Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A stochastic-hydrodynamic model of halo formation in charged particle
  beams   The formation of the beam halo in charged particle accelerators is studied in
the framework of a stochastic-hydrodynamic model for the collective motion of
the particle beam. In such a stochastic-hydrodynamic theory the density and the
phase of the charged beam obey a set of coupled nonlinear hydrodynamic
equations with explicit time-reversal invariance. This leads to a linearized
theory that describes the collective dynamics of the beam in terms of a
classical Schr\"odinger equation. Taking into account space-charge effects, we
derive a set of coupled nonlinear hydrodynamic equations. These equations
define a collective dynamics of self-interacting systems much in the same
spirit as in the Gross-Pitaevskii and Landau-Ginzburg theories of the
collective dynamics for interacting quantum many-body systems. Self-consistent
solutions of the dynamical equations lead to quasi-stationary beam
configurations with enhanced transverse dispersion and transverse emittance
growth. In the limit of a frozen space-charge core it is then possible to
determine and study the properties of stationary, stable core-plus-halo beam
distributions. In this scheme the possible reproduction of the halo after its
elimination is a consequence of the stationarity of the transverse distribution
which plays the role of an attractor for every other distribution.

25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn