2,947 research outputs found
Two-particle scattering theory for anyons
We consider potential scattering theory of a nonrelativistic quantum
mechanical 2-particle system in R^2 with anyon statistics. Sufficient
conditions are given which guarantee the existence of wave operators and the
unitarity of the S-matrix. As examples the rotationally invariant potential
well and the delta-function potential are discussed in detail. In case of a
general rotationally invariant potential the angular momentum decomposition
leads to a theory of Jost functions. The anyon statistics parameter gives rise
to an interpolation for angular momenta analogous to the Regge trajectories for
complex angular momenta. Levinson's theorem is adapted to the present context.
In particular we find that in case of a zero energy resonance the statistics
parameter can be determined from the scattering phase.Comment: 42 pages of RevTex and 5 figures (included
Stabilization not for certain and the usefulness of bounds
Stabilization is still a somewhat controversial issue concerning its very
existence and also the precise conditions for its occurrence. The key quantity
to settle these questions is the ionization probability, for which hitherto no
computational method exists which is entirely agreed upon. It is therefore very
useful to provide various consistency criteria which have to be satisfied by
this quantity, whose discussion is the main objective of this contribution. We
show how the scaling behaviour of the space leads to a symmetry in the
ionization probability, which can be exploited in the mentioned sense.
Furthermore, we discuss how upper and lower bounds may be used for the same
purpose. Rather than concentrating on particular analytical expressions we
obtained elsewhere for these bounds, we focus in our discussion on the general
principles of this method. We illustrate the precise working of this procedure,
its advantages, shortcomings and range of applicability. We show that besides
constraining possible values for the ionization probability these bounds, like
the scaling behaviour, also lead to definite statements concerning the physical
outcome. The pulse shape properties which have to be satitisfied for the
existence of asymptotical stabilization is the vanishing of the total classical
momentum transfer and the total classical displacement and not smoothly
switched on and off pulses. Alternatively we support our results by general
considerations in the Gordon-Volkov perturbation theory and explicit studies of
various pulse shapes and potentials including in particular the Coulomb- and
the delta potential.Comment: 12 pages Late
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Analytical treatment of stabilization
We present a summarizing account of a series of investigations whose central topic is to address the question whether atomic stabilization exists in an analytical way. We provide new aspects on several issues of the matter in the theoretical context when the dynamics is described by the Stark Hamiltonian. The main outcome of these studies is that the governing parameters for this phenomenon are the total classical momentum transfer and the total classical displacement. Whenever these two quantities vanish, asymptotically weak stabilization does exist. For all other situations we did not find any evidence for stabilization. We found no evidence that strong stabilization might occur. Our results agree qualitatively with the existing experimental findings
California Cooperative Fisheries Investigations. Hydrographic data report. Monterey Bay. July to December, 1974
In July 1974 Moss Landing Marine Laboratories began the continuation
of the bi-weekly hydrographic observations in Monterey Bay.
From 1951 to this date, these stations were sampled by personnel at Hopkins Marine Station in Pacific Grove.
Small changes were made in the sampling routine: 1) to facilitate squid (Loligo opa1escens) studies, our observations were made at night, and 2) stations 1125 and 1154 are sampled in addition to five stations originally used by Hopkins Marine Station (2201, 2202, 2203, 2204, and 2205). These additional stations will provide important
data of the nearshore environment. PDF contains 86 pages
P02.83. Mindfulness meditation in community dwelling older adults with postherpetic neuralgia
Relativistic coupled-cluster single-double calculations of positron-atom bound states
Relativistic coupled-cluster single-double approximation is used to calculate
positron-atom bound states. The method is tested on closed-shell atoms such as
Be, Mg, Ca, Zn, Cd, and Hg where a number of accurate calculations is
available. It is then used to calculate positron binding energies for a range
of open-shell transition metal atoms from Sc to Cu, from Y to Pd, and from Lu
to Pt. These systems possess Feshbach resonances, which can be used to search
for positron-atom binding experimentally through resonant annihilation or
scattering.Comment: submitted to Phys. Rev.
Positronic lithium, an electronically stable Li-e ground state
Calculations of the positron-Li system were performed using the Stochastic
Variational Method and yielded a minimum energy of -7.53208 Hartree for the L=0
ground state. Unlike previous calculations of this system, the system was found
to be stable against dissociation into the Ps + Li channel with a binding
energy of 0.00217 Hartree and is therefore electronically stable. This is the
first instance of a rigorous calculation predicting that it is possible to
combine a positron with a neutral atom and form an electronically stable bound
state.Comment: 11 pages, 2 tables. To be published in Phys.Rev.Let
Grassmann-Gaussian integrals and generalized star products
In quantum scattering on networks there is a non-linear composition rule for
on-shell scattering matrices which serves as a replacement for the
multiplicative rule of transfer matrices valid in other physical contexts. In
this article, we show how this composition rule is obtained using Berezin
integration theory with Grassmann variables.Comment: 14 pages, 2 figures. In memory of Al.B. Zamolodichiko
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