4,574 research outputs found
Effective-Mass Klein-Gordon-Yukawa Problem for Bound and Scattering States
Bound and scattering state solutions of the effective-mass Klein-Gordon
equation are obtained for the Yukawa potential with any angular momentum
. Energy eigenvalues, normalized wave functions and scattering phase
shifts are calculated as well as for the constant mass case. Bound state
solutions of the Coulomb potential are also studied as a limiting case.
Analytical and numerical results are compared with the ones obtained before.Comment: 13 pages, 1 figur
Perturbation Theory of Coulomb Gauge Yang-Mills Theory Within the First Order Formalism
Perturbative Coulomb gauge Yang-Mills theory within the first order formalism
is considered. Using a differential equation technique and dimensional
regularization, analytic results for both the ultraviolet divergent and finite
parts of the two-point functions at one-loop order are derived. It is shown how
the non-ultraviolet divergent parts of the results are finite at spacelike
momenta with kinematical singularities on the light-cone and subsequent branch
cuts extending into the timelike region.Comment: 23 pages, 6 figure
Volume Dependence of Bound States with Angular Momentum
We derive general results for the mass shift of bound states with angular
momentum l >= 1 in a finite periodic volume. Our results have direct
applications to lattice simulations of hadronic molecules as well as atomic
nuclei. While the binding of S-wave bound states increases at finite volume, we
show that the binding of P-wave bound states decreases. The mass shift for
D-wave bound states as well as higher partial waves depends on the
representation of the cubic rotation group. Nevertheless, the
multiplet-averaged mass shift for any angular momentum l can be expressed in a
simple form, and the sign of the shift alternates for even and odd l. We verify
our analytical results with explicit numerical calculations. We also show
numerically that similar volume corrections appear in three-body bound states.Comment: 4 pages, 3 figures, final versio
Coherent Destruction of Photon Emission from a Single Molecule Source
The behavior of a single molecule driven simultaneously by a laser and by an
electric radio frequency field is investigated using a non-Hermitian
Hamiltonian approach. Employing the renormalization group method for
differential equations we calculate the average waiting time for the first
photon emission event to occur, and determine the conditions for the
suppression and enhancement of photon emission. An abrupt transition from
localization-like behavior to delocalization behavior is found.Comment: 5 pages, 4 figure
Closed-orbit theory for spatial density oscillations
We briefly review a recently developed semiclassical theory for quantum
oscillations in the spatial (particle and kinetic energy) densities of finite
fermion systems and present some examples of its results. We then discuss the
inclusion of correlations (finite temperatures, pairing correlations) in the
semiclassical theory.Comment: LaTeX, 10pp., 2 figure
Controlling Polymer Capture and Translocation by Electrostatic Polymer-Pore Interactions
Polymer translocation experiments typically involve anionic polyelectrolytes
such as DNA molecules driven through negatively charged nanopores. Quantitative
modelling of polymer capture to the nanopore followed by translocation
therefore necessitates the consideration of the electrostatic barrier resulting
from like-charge polymer-pore interactions. To this end, in this work we couple
mean-field level electrohydrodynamic equations with the Smoluchowski formalism
to characterize the interplay between the electrostatic barrier, the
electrophoretic drift, and the electro-osmotic liquid flow. In particular, we
find that due to distinct ion density regimes where the salt screening of the
drift and barrier effects occur, there exists a characteristic salt
concentration maximizing the probability of barrier-limited polymer capture
into the pore. We also show that in the barrier-dominated regime, the polymer
translocation time increases exponentially with the membrane charge and decays
exponentially fast with the pore radius and the salt concentration. These
results suggest that the alteration of these parameters in the barrier-driven
regime can be an efficient way to control the duration of the translocation
process and facilitate more accurate measurements of the ionic current signal
in the pore
Stability analysis of the Witten black hole (cigar soliton) under world-sheet RG flow
We analyze the stability of the Euclidean Witten black hole (the cigar
soliton in mathematics literature) under first-order RG (Ricci) flow of the
world-sheet sigma model. This analysis is from the target space point of view.
We find that the Witten black hole has no unstable normalizable perturbative
modes in a linearized mode analysis in which we consider circularly symmetric
perturbations. Finally, we discuss a result from mathematics that implies the
existence of a non-normalizable mode of the Witten black hole under which the
geometry flows to the sausage solution studied by Fateev, Onofri and
Zamolodchikov.Comment: 17 pages, version to appear in Physical Review D, and now has
complete proof of stability for circularly symmetric perturbations, in
response to referee comment
Impedance of a sphere oscillating in an elastic medium with and without slip
The dynamic impedance of a sphere oscillating in an elastic medium is
considered. Oestreicher's formula for the impedance of a sphere bonded to the
surrounding medium can be expressed simply in terms of three lumped impedances
associated with the displaced mass and the longitudinal and transverse waves.
If the surface of the sphere slips while the normal velocity remains
continuous, the impedance formula is modified by adjusting the definition of
the transverse impedance to include the interfacial impedance.Comment: 10 pages, 2 figure
Reflection and Transmission at the Apparent Horizon during Gravitational Collapse
We examine the wave-functionals describing the collapse of a self-gravitating
dust ball in an exact quantization of the gravity-dust system. We show that
ingoing (collapsing) dust shell modes outside the apparent horizon must
necessarily be accompanied by outgoing modes inside the apparent horizon, whose
amplitude is suppressed by the square root of the Boltzmann factor at the
Hawking temperature. Likewise, ingoing modes in the interior must be
accompanied by outgoing modes in the exterior, again with an amplitude
suppressed by the same factor. A suitable superposition of the two solutions is
necessary to conserve the dust probability flux across the apparent horizon,
thus each region contains both ingoing and outgoing dust modes. If one
restricts oneself to considering only the modes outside the apparent horizon
then one should think of the apparent horizon as a partial reflector, the
probability for a shell to reflect being given by the Boltzmann factor at the
Hawking temperature determined by the mass contained within it. However, if one
considers the entire wave function, the outgoing wave in the exterior is seen
to be the transmission through the horizon of the interior outgoing wave that
accompanies the collapsing shells. This transmission could allow information
from the interior to be transferred to the exterior.Comment: 19 pages, no figures. To appear in Phys. Rev.
Energy conditions for a generally coupled scalar field outside a reflecting sphere
We calculate the stress-energy tensor for a scalar field with general
curvature coupling, outside a perfectly reflecting sphere with Dirichlet
boundary conditions. For conformal coupling we find that the null energy
condition is always obeyed, and therefore the averaged null energy condition
(ANEC) is also obeyed. Since the ANEC is independent of curvature coupling, we
conclude that the ANEC is obeyed for scalar fields with any curvature coupling
in this situation. We also show how the spherical case goes over to that of a
flat plate as one approaches the sphere.Comment: Accepted for publication in Phys. Rev.
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