Classical Dynamics of Anyons and the Quantum Spectrum

In this paper we show that (a) all the known exact solutions of the problem of N-anyons in oscillator potential precisely arise from the collective degrees of freedom, (b) the system is pseudo-integrable ala Richens and Berry. We conclude that the exact solutions are trivial thermodynamically as well as dynamically.Comment: 19 pages, ReVTeX, IMSc/93/0

Hamiltonian Description of Composite Fermions: Aftermath

The Lowest Landau Level (LLL), long distance theory of Composite Fermions (CF) developed by Murthy and myself is minimally extended to all distances, guided by very general principles. The resulting theory is mathematically consistent, and physically appealing: we clearly see the electron and the vortices binding to form the CF. The meaning of the constraints, their role in ensuring compressibility of dipolar objects at $\nu =1/2$, and the observability of dipoles are clarified.Comment: Revised for publication in PRL, 4 - epsilon page

Magnetic phenomena at and near nu =1/2 and 1/4: theory, experiment and interpretation

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 quantum Hall states at filling nu = p/(2ps+1), at and near nu = 1/2 and 1/4, at zero and nonzero temperatures. I show how rotational invariance and two dimensionality can make the underlying interacting theory behave like a free one in a limited context.Comment: Latex 4 pages, 2 figure

Finite Temperature Magnetism in Fractional Quantum Hall Systems: Composite Fermion Hartree-Fock and Beyond

Using the Hamiltonian formulation of Composite Fermions developed recently, the temperature dependence of the spin polarization is computed for the translationally invariant fractional quantum Hall states at $\nu=1/3$ and $\nu=2/5$ in two steps. In the first step, the effect of particle-hole excitations on the spin polarization is computed in a Composite Fermion Hartree-Fock approximation. The computed magnetization for $\nu=1/3$ lies above the experimental results for intermediate temperatures indicating the importance of long wavelength spin fluctuations which are not correctly treated in Hartree-Fock. In the second step, spin fluctuations beyond Hartree-Fock are included for $\nu=1/3$ by mapping the problem on to the coarse-grained continuum quantum ferromagnet. The parameters of the effective continuum quantum ferromagnet description are extracted from the preceding Hartree-Fock analysis. After the inclusion of spin fluctuations in a large-N approach, the results for the finite-temperature spin polarization are in quite good agreement with the experiments.Comment: 10 pages, 8 eps figures. Two references adde

Novel Phases of Planar Fermionic Systems

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 mean-field) to an intermediate, inhomogeneous state (with nonstandard ordering momentum) , which in turn goes by a first order transition to a state with canonical order parameter. We analyze two examples: (i) a superconductor in a parallel magnetic field (which was discussed independently by Bulaevskii)for which the inhomogeneous state is obtained for $1.86 T_c \stackrel{\sim}{<} B \stackrel{\sim}{<} 1.86 \sqrt{2} T_c$ where $T_c$ is the critical temperature (in Kelvin) of the superconductor without a field and $B$ is measured in Tesla, and (ii) spinless (or, as is explained, spin polarized) fermions near half-filling where a similar, sizeable window (which grows in size with anisotropy) exists for the intermediate CDW phase at an ordering momentum different from $(\pi , \pi )$. We discuss the experimental conditions for realizing and observing these phases and the Renormalization Group approach to the transitions.Comment: ([email protected],[email protected]) 29 p Latex 4 figs uuencoded separatel

Tree-Level Stability Without Spacetime Fermions: Novel Examples in String Theory

Is perturbative stability intimately tied with the existence of spacetime fermions in string theory in more than two dimensions? Type 0'B string theory in ten-dimensional flat space is a rare example of a non-tachyonic, non-supersymmetric string theory with a purely bosonic closed string spectrum. However, all known type 0' constructions exhibit massless NSNS tadpoles signaling the fact that we are not expanding around a true vacuum of the theory. In this note, we are searching for perturbatively stable examples of type 0' string theory without massless tadpoles in backgrounds with a spatially varying dilaton. We present two examples with this property in non-critical string theories that exhibit four- and six-dimensional Poincare invariance. We discuss the D-branes that can be embedded in this context and the type of gauge theories that can be constructed in this manner. We also comment on the embedding of these non-critical models in critical string theories and their holographic (Little String Theory) interpretation and propose a general conjecture for the role of asymptotic supersymmetry in perturbative string theory.Comment: harvmac, 29 pages; v2 minor changes, version to appear in JHE

P and T Violation From Certain Dimension Eight Weinberg Operators

Dimension eight operators of the Weinberg type have been shown to give important contributions to CP violating phenomena, such as the electric dipole moment of the neutron. In this note we show how operators related to these (and expected to occur on equal footing) can give rise to time-reversal violating phenomena such as atomic electric dipole moments. We also estimate the induced parity violating phenomena such as small ``wrong'' parity admixtures in atomic states and find that they are negligible. Uses harvmac.tex and epsf.tex; one figure submitted as a uuencoded, compressed EPS file.Comment: 6 pages, EFI-92-5