Research Interests
In my research activity (mostly initiated when
I was at DAMTP -
University of Cambridge) I work
on Superstring Effects in Early Universe Scenarios.
The physical background is as follows. 10-dimensional superstring theory is one of the most promising candidates
for the ultimate theory of the quantum gravitational field, incorporating the
hope that quantum gravity is unified with the other fundamental interactions.
Five distinct consistent string
theories are known, related
by important transformation properties
denoted by S, T and U - dualities. It
now seems they can be interpreted
as different realisations of a deeper new theory called
M-theory, where 11-dimensional supergravity is also
present. This is indeed quite fascinating, opening new grounds
to explore, culminating (or leading) many of the new
theoretical developments in the XXth century into
new (often changing) borders. The status of
current research is so exciting that it may
suggestively remind the words of L. Wittgenstein:
"In order to draw a limit to thinking,
we should have to think both sides of that
limit", in: Tractatus Logico-Philosophicus (1961).
A natural arena where Superstring-Supergravity-M-theory
concepts may be tested is given
by early universe cosmology. Indeed,
early universe
cosmology should be re-examined in the context of Supergravity/Superstring theory
since
the field equations have a different structure from Einstein
equations. Moreover, symmetries of string theory provide an alternative
picture (with an higher dimensional spacetime).
In this context, part of my recent research has focused on
Quantum Cosmological Models in Superstring Theory and
M-Theory:
(See the mentioned papers for a more detailed
description of the achieved results, as well as
subsequently proposed new directions that are currently
being investigated)
- Employing
inhomogenous perturbations of the metric and dilaton fields, I have
searched for new
(quantum) states, which would have a physical significance regarding a period
of evolution from String/Supergravity cosmological physics towards a semi-classical
stage. In particular,
identifying the existence of any (quantum) state associated with
dilaton-inflation and to structure formation.
- Quite recently,
numerical simulations regarding inhomogenous cosmological models in string
cosmology have been investigated. However, they have not provided a full
agreement or a consistent scenario. My purpose is to further investigate these
models within the general scenario of
scalar-tensor theories, where the dilaton kinetic term is multiplied by a
constant factor.
- Pre Big-Bang cosmologies (extracted from string inspired theories)
quantized from the point of view of a de Broglie-Bohm approach
predict classical scenarios for small values of the
scale-factor, in contrast with conventional views of quantum cosmology.
I aim to further
investigated these systems in the presence of dilaton potentials and
extra spatial dimensions.
- DE BROGLIE-BOHM FRW UNIVERSES IN QUANTUM STRING COSMOLOGY,
by J. Marto and P. Vargas Moniz,
published in
Phys.Rev.D65:023516,2002
I have been analysing
the canonical and quantum cosmological implications of a spatially
flat, 4-D Friedmann-Robertson-Walker (FRW) model that is
derived from the M-theory effective action . Investigation
was
directed in studying whether and how
axions and form fields
influence a
four-dimensional FRW spacetime, first contracting from a strong coupling
regime
and then expanding to a weak coupling regime, while the internal space ever
contracts.
- I also became interested in
issues relating (A)dS stability and large extra dimensions.
For this purpose, a non-linear gravitational model with a
multidimensional warped product geometry and
quadratic scalar curvature terms was considered together
with p-form fields.
The 4--dimensional effective cosmological
constant as well as the bulk cosmological constant may become
negative or positive for actual times but more needs to be
investigated.
- ASYMPTOTICAL ADS FROM NONLINEAR GRAVITATIONAL MODELS WITH STABILIZED
EXTRA DIMENSIONS, by U. Gunther, P. Moniz and A. Zhuk,
published in
Phys.Rev.D66:044014,2002
- Actions of the Born-Infeld (BI) type have been the subject of wide
interest in the context of M/string theory. This comes
from the result that the effective action for the open string
ending on D-branes can be written in a BI form.
If either
string or brane effects are present, it can be expected that they may
bring modifications and elucidate on current problems.
Closed FRW models in the presence of a SO(N) gauge sector
described by a non-Abelian Born-Infeld action have been investigated.
Applications of Born-Infeld cosmology to early evolution,
quintessence and alpha-varying effects were
discussed recently by myself.
- QUINTESSENCE AND BORN-INFELD COSMOLOGY, by P. Vargas Moniz,
published in
Phys.Rev.D66:103501,2002
- FRW WORMHOLE INSTANTONS IN THE NONABELIAN BORN-INFELD THEORY,
by P. Vargas Moniz, published in
Phys.Rev.D66:064012,2002
- FRW QUANTUM COSMOLOGY IN THE NON-ABELIAN BORN-INFELD THEORY,
by P.V. Moniz, published in
Class.Quant.Grav.19:L127-L134,2002
- QUANTUM COSMOLOGICAL MULTIDIMENSIONAL EINSTEIN YANG-MILLS MODEL IN A R
X S3 X SD TOPOLOGY, by O. Bertolami, P.D. Fonseca and P.V. Moniz,
published in
Phys.Rev.D56:4530-4543,1997
- HOMOGENEOUS AND ISOTROPIC CLOSED COSMOLOGIES WITH A GAUGE SECTOR, by
P.V. Moniz and J.M. Mourao, published in
Class.Quant.Grav.8:1815-1832,1991
In addition, I have also investigated
quantum gravity, under the effects of matter, by
means of a scalar (spin-0) field. I have been
studying a wider range of situations, allowing for
the realistic presence
of
fermionic partners, within a supersymmetric context.
More specifically,
I have been focusing on the following
topic:
upersymmetric quantum cosmology (SQC)
(See the mentioned papers for a more detailed
description of the achieved results, as well as
subsequantly proposed new directions that are currently
being investigated)
- Examining how the presence of duality transformations
induces the existence of SUSY invariance. Previous studies involving FRW models
(that is, isotropic) have suggested N=2
SUSY. We will test this assertion towards a larger range by analysing Bianchi
models, which are not isotropic.
- Analysing Bianchi
models derived N=1 supergravity, where a fermionic
matter sector is explicitly present.
This an urgent and pertinent issue: previous results with other models and
different matter contents have pointed
instead to N=4 SUSY.
- QUANTIZATION OF THE BIANCHI TYPE IX MODEL IN SUPERGRAVITY WITH A
COSMOLOGICAL CONSTANT, by A.D.Y. Cheng, P.D. D'Eath, P.R.L.V. Moniz,
published in
Phys.Rev.D49:5246-5251,1994
- QUANTIZATION OF THE BIANCHI TYPE IX MODEL IN N=1 SUPERGRAVITY IN THE
PRESENCE OF SUPERMATTER, by P.V. Moniz, published
in
Int.J.Mod.Phys.A11:1763-1796,1996
-
Investigating the validity of minisuperspace
approximation in supersymmetric quantum cosmology: A minisuperspace
is a truncation in the inhomogenous modes of the field
variables. How does this affect a supersymmetric theory and what does
supersymmetry brings about as far as minisuperspace approach
is concerned?
- Addressing the existence of physical states in the
full theory
of N=1 supergravity (without truncations), namely
analysing a recent conjecture.
It seems only a wormhole state can be obtained in the
infinite fermionic sector but not a Hartle-Hawking
(no-boundary) solution.
- WAVE FUNCTION OF A SUPERSYMMETRIC FRW MODEL WITH VECTOR FIELDS, by
P.V. Moniz,
published in
Int.J.Mod.Phys.D6:465-478,1997
- SUPERSYMMETRIC QUANTUM COSMOLOGY: SHAKEN NOT STIRRED, by P.V. Moniz,
published in
Int.J.Mod.Phys.A11:4321-4382,1996
- IS THERE A PROBLEM WITH QUANTUM WORMHOLE STATES IN N=1 SUPERGRAVITY?, by P.V. Moniz,
published in
Gen.Rel.Grav.28:97-115,1996
- QUANTIZATION OF A FRIEDMANN-ROBERTSON-WALKER MODEL IN N=1 SUPERGRAVITY
WITH GAUGED SUPERMATTER, by A.D.Y. Cheng, P.D. D'Eath, P.R.L.V. Moniz,
published in
Class.Quant.Grav.12:1343-1354,1995
- Investigating the possibility of
constructing conserved currents in locally supersymmetric minisuperspaces.
- Investigating the scenario of spontaneous supersymmetry
breaking from a canonical quantization point of view: How does
the presence or absence of a potential influences the quantum
mechanical description (e.g., the wave function of the universe)
for a specific cosmomogical model?
More details of my current and forthcoming research activity
can be found here, where
the above mentioned and may other
original papers (with the journals site) are also
included.
Finally, I would like to stress I have received three prizes for research
in three international competitions/events:
-
Hounorable Mention for the work "Is there a problem with
quantum wormholes in N=1 Supergravity?" (author: P.V. Moniz), DAMTP report
R95/19, in
the 1995 Gravity Research Foundation Awards for Essays in Gravitation
-
Third Prize in the Poster competition at the
46-SUSSP NATO ASI -- General Relativity -- Aberdeen University,
July 16-29 1995, for the work
entitled "Why
Two makes it more exciting than One"
(authors: A.D.Y. Cheng and P. Moniz), DAMTP Report
-
Hounorable Mention for the work
"Origin of Structure in Supersymmetric Quantum Cosmology"
(author: P.V. Moniz), in
the 1997 Gravity Research Foundation Awards for Essays in Gravitation
As far as my research
aspirations are concerned, I have more information about my
research projects separately (found here!).
I would like
to stress my total commitment to continue my
research in quantum
gravity and cosmology, the physics
of the very early universe and structure formation.
These are indeed fascinating and active subjects with a plethora of
open issues, and where I wish to contribute enthusiastically.
My aspirations also include establishing more
contacts with other gravity groups, especially
in Europe, and starting or participating in the formation of Research Networks.
If you are a researcher with common or similar interests (at some point)
do contact me. Maybe we could produce a joint proposal to get some funding, as well
as produce some really interesting research papers.
And, yes, you are indeed quite
right! This is the cover of J. Saramago (1999 Literature
Nobel prize winner)
recent book "A CAVERNA" (The cave). As you can see, it is
signed by him(!), where he also
wrote To Paulo Monizand for the
ADS/CFT. For those eager to see what is ADS/CFT, what
possible relation to Plato, the cave and all that,
in view of avant-garde research in theoretical physics,
click
here
or there.
And
have fun!!!
Back to my homepage!