Dynamics of warped compactifications and the shape of the warped landscape

The dynamics of warped/flux compactifications is studied, including warping effects, providing a firmer footing for investigation of the "landscape." We present a general formula for the four-dimensional potential of warped compactifications in terms of ten-dimensional quantities. This allows a systematic investigation of moduli-fixing effects and potentials for mobile branes. We provide a necessary criterion, "slope-dominance," for evading "no-go" results for de Sitter vacua. We outline the ten-dimensional derivation of the non-perturbative effects that should accomplish this in KKLT examples, and outline a systematic discussion of their corrections. We show that potentials for mobile branes receive generic contributions inhibiting slow-roll inflation. We give a linearized analysis of general scalar perturbations of warped IIB compactifications, revealing new features for both time independent and dependent moduli, and new aspects of the kinetic part of the four-dimensional effective action. The universal Kahler modulus is found_not_ to be a simple scaling of the internal metric, and a prescription is given for defining holomorphic Kahler moduli, including warping effects. In the presence of mobile branes, this prescription elucidates couplings between bulk and brane fields. Our results are thus relevant to investigations of the existence of de Sitter vacua in string theory, and of their phenomenology, cosmology, and statistics.Comment: (80 pages; two appendices; harvmac. v3: minor corrections, and references added. v4: argument that pure Kahler deformations are flat.

Gauged supergravity from dimensional reduction

We perform a generalised Scherk-Schwarz reduction of the effective action of the heterotic string on T6 to obtain a massive N = 4 supergravity theory in four dimensions. The local symmetry-group of the resulting d = 4 theory includes a Heisenberg group, which is a subgroup of the global 0(6,6 + n) obtained in the standard reduction. We show explicitly that the same theory can be obtained by gauging this Heisenberg group in d = 4, N = 4 supergravity.

Flux vacua with approximate flat directions

We present a novel method to obtain type IIB flux vacua with flat directions at tree level. We perform appropriate choices of flux quanta that induce relations between the flux superpotential and its derivatives. This method is implemented in toroidal and Calabi-Yau compactifications in the large complex structure limit. Explicit solutions are obtained and classified on the basis of duality equivalences. In the toroidal case we present solutions with N = 1 and N = 2 supersymmetry and arbitrarily weak coupling. In Calabi-Yaus we find novel perturbatively flat vacua, as well as solutions with non-zero flux superpotential and an axionic flat direction which represent a promising starting point for de Sitter constructions from non-zero F-terms in the complex structure sector. The higher order (perturbative and non-perturbative) effects that can lift these flat directions are discussed. We also outline applications in a wide variety of settings involving the classical Regge growth conjecture, inflation and quintessence, supersymmetry breaking and F-term de Sitter uplifting

Recent developments in quantum string cosmology

In this talk we discuss the quantisation of a class of string cosmology models characterised by scale factor duality invariance. The amplitudes for the full set of classically allowed and forbidden transitions are computed by applying the reduced phase space and path integral methods. In particular, the path integral calculation clarifies the meaning of the instanton-like behaviour of the transition amplitudes that has been first pointed out in previous investigations.Comment: 4 pages, one eps figures, uses espcrc2.sty. Talk given at the Third Conference on Constrained Dynamics and Quantum Gravit

Gravitational effects in ultrahigh-energy string scattering

Ultrahigh-energy string scattering is investigated to clarify the relative role of string and gravitational effects, and their possible contributions to nonlocal behavior. Different regimes can be characterized by varying the impact parameter at fixed energy. In the regime where momentum transfers reach the string scale, string effects appear subdominant to higher-loop gravitational processes, approximated via the eikonal. At smaller impact parameters, "diffractive" or "tidal" string excitation leads to processes dominated by highly excited strings. However, new evidence is presented that these excitation effects do not play a direct role in black hole formation, which corresponds to breakdown of gravitational perturbation theory and appears to dominate at sufficiently small impact parameters. The estimated amplitudes violate expected bounds on high-energy behavior for local theories.Comment: 19 pages, harvmac. v2: fixed typos, added refs and discussion of longitudinal spread. v3: minor changes to agree with published versio

Particle Spectrum of the Supersymmetric Standard Model from the Massless Excitations of a Four Dimensional Superstring

A superstring action is quantised with Neveu Schwarz(NS) and Ramond(R) boundary conditions. The zero mass states of the NS sector are classified as the vector gluons, W-mesons, $B_{\mu}$-mesons and scalars containing Higgs. The fifteen zero mass fermions are obtained from the Ramond sector. A space time supersymmetric Hamiltonian of the Standard Model is presented without any conventional SUSY particles

Boosting Away Singularities from Conformal String Backgrounds

Generalizing our previous work, we show how $O(d,d)$ transformations can be used to "boost away" in new dimensions the physical singularities that occur generically in cosmological and/or black-hole string backgrounds. As an example, we show how a recent model by Nappi and Witten can be made singularity-free via $O(3,3)$ boosts involving a fifth dimension.Comment: 11 pages, CERN-TH.6634/9

ANTI-HYPERGLYCEMIC EFFECT OF DIFFERENT FRACTIONS OF ANNONA RETICULATA LEAF

ABSTRACTContext: Several species of the genus Annona were reported to have hypoglycemic properties and this makes Annona reticulata Linn. (Annonaceae)an interesting plant for investigating its anti-hyperglycemic potential.Objective: Different fractions prepared from hydro-alcoholic extract of A. reticulata leave were investigated for their blood glucose lowering effect onStreptozotocin (STZ) induced hyperglycemic rats.Methods: Ethyl acetate, methanol, and residual fractions (at dose level of 100 mg/kg by oral route) prepared from the hydro-alcoholic extract ofA. reticulata leave were administered for 14 consecutive days to STZ induced hyperglycemic rats for evaluation of their anti-hyperglycemic potential.Anti-hyperglycemic potential was assessed by observation of a decrease in fasting blood glucose level.Results: The studies revealed that ethyl acetate fraction decreased the blood glucose level of hyperglycemic rats from 447.67 to 234.17 mg/dL and issignificant (p<0.001) when compared with diabetic control group. The residual fraction and methanolic fraction decreased blood glucose level from417.83 to 402.50 mg/dL and 432.33 to 371.67 mg/dL respectively but not significant when compared with the diabetic control group. Standard drugmetformin (dose 300 mg/kg) reduced the blood glucose level from 447.33 to 219.50 mg/dL.Discussion: Ethyl acetate fraction at tested dose level was capable not only to control the elevated blood glucose level but also able to attenuatecertain secondary parameters associated with STZ induced hyperglycemia.Conclusion: This study suggested that the ethyl acetate fraction prepared from hydro-alcoholic extract of A. reticulata leave exhibit potential antihyperglycemicpropertyin the testedexperimentalmodels and should be investigatedfurther.Keywords: Streptozotocin, Diabetes, Dyslipidemia

Black Holes and U-Duality

We find the general charged rotating black hole solutions of the maximal supergravities in dimensions $4\le D\le 9$ arising from toroidally compactified Type II string or M-theories. In each dimension, these are obtained by acting on a generating solution with classical duality symmetries. In D=4, D=5 and $6\le D \le 9$ the generating solution is specified by the ADM mass, $[{D-1}/2]$-angular momentum components and five, three and two charges, respectively. We discuss the BPS-saturated (static) black holes and derive the U-duality invariant form of the area of the horizon. We also comment on the U-duality invariant form of the BPS mass formulae.Comment: Minor corrections. Version to appear in Nuclear Physics

Entropy of Non-Extreme Charged Rotating Black Holes in String Theory

We give the explicit expression for four-dimensional rotating charged black hole solutions of N=4 (or N=8) superstring vacua, parameterized by the ADM mass, four charges (two electric and two magnetic charges, each arising from a different U(1) gauge factors), and the angular momentum (as well as the asymptotic values of four toroidal moduli of two-torus and the dilaton-axion field). The explicit form of the thermodynamic entropy is parameterized in a suggestive way as a sum of the product of the `left-moving' and the `right-moving' terms, which may have an interpretation in terms of the microscopic degrees of freedom of the corresponding D-brane configuration. We also give an analogous parameterization of the thermodynamic entropy for the recently obtained five-dimensional rotating charged black holes parameterized by the ADM mass, three U(1) charges and two rotational parameters (as well as the asymptotic values of one toroidal modulus and the dilaton).Comment: 14 pages, uses RevTex, the revised version with minor corrections to appear in Phys. Rev.