Results for "Surjeet Singh"

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Crystal growth of the non-magnetic Zn$^{2+}$ and magnetic Co$^{2+}$ doped quasi one-dimensional spin chain compound SrCuO$_{2}$ using the travelling solvent floating zone methodJan 10 2015We report on the crystal growth of the quasi one-dimensional quantum spin chain compound SrCuO$_{2}$ and its doped variants containing magnetic cobalt (0.25%, 0.5%, 1% and 2.5%) and non-magnetic zinc (0.5\% and 1\%) impurities. Crystals are grown using ... More
Effects of quantum impurity spins on the magnetic properties of zigzag and linear spin chainsFeb 11 2016We investigated the magnetic ground state and low-energy excitations of the spin chains compounds SrCuO$_{2}$ (zigzag chains) and Sr$_{2}$CuO$_{3}$ (linear chains) in the presence of quantum impurities induced by lightly doping ($\leq 1 \%$) with Zn$^{2+}$ ... More
Anomalous lattice contraction and emergent electronic phases in Bi-doped Eu$_2$Ir$_2$O$_7$Feb 08 2019We study the pyrochlore series (Eu$_{1-x}$Bi$_x$)$_2$Ir$_2$O$_7$ for $ 0 \leq x \leq 1$. We show that for small $x$, the lattice undergoes an anomalous contraction but the all-in/all-out and metal-to-insulator transitions remain robust, and the resistivity ... More
Finite-size effects in the quasi-one-dimensional quantum magnets Sr$_{2}$CuO$_{3}$, Sr$_{2}$Cu$_{0.99}$M$_{0.01}$O$_{3}$ (M = Ni, Zn), and SrCuO$_{2}$Jan 10 2015Jun 17 2015We studied the finite-size effects on the magnetic behavior of the quasi-one-dimensional spin S = $\frac{1}{2}$ Heisenberg antiferromagnets Sr$_{2}$CuO$_{3}$, Sr$_{2}$Cu$_{0.99}$M$_{0.01}$O$_{3}$ (M = Zn and Ni), and SrCuO$_{2}$. Magnetic susceptibility ... More
Magnetic ordering of Mn sublattice, dense Kondo lattice behavior of Ce in (RPd3)8Mn (R = La, Ce)Apr 02 2003We have synthesized two new interstitial compounds (RPd3)8Mn (R = La and Ce). The Mn ions present in "dilute" concentration of just 3 molar percent form a sublattice with an unusually large Mn-Mn near neighbor distance of ~ 85 nm. While the existence ... More
Coupled antiferromagnetic-ferroelectric transition, higher compensation temperature and enhanced exchange bias in SmFeO3 nanoparticlesNov 09 2016In transition metal oxides, quantum confinement arising from a large surface to volume ratio often gives rise to novel physico-chemical properties at nanoscale. Their size dependent properties have potential applications in diverse areas, including therapeutics, ... More
Rings of Invariant Module Type and Automorphism-Invariant ModulesJul 23 2012A module is called automorphism-invariant if it is invariant under any automorphism of its injective hull. In [Algebras for which every indecomposable right module is invariant in its injective envelope, Pacific J. Math., vol. 31, no. 3 (1969), 655-658] ... More
Rings and modules which are stable under automorphisms of their injective hullsJan 24 2013It is proved, among other results, that a prime right nonsingular ring (in particular, a simple ring) $R$ is right self-injective if $R_R$ is invariant under automorphisms of its injective hull. This answers two questions raised by Singh and Srivastava, ... More
Low temperature and high pressure Raman and x-ray studies of pyrochlore Tb$_2$Ti$_2$O$_7$ : phonon anomalies and possible phase transitionApr 23 2009We have carried out temperature and pressure-dependent Raman and x-ray measurements on single crystals of Tb$_2$Ti$_2$O$_7$. We attribute the observed anomalous temperature dependence of phonons to phonon-phonon anharmonic interactions. The quasiharmonic ... More
On the gaps between non-zero Fourier coefficients of eigenforms with CMAug 15 2016Suppose $E$ is an elliptic curve over $\mathbb{Q}$ of conductor $N$ with complex multiplication (CM) by $\mathbb{Q}(i)$, and $f_E$ is the corresponding cuspidal Hecke eigenform in $S^{\mathrm{new}}_2(\Gamma_0(N))$. Then $n$-th Fourier coefficient of $f_E$ ... More
Dilute stuffing in the pyrochlore iridate $Eu_2Ir_2O_7$May 04 2018The pyrochlore Eu$_2$Ir$_2$O$_7$ has recently attracted significant attention as a candidate Weyl semimetal. The previous reports on this compound unanimously show a thermally induced metal to insulator (MI) transition, concomitant with antiferromagnetic ... More
CeMnNi4: A soft ferromagnet with a high degree of transport spin polarizationSep 05 2005Oct 20 2005In this letter we introduce a new soft ferromagnetic compound, i.e. CeMnNi4, which exhibits a large moment (~4.95mu_B/Mn) and high degree of spin polarization. The system has a ferromagnetic transition temperature of 148K. Isothermal magnetization measurements ... More
Baryonecrosis: Displaced Vertices from $R$-Parity ViolationOct 14 2013Mar 09 2014The LHC has placed stringent limits on superpartner masses, in conflict with naturalness. R-parity violation is one of the few scenarios that allows reduction of these limits and is thus worth significant exploration at the LHC. We demonstrate that if ... More
Mining Education Data to Predict Student's Retention: A comparative StudyMar 14 2012The main objective of higher education is to provide quality education to students. One way to achieve highest level of quality in higher education system is by discovering knowledge for prediction regarding enrolment of students in a course. This paper ... More
Single-crystal growth and magnetic properties of the metallic molybdate pyrochlore Sm2Mo2O7Aug 24 2007We have successfully grown cm3-size single crystals of the metallic-ferromagnet Sm2Mo2O7 by the floating-zone method using an infrared-red image furnace. The growth difficulties and the remedies found using a 2-mirror image furnace are discussed. Magnetization ... More
Ordered spin-ice state in the geometrically frustrated metallic-ferromagnet Sm2Mo2O7Jun 28 2007The recent discovery of Spin-ice is a spectacular example of non-coplanar spin arrangements that can arise in the pyrochlore A2B2O7 structure. We present magnetic and thermodynamic studies on the metallic-ferromagnet pyrochlore Sm2Mo2O7. Our studies, ... More
Manifestation of geometric frustration on magnetic and thermodynamic properties of pyrochlores $Sm_2X_2O_7$ (X=Ti, Zr)Dec 18 2007We present here magnetization, specific heat and Raman studies on single-crystalline specimens of the first pyrochlore member $Sm_2Ti_2O_7$ of the rare-earth titanate series. Its analogous compound $Sm_2Zr_2O_7$ in the rare-earth zirconate series is also ... More
Study of CeNi4Mn by neutron diffractionOct 17 2006We report neutron diffraction measurements on CeNi4Mn, which has recently been identified as a soft ferromagnet (Tc ~ 140 K) with a sizeable spin-transport polarization. Our data show conclusively that the Mn atoms occupy a unique site (4c) in the unit ... More
Temperature dependent Raman and x-ray studies of spin-ice pyrochlore $Dy_2Ti_2O_7$ and non-magnetic pyrochlore $Lu_2Ti_2O_7$Nov 28 2008We present here temperature-dependent Raman, x-ray diffraction and specific heat studies between room temperature and 12 K on single crystals of spin-ice pyrochlore compound $Dy_2Ti_2O_7$ and its non-magnetic analogue $Lu_2Ti_2O_7$. Raman data show a ... More
Gravitational Wave Detection with Atom InterferometryDec 08 2007Jun 22 2009We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford $10 \text{m}$ atom interferometer presently under construction. The terrestrial experiment ... More
Effect of defects on thermal denaturation of DNA OligomersMay 03 2001Aug 29 2001The effect of defects on the melting profile of short heterogeneous DNA chains are calculated using the Peyrard-Bishop Hamiltonian. The on-site potential on a defect site is represented by a potential which has only the short-range repulsion and the flat ... More
Case Study Based Software Engineering Project Development: State of ArtJun 11 2013This research paper designates the importance and usage of the case study approach effectively to educating and training software designers and software engineers both in academic and industry. Subsequently an account of the use of case studies based ... More
Statistical Theory of Force Induced Unzipping of DNAMay 07 2004May 18 2005The unzipping transition under the influence of external force of a dsDNA molecule has been studied using the Peyrard-Bishop Hamiltonian. The critical force $F_c(T)$ is found to depend on the potential parameters $k$, represents the stiffness of single ... More
Reusability Framework for Cloud ComputingOct 30 2012Cloud based development is a challenging task for several software engineering projects, especially for those which needs development with reusability. Present time of cloud computing is allowing new professional models for using the software development. ... More
Pulling short DNA molecules having defects on different locationsSep 28 2015We present a study on the role of defects on the stability of short DNA molecules. We consider short DNA molecules (16 base pairs) and investigate the thermal as well as mechanical denaturation of these molecules in the presence of defects that occurs ... More
A Text to Speech (TTS) System with English to Punjabi ConversionNov 13 2014The paper aims to show how an application can be developed that converts the English language into the Punjabi Language, and the same application can convert the Text to Speech(TTS) i.e. pronounce the text. This application can be really beneficial for ... More
Effect of salt concentration on the stability of heterogeneous DNASep 28 2015We study the role of cations on the stability of double stranded DNA (dsDNA) molecules.It is known that the two strands of double stranded DNA(dsDNA) have negative charge due to phosphate group. Cations in the form of salt in the solution, act as shielding ... More
Phase diagram of mechanically stretched DNA: The salt effectSep 05 2014The cations, in form of salt, present in the solution containing DNA play a crucial role in the opening of two strands of DNA. We use a simple non linear model and investigate the role of these cations on the mechanical unzipping of DNA. The Hamiltonian ... More
Design and Implementation of Bit Transition CounterFeb 11 2014In today VLSI system design, power consumption is gaining more attention as compared to performance and area. This is due to battery life in portable devices and operating frequency of the design. Power consumption mainly consists of static power, dynamic ... More
On Equality of Certain Automorphism GroupsMay 21 2015Jan 29 2016Let $G = H\times A$ be a group, where $H$ is a purely non-abelian subgroup of $G$ and $A$ is a non-trivial abelian factor of $G$. Then, for $n \geq 2$, we show that there exists an isomorphism $\phi : Aut_{Z(G)}^{\gamma_{n}(G)}(G) \rightarrow Aut_{Z(H)}^{\gamma_{n}(H)}(H)$ ... More
Data Mining: A Prediction for Performance Improvement of Engineering Students using ClassificationMar 17 2012Now-a-days the amount of data stored in educational database increasing rapidly. These databases contain hidden information for improvement of students' performance. Educational data mining is used to study the data available in the educational field ... More
Statistical Mechanics of thermal denaturation of DNA oligomersMay 07 2004Double stranded DNA chain is known to have nontrivial elasticity. We study the effect of this elasticity on the denaturation profile of DNA oligomer by constraining one base pair at one end of the oligomer to remain in unstretched (or intact) state. The ... More
Effect of genome sequence on the force-induced unzipping of a DNA moleculeMar 14 2006We considered a dsDNA polymer in which distribution of bases are random at the base pair level but ordered at a length of 18 base pairs and calculated its force elongation behaviour in the constant extension ensemble. The unzipping force $F(y)$ vs. extension ... More
Microcontroller Based Testing of Digital IP-CoreMay 09 2012Testing core based System on Chip is a challenge for the test engineers. To test the complete SOC at one time with maximum fault coverage, test engineers prefer to test each IP-core separately. At speed testing using external testers is more expensive ... More
Unbiased Ratio-Type Estimator Using Transformed Auxiliary Variable In Negative Correlation CaseOct 06 2012The objective of this paper is to propose an unbiased ratio-type estimator for finite population mean when the variables are negatively correlated. Hartley and Ross[2] and Singh and Singh [6] estimators are identified as particular cases of the proposed ... More
Classification of non-homogeneous Fourier matrices associated with modular data up to rank 5Oct 17 2016Modular data is an important topic of study in rational conformal field theory. A modular datum defines finite dimensional representations of the modular group $\mbox{SL}_2(\mathbf{Z})$. For every Fourier matrix in a modular datum there exists an Allen ... More
Impact of peer interaction on conceptual test performanceFeb 24 2016We analyze the effectiveness of working in pairs on the Conceptual Survey of Electricity and Magnetism test in a calculus-based introductory physics course. Students who collaborated with a peer showed significantly larger normalized gain on individual ... More
Student understanding of symmetry and Gauss's law of electricityFeb 24 2016We investigate the difficulties that students in calculus-based introductory physics courses have with the concepts of symmetry, electric field, and electric flux which are important for applying Gauss's law. The determination of the electric field using ... More
When physical intuition failsFeb 22 2016We analyze the problem solving strategies of physics professors in a case where their physical intuition fails. A non-intuitive introductory-level problem was identified and posed to twenty physics professors. The problem placed the professors in a situation ... More
Assessing Student Expertise in Introductory Physics with Isomorphic Problems, Part II: Effect of Some Potential Factors on Problem Solving and TransferFeb 20 2016In this companion paper, we explore the use of isomorphic problem pairs (IPPs) to assess introductory physics students' ability to solve and successfully transfer problem-solving knowledge from one context to another in mechanics. We call the paired problems ... More
Uniresolution representations of white-matter data from CoCoMacFeb 19 2016Tracing data as collated by CoCoMac, a seminal neuroinformatics database, is at multiple resolutions -- white matter tracts were studied for areas and their subdivisions by different reports. Network theoretic analysis of this multi-resolution data often ... More
Hybrid Memristor-CMOS (MeMOS) based Logic Gates and Adder CircuitsJun 19 2015Practical memristor came into picture just few years back and instantly became the topic of interest for researchers and scientists. Memristor is the fourth basic two-terminal passive circuit element apart from well known resistor, capacitor and inductor. ... More
Emergence of statistical behavior in many particle mechanical systems: Boltzmann's ideas on macroscopic irreversibilityOct 09 2014An attempt is made to de-mystify the apparent "paradox" between microscopic time revsersibility and macroscopic time irreversibility. It is our common experience that a hot cup of coffee cools down to room temperature and it never automatically becomes ... More
Two-Temperature Model of non-equilibrium electron relaxation: A ReviewFeb 14 2007Mar 23 2009The present paper is a review of the phenomena related to non-equilibrium electron relaxation in bulk and nano-scale metallic samples. The workable Two-Temperature Model (TTM) based on Boltzmann-Bloch-Peierls (BBP) kinetic equation has been applied to ... More
Phase controllable dynamical localization: a generalization of the Dunlap-Kenkre resultOct 31 2011Dunlap-Kenkre result states that Dynamical Localization (DL) of a field driven quantum particle in a discrete periodic lattice happens when the ratio of the field magnitude to the field frequency (say, $\eta$) of the diagonal sinusoidal drive is a root ... More
How and why does statistical mechanics workMar 21 2011Apr 25 2011As the title says we want to answer the question; how and why does statistical mechanics work? As we know from the most used prescription of Gibbs we calculate the phase space averages of dynamical quantities and we find that these phase averages agree ... More
Relaxation between electrons and surface phonons in nanoscale metal filmsDec 05 2006Dec 07 2006The Two Temperature model of M I Kaganov, I M Lifshitz and L V Tanatarov (Sov. Phys. JETP 4, 173 (1957)) about relaxation between electrons and bulk phonons is extended to the case of surface phonons. The state of electrons and phonons is described by ... More
Role of spd- Continuum Components in the Halo Nucleus 6HeMar 22 2016Role of different continuum components in the weakly bound nucleus 6He is studied by coupling unbound spd-waves of 5He by using simple pairing contact-delta interaction. The results show that 6He ground state $0^+$ displays collective nature by taking ... More
Sums of products of power sumsAug 08 2013Jul 07 2015For any two arithmetic functions $f,g$ let $\bullet$ be the commutative and associative arithmetic convolution $(f\bullet g)(k):=\sum_{m=0}^k \left( \begin{array}{c} k m \end{array} \right)f(m)g(k-m)$ and for any $n\in\mathbb{N},$ $f^n=f\bullet \cdots\bullet ... More
An Algorithm to Reduce the Time Complexity of Earliest Deadline First Scheduling Algorithm in Real-Time SystemDec 30 2010In this paper I have study to Reduce the time Complexity of Earliest Deadline First (EDF), a global scheduling scheme for Earliest Deadline First in Real Time System tasks on a Multiprocessors system. Several admission control algorithms for Earliest ... More
Lifshitz/Schrödinger D-p-branes and dynamical exponentsFeb 29 2012Feb 20 2013We extend our earlier study of special double limits of `boosted' $AdS_5$ black hole solutions to include all black D$p$-branes of type II strings. We find that Lifshitz solutions can be obtained in generality, with varied dynamical exponents, by employing ... More
More on the scalar-tensor B-F theoryJul 16 2009Jul 24 2009This work is based on an earlier proposal \cite{hs} that the membrane B-F theory consists of matter fields alongwith Chern-Simons fields as well as the auxiliary pairs of scalar and tensor fields. We especially discuss the supersymmetry aspects of such ... More
More on Tachyon Cosmology in De Sitter GravityMay 02 2005Oct 06 2005We aim to study rolling tachyon cosmological solutions in de Sitter gravity. The solutions are taken to be flat FRW type and these are not time-reversal symmetric. We find that cosmological constant of our universe has to be fine-tuned at the level of ... More
Lifshitz to AdS flow with interpolating p-brane solutionsMay 16 2013Jul 26 2013In continuation with our studies of Lifshitz like D$p$-brane solutions, we propose a class of 1/4 BPS supersymmetric interpolating solutions which interpolate between IR Lifshitz solutions and UV AdS solutions smoothly. We demonstrate properties of these ... More
Galilean anti-de-Sitter spacetime in Romans theorySep 09 2009Sep 17 2009The Romans type IIA theory is the only known example of 10-dimensional maximal supergravity where (tensor) fields are explicitly massive. We provide an example of a non-relativistic anti-de Sitter $NRadS_4\times S^6$ background as a solution in massive ... More
de Sitter space, (D)pp-Waves and a star-Matrix modelFeb 01 2005Feb 12 2005We consider de Sitter spacetime solutions and the corresponding de Sitter kind of plane-wave solutions in M* theory. We attempt to write down corresponsing matrix model which is found to have explicit negative energy mass terms as well as negative energy ... More
M5-branes with 3/8 supersymmetry in pp-wave backgroundMay 02 2002Jul 31 2002We construct M5-branes in pp-wave background and find that they preserve exactly half of the background pp-wave supersymmetries. We explicitly write down the standard as well as supernumerary Killing spinors and find that their respective numbers are ... More
Duality symmetric massive type II theories in D=8 and D=6Sep 19 2001Apr 20 2002We study $T^2$ compactification of massive type IIA supergravity in presence of possible Ramond-Ramond (RR) background fluxes. The resulting theory in D=8 is shown to possess full $SL(2,R)\times SL(2,R)$ T-duality symmetry similar to the massless case. ... More
Breaking the Limits -- Redefining the Instantaneous FrequencyApr 09 2016Sep 05 2016The Carson and Fry (1937) introduced the concept of variable frequency as a generalization of the constant frequency. The instantaneous frequency (IF) is the time derivative of the instantaneous phase and it is well-defined only when this derivative is ... More
Algebraic theory for higher-order methods in computational quantum mechanicsOct 23 2015Nov 25 2015We present the algebraic foundations of the symmetric Zassenhaus algorithm and some of its variants. These algorithms have proven effective in devising higher-order methods for solving the time-dependent Schr\"{o}dinger equation in the semiclassical regime. ... More
Physics from Angular Projection of Rectangular GridsDec 08 2014In this paper, we present a mathematical model for the angular projection of a rectangular arrangement of points in a grid. This simple, yet interesting problem, has both a scholarly value and applications for data extraction techniques to study the physics ... More
Finite-$U$ induced competing interactions, frustration, and quantum phase transition in a triangular-lattice antiferromagnetNov 06 2004Apr 26 2005The $120^0$ ordered antiferromagnetic state of the Hubbard model on a triangular lattice presents an interesting case of $U$-controlled competing interactions and frustration. The spin stiffness is found to vanish at $U^* _{\rm stiff} \approx 6$ and the ... More
Equation of motion approach for the Hubbard model: improved decoupling scheme, charge fluctuations, and the metal-insulator transitionJan 28 2000A new decoupling scheme is developed for the Hubbard model which provides a unified description of the spin-symmetric (paramagnetic metallic and insulating) phases as well as the broken-symmetry AFI phase. Independent of magnetic ordering, the scheme ... More
Neutrino mass hierarchy and δ^{CP} investigation within the biprobability (P-P^T ) planeJun 09 2016This article illustrates the possibility of investigating mass hierarchy and CP-violating phase \delta^{CP}, in the context of CP trajectory diagrams in the bi-probability plane. Separation between normal mass hierarchy (NH) and inverted mass hierarchy ... More
Z_2 actions on complexes with three non-trivial cellsAug 31 2007Sep 27 2010In this paper, we study $Z_2$ actions on a cell complex X having the cohomology ring isomorphic to that of the wedge sum $P^2 (n) V S^{3n}$ or $S^n V S^{2n} V S^{3n}$. We determine the possible fixed point sets depending on whether or not X is totally ... More
Vertex-disjoint Cycle Cover for graph signal processingFeb 19 2016Eigenvectors of the Laplacian of a cycle graph exhibit the sinusoidal characteristics of the standard DFT basis, and signals defined on such graphs are amenable to linear shift invariant (LSI) operations. In this paper we propose to reduce a generic graph ... More
Interactive learning tutorials on quantum mechanicsMar 10 2016We discuss the development and evaluation of quantum interactive learning tutorials (QuILTs) which are suitable for undergraduate courses in quantum mechanics. QuILTs are based on the investigation of student difficulties in learning quantum physics. ... More
An Analytic Perturbation Approach for Classical Spinning Particle DynamicsJun 07 2007Apr 10 2008A perturbation method to analytically describe the dynamics of a classical spinning particle, based on the Mathisson-Papapetrou-Dixon (MPD) equations of motion, is presented. By a power series expansion with respect to the particle's spin magnitude, it ... More
Student understanding of Symmetry and Gauss' lawFeb 24 2016Helping students learn why Gauss' law can or cannot be easily applied to determine the strength of the electric field at various points for a particular charge distribution, and then helping them learn to determine the shape of the Gaussian surfaces if ... More
Bohm's realist interpretation of Quantum mechanicsMay 13 2008A brief account of the world view of classical physics is given first. We then recapitulate as to why the Copenhagen interpretation of the quantum mechanics had to renounce most of the attractive features of the clasical world view such as a causal description, ... More
Hidden Variables, Non Contextuality and Einstein-Locality in Quantum MechanicsJul 19 2005Jul 25 2005We discuss the problem of hidden variables and the motivation for introducting them in quantum mechanics. These include determinism, and the problem of meassurement and incompleteness. We first discuss Von-Neumann's imposisbility proof and then analyse ... More
On the failure of mean-field theories near a critical pointFeb 27 2014Mar 04 2014It is well known that mean-field theories fail to reproduce the experimentally known critical exponents. The traditional argument which explain this failure of mean-field theories near a critical point is the Ginsburg criterion in which diverging fluctuations ... More
Thermodynamical Phase transitions, the mean-field theories, and the renormalization (semi)group: A pedagogical introductionFeb 27 2014While analyzing second order thermodynamical phase transitions, Lev Landau (the famous Russian physicist) introduced a very vital concept, the concept of an "order parameter". This not only amalgamated the previous fragmentary theoretical understanding ... More
Perfect Powers of Five with Few Ternary DigitsApr 18 2013In this note we will analyze a diophantine equation raised by Michael Bennett in [1] that is pivotal in establishing that powers of five has few digits in its ternary expansion. We will show that the Diophantine equation $3^{a}+3^{b}+2=n^5$, where $(n,3)=1$ ... More
Rates of convergence of a transient diffusion in a spectrally negative Lévy potentialJun 19 2006Jan 02 2008We consider a diffusion process $X$ in a random L\'{e}vy potential $\mathbb{V}$ which is a solution of the informal stochastic differential equation \begin{eqnarray*}\cases{dX_t=d\beta_t-{1/2}\mathbb{V}'(X_t) dt,\cr X_0=0,}\end{eqnarray*} ($\beta$ B. ... More
Spin fluctuations in a metallic antiferromagnetJul 01 2002The magnon energy and amplitude renormalization due to intraband particle-hole excitations are studied in a metallic antiferromagnet. The change in sign of the intraband contribution with $\omega$ results in significant differences between static and ... More
Real Elements in Spin GroupsApr 08 2008Let $F$ be a field of characteristic $\neq 2$. Let $G$ be an algebraic group defined over $F$. An element $t\in G(F)$ is called {\bf real} if there exists $s\in G(F)$ such that $sts^{-1}=t^{-1}$. A semisimple element $t$ in $GL_n(F), SL_n(F), O(q), SO(q), ... More
Spin waves in a band ferromagnet: spin-rotationally symmetric study with self-energy and vertex correctionsDec 26 2005Jan 19 2007First-order quantum corrections to the transverse spin-fluctuation propagator are obtained within a systematic inverse-degeneracy 1/N expansion, which provides a spin-rotationally symmetric scheme for including self-energy and vertex corrections while ... More
Spectral function of transverse spin fluctuations in an antiferromagnetJun 06 2000The spectral function of transverse spin fluctuations, including the contributions from both the single-particle and the collective (magnon) excitations in an antiferromagnet, is evaluated for the Hubbard model with NN and NNN hoppings in the full U-range ... More
On evaluation of transverse spin fluctuations in quantum magnetsFeb 04 1998Jan 28 2000A numerical method is described for evaluating transverse spin correlations in the random phase approximation. Quantum, spin-fluctuation corrections to sublattice magnetization are evaluated for the half-filled Hubbard antiferromagnet in two and three ... More
Quantum Stern-Gerlach experiment and path entanglement of Bose-Einstein condensateAug 14 2016In this paper, a quantum Stern-Gerlach thought experiment is introduced where, in addition to the intrinsic angular momentum of an atom, the magnetic field is also treated quantum mechanically. A freely falling spin polarised Bose-Einstein condensate ... More
Fixed points of circle actions on spaces with rational cohomology of $S^n V S^{2n} V S^{3n}$ or $P^2(n) V S^{3n}$Dec 14 2007Sep 28 2010Let $X$ be a finitistic space with its rational cohomology isomorphic to that of the wedge sum $P^2(n)\vee S^{3n} $ or $S^{n} \vee S^{2n}\vee S^{3n}$. We study continuous $\mathbb{S}^1$ actions on $X$ and determine the possible fixed point sets up to ... More
Numerical loop quantum cosmology: an overviewAug 27 2012A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key prediction of ... More
Loop cosmological dynamics and dualities with Randall-Sundrum braneworldsMar 11 2006The discrete quantum geometric effects play an important role in dynamical evolution in the loop quantum cosmology. These effects which are significant at the high energies lead to the quadratic energy density modifications to the Friedmann equation, ... More
Time-Frequency analysis via the Fourier RepresentationApr 18 2016The nonstationary nature of signals and nonlinear systems require the time-frequency representation. In time-domain signal, frequency information is derived from the phase of the Gabor's analytic signal which is practically obtained by the inverse Fourier ... More
The Yang-Mills and chiral fields in six dimensionsNov 14 2012Feb 20 2013In previous work (Singh, 2011), we constructed an action in six dimensions using Yang-Mills fields and an auxiliary Abelian field. Here we first write down all the equations of motion and the constraints which arise from such an action. From these equations ... More
Super-Yang-Mills and M5-branesJul 18 2011Aug 23 2011We uplift 5-dimensional super-Yang-Mills theory to a 6-dimensional gauge theory with the help of a space-like constant vector $\eta^M$, whose norm determines the Yang-Mills coupling constant. After the localization of $\eta^M$ the 6D gauge theory acquires ... More
New Supersymmetric Vacua for N=4, D=4 Gauged SupergravityJan 08 1998May 26 1998In this paper we obtain supersymmetric brane-like configurations in the vacuum of N=4 gauged $SU(2)\times SU(2)$ supergravity theory in four spacetime dimensions. Almost all of these vacuum solutions preserve either half or one quarter of the supersymmetry ... More
Macroscopic String-like Solutions in Massive SupergravityOct 24 1997Nov 25 1997In this report we obtain explicit string-like solutions of equations of motion of massive heterotic supergravity recently obtained by Bergshoeff, Roo and Eyras. We also find consistent string source which can be embedded in these backgrounds when space-time ... More
SU(N) membrane $B\wedge F$ theory with dual-pairsNov 11 2008Dec 04 2008We construct a SU(N) membrane $B\wedge F$ theory with dual pairs of scalar and tensor fields. The moduli space of the theory is precisely that of $N$ M2-branes on the noncompact flat space. The theory possesses explicit SO(8) invariance and is an extension ... More
3-Branes on Eguchi-Hanson 6D InstantonsJan 15 2007Apr 27 2007We use the approach used by Eguchi-Hanson in constructing four-dimensional instanton metrics and construct a class of regular six-dimensional instantons which are nothing but $S^2\times S^2$ resolved conifolds. We then also obtain D3-brane solutions on ... More
Generalised Penrose Limits and PP-WavesJul 09 2003Jan 31 2004In this paper we construct generalised Penrose limits for the solutions of massive type IIA supergravity. We consider a Freund-Rubin type solution and apply these {\it massive} Penrose limits and obtain supersymmetric pp-wave which is a standard type ... More
Magnetic Wormholes and Vertex OperatorsJul 20 1994We consider wormhole solutions in $2+1$ Euclidean dimensions. A duality transformation is introduced to derive a new action from magnetic wormhole action of Gupta, Hughes, Preskill and Wise. The classical solution is presented. The vertex operators corresponding ... More
Proposal for designing a two-stage buffer gas cooled beam sourceJan 11 2019A novel two-stage helium buffer gas cooled beam source is introduced. The properties of the molecular beams produced from this source are investigated theoretically using the CaF as a test molecule. The gas phase molecules are first produced inside a ... More
Parametrized Borsuk-Ulam problem for projective space bundlesOct 26 2008Sep 27 2010Let $\pi: E \to B$ be a fiber bundle with fiber having the mod 2 cohomology algebra of a real or a complex projective space and let $\pi^{'}: E^{'} \to B$ be vector bundle such that $\mathbb{Z}_2$ acts fiber preserving and freely on $E$ and $E^{'}-0$, ... More
Classification of non-homogeneous Fourier matrices associated with modular data up to rank 5Oct 17 2016Nov 02 2016Modular data is an important topic of study in rational conformal field theory. A modular datum defines finite dimensional representations of the modular group $\mbox{SL}_2(\mathbf{Z})$. For every Fourier matrix in a modular datum there exists an Allen ... More
Conormal Varieties on the Cominuscule Grassmannian - IIMay 31 2018Sep 24 2018Let $X_w$ be a Schubert subvariety of a cominuscule Grassmannian $X$, and let $\mu:T^*X\rightarrow\mathcal N$ be the Springer map from the cotangent bundle of $X$ to the nilpotent cone $\mathcal N$. In this paper, we construct a resolution of singularities ... More
Reduction of Blocking Artifacts In JPEG Compressed ImageOct 03 2012Feb 12 2014In JPEG (DCT based) compresses image data by representing the original image with a small number of transform coefficients. It exploits the fact that for typical images a large amount of signal energy is concentrated in a small number of coefficients. ... More
Orthogonal Hypergeometric Groups with a Maximally Unipotent MonodromyJun 23 2014Mar 10 2015Similar to the symplectic cases, there is a family of fourteen orthogonal hypergeometric groups with a maximally unipotent monodromy (cf. Table 1.1). We show that two of the fourteen orthogonal hypergeometric groups associated to the pairs of parameters ... More
String Cosmology with Magnetic field in Anisotropic Space-timeSep 26 2012May 06 2013In this paper we study the effect of the magnetic field in string cosmology for a spatially homogenous and anisotropic Bianchi type -V space-time model. In order to study the effect of magnetic field, the standard form of the energy momentum tensor for ... More