Results for "Renata Jora"

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About the mass corrections in an abelian Higgs modelMar 14 2016We study the corrections to the scalar boson mass in an abelian Higgs model by considering the global properties of the partition function. We find that although the two point function for the Higgs boson receives quantum corrections, the mass of the ... More
The abelian Higgs model and its phase transitions revisitedFeb 15 2015The abelian Higgs model and its phase structure are discussed from the perspective that the gauge and scalar fields admit a dual description in terms of fermion variables. The results which indicate the presence of three main phases: Coulomb, Higgs and ... More
Note about Yang Mills, QCD and their supersymmetric counterpartsJan 07 2011Apr 25 2011We analyze in an effective Lagrangian framework the connection between Super QCD (Super Yang Mills) and QCD (Yang Mills) by highlighting the crucial role that the zero modes play in the process of decoupling gluinos and squarks.
Vacuum energy in some particular quantum field theoriesFeb 19 2016We study the properties of a class of quantum field theories endowed with an equal number of anti commuting and commuting field variables, the most common example being the supersymmetric models. Based on the scaling properties of the partition function ... More
About the role of scalars in a gauge theoryOct 23 2013Dec 07 2013We consider a new effective symmetry that acts on a gauge invariant Lagrangian. We show that the standard model after spontaneous symmetry breakdown is invariant under this symmetry which identifies up to a scale factor the gauge parameter with the elementary ... More
A hint of a strong supersymmetric standard modelMar 15 2014We discuss the supersymmetric standard model from the perspective that the up and down Higgs supermultiplets are composite states. We show that a Higgs multiplet in which the scalar states are bound states of two squarks and the corresponding Higgsinos ... More
Naturalness in a simple two Higgs doublet modelFeb 26 2013Apr 19 2013We study the implications of a criterion of naturalness for a simple two Higgs doublet model in the context of the discovery of a Higgs like particle with a mass at 125 GeV. This condition which measures the amount of fine tuning further limits the parameter ... More
A semiclassical approach for the Higgs bosonSep 28 2014Starting from the equations of motion of the fields involved in a theory with spontaneous symmetry breaking and by making simple assumptions regarding their behavior we derive simple tree level relations between the mass of the Higgs boson in the theory ... More
Mass Ansatze for the standard model fermions from a composite perspectiveAug 26 2016Aug 29 2016We consider a composite model in which the standard model fermions are bound states of elementary spin $\frac{1}{2}$ particles, the preons, situated in the conjugate product representation of the color group. In this framework we propose and analyze two ... More
Do we need Feynman diagrams for higher orders perturbation theory?Feb 07 2012Jun 05 2012We compute the two and three loop corrections to the beta function for Yang-Mills theories in the background gauge field method and using the background gauge field as the only source. The calculations are based on the separation of the one loop effective ... More
Exotic MSSMJan 11 2013We present an exotic version of the MSSM with the same particle content but with some of the states with negative kinetic energies. We discuss how the model can work quantum mechanically and also resolve some of the pressing issues of the regular MSSM. ... More
About the particle structure and content of the standard modelOct 28 2015We determine the number and distribution of the fermion states in the standard model based on the possible fermion representations of the gauge bosons. By extracting the even parity scalars from the fermion states we suggest the existence of multiple ... More
Higgs boson mass from gauge invariant operatorsJul 07 2016Oct 31 2016We make the assumption that the vacuum correlators of the gauge invariant kinetic term of the Higgs doublet are the same before and after the spontaneous symmetry breaking of the theory. Based on this we determine the mass of the standard model Higgs ... More
Phase transitions for SU(N) gauge theories with arbitrary number of flavorsMay 27 2015Nov 28 2015We study the phase diagram of an $SU(N)$ gauge theory in terms of the number of colors $N$ and flavors $N_f$ with emphasis on the confinement and chiral symmetry breaking phases. We argue that as opposed to SUSY QCD there is a small region in the $(N,N_f)$ ... More
Higgs boson otherwiseMay 03 2009We propose an electroweak model based on the identification of the Higgs with the dilaton. We show that it is possible in this context to have a massless Higgs boson at tree and one loop levels without contradicting the main experimental and theoretical ... More
About the electroweak vacuum and its connection with the quark condensatesNov 11 2016We make a change of variable in the standard model Higgs field by a fermion operator and show that the latter is responsible for the electroweak vacuum. By computing the vacuum expectation value of this fermion operator in the path integral formalism ... More
About flavor, spin and colorApr 21 2010Aug 19 2010Chiral symmetry breaking (restoration) for SU(N) gauge theories is a topic of great interest and not yet fully explained. We consider the phenomenon as a collective spin effect and determine its behavior in terms of the number of flavors, N_f.
A nonperturbative method for the scalar field theoryMar 10 2014Jan 10 2015We compute an all order correction to the scalar mass in the \Phi^4 theory using a new method of functional integration adjusted also to the large couplings regime.
A theoretical estimate of the Higgs boson massAug 18 2012Using the invariance of the electroweak vacuum in the presence of a background Z field we estimate the mass of the Higgs boson in the standard model at m_H=125.9 GeV.
A nonperturbative method for QCDJun 22 2015Based on specific properties of the partition function and of the quantum correlators we derive the exact form of the beta function in the background gauge field method for QCD with an arbitrary number of flavors. The all order beta function we obtain ... More
$Φ^4$ theory is trivialMar 25 2015We prove that the $\Phi^4$ theory is trivial for any values of the bare coupling constant $\lambda$ thus extending previous results referring to very strong couplings to the full range of values for this parameter. The method is based on all order properties ... More
A nonperturbative method for the Yang Mills LagrangianNov 02 2014May 05 2015Using the properties of the partition function for a Yang Mills theory we compute simple relations among the renormalization constants. In the particular case of the background gauge field method we obtain that the all orders beta function for the gauge ... More
CP violating phases and a solution to the strong CP problemFeb 08 2018We present a solution to the strong CP problem based on the identification of the theta angle with twice the CP violating phase present in the CKM quark matrix. This solution washes out all the unwanted issues stemming form the strong CP phase and is ... More
Remark on pion scattering lengthsApr 14 2009Jul 29 2009First it is shown that the tree amplitude for pion pion scattering in the minimal linear sigma model has an exact expression which is proportional to a geometric series in the quantity (s-$m_\pi^2$)/($m_B^2-m_\pi^2$), where $m_B$ is the sigma mass which ... More
A semi perturbative method for QEDJul 23 2014We compute the QED beta function using a new method of functional integration. It turns out that in this procedure the beta function contains only the first two orders coefficients and thus corresponds to a new renormalization scheme, long time supposed ... More
Note about the implementation of finite symmetries in the lepton sectorMar 15 2013Dec 09 2013Assuming that the leptonic mixing matrix is given in first approximation by the tribimaximal form we deduce some consequences with regard to the finite symmetries that may be applied in the minimal lepton sector of the electroweak theory.
Spontaneous symmetry breaking and Goldstone theorem for composite states revisitedJul 05 2016We discuss the well-known phenomenon of spontaneous symmetry breaking for a linear sigma model for scalar and pseudoscalar mesons based on the meson composite structure and the normalization of the quantum states. To test our formulation and validate ... More
Examining a possible cascade effect in chiral symmetry breakingAug 29 2016We examine a toy model and a cascade effect for confinement and chiral symmetry breaking which consists in several phase transitions corresponding to the formation of bound states and chiral condensates with different number of fermions for a strong group. ... More
Note on the standard model as an effective theoryOct 28 2015We present a criterion of consistency derived from the analogy between the partition function of a quantum field theory and that of a statistical system. Based on this we examine a new class of higher dimension operators that might act in the standard ... More
A purely quark Lagrangian from QCDSep 20 2015We present a method for determining a purely quark Lagrangian by mocking up the QCD partition function for large gauge couplings $g$. The resulting effective theory displays all the symmetries of low energy QCD and can be potentially used to explore hadron ... More
A solution to the naturalness problemMay 30 2015We present a solution to the naturalness problem of the electroweak scale based on a change of variable in the Fourier space of non supersymmetric nature that transforms a boson into a fermion and viceversa. This is exemplified for that part of the standard ... More
Naturally perturbed S$_3$ neutrinosOct 25 2012Apr 07 2013We simplify and extend our previous model for the masses and mixing matrix of three Majorana neutrinos based on permutation symmetry $S_3$ and the perturbations which violate this symmetry. The perturbations are arranged such that we get the smaller solar ... More
Doubly perturbed $S_3$ neutrinos and the $s_{13}$ mixing parameterJun 16 2010We further study a predictive model for the masses and mixing matrix of three Majorana neutrinos. At zeroth order the model yielded degenerate neutrinos and a generalized ``tribimaximal" mixing matrix. At first order the mass splitting was incorporated ... More
Perturbed S3 neutrinosSep 24 2009Dec 16 2010We study the effects of the perturbation which violates the permutation symmetry of three Majorana neutrinos but preserves the well known (23) interchange symmetry. This is done in the presence of an arbitrary Majorana phase which serves to insure the ... More
Low energy scattering with a nontrivial pionAug 24 2007An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark ... More
Toy model for two chiral nonetsJun 16 2005Jul 27 2005Motivated by the possibility that nonets of scalar mesons might be described as mixtures of "two quark" and "four quark" components, we further study a toy model in which corresponding chiral nonets (containing also the pseudoscalar partners) interact ... More
Exploration of a physical picture for the QCD scalar channelOct 25 2008A generalized linear sigma model is employed to study the quark structure of low lying scalar as well as pseudoscalar states. The model allows the possible mixing of quark anti-quark states with others made of two quarks and two antiquarks but no a priori ... More
Model for light scalars in QCDDec 15 2006Jun 12 2007We propose a systematic procedure to study a generalized linear sigma model which can give a physical picture of possible mixing between $q{\bar q}$ and $qq{\bar q}{\bar q}$ low lying spin zero states. In the limit of zero quark masses, we derive the ... More
Two chiral nonet model with massless quarksJul 05 2007We present a detailed study of a linear sigma model containing one chiral nonet transforming under U(1)$_A$ as a quark-antiquark composite and another chiral nonet transforming as a diquark-anti diquark composite (or, equivalently from a symmetry point ... More
An analytical treatment of the neutrino masses and mixingsApr 30 2013Dec 09 2013We obtain analytical formulas which connect the neutrino masses and the leptonic mixing matrix with the entries in the mass matrix for the approximation in which the charged lepton mixing matrix is the unit matrix. We also extract the CP violation phase ... More
Note about lepton masses and mixings in two AnsatzeDec 09 2013We consider two Ansatze for the neutrino masses and mixings in which the permutation symmetry is implemented in various orders. We discuss the possible see-saw mechanisms and the charged lepton masses for the two cases in the presence of a Higgs triplet ... More
An approach to permutation symmetry for the electroweak theoryMay 06 2006Sep 08 2006The form of the leptonic mixing matrix emerging from experiment has, in the last few years, generated a lot of interest in the so-called tribimaximal type. This form may be naturally associated with the possibility of a discrete permutation symmetry ($S_3$) ... More
How important is $iε$ in QFT?Feb 28 2015May 25 2015We discuss the role of $i\epsilon$ in quantum field theories and suggest that it can be identified with the dimensional regularization parameter $i\epsilon=4-d$ thus clarifying and simplifying issues related to the infrared divergences without altering ... More
Tree level relations in a composite electroweak theoryJul 24 2014Nov 02 2014We work out simple tree level relations in a top condensate model with dynamical electroweak symmetry breaking. We find that in this picture the mass of the composite Higgs boson at tree level is given by $m_H^2=\frac{m_t^2}{2}$ where $m_t$ is the mass ... More
Note on a sigma model connection with instanton dynamicsJan 16 2008Feb 01 2008It is well known that the instanton approach to QCD generates an effective term which looks like a three flavor determinant of quark bilinears. This has the right behavior to explain the unusual mass and mixing of the $\eta(958)$ meson, as is often simply ... More
Generalized Sigma Model Description of the Light J=0 MesonsJan 26 2006Within a linear sigma model framework, possible mixing between two chiral nonets (a two quark nonet, and a four quark nonet) below 2 GeV is studied. Incorporating the U(1)$_A$ behavior of the underlying QCD, and working in the isospin invariant limit, ... More
Quark and glue spectroscopy of scalars and pseudoscalars in SU(3) flavor limitOct 24 2018Within the framework of the generalized linear sigma model with glueballs recently proposed [1,2], we study the schematic spectroscopy of scalar and pseudoscalar mesons in the SU(3) flavor limit and explore their quark and glue contents. In this framework, ... More
Light Scalar Puzzle in QCDMay 25 2010An approach to understanding the light scalar meson phenomenology is briefly reviewed.
Global aspects of the scalar meson puzzleFeb 17 2009A generalized linear sigma model for low energy QCD is employed to study the quark structure of eight low lying scalar isomultiplets as well as eight low lying pseudoscalar isomultiplets. The model, building on earlier work, assumes the possible mixing ... More
Scalar mesons from an effective Lagrangian approachNov 14 2007Jan 16 2008A brief discussion of the recent interest in light scalar mesons motivates the study of a generalized linear sigma model. In an SU(3) flavor invariant version of the model there is a prediction that the the lighter scalars have sizeable "four quark" content. ... More
A top condensate model with a Higgs doublet and a Higgs tripletApr 26 2013We reconsider top condensate models from the perspective that not only two quark composite fields can form but also four quark ones. We obtain a model which contains a Higgs doublet and a Higgs triplet, where one of the neutral components of the Higgs ... More
Why are there three generations of fermions in the standard model?Dec 24 2014We show that by decomposing the gauge fields in fermion degrees of freedom and by saturating the remaining degrees of freedom as dynamical fields in the Lagrangian one might explain the proliferation of fermion states in the standard model Lagrangian. ... More
Are three flavors special?Dec 22 2010It has become clearer recently that the regular pattern of three flavor nonets describing the low spin meson multiplets seems to require some modification for the case of the spin 0 scalar mesons. One picture which has had some success, treats the scalars ... More
A hierarchy of the quark masses in a top condensate model with multiple HiggsesOct 07 2013Mar 06 2014We discuss the quark masses in a top condensate model where not only two quark but also four quark composite states may exist. We show that the presence of the top color group SU(3)_1\times SU(3)_2 with the correct non anomalous quark representations ... More
Semi-leptonic $D_s^+$(1968) decays as a scalar meson probeAug 17 2011The unusual multiplet structures associated with the light spin zero mesons have recently attracted a good deal of theoretical attention. Here we discuss some aspects associated with the possibility of getting new experimental information on this topic ... More
Chiral Nonet Mixing in pi pi ScatteringJun 22 2011Pion pion scattering is studied in a generalized linear sigma model which contains two scalar nonets (one of quark-antiquark type and the other of diquark-antidiquark type) and two corresponding pseudoscalar nonets. An interesting feature concerns the ... More
Probing scalar mesons in semi-leptonic decays of $D_s^+$, $D^+$ and $D^0$Jul 27 2014With the primary motivation of probing the quark substructure of scalar mesons, a generalized linear sigma model for the lowest and the next-to-lowest scalar and pseudoscalar mesons is employed to investigate several semi-leptonic decays of $D$ mesons. ... More
An Update on Perturbative N=8 SupergravityDec 22 2014According to the recent pure spinor analysis of the UV divergences by Karlsson, there are no divergent 1PI structures beyond 6 loops in D=4 N=8 supergravity. In combination with the common expectation that the UV divergences do not appear at less than ... More
On solving the densest $k$-subgraph problem on large graphsJan 18 2019The densest $k$-subgraph problem is the problem of finding a $k$-vertex subgraph of a graph with the maximum number of edges. In order to solve large instances of the densest $k$-subgraph problem, we introduce two algorithms that are based on the random ... More
Matter-coupled de Sitter SupergravitySep 07 2015De Sitter supergravity describes interaction of supergravity with general chiral and vector multiplets as well as one nilpotent chiral multiplet. The extra universal positive term in the potential due to the nilpotent multiplet, corresponding to the anti-D3 ... More
The Ultraviolet Finiteness of N=8 SupergravitySep 06 2010Nov 03 2010We study counterterms (CT's), candidates for UV divergences in the four-dimensional N=8 supergravity. They have been constructed long ago in a Lorentz covariant on shell superspace and recently in the chiral light-cone (LC) superspace. We prove that all ... More
On a possibility of a UV finite N=8 supergravityAug 18 2008Nov 15 2008The Lorentz covariant all-loop counterterms built in the 4+32 on shell superspace of N=8 supergravity imply that the theory is not UV finite. Meanwhile, the relevant counterterms depending on the light-cone superfields in 4+16 superspace have not been ... More
On Absence of 3-loop Divergence in N=4 SupergravityFeb 21 2012We argue that N=4 supergravity is 3-loop UV finite because the relevant supersymmetric candidate counterterm is known to be SL(2, R)x SO(6) invariant, which violates the Noether-Gaillard-Zumino current conservation. Analogous arguments, based on the universality ... More
N=8 Counterterms and E7(7) Current ConservationApr 28 2011We examine conservation of the E7(7) Noether-Gaillard-Zumino current in the presence of N=8 supergravity counterterms using the momentum space helicity formalism, which significantly simplifies the calculations. The main result is that the 4-point counterterms ... More
Worldvolume SupersymmetrySep 09 1997A general set of rules is given how to convert a local kappa-symmetry of a brane action and space-time supersymmetry into the global supersymmetry of the worldvolume. A Killing spinor adapted gauge for quantization of kappa-symmetry is defined for this ... More
From BPS to Non-BPS Black Holes CanonicallyMar 01 2006We describe the ``action-angle'' integrable system underlying the structure of double-extremal black holes. This implies the existence of a canonical transformation from BPS to non-BPS black holes. We give examples of such canonical transformation for ... More
N=2 Supersymmetry and de Sitter spaceSep 21 2001Oct 31 2001We present a (unique?) possibility of de Sitter solution in the framework of N=2 supersymmetry (hypersymmetry). We show that a model with a vector and a charged hypermultiplet has a hybrid inflation type potential. It leads to a slow-roll regime in de ... More
Graph bisection revisitedNov 22 2016The graph bisection problem is the problem of partitioning the vertex set of a graph into two sets of given sizes such that the sum of weights of edges joining these two sets is optimized. We present a semidefinite programming relaxation for the graph ... More
Nonlinear (Super)Symmetries and AmplitudesSep 28 2016There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were ... More
Nonlinear (Super)Symmetries and AmplitudesSep 28 2016Nov 29 2016There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were ... More
An Implementation, Empirical Evaluation and Proposed Improvement for Bidirectional Splitting Method for Argumentation Frameworks under Stable SemanticsAug 11 2018Abstract argumentation frameworks are formal systems that facilitate obtaining conclusions from non-monotonic knowledge systems. Within such a system, an argumentation semantics is defined as a set of arguments with some desired qualities, for example, ... More
Simple two Higgs doublet modelMay 02 2008Jul 23 2009We study a simple two Higgs doublet model which reflects, in a phenomenological way, the idea of compositeness for the Higgs sector. It is relatively predictive. In one scenario, it allows for a "hidden" usual Higgs particle in the 100 GeV region and ... More
A note on large N scalar QCD_2Dec 03 2008We review the features of the bound state equation in large N scalar QCD in two dimensions, the 't Hooft model, and compute the discrete hadron mass spectrum in this theory. We make the Ansatz that the scalar fields of this model represent spin zero diquarks ... More
Noise and Dissipation During PreheatingJul 27 2002We study the consequences of noise and dissipation for parametric resonance during preheating. The effective equations of motion for the inflaton and the radiation field are obtained and shown to present self-consistent noise and dissipation terms. The ... More
Cosmological Attractor Models and Higher Curvature SupergravityMar 12 2014We study cosmological $\alpha$-attractors in superconformal/supergravity models, where $\alpha$ is related to the geometry of the moduli space. For $\alpha=1$ attractors \cite{Kallosh:2013hoa} we present a generalization of the previously known manifestly ... More
Non-minimal Inflationary AttractorsJul 30 2013Sep 08 2013Recently we identified a new class of (super)conformally invariant theories which allow inflation even if the scalar potential is very steep in terms of the original conformal variables. Observational predictions of a broad class of such theories are ... More
Obstruction to E_{7(7)} Deformation in N=8 SupergravityMar 14 2013Candidate counterterms break Noether-Gaillard-Zumino E_{7(7)} current conservation in N=8 supergravity in four dimensions. Bossard and Nicolai proposed a scheme for deforming the subsector involving vector fields in a Lorentz covariant manner, so as to ... More
Event shape sortingJun 22 2015Mar 31 2016We propose a novel method for sorting events of multiparticle production according to the azimuthal anisotropy of their momentum distribution. Although the method is quite general, we advocate its use in analysis of ultra-relativistic heavy-ion collisions ... More
Calibrations and isoperimetric profilesJan 07 2007We equip many non compact non simply connected surfaces with smooth Riemannian metrics whose isoperimetric profile is smooth, a highly non generic property. The computation of the profile is based on a calibration argument, a rearrangement argument, the ... More
Multiple periodic solutions to a discrete p(k)- Laplacian problemNov 07 2013We investigate the existence of multiple periodic solutions to the anisotropic discrete system. We apply the linking method and a new three critical point theorem which we provide.
Escher in the SkyMar 23 2015May 05 2015The cosmological models called $\alpha$-attractors provide an excellent fit to the latest observational data. Their predictions $n_{s} = 1-2/N$ and $r = 12\alpha/N^{2}$ are very robust with respect to the modifications of the inflaton potential. An intriguing ... More
Hidden Superconformal Symmetry of the Cosmological EvolutionNov 13 2013Jan 08 2014In the superconformal formulation of supergravity, the standard supergravity action appears as a result of spontaneous symmetry breaking when the conformal compensator scalar field, the conformon, acquires a nonzero value, giving rise to the Planck mass. ... More
Multi-field Conformal Cosmological AttractorsSep 08 2013We describe a broad class of multi-field inflationary models with spontaneously broken conformal invariance. It generalizes the recently discovered class of cosmological attractors with a single inflaton field. In the new multi-field theories, just as ... More
A polynomial time algorithm for the linearization problem of the QSPP and its applicationsFeb 07 2018Given an instance of the quadratic shortest path problem (QSPP) on a digraph $G$, the linearization problem for the QSPP asks whether there exists an instance of the linear shortest path problem on $G$ such that the associated costs for both problems ... More
Event shape analysis in ultrarelativistic nuclear collisionsMar 16 2016We present a novel method for sorting events. So far, single variables like flow vector magnitude were used for sorting events. Our approach takes into account the whole azimuthal angle distribution rather than a single variable. This method allows us ... More
Simple Sinflaton-less $α$-attractorsJan 25 2019We construct the simplest inflationary $\alpha$-attractor models in supergravity: it has only one scalar, the inflaton. There is no sinflaton since the inflaton belongs to an orthogonal nilpotent superfield where the sinflaton depends on fermion bilinears. ... More
Universality Class in Conformal InflationJun 21 2013Sep 08 2013We develop a new class of chaotic inflation models with spontaneously broken conformal invariance. Observational consequences of a broad class of such models are stable with respect to strong deformations of the scalar potential. This universality is ... More
Superconformal generalizations of the Starobinsky modelJun 13 2013Jun 19 2013We find a way to represent the Starobinsky model in terms of a simple conformally invariant theory with spontaneous symmetry breaking. We also present a superconformal theory, which, upon spontaneous breaking of the superconformal symmetry, provides a ... More
Light-by-Light Scattering Effect in Light-Cone SupergraphsJun 24 2010We give a relatively simple explanation of the light-cone supergraph prediction for the UV properties of the maximally supersymmetric theories. It is based on the existence of a dynamical supersymmetry which is not manifest in the light-cone supergraphs. ... More
De Sitter Supergravity Model BuildingSep 07 2015We present the explicit de Sitter supergravity action describing the interaction of supergravity with an arbitrary number of chiral and vector multiplets as well as one nilpotent chiral multiplet. The action has a non-Gaussian dependence on the auxiliary ... More
A Landesman-Lazer type result for periodic parabolic problems on $\mathbb{R}^N$ at resonanceOct 13 2014Nov 17 2014We are concerned with $T$-periodic solutions of nonautonomous parabolic problem of the form $u_t = \Delta u + V(x) u + f(t,x,u)$, $t >0$, $x \in \mathbb{R}^N$, with $V \in L^\infty (\mathbb{R}^N)+L^p(\mathbb{R}^N)$, $p \geq N$ and $T$-periodic continuous ... More
M-theory, Cosmological Constant and Anthropic PrincipleAug 21 2002Nov 08 2002We discuss the theory of dark energy based on maximally extended supergravity and suggest a possible anthropic explanation of the present value of the cosmological constant and of the observed ratio between dark energy and energy of matter.
Testing String Theory with CMBApr 05 2007Future detection/non-detection of tensor modes from inflation in CMB observations presents a unique way to test certain features of string theory. Current limit on the ratio of tensor to scalar perturbations, r=T/S, is r < 0.3, future detection may take ... More
Supersymmetry and the Brane WorldJan 11 2000Feb 07 2000We investigate the possibility of gravity localization on the brane in the context of supersymmetric theories. To realize this scenario one needs to find a theory with the supersymmetric flow stable in IR at two critical points, one with positive and ... More
Black Hole Superpartners and Fixed ScalarsNov 21 1996Some bosonic solutions of supergravities admit Killing spinors of unbroken supersymmetry. The anti-Killing spinors of broken supersymmetry can be used to generate the superpartners of stringy black holes. This has a consequent feedback on the metric and ... More
Brane-anti-brane DemocracyApr 30 1996We suggest a duality invariant formula for the entropy and temperature of non-extreme black holes in supersymmetric string theory. The entropy is given in terms of the duality invariant parameter of the deviation from extremality and 56 SU(8) covariant ... More
O(6,22) BPS Configurations of the Heterotic StringSep 19 1995We present a static multi-center magnetic solution of toroidally compactified heterotic string theory, which is T-duality covariant. The space-time geometry depends on the mass M and on the O(6,22)-norm N of the magnetic charges. For different range of ... More
Charge Quantization of Axion-Dilaton Black HolesFeb 23 1993We present axion-dilaton black-hole and multi-black-hole solutions of the low-energy string effective action. Under $SL(2,R)$ electric-magnetic duality rotations only the ``hair" (charges and asymptotic values of the fields) of our solutions is transformed. ... More
E(7) Symmetric Area of the Black Hole HorizonFeb 05 1996Feb 15 1996Extreme black holes with 1/8 of unbroken N=8 supersymmetry are characterized by the non-vanishing area of the horizon. The central charge matrix has four generic eigenvalues. The area is proportional to the square root of the invariant quartic form of ... More
Bounded geometry, growth and topologyAug 28 2010We characterize functions which are growth types of Riemannian manifolds of bounded geometry.