Fermi surfaces in general co-dimension and a new controlled non-trivial fixed point (2008)
Traditionally Fermi surfaces for problems in $d$ spatial dimensions have dimensionality $d-1$, i.e., codimension $d_c=1$ along which energy varies. Situations with $d_c >1$ arise when the gapless...
Baskaran, G., Sen, Diptiman, Shankar, R.
In the first part of this paper, we study the spin-S Kitaev model using spin wave theory. We discover a remarkable geometry of the minimum energy surface in the N-spin space. The classical ground...
Flux Hamiltonians, Lie Algebras and Root Lattices With Minuscule Decorations (2008)
Shankar, R., Burnell, F. J., Sondhi, S. L.
We study a family of Hamiltonians of fermions hopping on a set of lattices in the presence of a background gauge field. The lattices are constructed by decorating the root lattices of various Lie...
Exact Haldane mapping for all $S$ and super universality in spin chains (2008)
Pruisken, A. M. M., Shankar, R., Surendran, N.
The low energy dynamics of the anti-ferromagnetic Heisenberg spin $S$ chain in the semiclassical limit $S\to\infty$ is known to map onto the $O(3)$ nonlinear $\sigma$ model with a $\theta$ term in...
Chaotic quantum dots with strongly correlated electrons (2007)
Quantum dots pose a problem where one must confront three obstacles: randomness, interactions and finite size. Yet it is this confluence that allows one to make some theoretical advances by invoking...
Symmetry breaking by the sea of Dirac-Landau levels in graphene (2007)
The quantum Hall states of graphene have a filled Dirac sea of Landau levels. The short ranged SU(4) symmetry breaking interactions can induce a staggered polarization of the sea of Dirac-Landau...
The Hamiltonian Theory of the fractional quantum Hall effect is an operator description that subsumes many properties of Composite Fermions, applies to gapped and gapless cases, and has been found to...
Field-driven biofunctionalization of polymer fiber surfaces during electrospinning (2007)
Sun, X. Y., Shankar, R., Börner, H. G., Ghosh, T. K., Spontak, R. J.
Exact results for spin dynamics and fractionization in the Kitaev Model (2006)
Baskaran, G., Mandal, Saptarshi, Shankar, R.
We present certain exact analytical results for dynamical spin correlation functions in the Kitaev Model. It is the first result of its kind in non-trivial quantum spin models. The result is also...
Large spin-orbit effects in small quantum dots (2006)
We consider small ballistic quantum dots weakly coupled to the leads in the chaotic regime and look for significant spin-orbit effects. We find that these effects can become quite prominent in the...
Novel electric field effects on Landau levels in Graphene (2006)
Lukose, Vinu, Shankar, R., Baskaran, G.
A single graphene layer exhibits an anomalous Landau level spectrum. A massless Dirac like low energy electronic spectrum underlies this anomaly. We study, analytically and numerically, the effect of...
Massless excitations at $\theta =\pi$ in the $CP^{N-1}$ model with large values of $N$ (2006)
Pruisken, A. M. M., Burmistrov, I. S., Shankar, R.
We study the instanton vacuum of the $CP^{N-1}$ model with large values of $N$ in 1+1 space-time dimensions. Unlike the longstanding claims which state that the theory always has a mass gap, we for...
Routing, as a basic phenomena, by itself, has got umpteen scopes to analyse, discuss and arrive at an optimal solution for the technocrats over years. Routing is analysed based on many factors; few...
Neto, A. H. Castro, Shankar, R., Campbell, D. K.
We present the numerical solution of the renormalization group (RG) equations derived in Ref. [1], for the problem of superconductivity in the presence of both electron-electron and electron-phonon...
General topological features and instanton vacuum in quantum Hall and spin liquids (2005)
Pruisken, A. M. M., Shankar, R., Surendran, Naveen
We introduce the concept of super universality in quantum Hall and spin liquids which has emerged from previous studies. It states that all the fundamental features of the quantum Hall effect are...
Comment on "The Great Sumatra-Andaman Earthquake of 26 December 2004" (2005)
Neetu, S., Suresh, I., Shankar, R., Shankar, D., Shenoi, S.S.C., Shetye, S.R., ...
Lay et al. (Special Section, 20 May 2005, p.1127) estimated a 600-km length for the tsunami source region. Adding tide-gauge data from Paradip, the northernmost of the Indian east-coast stations and...
Geochemistry of two sediment cores from the west coast of India (2005)
Copper, Pb, Zn, Ni, Co, Mn, AI, Ca, magnetic susceptibility and loss on ignition of sediments from two cores near Mangalore along the western continental shelf of India have been studied. The...
Nair, T.M.B., Ittekkot, V., Shankar, R., Guptha, M.V.S.
Time series measurement of biogenic and barium fluxes was made using nine sediment traps deployed in the western, central and eastern part of the Arabian Sea with the objective of evaluating barium...
Murthy, Ganpathy, Shankar, R., Mathur, Harsh
In previous work we have found a regime in ballistic quantum dots where interelectron interactions can be treated asymptotically exactly as the Thouless number $g$ of the dot becomes very large....
The renormalization group for interacting fermions: from Fermi liquids to quantum dots (2004)
The renormalization group approach as developed by the author for Fermi liquids is applied to clean Fermi liquids and ballistic quantum dots. In the former case Landau theory is shown to be a fixed...
Renormalization Group Approach to Strong-Coupled Superconductors (2004)
Neto, A. H. Castro, Shankar, R., Campbell, D. K.
We develop an asymptotically exact renormalization group (RG) approach that treats electron-electron and electron-phonon interactions on equal footing. The approach allows an unbiased study of the...
Murthy, Ganpathy, Shankar, R., Herman, Damir, Mathur, Harsh
We provide a framework for analyzing the problem of interacting electrons in a ballistic quantum dot with chaotic boundary conditions within an energy $E_T$ (the Thouless energy) of the Fermi energy....
Random sampling of an AC source: A tool to teach probabilistic observations (2003)
Chandi, P. S., Singh, R. C., Indumathi, D., Shankar, R.
An undergraduate level experiment is described to demonstrate the role of probabilistic observations in physics. A capacitor and a DC voltmeter are used to randomly sample an AC voltage source. The...
The amoral scientists - The tragedy of Hiroshima (2000)
Murthy, M.V.N., Shankar, R., Rao, Madan, Samuel, J., Sitaram, Alladi
Magnetic phenomena at and near nu =1/2 and 1/4: theory, experiment and interpretation (1999)
I show that the hamiltonian theory of Composite Fermions (CF) is capable of yielding a unified description in fair agreement with recent experiments on polarization P and relaxation rate 1/T_1 in...
A hidden Goldstone mechanism in the Kagom\'e lattice antiferromagnet (1999)
In this paper, we study the phases of the Heisenberg model on the \kagome lattice with antiferromagnetic nearest neighbour coupling $J_1$ and ferromagnetic next neighbour coupling $J_2$. Analysing...
We examine the Ising chain in a transverse field at zero temperature from the point of view of a family of moment formalisms based upon the cumulant generating function, where we find exact solutions...
Exclusion statistics: A resolution of the problem of negative weights (1999)
We give a formulation of the single particle occupation probabilities for a system of identical particles obeying fractional exclusion statistics of Haldane. We first derive a set of constraints...
Hamiltonian Description of Composite Fermions: Calculation of Gaps (1998)
We analytically calculate gaps for the 1/3, 2/5, and 3/7 polarized and partially polarized Fractional Quantum Hall states based on the Hamiltonian Chern-Simons theory we have developed. For a class...
Field Theory of the Fractional Quantum Hall Effect-I (1998)
We provide details of a shorter letter and cond-mat/9702098 and some new results. We describe a Chern-Simons theory for the fractional quantum Hall states in which magnetoplasmon degrees of freedom...
Effective Field Theory in Condensed Matter Physics (1997)
Some personal reminiscences are followed by a brief illustration of how effective field theories are used in condensed matter physics. Examples include Landau's Fermi liquid, sigma models with...
Spin Polarizations at and about the Lowest Filled Landau Level (1997)
Chakraborty, Tapash, Pietiläinen, P., Shankar, R.
The spin polarization versus temperature at or near a fully filled lowest Landau level is explored for finite-size systems in a periodic rectangular geometry. Our results at $\nu=1$ which also...
Shape Deformation driven Structural Transitions in Quantum Hall Skyrmions (1997)
Rao, Madan, Sengupta, Surajit, Shankar, R.
The Quantum Hall ground state away from $\nu = 1$ can be described by a collection of interacting skyrmions. We show within the context of a nonlinear sigma model, that the classical ground state...
Towards a field theory of the fractional quantum Hall states (1997)
We present a Chern-Simons theory of the fractional quantum Hall effect in which flux attachment is followed by a transformation that effectively attaches the correlation holes. We extract the...
Plasmons, Magnetoplasmons and the \nu = 1/2 Quantum Hall Effect (1996)
We address the problem of separating the short-distance, high-energy physics of cyclotron motion from the long- distance, low-energy physics within the Lowest Landau Level in field theoretic...
Malignant schwannoma in neurofibromatosis [Letter to editor] (1996)
Rao, G, Hayath, M, Murthy, C, Janaki, M, Mallikarjun, B, Shankar, R, ...
Field Theory of Quantum Antiferromagnets : From the Triangular to the Kagome Lattice (1996)
We analyse a family of models, that interpolates between the Triangular lattice antiferromagnet (TLAF) and the Kagome lattice antiferromagnet (KLAF). We identify the field theories governing the low...
Martin-Delgado, M. A., Shankar, R., Sierra, G.
We map spin ladders with $n_l$ legs and couplings $J'$ across all rungs and $J(1 \pm \gamma)$ along the legs, staggered in both directions, to a sigma model. Setting its $\theta = (2m+1)\pi$ (where...
Novel Phases of Planar Fermionic Systems (1995)
We discuss a {\em family} of planar (two-dimensional) systems with the following phase strucure: a Fermi liquid, which goes by a second order transition (with non classical exponent even in...
Haldane exclusion statistics and the charge fractionalisation in chiral bags (1994)
Bhaduri, R. K., Murthy, M. V. N., Shankar, R.
It is proposed that the phenomenon of charge fractionalisation of the spatially confined particle in a topological chiral bag may be interpreted as a manifestation of the exclusion statistics...
Thermodynamics of an one-dimensional ideal gas with fractional exclusion statistics (1994)
We show that the particles in the Calogero-Sutherland Model obey fractional exclusion statistics as defined by Haldane. We construct anyon number densities and derive the energy distribution...
Thomas Precession, Berry potential and the Meron (1994)
We begin with a prior observation by one of us that Thomas precession in the nonrelativistic limit of the Dirac equation may be attributed to a nonabelian Berry vector potential. We ask what object...
Haldane exclusion statistics and second virial coefficient (1994)
We show that Haldanes new definition of statistics, when generalised to infinite dimensional Hilbert spaces, is equal to the high temperature limit of the second virial coefficient. We thus show that...
Sachdev, Subir, Senthil, T., Shankar, R.
Consider a $d$-dimensional antiferromagnet with a quantum disordered ground state and a gap to bosonic excitations with non-zero spin. In a finite external magnetic field, this antiferromagnet will...
Coulomb Interaction and the Fermi Liquid State: Solution by Bosonization (1993)
Houghton, A., Marston, J. B., Shankar, R.
We investigate the effects of the Coulomb two-body interaction on Fermi liquids via bosonization. The Coulomb interaction is singular in the limit of low momentum transfer, and recent interest in the...
Maxwell-Chern-Simons Electrodynamics on a Disk (1993)
Balachandran, A. P., Chandar, L., Ercolessi, E., Govindarajan, T. R., Shankar, R.
The Maxwell-Chern-Simons (MCS) Lagrangian is the Maxwell Lagrangian augmented by the Chern-Simons (CS) term. In this paper, we study the MCS and Maxwell Lagrangians on a disk $D$. They are of...
Renormalization Group Approach to Interacting Fermions (1993)
The stability of nonrelativistic fermionic systems to interactions is studied within the Renormalization Group framework. A brief introduction to $\phi^4$ theory in four dimensions and the path...
O(3) Non-linear $\sigma$ model with Hopf term and Higher spin theories (1993)
Govindarajan, T. R., Shankar, R., Shaji, N., Sivakumar, M.
Following our earlier work we argue in detail for the equivalence of the nonlinear $\sigma$ model with Hopf term at~$\theta=\pi/2s$ ~and an interacting spin-s theory. We give an ansatz for spin-s...
Is the $O(3)~\sigma$ Model with the Hopf Term Exactly Equivalent to a Higher Spin Theory? (1992)
Govindarajan, T. R., Shankar, R., Shaji, N., Sivakumar, M.
We write down a local $CP_1$ model involving two gauge fields, which is exactly equivalent to the O(3) $\sigma$ model with the Hopf term. We impose the $CP_1$ constraint by using the gaussian...
Applications of topology to the study of ordered systems (1977)
This paper is a detailed version of a recent preprint wherein the above topic was analysed rather concisely. A pedagogical introduction to homotopy theory is followed by its applications to the study...
Applications of topology to the study of ordered systems (1977)
This paper is a detailed version of a recent preprint wherein the above topic was analysed rather concisely. A pedagogical introduction to homotopy theory is followed by its applications to the study...
Applications of topology to the study of ordered systems (1977)
This paper is a detailed version of a recent preprint wherein the above topic was analysed rather concisely. A pedagogical introduction to homotopy theory is followed by its applications to the study...
Exploitation of the small pion mass in multi-Regge theory. (1974)
Thesis (Ph. D. in Physics)--University of California, Berkeley, June 1974.
Shankar, R, Zhu, J S, Ladd, B, Henry, D, Shen, H Q, Baron, A D
Systemic inhibition of nitric oxide synthase (NOS) with NG-monomethyl-L-arginine (L-NMMA) causes acute insulin resistance (IR), but the mechanism is unknown. We tested whether L-NMMA-induced IR...
Effects of tetrodotoxin and anaesthetics on brain metabolism and transport during anoxia
1. Tetrodotoxin, at concentrations at which it abolishes generation of action potentials in the nervous system, enhances by about 300% the rate of anaerobic glycolysis of brain-cortex slices from...
Mechanisms of neutropenia involving myeloid maturation arrest in burn sepsis.
Shoup, M, Weisenberger, J M, Wang, J L, Pyle, J M, Gamelli, R L, Shankar, R
OBJECTIVE: To determine the mechanisms that lead to the decrease in bone marrow production of neutrophils during burn sepsis. SUMMARY BACKGROUND DATA: Impaired bone marrow granulopoiesis during burn...
Heparin and heparan sulphate protect basic fibroblast growth factor from non-enzymic glycosylation.
Nissen, N N, Shankar, R, Gamelli, R L, Singh, A, DiPietro, L A
Non-enzymic glycosylation of basic fibroblast growth factor (bFGF, FGF-2) has recently been demonstrated to decrease the mitogenic activity of intracellular bFGF. Loss of this bioactivity has been...
Indoor air quality and acute lower respiratory infection in Indian urban slums.
Sharma, S, Sethi, G R, Rohtagi, A, Chaudhary, A, Shankar, R, Bapna, J S, ...
The present prospective study was conducted at two urban slums of Delhi, Kusumpur Pahari and Kathputly Colony, in the peak winter season from November 1994 through February 1995. We studied 642...
Martins, S.B., Lai, S., Tu, S., Shankar, R., Hastings, S.N., Hoffman, B.B., ...
ATHENA-HTN is a clinical decision support system (CDSS) that delivers guideline-based patient-specific recommendations about hypertension management at the time of clinical decision-making. The...