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Avinash Khare

Publications and source records attributed to Avinash Khare.

At least 181 records · Page 10Linked to original sources
arXiv1998

Exact Solution of a Class of Three-Body Scattering Problems in One dimension

We present an exact solution of the three-body scattering problem for a one parameter family of one dimensional potentials containing the Calogero and Wolfes potentials as special limiting cases. The result is an interesting nontrivial relationship between the final momenta $p'_i$ and the initial momenta $p_i$ of the three particles. We also discuss another one parameter family of potentials for all of which $p'_i=-p_i~(i=1,2,3)$.

quant-ph↗
arXiv1997

Exact Ground State of Several N-body Problems With an N-body Potential

I consider several N-body problems for which exact (bosonic) ground state and a class of excited states are known in case the N-bodies are also interacting via harmonic oscillator potential. I show that for all these problems the exact (bosonic) ground state and a class of excited states can also be obtained in case they interact via an N-body potential of the form $-e^2/\sqrt{\sumr^2_i}$ (or $-e^2/\sqrt{\sum_{i<j} (r_i - r_j)^2}$). Based on these and previously known examples, I conjecture that whenever an N-body problem is solvable in case the N-bodies are interacting via an oscillator potential, the same problem is also solvable in case they are interacting via the N-body potential. Based on several examples, I also conjecture that in either case one can always add an N-body potential of the form $β^2/{\sum_{i} r_i^2}$ and the problem is still solvable except that the degeneracy in the bound state spectrum is now much reduced.

cond-mat.stat-mech↗
arXiv1997

Anti-isospectral Transformations, Orthogonal Polynomials and Quasi-Exactly Solvable Problems

We consider the double sinh-Gordon potential which is a quasi-exactly solvable problem and show that in this case one has two sets of Bender-Dunne orthogonal polynomials . We study in some detail the various properties of these polynomials and the corresponding quotient polynomials. In particular, we show that the weight functions for these polynomials are not always positive. We also study the orthogonal polynomials of the double sine-Gordon potential which is related to the double sinh-Gordon case by an anti-isospectral transformation. Finally we discover a new quasi-exactly solvable problem by making use of the anti-isospectral transformation.

quant-ph↗
arXiv1997

Do Quasi-Exactly Solvable Systems Always Correspond to Orthogonal Polynomials?

We consider two quasi-exactly solvable problems in one dimension for which the Schrödinger equation can be converted to Heun's equation. We show that in neither case the Bender-Dunne polynomials form an orthogonal set. Using the anti-isopectral transformation we also discover a new quasi-exactly solvable problem and show that even in this case the polynomials do not form an orthogonal set.

math-ph↗
arXiv1997

Subatomic Physics-100 Not Out and Still Going Strong!

On the occasion of the birth centenary of the discovery of electron, I discuss its role in the area of Elementary Particle Physics. I emphasize that the discovery of electron marks the end of the speculation era lasting more than 2500 years. The key developments leading to the discovery of electron by J.J. Thomson are mentioned. The standard model is briefly described. It is emphasized that this model is unsatisfactory in several respects, however no further progress beyond standard model is possible unless there is a dramatic advance in instrumentation.

physics.ed-ph↗
arXiv1997

Exact Thermodynamics of the Double sinh-Gordon Theory in 1+1-Dimensions

We study the classical thermodynamics of a 1+1-dimensional double-well sinh-Gordon theory. Remarkably, the Schrodinger-like equation resulting from the transfer integral method is quasi-exactly solvable at several temperatures. This allows exact calculation of the partition function and some correlation functions above and below the short-range order (``kink'') transition, in striking agreement with high resolution Langevin simulations. Interesting connections with the Landau-Ginzburg and double sine-Gordon models are also established.

cond-mat.stat-mech↗
arXiv1997

A Quantum Many-body Problem in Two Dimensions: Ground State

We obtain the exact ground state for the Calogero-Sutherland problem in arbitrary dimensions. In the special case of two dimensions, we show that the problem is connected to the random matrix problem for complex matrices, provided the strength of the inverse-square interaction $g = 2$. In the thermodynamic limit, we obtain the ground state energy and the pair-correlation function and show that in this case there is no long-range order.

hep-th↗
arXiv1997

Compacton Solutions in a Class of Generalized Fifth Order Korteweg-de Vries Equations

We study a class of generalized fifth order Korteweg-de Vries (KdV) equations which are derivable from a Lagrangian L(p,m,n,l) which has variable powers of the first and second derivatives of the field with powers given by the parameters p,m,n,l. The resulting field equation has solitary wave solutions of both the usual (non-compact) and compact variety ("compactons"). For the particular case that p=m=n+l, the solitary wave solutions have compact support and the feature that their width is independent of the amplitude. We discuss the Hamiltonian structure of these theories and find that mass, momentum, and energy are conserved. We find in general that these are not completely integrable systems. Numerical simulations show that an arbitrary compact initial wave packet whose width is wider than that of a compacton breaks up into several compactons all having the same width. The scattering of two compactons is almost elastic, with the left over wake eventually turning into compacton-anticompacton pairs. When there are two different compacton solutions for a single set of parameters the wider solution is stable, and this solution is a minimum of the Hamiltonian.

patt-sol↗
arXiv1997

Generalized Haldane-Shastry Models as Supersymmetric Partners of the Calogero-Sutherland Type Models

We consider the supersymmetric Calogero-Sutherland type N-particle problems in one dimension and show that the corresponding fermionic part can be identified with the generalized X-Y models in the presence of an inhomogeneous magnetic field. In particular we show that the generalized Haldane-Shastry models (with magnetic field) are themselves the fermionic partners of the Calogero-Sutherland type models. Several such models are discussed and a recipe is given for constructing spin models and finding their ground state energy from the corresponding N-particle problems.

cond-mat.stat-mech↗
arXiv1996

Novel correlations in two dimensions: Two-body problem

We discuss a many-body Hamiltonian with two- and three-body interactions in two dimensions introduced recently by Murthy, Bhaduri and Sen. Apart from an analysis of some exact solutions in the many-body system, we analyze in detail the two-body problem which is completely solvable. We show that the solution of the two-body problem reduces to solving a known differential equation due to Heun. We show that the two-body spectrum becomes remarkably simple for large interaction strength and the level structure resembles that of the Landau Levels. We also clarify the "ultraviolet" regularization which is needed to define an inverse-square potential properly and discuss its implications for our model.

cond-mat↗
arXiv1995

A Calogero-Sutherland Type Model For Branched Polymers

We show that a Calogero-Sutherland type model with anharmonic interactions of fourth and sixth orders leads to the matrix model corresponding to the branched polymers. We also show that by suitably modifying this model one can also obtain N-particle problems which are connected to matrix models corresponding to the pure gravity phase as well as corresponding to the transition point between the soap bubble and the branched polymer phase.

cond-mat↗
arXiv1995

A Class of Exact Solutions For N-Anyons in a N-body Potential

A class of exact solutions are obtained for the problem of N-anyons interacting via the N-body potential $V (\vec x_1,\vec x_2,...,\vec x_N)$ = $-{e^2\over\sqrt{{1\over N}\sum_{i<j} (\vec x_i-\vec x_j)^2}}$ Unlike the oscillator case the resulting spectrum is not linear in the anyon parameter $α(0\leq α\leq 1)$. However, a la oscillator case, cross-over between the ground states is shown to occur for N-anyons $(N\geq 3)$ experiencing the above potential.

hep-th↗
arXiv1995

Fifty Years of the Exact Solution of the Two-Dimensional Ising Model by Onsager

The exact solution of the two-dimensional Ising model by Onsager in 1944 represents one of the landmarks in theoretical physics. On the occassion of the fifty years of the exact solution, we give a historical review of this model. After briefly discussing the exact solution by Onsager, we point out some of the recent developments in this field. The exact solution by Onsager has inspired several developments in various other fields. Some of these are also briefly mentioned.

cond-mat↗
arXiv1995

Exact Solution of a N-body Problem in One Dimension

Complete energy spectrum is obtained for the quantum mechanical problem of N one dimensional equal mass particles interacting via potential $$V(x_1,x_2,...,x_N) = g\sum^N_{i < j}{1\over (x_i-x_j)^2} - {α\over \sqrt{\sum_{i < j} (x_i-x_j)^2}}$$ Further, it is shown that scattering configuration, characterized by initial momenta $p_i (i=1,2,...,N)$ goes over into a final configuration characterized uniquely by the final momenta $p'_i$ with $p'_i=p_{N+1-i}$.

hep-th↗
arXiv1995

Exact Solutions To The Generalized Lienard Equations

Many new solitary wave solutions of the recently studied Lienard equation are obtained by mapping it to the field equation of the $ϕ^6-$field theory. Further, it is shown that the exact solutions of the Lienard equation are also the exact solutions of the various perturbed soliton equations. Besides, we also consider a one parameter family of generalised Lienard equations and obtain exact solitary wave solutions of these equations and show that these are also the exact solutions of the various other generalised nonlinear equations.

hep-th↗
arXiv1995

Coherent States for Isospectral Hamiltonians

We show that for the strictly isospectral Hamiltonians, the corresponding coherent states are related by a unitary transformation. As an illustration, we discuss, the example of strictly isospectral one-dimensional harmonic oscillator Hamiltonians and the associated coherent states.

quant-ph↗
arXiv1995

Methods for Generating Quasi-Exactly Solvable Potentials

We describe three different methods for generating quasi-exactly solvable potentials, for which a finite number of eigenstates are analytically known. The three methods are respectively based on (i) a polynomial ansatz for wave functions; (ii) point canonical transformations; (iii) supersymmetric quantum mechanics. The methods are rather general and give considerably richer results than those available in the current literature.

hep-th↗