Quantum mechanics of a constrained electrically charged particle in the presence of electric currents

We discuss the dynamics of a classical spinless quantum particle carrying electric charge and constrained to move on a non singular static surface in ordinary three dimensional space in the presence of arbitrary configurations of time independent electric currents. Starting from the canonical action in the embedding space we show that a charged particle with charge $q$ couples to a term linear in $qA^3M$, where $A^3$ is the transverse component of the electromagnetic vector potential and $M$ is the mean curvature in the surface. This term cancels exactly a curvature contribution to the orbital magnetic moment of the particle. It is shown that particles, independently of the value of the charge, in addition to the known couplings to the geometry also couple to the mean curvature in the surface when a Neumann type of constraint is applied on the transverse fluctuations of the wave function. In contrast to a Dirrichlet constraint on the transverse fluctuations a Neumann type of constraint on these degrees of freedom will in general make the equations of motion non separable. The exceptions are the equations of motion for electrically neutral particles on surfaces with constant mean curvature. In the presence of electric currents the equation of motion of a charged particle is generally non separable independently of the coupling to the geometry and the boundary constraints.Comment: to appear in Phys.Rev.

Ionization of Rydberg atoms in a low frequency field: modelling by maps of transition to chaotic behavior

We investigate a microwave ionization of highly excited atom in a low frequency field and show that such a process may be studied on the bases of map for the electron energy change during the period of the electron motion between two subsequent passages at aphelion. Simple approximate criterion results to the threshold field for transition to chaotic behavior very close to the numerical results. We show that transition from adiabatic to chaotic ionization mechanism takes place when the field frequency to the electron's Kepler frequency ration approximately equals 0.1.Comment: 5 pages, LaTEX, 37Kb, 2 figures (compressed and uuencoded PostScript) included in text. To be published in Chaos: The interplay between stochastics, classics and quanta, Ed. by P. Garbaczewski, et al. Lecture notes in Physics, 1995

Quenching of spectroscopic factors for proton removal in oxygen isotopes

We present microscopic coupled-cluster calculations of the spectroscopic factors for proton removal from the closed-shell oxygen isotopes $^{14,16,22,24,28}$O with the chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order. We include coupling-to-continuum degrees of freedom by using a Hartree-Fock basis built from a Woods-Saxon single-particle basis. This basis treats bound and continuum states on an equal footing. We find a significant quenching of spectroscopic factors in the neutron-rich oxygen isotopes, pointing to enhanced many-body correlations induced by strong coupling to the scattering continuum above the neutron emission thresholds.Comment: 3 figure

Firm Structure, Multinationals, and Manufacturing Plant Deaths

Plant shutdowns shape industry productivity, the dynamics of employment, and industrial restructuring. Plant closures account for more than half of gross job destruction in US manufacturing. This paper examines the effects of firm structure on US manufacturing plant closures. Plants belonging to multi-plant firms and those owned by US multinationals are less likely to exit. However, the superior survival chances are due to the characteristics of the plants rather than the nature of the firms. Controlling for plant and industry attributes, we find that plants owned by multi-unit firms and US multinationals are much more likely to close.Exit, shutdown, closure, multi-plant firms, multinational firms, takeovers, entry costs, agglomeration, specialization