  We investigate the radiation from a charged particle moving outside a
dielectric cylinder parallel to its axis. It is assumed that the cylinder is
immersed into a homogeneous medium. The expressions are given for the vector
potential and for the electric and magnetic fields. The spectral distributions
are studied for three types of the radiations: (i) Cherenkov radiation (CR) in
the exterior medium, (ii) radiation on the guided modes of the dielectric
cylinder, and (iii) emission of surface polaritons. Unlike the first two types
of radiations, there is no velocity threshold for the generation of surface
polaritons. The corresponding radiation is present in the spectral range where
the dielectric permittivities of the cylinder and surrounding medium have
opposite signs. The spectral range of the emitted surface polaritons becomes
narrower with decreasing energy of the particle. The general results are
illustrated for a special case of the Drude model for dispersion of the
dielectric permittivity of the cylinder. We show that the presence of the
cylinder may lead to the appearance of strong narrow peaks in the spectral
distribution of the CR in the exterior medium. The conditions are specified for
the appearance of those peaks and the corresponding heights and widths are
analytically estimated. The collective effects of particles in bunches are
discussed.
