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Particle filter efficiency under limited communicationApr 21 2019Sequential Monte Carlo (SMC) methods are typically not straightforward to implement on parallel architectures. This is because standard resampling schemes involve communication between all particles in the system. In this article, we consider the $\alpha$-SMC ... More

Efficient posterior sampling for high-dimensional imbalanced logistic regressionMay 27 2019High-dimensional data are routinely collected in many application areas. In this article, we are particularly interested in classification models in which one or more variables are imbalanced. This creates difficulties in estimation. To improve performance, ... More

On Coupling Particle Filter TrajectoriesJun 03 2016Mar 16 2017Particle filters are a powerful and flexible tool for performing inference on state-space models. They involve a collection of samples evolving over time through a combination of sampling and re-sampling steps. The re-sampling step is necessary to ensure ... More

On Coupling Particle Filter TrajectoriesJun 03 2016Particle filtering is a powerful and flexible tool to deal with state-space models. They involve a collection of particles evolving over time through a combination of sampling and re-sampling steps. The re-sampling step is necessary to ensure that weight ... More

Some Contributions to Sequential Monte Carlo Methods for Option PricingAug 11 2016Pricing options is an important problem in financial engineering. In many scenarios of practical interest, financial option prices associated to an underlying asset reduces to computing an expectation w.r.t.~a diffusion process. In general, these expectations ... More

Bayesian inferences on uncertain ranks and orderingsJul 10 2019It is common to be interested in rankings or order relationships among entities. In complex settings where one does not directly measure a univariate statistic upon which to base ranks, such inferences typically rely on statistical models having entity-specific ... More

On Testing Independence and Goodness-of-fit in Linear ModelsFeb 23 2013May 05 2014We consider a linear regression model and propose an omnibus test to simultaneously check the assumption of independence between the error and the predictor variables, and the goodness-of-fit of the parametric model. Our approach is based on testing for ... More

On extending Soulé's variant of Bloch-Quillen identificationApr 14 2016Based on Balmer's tensor triangular Chow group [2], we propose (Milnor)K-theoretic Chow groups of derived categories of schemes. These Milnor K-theoretic Chow groups recover the classical ones [6] for smooth projective varieties and can detect nilpotent, ... More

Deformation theory of K-theoretic cyclesMar 03 2016Sep 30 2016By using higher K-theory, we study deformation theory of K-theoretic cycles. As an application, we answer affirmatively two questions posed by Mark Green and Philip Griffiths: (1). How to define tangent spaces to algebraic cycles in general? (2). Obstruction ... More

Observations and Open Questions in Beam-Beam InteractionFeb 11 2011A review article on the physics of beam-beam interactions in circular colliders.

On Kernel of the regulator mapJun 10 2016Jan 05 2017By using the infinitesimal methods due to Bloch, Green and Griffiths, we construct an infinitesimal form of the regulator map and verify that its kernel is $\Omega^{1}_{\mathbb{C}/\mathbb{Q}}$, which suggests Question 1.1 seems reasonable at the infinitesimal ... More

Prikry-type forcing and minimal $α$-degreeOct 03 2013In this paper, we introduce several classes of Prikry-type forcing notions, two of which are used to produce minimal generic extensions, and the third is applied in $\alpha$-recursion theory to produce minimal covers. The first forcing as a warm up yields ... More

A Survey on Security and Privacy Protocols for Cognitive Wireless Sensor NetworksAug 03 2013Wireless sensor networks have emerged as an important and new area in wireless and mobile computing research because of their numerous potential applications that range from indoor deployment scenarios in home and office to outdoor deployment in adversary's ... More

Security and Privacy Issues in Wireless Mesh Networks: A SurveyFeb 05 2013This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different ... More

A Robust and Efficient Node Authentication Protocol for Mobile Ad Hoc NetworksDec 31 2010A mobile ad hoc network (MANET) is a collection of mobile nodes that communicate with each other by forming a multi-hop radio network. Security remains a major challenge for these networks due to their features of open medium, dynamically changing topologies, ... More

A Survey on Reputation and Trust-Based Systems for Wireless Communication NetworksDec 12 2010Traditional approach of providing network security has been to borrow tools and mechanisms from cryptography. However, the conventional view of security based on cryptography alone is not sufficient for the defending against unique and novel types of ... More

A Survey on Wireless Sensor Network SecurityNov 06 2010Wireless sensor networks (WSNs) have recently attracted a lot of interest in the research community due their wide range of applications. Due to distributed nature of these networks and their deployment in remote areas, these networks are vulnerable to ... More

Secure and Privacy-Preserving Authentication Protocols for Wireless Mesh NetworksSep 09 2012Wireless mesh networks (WMNs) have emerged as a promising concept to meet the challenges in next-generation wireless networks such as providing flexible, adaptive, and reconfigurable architecture while offering cost-effective solutions to service providers. ... More

Secure and Privacy-Preserving Data Aggregation Protocols for Wireless Sensor NetworksMar 06 2012This chapter discusses the need of security and privacy protection mechanisms in aggregation protocols used in wireless sensor networks (WSN). It presents a comprehensive state of the art discussion on the various privacy protection mechanisms used in ... More

A Robust Mechanism for Defending Distributed Denial OF Service Attacks on Web ServersMar 17 2011Distributed Denial of Service (DDoS) attacks have emerged as a popular means of causing mass targeted service disruptions, often for extended periods of time. The relative ease and low costs of launching such attacks, supplemented by the current inadequate ... More

A Robust and Secure Aggregation Protocol for Wireless Sensor NetworksJan 16 2011The purpose of a wireless sensor network (WSN) is to provide the users with access to the information of interest from data gathered by spatially distributed sensors. Generally the users require only certain aggregate functions of this distributed data. ... More

A Trust-Based Detection Algorithm of Selfish Packet Dropping Nodes in a Peer-to-Peer Wireless Mesh NetworkDec 12 2010Wireless mesh networks (WMNs) are evolving as a key technology for next-generation wireless networks showing raid progress and numerous applications. These networks have the potential to provide robust and high-throughput data delivery to wireless users. ... More

Fundamental Strings in Open String Theory at the Tachyonic VacuumOct 26 2000Oct 30 2000We show that the world-volume theory on a D-p-brane at the tachyonic vacuum has solitonic string solutions whose dynamics is governed by the Nambu-Goto action of a string moving in (25+1) dimensional space-time. This provides strong evidence for the conjecture ... More

Strong Coupling Dynamics of Branes from M-theoryAug 01 1997Aug 21 1997We study some aspects of the strong coupling dynamics of Dirichlet six branes, anti- six branes, and orientifold planes by using the equivalence of type IIA string theory and M-theory on S^1. In the strong coupling limit there exists static configuration ... More

BPS D-branes on Non-supersymmetric CyclesDec 03 1998Feb 16 1999In certain regions of the moduli space of K3 and Calabi-Yau manifolds, D-branes wrapped on non-supersymmetric cycles may give rise to stable configurations. We show that in the orbifold limit, some of these stable configurations can be described by solvable ... More

A Note on Enhanced Gauge Symmetries in M- and String TheoryJul 13 1997Aug 11 1997Two different mechanisms exist in non-perturbative String / M- theory for enhanced SU(N) (SO(2N)) gauge symmetries. It can appear in type IIA string theory or M-theory near an $A_{N-1}$ (D_N) type singularity where membrnes wrapped around two cycles become ... More

STRING STRING DUALITY CONJECTURE IN SIX DIMENSIONS AND CHARGED SOLITONIC STRINGSApr 06 1995It has recently been conjectured that the type IIA string theory compactified on K3 and the heterotic string theory compactified on a four dimensional torus describe identical string theories. The fundamental heterotic string can be regarded as a non-singular ... More

DUALITY SYMMETRY GROUP OF TWO DIMENSIONAL HETEROTIC STRING THEORYMar 09 1995The equations of motion of the massless sector of the two dimensional string theory, obtained by compactifying the heterotic string theory on an eight dimensional torus, is known to have an affine o(8,24) symmetry algebra generating an O(8,24) loop group. ... More

Strong-Weak Coupling Duality in Three Dimensional String TheoryAug 15 1994Oct 09 1994Following an old result of Marcus and Schwarz we argue that in the heterotic string theory compactified on a seven dimensional torus, the target space duality group O(7,23;Z) and the strong-weak coupling duality transformations combine into the group ... More

SL(2, Z) Duality and Magnetically Charged StringsFeb 10 1993Postulate of SL(2,\Z) invariance of toroidally compactified heterotic string theory in four dimensions implies the existence of new string (dual string) states carrying both, electric and magnetic charges. In this paper we study the interaction between ... More

Twisted Black p-Brane Solutions in String TheoryAug 21 1991It has been shown that given a classical background in string theory which is independent of $d$ of the space-time coordinates, we can generate other classical backgrounds by $O(d)\otimes O(d)$ transformation on the solution. We study the effect of this ... More

Unitarity of Superstring Field TheoryJul 27 2016Dec 06 2016We complete the proof of unitarity of (compactified) heterotic and type II string field theories by showing that in the cut diagrams only physical states appear in the sum over intermediate states. This analysis takes into account the effect of mass and ... More

Gauge Invariant 1PI Effective Action for Superstring Field TheoryNov 27 2014Jan 05 2015We construct gauge invariant 1PI effective action for the NS sector of type II and heterotic string field theory. By construction, zero eigenvalues of the kinetic operator of this action determine the renormalized physical masses, and tree level amplitudes ... More

A Twist in the Dyon Partition FunctionNov 09 2009Feb 20 2010In four dimensional string theories with N=4 and N=8 supersymmetries one can often define twisted index in a subspace of the moduli space which captures additional information on the partition function than the ones contained in the usual helicity trace ... More

Quantum Entropy Function from AdS(2)/CFT(1) CorrespondenceSep 19 2008Sep 21 2008We review and extend recent attempts to find a precise relation between extremal black hole entropy and degeneracy of microstates using AdS_2/CFT_1 correspondence. Our analysis leads to a specific relation between degeneracy of black hole microstates ... More

Negative discriminant states in N=4 supersymmetric string theoriesApr 08 2011Sep 29 2011Single centered BPS black hole solutions exist only when the charge carried by the black hole has positive discriminant. On the other hand the exact dyon spectrum in heterotic string theory compactified on T^6 is known to contain states with negative ... More

Discrete Information from CHL Black HolesFeb 22 2010Feb 23 2010AdS_2/CFT_1 correspondence predicts that the logarithm of a Z_N twisted index over states carrying a fixed set of charges grows as 1/N times the entropy of the black hole carrying the same set of charges. In this paper we verify this explicitly by calculating ... More

Entropy Function and AdS(2)/CFT(1) CorrespondenceMay 01 2008Sep 17 2008Wald's formula for black hole entropy, applied to extremal black holes, leads to the entropy function formalism. We manipulate the entropy computed this way to express it as the logarithm of the ground state degeneracy of a dual quantum mechanical system. ... More

N=8 Dyon Partition Function and Walls of Marginal StabilityMar 07 2008Jul 30 2009We construct the partition function of 1/8 BPS dyons in type II string theory on T^6 from counting of microstates of a D1-D5 system in Taub-NUT space. Our analysis extends the earlier ones by Shih, Strominger and Yin and by Pioline by taking into account ... More

Black Holes, Elementary Strings and Holomorphic AnomalyFeb 15 2005Sep 11 2005In a previous paper we had proposed a specific route to relating the entropy of two charge black holes to the degeneracy of elementary string states in N=4 supersymmetric heterotic string theory in four dimensions. For toroidal compactification this proposal ... More

Dirac-Born-Infeld Action on the Tachyon Kink and VortexMar 07 2003Mar 24 2003The tachyon effective field theory describing the dynamics of a non-BPS D-brane in superstring theory has an infinitely thin but finite tension kink solution describing a codimension one BPS D-brane. We study the world-volume theory of massless modes ... More

Field Theory of Tachyon MatterApr 17 2002May 02 2002We propose a field theory for describing the tachyon on a brane-antibrane system near the minimum of the potential. This field theory realizes two known properties of the tachyon effective action: 1) absence of plane-wave solutions around the minimum, ... More

Background Independence of Closed Superstring Field TheoryNov 22 2017Given a family of world-sheet superconformal field theories related by marginal deformation, we can formulate superstring field theory based on any of these world-sheet theories. Background independence is the statement that these different superstring ... More

Equivalence of Two Contour Prescriptions in Superstring Perturbation TheoryOct 03 2016Conventional superstring perturbation theory based on the world-sheet approach gives divergent results for the S-matrix whenever the total center of mass energy of the incoming particles exceeds the threshold of production of any final state consistent ... More

Dimensional Reduction of Two-Dimensional Anyons to a One-Dimensional Interacting Bose GasDec 02 1994We conjecture that a two-dimensional anyon system reduces, when confined to a narrow channel, to a one-dimensional bose gas with a repulsive two-body $\delta$-function interaction. We verify this conjecture in first-order perturbation theory near bosons. ... More

Field Theoretic Studies of Quantum Spin Systems in One DimensionJul 04 2001We describe some field theoretic methods for studying quantum spin systems in one dimension. These include the nonlinear sigma-model approach which is particularly useful for large values of the spin, the idea of Luttinger liquids and bosonization which ... More

Integers and FractionsNov 03 1998This article briefly reviews the quantum Hall effect and the contributions of the winners of the 1998 Nobel Prize in Physics.

Measuring ConsciousnessSep 20 2016Feb 27 2018A measurement based formula for consciousness, C, as a function of time t, is constructed. The formula depends on identifying a natural relevant self-generated, time-dependent dynamical process inherent in any entity. For human beings the relevant dynamical ... More

Anisotropic Propagator for the Goldstone Modes in Color-flavor Locked Phase in the Presence of a Magnetic FieldMar 11 2015We consider the phase diagram of QCD at very high baryon density and at zero temperature in the presence of a strong magnetic field. The state of matter at such high densities and low temperatures is believed to be a phase known as the color-flavor locked ... More

A new family of implicit fourth order compact schemes for unsteady convection-diffusion equation with variable convection coefficientJan 16 2012In this paper, a new family of implicit compact finite difference schemes for computation of unsteady convection-diffusion equation with variable convection coefficient is proposed. The schemes are fourth order accurate in space and second or lower order ... More

Measurement of the energy flow in a large eta range and forward jets at LHC at sqrt(s)=0.9 TeV, 2.36 TeV and 7 TeVFeb 14 2011A measurement is presented for the energy flow of minimum bias events in the forward region (3.15 <|\eta |< 4.9, where \eta is the pseudorapidity) of the CMS detector at the LHC for center-of-mass energies sqrt(s) = 0.9 TeV, 2.36 TeV and 7 TeV. The measurement ... More

Average Entropy of a SubsystemJan 24 1996It was recently conjectured by D. Page that if a quantum system of Hilbert space dimension $nm$ is in a random pure state then the average entropy of a subsystem of dimension $m$ where $m \leq n$ is $ S_{mn} = \sum^{mn}_{k=n+1}(1/k) - (m-1)/2n$. In this ... More

Non-conservative kinetic exchange model of opinion dynamics with randomness and bounded confidenceMay 01 2012Jul 19 2012The concept of a bounded confidence level is incorporated in a nonconservative kinetic exchange model of opinion dynamics model where opinions have continuous values $\in [-1,1]$. The characteristics of the unrestricted model, which has one parameter ... More

Phase transitions in a two parameter model of opinion dynamics with random kinetic exchangesSep 22 2010Dec 13 2010Recently, a model of opinion formation with kinetic exchanges has been proposed in which a spontaneous symmetry breaking transition was reported [M. Lallouache et al, Phys. Rev. E, {\bf 82} 056112 (2010)]. We generalise the model to incorporate two parameters, ... More

Peierls Instability and Electron-Phonon Coupling in a One-dimensional Sodium WireJun 22 2006We have studied Peierls instability in an atomically thin wire of sodium atoms using first-principles density-functional methods. A Na wire has a stable uniform linear structure over a range of inter-atomic distances. At smaller inter-atomic distances ... More

Probability distribution and sizes of spanning clusters at the percolation thresholdsApr 14 1997For random percolation at p_c, the probability distribution P(n) of the number of spanning clusters (n) has been studied in large scale simulations. The results are compatible with $P(n) \sim \exp(-an^2)$ for all dimensions. We also study the variation ... More

Funnelling related phase transitions in networksJan 02 2008Mar 08 2010Funnelling effect, in the context of searching on networks, precisely indicates that the search takes place through a few specific nodes. We define the funnelling capacity $f$ of a node as the fraction of successful dynamic paths through it with a fixed ... More

On the question of ferromagnetism in alkali metal thin filmsNov 29 2007Electronic and magnetic structure of $(100)$ films of K and Cs are calculated within the plane-wave projector augmented wave (PAW) formalism of the density functional theory (DFT) using both local spin density approximation (LSDA) and the PW91 generalized ... More

On the largest component in the subcritical regime of the Bohman-Frieze processJul 08 2013Aug 21 2013Kang, Perkins and Spencer showed that the size of the largest component of the Bohman-Frieze process at a fixed time $t$ smaller than $t_c$, the critical time for the process is $L_1(t)=\Omega(\log n/(t_c-t)^2)$ with high probability. They also conjectured ... More

Cluster Entanglement Mean Field inspired approach to Criticality in Classical SystemsAug 05 2010We propose an entanglement mean field theory inspired approach for dealing with interacting classical many-body systems. It involves a coarse-graining technique that terminates a step before the mean field theory: While mean field theory deals with only ... More

Bound Genuine Multisite Entanglement: Detector of Gapless-Gapped Quantum Transitions in Frustrated SystemsFeb 05 2010We define a multiparty entanglement measure, called generalized geometric measure, that can detect and quantify genuine multiparty entanglement for any number of parties. The quantum phase transitions in exactly solvable models like the anisotropic XY ... More

Channel Capacities versus Entanglement Measures in Multiparty Quantum StatesSep 03 2009Sep 16 2009For quantum states of two subsystems, entanglement measures are related to capacities of communication tasks -- highly entangled states give higher capacity of transmitting classical as well as quantum information. However, we show that this is no more ... More

Entanglement Mean Field Theory and the Curie-Weiss LawNov 25 2009The mean field theory, in its different hues, form one of the most useful tools for calculating the single-body physical properties of a many-body system. It provides important information, like critical exponents, of the systems that do not yield to ... More

Measuring ConsciousnessSep 20 2016A measurement based formula for consciousness, C, as a function of time t, is constructed. The formula depends on identifying a natural relevant self-generated, time-dependent dynamical process inherent in any entity. For human beings the relevant dynamical ... More

Optimization on Sparse Random Hypergraphs and Spin GlassesJun 08 2016Jun 23 2016We establish that in the large degree limit, the value of certain optimization problems on sparse random hypergraphs is determined by an appropriate Gaussian optimization problem. This approach was initiated in Dembo et. al.(2016) for extremal cuts of ... More

Sinusoidal-Input Describing Function of a Simple Biomolecular Signaling SystemMay 19 2013Understanding biomolecular systems is important both for the analysis of naturally occurring systems as well as for the design of new ones. However, mathematical tools for analysis of such complex systems are generally lacking. Here, we present an application ... More

K-theoretic Chow groups of derived categories of schemes-on a question by Green-GriffithsNov 01 2013Feb 19 2016Based on Balmer's tensor triangular Chow group, we propose K-theoretic Chow groups of derived categories of noetherian schemes and their Milnor variants for regular schemes and their thickenings. We discuss functoriality and show that our Chow groups ... More

K-theory, local cohomology and tangent spaces to Hilbert schemesApr 10 2016By using K-theory, we construct a map from tangent spaces to Hilbert schemes to local cohomology groups. We use this map to discuss a question by Mark Green and Phillip Griffiths, see Question 1.2. For q = dim(X), our map agrees with the one constructed ... More

Eliminate obstructions: curves on a 3-foldNov 22 2016By using higher K-theory, we reinterpret and generalize an idea on eliminating obstructions of deformation of cycles, which is known to Mark Green, Phillip Griffiths and TingFai Ng. As an application, we show how to eliminate obstructions of deformation ... More

Anomalous beam diffusion near beam-beam synchro-betatron resonancesMay 16 2012The diffusion process near low order synchro-betatron resonances driven by beam-beam interactions at a crossing angle is investigated. Macroscopic observables such as beam emittance, lifetime and beam profiles are calculated. These are followed with detailed ... More

The $\varphi\dim$ of Cyclic Nakayama AlgebrasJun 05 2018K. Igusa and G. Todorov introduced $\varphi$ function which generalizes the notion of projective dimension. We study the behavior of the $\varphi$ functions for cyclic Nakayama algebras of infinite global dimension. We prove that it is always an even ... More

Statistical Physics in a Finite Volume with Absolute Conservation LawsMar 12 2002Recursion relations are used to exactly calculate the partition function of a canonical ensemble in which all additive charges as well as the total isospin are strictly conserved. The ensemble can consist of particles that obey either classical or quantum ... More

Self-dual forms: Action, Hamiltonian and CompactificationMar 28 2019It has been shown that, by adding an extra free field that decouples from the dynamics, one can construct actions for interacting 2n-form fields with self-dual field strengths in 4n+2 dimensions. In this paper we analyze canonical formulation of these ... More

Quantization of the Derivative Nonlinear Schrodinger EquationDec 09 1996Jun 10 1997We study the quantum mechanics of the derivative nonlinear Schrodinger equation which has appeared in many areas of physics and is known to be classically integrable. We find that the N-body quantum problem is exactly solvable with both bound states (with ... More

Semiclassical analysis of two- and three-spin antiferromagnets and anyons on a sphereApr 28 1993We do a semiclassical analysis for two or three spins which are coupled antiferromagnetically to each other. The semiclassical wave functions transform correctly under permutations of the spins if one takes into account the Wess-Zumino term present in ... More

Security and Privacy Issues in Cloud ComputingMar 20 2013Cloud computing transforms the way information technology (IT) is consumed and managed, promising improved cost efficiencies, accelerated innovation, faster time-to-market, and the ability to scale applications on demand (Leighton, 2009). According to ... More

An Efficient and User Privacy-Preserving Routing Protocol for Wireless Mesh NetworksJan 14 2011Wireless mesh networks (WMNs) have emerged as a key technology for next generation wireless broadband networks showing rapid progress and inspiring numerous compelling applications. A WMN comprises of a set of mesh routers (MRs) and mesh clients (MCs), ... More

A Robust and Fault-Tolerant Distributed Intrusion Detection SystemDec 31 2010Since it is impossible to predict and identify all the vulnerabilities of a network, and penetration into a system by malicious intruders cannot always be prevented, intrusion detection systems (IDSs) are essential entities for ensuring the security of ... More

Privacy Preservation Technologies in Internet of ThingsDec 10 2010May 04 2012Since the beginning of the Internet thirty years ago, we have witnessed a number of changes in the application of communication technologies. Today, the Internet can be described to a large extent as a ubiquitous infrastructure that is always accessible. ... More

An Agent-Based Intrusion Detection System for Local Area NetworksNov 06 2010Since it is impossible to predict and identify all the vulnerabilities of a network beforehand, and penetration into a system by malicious intruders cannot always be prevented, intrusion detection systems (IDSs) are essential entities to ensure the security ... More

A Distributed Trust Management Framework for Detecting Malicious Packet Dropping Nodes in a Mobile Ad Hoc NetworkOct 25 2010In a multi-hop mobile ad hoc network (MANET) mobile nodes communicate with each other forming a cooperative radio network. Security remains a major challenge for these networks due to their features of open medium, dynamically changing topologies, reliance ... More

Security in Wireless Sensor NetworksJan 22 2013Wireless sensor networks have attracted a lot of interest over the last decade in wireless and mobile computing research community. Applications of these networks are numerous and growing, which range from indoor deployment scenarios in the home and office ... More

Reputation- and Trust-Based Systems for Wireless Self-organizing NetworksOct 02 2011Jun 19 2012Traditional approach of providing network security has been to borrow tools and mechanisms from cryptography. However, the conventional view of security based on cryptography alone is not sufficient for the defending against unique and novel types of ... More

An Efficient Algorithm for Detection of Selfish Packet Dropping Nodes in Wireless Mesh NetworksApr 06 2011Jun 16 2012In a wireless mesh network (WMN), high speed routers equipped with advanced antennas, communicate with each other in a multi-hop fashion over wireless channels and form a broadband backhaul. WMNs provide reliable connectivity and fault-tolerance, as each ... More

A Novel Mechanism for Detection of Distributed Denial of Service AttacksJan 14 2011The increasing popularity of web-based applications has led to several critical services being provided over the Internet. This has made it imperative to monitor the network traffic so as to prevent malicious attackers from depleting the resources of ... More

BV Master Action for Heterotic and Type II String Field TheoriesAug 21 2015Jan 29 2016We construct the quantum BV master action for heterotic and type II string field theories.

Subleading Soft Graviton Theorem for Loop AmplitudesFeb 28 2017Apr 15 2017Superstring field theory gives expressions for heterotic and type II string loop amplitudes that are free from ultraviolet and infrared divergences when the number of non-compact space-time dimensions is five or more. We prove the subleading soft graviton ... More

Riding Gravity Away from DoomsdayMar 27 2015The discovery that most of the energy density in the universe is stored in the form of dark energy has profound consequences for our future. In particular our current limited understanding of quantum theory of gravity indicates that some time in the future ... More

Multiple scales kinetic theory for rotationally constrained slow inertial waves and anisotropic dynamicsDec 29 2013Feb 20 2017Wave kinetic theory for rapidly rotating flows is developed in this paper using a rigorous application of multiple scales perturbation theory. The governing equations are an asymptotically reduced set of equations that are derived from the incompressible ... More

Two Centered Black Holes and N=4 Dyon SpectrumMay 27 2007Jul 25 2007The exact spectrum of dyons in a class of N=4 supersymmetric string theories is known to change discontinuously across walls of marginal stability. We show that the change in the degeneracy across the walls of marginal stability can be accounted for precisely ... More

Logarithmic Corrections to Rotating Extremal Black Hole Entropy in Four and Five DimensionsSep 16 2011Mar 29 2012We compute logarithmic corrections to the entropy of rotating extremal black holes using quantum entropy function i.e. Euclidean quantum gravity approach. Our analysis includes five dimensional supersymmetric BMPV black holes in type IIB string theory ... More

How Do Black Holes Predict the Sign of the Fourier Coefficients of Siegel Modular Forms?Aug 25 2010Single centered supersymmetric black holes in four dimensions have spherically symmetric horizon and hence carry zero angular momentum. This leads to a specific sign of the helicity trace index associated with these black holes. Since the latter are given ... More

Arithmetic of Quantum Entropy FunctionMar 09 2009Jul 29 2009Quantum entropy function is a proposal for computing the entropy associated with the horizon of a black hole in the extremal limit, and is related via AdS/CFT correspondence to the dimension of the Hilbert space in a dual quantum mechanics. We show that ... More

U-duality Invariant Dyon Spectrum in type II on T^6Apr 04 2008Jul 30 2009We give a manifestly U-duality invariant formula for the degeneracy of 1/8 BPS dyons in type II string theory on T^6 for a U-duality invariant subset of charge vectors. Besides depending on the Cremmer-Julia invariant the degeneracy also depends on other ... More

Study of Chemical Equilibration of a Baryon Rich QGPFeb 26 2008Dec 14 2008Parton equilibration studies for thermally equilibrated but chemically non-equilibrated quark-gluon-plasma (QGP), likely to be formed at the relativistic colliders at BNL and CERN is presented.Parton equilibration is studied enforcing baryon number conservation. ... More

Geometric Tachyon to Universal Open String TachyonMar 17 2007A system of k Neveu-Schwarz (NS) 5-branes of type II string theory with one transverse direction compactified on a circle admits various unstable D-brane systems, - some with geometric instability arising out of being placed at a point of unstable equilibrium ... More

Moduli Space of Unstable D-branes on a Circle of Critical RadiusNov 29 2003Dec 13 2003We study the moduli space of the boundary conformal field theories describing an unstable D-brane of type II string theory compactified on a circle of critical radius. This moduli space has two branches, -- a three dimensional branch S^3/Z_2 and a two ... More

Open-Closed Duality at Tree LevelJun 14 2003We study decay of unstable D-branes in string theory in the presence of electric field, and show that the classical open string theory results for various properties of the final state agree with the properties of closed string states into which the system ... More

Open and Closed Strings from Unstable D-branesMay 01 2003May 12 2003The tachyon effective field theory describing the dynamics of a non-BPS D-$p$-brane has electric flux tube solutions where the electric field is at its critical value and the tachyon is at its vacuum. It has been suggested that these solutions have the ... More

Energy Momentum Tensor and Marginal Deformations in Open String Field TheoryMar 22 2004Dec 12 2004Marginal boundary deformations in a two dimensional conformal field theory correspond to a family of classical solutions of the equations of motion of open string field theory. In this paper we develop a systematic method for relating the parameter labelling ... More