6,365 research outputs found
Status of Spin Physics - Experimental Summary
The current status of spin physics experiments, based on talks presented at
the Third Circum-Pan-Pacific Symposium on High Energy Spin Physics held in
Beijing, 2001, is summarized in this article. Highlights of recent experimental
results at SLAC, JLab, and DESY, as well as future plans at these facilities
and at RHIC-spin are discussed.Comment: 18 pages, 7 figures, Invited talk presented at the Third
Circum-Pan-Pacific Symposium on High Energy Spin Physics held in Beijing,
October, 200
Jet-like tunneling from a trapped vortex
We analyze the tunneling of vortex states from elliptically shaped traps.
Using the hydrodynamic representation of the Gross-Pitaevskii (Nonlinear
Schr\"odinger) equation, we derive analytically and demonstrate numerically a
novel type of quantum fluid flow: a jet-like singularity formed by the
interaction between the vortex and the nonhomogenous field. For strongly
elongated traps, the ellipticity overwhelms the circular rotation, resulting in
the ejection of field in narrow, well-defined directions. These jets can also
be understood as a formation of caustics since they correspond to a convergence
of trajectories starting from the top of the potential barrier and meeting at a
certain point on the exit line. They will appear in any coherent wave system
with angular momentum and non-circular symmetry, such as superfluids,
Bose-Einstein condensates, and light.Comment: 4 pages, 4 figure
On scattering of solitons for the Klein-Gordon equation coupled to a particle
We establish the long time soliton asymptotics for the translation invariant
nonlinear system consisting of the Klein-Gordon equation coupled to a charged
relativistic particle. The coupled system has a six dimensional invariant
manifold of the soliton solutions. We show that in the large time approximation
any finite energy solution, with the initial state close to the solitary
manifold, is a sum of a soliton and a dispersive wave which is a solution of
the free Klein-Gordon equation. It is assumed that the charge density satisfies
the Wiener condition which is a version of the ``Fermi Golden Rule''. The proof
is based on an extension of the general strategy introduced by Soffer and
Weinstein, Buslaev and Perelman, and others: symplectic projection in Hilbert
space onto the solitary manifold, modulation equations for the parameters of
the projection, and decay of the transversal component.Comment: 47 pages, 2 figure
Recent tests for the statistical parton distributions
We compare some recent experimental results obtained at DESY, SLAC and
Jefferson Lab., with the predictions of the statistical model, we have
previously proposed. The result of this comparison is very satisfactory.Comment: 12 pages, 6 eps figures, version to appear in Mod. Phys. Lett.
Representation of Quantum Mechanical Resonances in the Lax-Phillips Hilbert Space
We discuss the quantum Lax-Phillips theory of scattering and unstable
systems. In this framework, the decay of an unstable system is described by a
semigroup. The spectrum of the generator of the semigroup corresponds to the
singularities of the Lax-Phillips -matrix. In the case of discrete (complex)
spectrum of the generator of the semigroup, associated with resonances, the
decay law is exactly exponential. The states corresponding to these resonances
(eigenfunctions of the generator of the semigroup) lie in the Lax-Phillips
Hilbert space, and therefore all physical properties of the resonant states can
be computed.
We show that the Lax-Phillips -matrix is unitarily related to the
-matrix of standard scattering theory by a unitary transformation
parametrized by the spectral variable of the Lax-Phillips theory.
Analytic continuation in has some of the properties of a method
developed some time ago for application to dilation analytic potentials.
We work out an illustrative example using a Lee-Friedrichs model for the
underlying dynamical system.Comment: Plain TeX, 26 pages. Minor revision
Reflective Scattering and Unitarity
Interpretation of unitarity saturation as reflective scattering is discussed.
Analogies with optics and Berry phase alongside with the experimental
consequences of the proposed interpretation at the LHC energies are considered.Comment: 4 pages, 1 figure, talk given by S. Troshin at Diffraction 2008,
September 9-14, La Londe-les-Maures, Franc
Studying the Sivers function by model calculations
A formalism is presented to evaluate the Sivers function in constituent quark
models. A non-relativistic reduction of the scheme is performed and applied to
the Isgur-Karl model. The sign for the and flavor contributions that we
obtained turns out to be opposite. The Burkardt Sum Rule is fulfilled to a
large extent. After the estimate of the QCD evolution of the results from the
momentum scale of the model to the experimental one, a reasonable agreement
with the available data is obtained.Comment: To appear in the proceedings of Diffraction 2008: International
Workshop On Diffraction In High Energy Physics, 9-14 Sep 2008, La
Londe-les-Maures, France. Misprints corrected, reference adde
Prompt photon hadroproduction in the k_T-factorization approach
We study the production of prompt photons at high energy in the framework of
the k_T-factorization approach. The amplitude for production of a single photon
associated with quark pair in the fusion of two off-shell gluons is calculated.
Theoretical results are compared with the Tevatron data.Comment: 4 pages, 3 figures, to be published in the Proceedings of Workshop
"Diffraction 2008", La Londe-les-Maures, France, Sept. 9-14, 200
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