  We study amplitude zeros in radiative decay processes with a photon or a
gluon emission of all possible scalar particles(e.g. scalar leptoquarks) which
may interact with the usual fermions in models beyond the standard model. For
the decays with a photon emission, the amplitudes clearly exhibit the
factorization property and the differential decay rates vanish at specific
values of a certain variable which are determined only by the electric charges
of the particles involved and independent of the particle masses and the
various couplings. For the decays with a gluon emission, even though the zeros
are washed away, the differential decay rates still have distinct minima. The
branching ratios as a function of leptoquark masses are presented for the
scalar leptoquark decays. We also comment on the decays of vector particles
into two fermions and a photon.
