On Pauli Pairs

The state of a system in classical mechanics can be uniquely reconstructed if we know the positions and the momenta of all its parts. In 1958 Pauli has conjectured that the same holds for quantum mechanical systems. The conjecture turned out to be wrong. In this paper we provide a new set of examples of Pauli pairs, being the pairs of quantum states indistinguishable by measuring the spatial location and momentum. In particular, we construct a new set of spatially localized Pauli pairs.Comment: submitted to JM

Universality in Two Dimensional Gauge Theory.

We discuss two dimensional Yang -- Mills theories with massless fermions in arbitrary representations of a gauge group $G$. It is shown that the physics (spectrum and interactions) of the massive states in such models is independent of the detailed structure of the model, and only depends on the gauge group $G$ and an integer $k$ measuring the total anomaly. The massless physics, which does depend on the details of the model, decouples (almost) completely from that of the massive one. As an example, we discuss the equivalence of QCD$_2$ coupled to fermions in the adjoint, and fundamental representations.Comment: 16 pages, harvma

The use of an aircraft test stand for VTOL handling qualities studies

The VTOL flight tests stand for testing control concepts on the X-14B VSS aircraft in hover, is described. This stand permits realistic and safe piloted evaluation and checkout of various control systems and of parameter variations within each system to determine acceptability to the pilot. Pilots can use it as a practical training tool to practice procedures and flying techniques and become familiar with the aircraft characteristics. Some examples of test experience are given. The test stand allows the X14B to maneuver in hover from centered position + or - 9.7 deg in roll and + or - 9.3 deg in pitch, about + or - 6 deg in yaw, and + or - 15 cm in vertical translation. The unique vertical free flight freedom enables study of liftoffs and landings with power conditions duplicated. The response on the stand agrees well with that measured in free hovering flight, and pilot comments confirm this

Masses of the physical mesons from an effective QCD--Hamiltonian

The front form Hamiltonian for quantum chromodynamics, reduced to an effective Hamiltonian acting only in the $q\bar q$ space, is solved approximately. After coordinate transformation to usual momentum space and Fourier transformation to configuration space a second order differential equation is derived. This retarded Schr\"odinger equation is solved by variational methods and semi-analytical expressions for the masses of all 30 pseudoscalar and vector mesons are derived. In view of the direct relation to quantum chromdynamics without free parameter, the agreement with experiment is remarkable, but the approximation scheme is not adequate for the mesons with one up or down quark. The crucial point is the use of a running coupling constant $\alpha_s(Q^2)$, in a manner similar but not equal to the one of Richardson in the equal usual-time quantization. Its value is fixed at the Z mass and the 5 flavor quark masses are determined by a fit to the vector meson quarkonia.Comment: 18 pages, 4 Postscript figure

A low-metallicity massive contact binary undergoing slow Case A mass transfer: A detailed spectroscopic and orbital analysis of SSN 7 in NGC 346 in the SMC

Most massive stars are believed to be born in close binary systems where they can exchange mass, which impacts the evolution of both binary components. Their evolution is of great interest in the search for the progenitors of gravitational waves. However, there are unknowns in the physics of mass transfer as observational examples are rare, especially at low metallicity. Nearby low-metallicity environments are particularly interesting hunting grounds for interacting systems as they act as the closest proxy for the early universe where we can resolve individual stars. Using multi-epoch spectroscopic data, we complete a consistent spectral and orbital analysis of the early-type massive binary SSN 7 hosting a ON If$^\ast$+O5.5 V((f)) star. Using these detailed results, we constrain an evolutionary scenario that can help us to understand binary evolution in low metallicity. We were able to derive reliable radial velocities of the two components from the multi-epoch data, which were used to constrain the orbital parameters. The spectroscopic data covers the UV, optical, and near-IR, allowing a consistent analysis with the stellar atmosphere code, PoWR. Given the stellar and orbital parameters, we interpreted the results using binary evolutionary models. The two stars in the system have comparable luminosities of ${\log (L_1/L_{\odot}) = 5.75}$ and ${\log (L_2/L_{\odot}) = 5.78}$ for the primary and secondary, respectively, but have different temperatures (${T_1=43.6\,\mathrm{kK}}$ and ${T_2=38.7\,\mathrm{kK}}$). The primary ($32\,M_{\odot}$) is less massive than the secondary ($55\,M_{\odot}$), suggesting mass exchange. The mass estimates are confirmed by the orbital analysis. The revisited orbital period is $3\,\mathrm{d}$. Our evolutionary models also predict mass exchange. Currently, the system is a contact binary undergoing a slow Case A phase, making it the most massive [Abridged]Comment: 20 page

Interference in Bohmian Mechanics with Complex Action

In recent years, intensive effort has gone into developing numerical tools for exact quantum mechanical calculations that are based on Bohmian mechanics. As part of this effort we have recently developed as alternative formulation of Bohmian mechanics in which the quantum action, S, is taken to be complex [JCP {125}, 231103 (2006)]. In the alternative formulation there is a significant reduction in the magnitude of the quantum force as compared with the conventional Bohmian formulation, at the price of propagating complex trajectories. In this paper we show that Bohmian mechanics with complex action is able to overcome the main computational limitation of conventional Bohmian methods -- the propagation of wavefunctions once nodes set in. In the vicinity of nodes, the quantum force in conventional Bohmian formulations exhibits rapid oscillations that pose severe difficulties for existing numerical schemes. We show that within complex Bohmian mechanics, multiple complex initial conditions can lead to the same real final position, allowing for the description of nodes as a sum of the contribution from two or more crossing trajectories. The idea is illustrated on the reflection amplitude from a one-dimensional Eckart barrier. We believe that trajectory crossing, although in contradiction to the conventional Bohmian trajectory interpretation, provides an important new tool for dealing with the nodal problem in Bohmian methods

Electronic Detection of Gravitational Disturbances and Collective Coulomb Interactions

The cross section for a gravitational wave antenna to absorb a graviton may be directly expressed in terms of the non-local viscous response function of the metallic crystal. Crystal viscosity is dominated by electronic processes which then also dominate the graviton absorption rate. To compute this rate from a microscopic Hamiltonian, one must include the full Coulomb interaction in the Maxwell electric field pressure and also allow for strongly non-adiabatic transitions in the electronic kinetic pressure. The view that the electrons and phonons constitute ideal gases with a weak electron phonon interaction is not sufficiently accurate for estimating the full strength of the electronic interaction with a gravitational wave.Comment: 7 pages LaTeX 1 figure afig1.ep

A Test of CPT Symmetry in K^0 vs \bar{K}^0 to \pi^+\pi^-\pi^0 Decays

I show that the CP-violating asymmetry in K^0 vs \bar{K}^0 \to \pi^+\pi^-\pi^0 decays differs from that in K_L \to \pi^+\pi^-, K_L \to \pi^0\pi^0 or the semileptonic K_L transitions, if there exists CPT violation in K^0-\bar{K}^0 mixing. A delicate measurement of this difference at a super flavor factory (e.g., the \phi factory) will provide us with a robust test of CPT symmetry in the neutral kaon system.Comment: 4 pages, 1 figure. To appear in the Proceedings of the International PHIPSI09 Workshop, October 2009, Beijing, Chin