Current-carrying string loops in black-hole spacetimes with a repulsive
  cosmological constant
  Current-carrying string loop dynamics in Schwarzschild-de Sitter spacetimes
characterized by the cosmological parameter {\lambda}=1/3{\Lambda}M^2 is
investigated. With attention concentrated to the axisymmetric motion of string
loops it is shown that the resulting motion is governed by the presence of an
outer tension barrier and an inner angular momentum barrier that are influenced
by the black hole gravitational field given by the mass M and the cosmic
repulsion given by the cosmological constant {\Lambda}. The gravitational
attraction could cause capturing of the string having low energy by the black
hole or trapping in its vicinity; with high enough energy, the string can
escape (scatter) to infinity. The role of the cosmic repulsion becomes
important in vicinity of the so-called static radius where the gravitational
attraction is balanced by the cosmic repulsion-it is demonstrated both in terms
of the effective potential of the string motion and the basin boundary method
reflecting its chaotic character, that a potential barrier exists along the
static radius behind which no trapped oscillations may exist. The trapped
states of the string loops, governed by the interplay of the gravitating mass M
and the cosmic repulsion, are allowed only in Schwarzschild-de Sitter
spacetimes with the cosmological parameter {\lambda}<{\lambda}_trap 0.00497.
The trapped oscillations can extend close to the radius of photon circular
orbit, down to r_mt 3.3M.
