of it, generalizations
of matrix model coordinates in D dimensions. In certain cases the bulk dynamics
can be chosen so the matrix model dynamics is recoverd for the boundary
observables. The bosonic and supersymmetric cases in D=3 and D=9 are studied,
and it is shown that the latter is, in a certain limit, related to the matrix
model formulation of M theory. This correspondence gives rise to a conjecture
concerning a background independent form of M theory in terms of which
excitations of the background independent membrane field theory that correspond
to strings and D0 branes are identified.Comment: Latex 46 pages, 21 figures, new results included which lead to a
modification of the statement of the basic conjecture. Presentation improve
Introduction to supersymmetric spin networks
In this paper we give a general introduction to supersymmetric spin networks.
Its construction has a direct interpretation in context of the representation
theory of the superalgebra. In particular we analyze a special kind of spin
networks with superalgebra . It turns out that the set of
corresponding spin network states forms an orthogonal basis of the Hilbert
space \cal L\mit^2(\cal A\mit/\cal G), and this argument holds even in the
q-deformed case. The spin networks are also discussed briefly. We
expect they could provide useful techniques to quantum supergravity and gauge
field theories from the point of non-perturbative view.Comment: 27 pages, 16 eps figures. Based on the talk given at Marcel Grossmann
Meeting IX in Rom