A theoretical analysis of electromagnetic forces on neutral particles in a
hollow waveguide is presented. We show that the effective scattering cross
section of a very small (Rayleigh) particle can be strongly modified inside
a waveguide. The coupling or the scattered dipolar field with the waveguid
e modes induces a resonant enhanced backscattering state of the scatterer-g
uide system close to the onset of new modes. The particle effective cross s
ection can then be as large as the wavelength even far from any transition
resonance. As we will show, a small particle can be strongly accelerated al
ong the guide axis while being highly confined in a narrow zone of the cros
s section of the guide.