R-Modes on Rapidly Rotating, Relativistic Stars: I. Do Type-I Bursts Excite Modes in the Neutron-Star Ocean?

During a Type-I burst, the turbulent deflagation front may excite waves in the neutron star ocean and upper atmosphere with frequencies, $\omega \sim 1$ Hz. These waves may be observed as highly coherent flux oscillations during the burst. The frequencies of these waves changes as the upper layers of the neutron star cool which accounts for the small variation in the observed QPO frequencies. In principle several modes could be excited but the fundamental buoyant $r-$mode exhibits significantly larger variability for a given excitation than all of the other modes. An analysis of modes in the burning layers themselves and the underlying ocean shows that it is unlikely these modes can account for the observed burst oscillations. On the other hand, photospheric modes which reside in a cooler portion of the neutron star atmosphere may provide an excellent explanation for the observed oscillations.Comment: 18 pages, 1 figure, substantial changes and additions to reflect version to appear in Ap

Chemical equilibrium and stable stratification of a multi-component fluid: thermodynamics and application to neutron stars

A general thermodynamic argument shows that multi-component matter in full chemical equilibrium, with uniform entropy per baryon, is generally stably stratified. This is particularly relevant for neutron stars, in which the effects of entropy are negligible compared to those of the equilibrium composition gradient established by weak interactions. It can therefore be asserted that, regardless of the uncertainties in the equation of state of dense matter, neutron stars are stably stratified. This has important, previously discussed consequences for their oscillation modes, magnetic field evolution, and internal angular momentum transport.Comment: AASTeX, 8 pages, including 1 PS figure. Accepted for publication in The Astrophysical Journa

Tunneling into fractional quantum Hall liquids

Motivated by the recent experiment by Grayson et.al., we investigate a non-ohmic current-voltage characteristics for the tunneling into fractional quantum Hall liquids. We give a possible explanation for the experiment in terms of the chiral Tomonaga-Luttinger liquid theory. We study the interaction between the charge and neutral modes, and found that the leading order correction to the exponent $\alpha$ $(I\sim V^\alpha)$ is of the order of $\sqrt{\epsilon}$ $(\epsilon=v_n/v_c)$, which reduces the exponent $\alpha$. We suggest that it could explain the systematic discrepancy between the observed exponents and the exact $\alpha =1/\nu$ dependence.Comment: Latex, 5 page

The triton and three-nucleon force in nuclear lattice simulations

We study the triton and three-nucleon force at lowest chiral order in pionless effective field theory both in the Hamiltonian and Euclidean nuclear lattice formalism. In the case of the Euclidean lattice formalism, we derive the exact few-body worldline amplitudes corresponding to the standard many-body lattice action. This will be useful for setting low-energy coefficients in future nuclear lattice simulations. We work in the Wigner SU(4)-symmetric limit where the S-wave scattering lengths {1}S{0} and {3}S{1} are equal. By comparing with continuum results, we demonstrate for the first time that the nuclear lattice formalism can be used to study few-body nucleon systems.Comment: 16 pages, 4 figure

Lattice calculations for A=3,4,6,12 nuclei using chiral effective field theory

We present lattice calculations for the ground state energies of tritium, helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our results were previously summarized in a letter publication. This paper provides full details of the calculations. We include isospin-breaking, Coulomb effects, and interactions up to next-to-next-to-leading order in chiral effective field theory.Comment: 38 pages, 11 figures, final publication versio

Conductance fluctuations at the integer quantum Hall plateau transition

We study numerically conductance fluctuations near the integer quantum Hall effect plateau transition. The system is presumed to be in a mesoscopic regime, with phase coherence length comparable to the system size. We focus on a two-terminal conductance G for square samples, considering both periodic and open boundary conditions transverse to the current. At the plateau transition, G is broadly distributed, with a distribution function close to uniform on the interval between zero and one in units of e^2/h. Our results are consistent with a recent experiment by Cobden and Kogan on a mesoscopic quantum Hall effect sample.Comment: minor changes, 5 pages LaTex, 7 postscript figures included using epsf; to be published Phys. Rev. B 55 (1997

Magnetic polarizability of hadrons from lattice QCD in the background field method

We present a calculation of hadron magnetic polarizability using the techniques of lattice QCD. This is carried out by introducing a uniform external magnetic field on the lattice and measuring the quadratic part of a hadron's mass shift. The calculation is performed on a $24^4$ lattice with standard Wilson actions at beta=6.0 (spacing $a=0.1$ fm) and pion mass down to about 500 MeV. Results are obtained for 30 particles covering the entire baryon octet ($n$, $p$, $\Sigma^0$, $\Sigma^-$, $\Sigma^+$, $\Xi^-$, $\Xi^0$, $\Lambda$) and decuplet ($\Delta^0$, $\Delta^-$, $\Delta^+$, $\Delta^{++}$, $\Sigma^{*0}$, $\Sigma^{*-}$, $\Sigma^{*+}$, $\Xi^{*0}$, $\Xi^{*-}$, $\Omega^-$), plus selected mesons ($\pi^0$, $\pi^+$, $\pi^-$, $K^0$, $K^+$, ${K}^-$, $\rho^0$, $\rho^+$, $\rho^-$, $K^{*0}$, $K^{*+}$, $K^{*-}$). The results are compared with available values from experiments and other theoretical calculations.Comment: 30 pages, 23 figures, 5 table

Resonance structures in the multichannel quantum defect theory for the photofragmentation processes involving one closed and many open channels

The transformation introduced by Giusti-Suzor and Fano and extended by Lecomte and Ueda for the study of resonance structures in the multichannel quantum defect theory (MQDT) is used to reformulate MQDT into the forms having one-to-one correspondence with those in Fano's configuration mixing (CM) theory of resonance for the photofragmentation processes involving one closed and many open channels. The reformulation thus allows MQDT to have the full power of the CM theory, still keeping its own strengths such as the fundamental description of resonance phenomena without an assumption of the presence of a discrete state as in CM.Comment: 7 page

Pseudo-binary phase diagram for Zr-based in situ ß phase composites

The pseudo-binary (quasi-equilibrium) phase diagram for Zr-based bulk metallic glasses with crystalline in situ precipitates (ß phase) has been constructed from high-temperature phase information and chemical composition analysis. The phase evolution was detected in situ by high-energy synchrotron x-ray diffraction followed by Rietveld analysis of the data for volume fraction estimation. The phase diagram delineates phase fields and allows the control of phase fractions. Combined with related previous work by the authors, this diagram offers a unique opportunity to control both the morphology and volume of the dendritic ß phase precipitates to enhance the properties of the composites

Nuclear and Particle Physics applications of the Bohm Picture of Quantum Mechanics

Approximation methods for calculating individual particle/ field motions in spacetime at the quantum level of accuracy (a key feature of the Bohm Picture of Quantum Mechanics (BP)), are studied. Modern textbook presentations of Quantum Theory are used throughout, but only to provide the necessary, already existing, tested formalisms and calculational techniques. New coherent insights, reinterpretations of old solutions and results, and new (in principle testable) quantitative and qualitative predictions, can be obtained on the basis of the BP that complete the standard type of postdictions and predictions.Comment: 41 page