The glob model of Lichard and Van Hove and the modified soft annihilation
model (MSAM) of Lichard and Thompson are used as a phenomenological tool for
relating results from various experiments on soft photon production in high
energy collisions. The total phenomenological expectation is composed of
contributions from classical bremsstrahlung, the soft annihilation model and
the glob model. The empirical excess above the background from hadronic decays
at very small longitudinal momenta of photons is well reproduced, as well as
that for transverse momenta pT >~ 10 MeV/c. Some data do not require the glob
model and MSAM components in the phenomenological mixture, but do not exclude
them. On the basis of consistency of all data with the total theoretical
expectation we argue that the results of all experiments are mutually
consistent. The models are unable to describe the excess of ultrasoft photons
(pT <~ 10 MeV/c), seen by some, but not all, experiments. This may indicate an
as yet unknown projectile-mass-dependent production mechanism. Possible
relations of soft photon production to other phenomena are discussed. A
simple-to-use, but physically equivalent version of the glob model is
developed, which enables an easy check of presented results.Comment: 25 pages, RevTeX, epsf.sty, 12 embedded figure