11,376 research outputs found
Rotational structures of long-range diatomic molecules
We present a systematic understanding of the rotational structure of a
long-range (vibrationally highly-excited) diatomic molecule. For example, we
show that depending on a quantum defect, the least-bound vibrational state of a
diatomic molecule with () asymptotic interaction can have only
1, 2, and up to a maximum of rotational states. A classification scheme
of diatomic molecules is proposed, in which each class has a distinctive
rotational structure and corresponds to different atom-atom scattering
properties above the dissociation limit.Comment: 8 page
Universal properties in ultracold ion-atom interactions
We present some of the universal properties in ion-atom interaction derived
from a newly formulated quantum-defect theory for type of long-range
interactions. For bound states, we present the universal bound spectrum, namely
the equivalent of the Rydberg formula, for ion-atom systems. For scattering, we
introduce the concept of universal resonance spectrum to give a systematic
understanding of many resonances present in ion-atom scattering. The theory
further provides a method for an accurate spectroscopic determination of the
atomic polarizability. It also suggests the existence of atom-like molecules,
in which multiple atoms orbit around a heavy ion.Comment: 4 pages, 2 figure
Influence of Heavy Quark Recombination on the Nucleon Strangeness Asymmetry
The nucleon strange and anti-strange distribution asymmetry is an important
issue in the study of the nucleon structure. In this work, we show that the
heavy quark recombination processes from a perturbative QCD picture can give a
sizable influence on the measurement of the nucleon strangeness asymmetry from
charged-current charm production processes, such as the CCFR and NuTeV dimuon
measurements. When the influence of heavy quark recombination is considered, a
positive effective should be added to the initially
extracted strangeness asymmetry , supporting
the strangeness asymmetry being positive, which is helpful to explain the
NuTeV anomaly within the framework of the standard model.Comment: 5 latex pages, 2 figure
Simple Theoretical Models for Resonant Cold Atom Interactions
Magnetically tunable scattering resonances have been used with great success
for precise control of s-wave scattering lengths in ultracold atomic
collisions. We describe relatively simple yet quite powerful analytic
treatments of such resonances based on the analytic properties of the van der
Waals long range potential. This theory can be used to characterize a number of
properties of specific resonances that have been used successfully in various
experiments with Rb, Rb, K, and Li. Optical Feshbach
resonances are also possible and may be practical with narrow intercombination
line photoassociative transitions in species like Sr and Yb.Comment: To be published in the Proceedings of the 20th International
Conference on Atomic Physics, held in Innsbruck, Austria, July 200
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