  Exact formulas of the acoustic radiation force and torque exerted by an
arbitrary time-harmonic wave on an absorbing compressible particle that is
suspended in an inviscid fluid are presented. It is considered that the
particle diameter is much smaller than the incident wavelength, i.e. the
so-called Rayleigh scattering limit. Moreover, the particle absorption assumed
here is due to the attenuation of compressional waves only. Shear waves inside
and outside the particle are neglected, since the inner and outer viscous
boundary layer of the particle are supposed to be much smaller than the
particle radius. The obtained radiation force formulas are used to establish
the trapping conditions of a particle by a single-beam acoustical tweezer based
on a spherically focused ultrasound beam. In this case, it is shown that the
particle absorption has a pivotal role in single-beam trapping at the
transducer focal region. Furthermore, it is found that only the first-order
Bessel vortex beam can generate the radiation torque on a small particle. In
addition, numerical evaluation of the radiation force and torque exerted on a
benzene and an olive oil droplet suspended in water are presented and
discussed.
