  An unusual published energy versus wave vector curve extending to the zone
edge determined by ARPES in 5% La-doped SrTiO3 is interpreted using
mixed-polaron theory. After modification of the theory to permit tight-binding
bare energy bands and anisotropy, a fit is made to the 24 points nearest to the
Fermi energy, adding constraints (a) that the Fermi volume is approximately
equal to that determined from the carrier concentration, and (b) that the
transport mass from experiments is approximately twice the bare mass. In order
to fit the remaining five of 29 observed points we empirically add the effect
of a kink. The fit to all points is good. From the parameters of the fit to the
24 points it appears that: (a) The energy overlap integral for the narrow band
in the heavy direction has the opposite sign to that for the wide band,
implying that it is energetically favourable for the nearly small polarons to
be centred in between two sites; and (b) The narrower energy band in the theory
may be nearly-small-polaron like in the heavy direction but large-polaron like
in the other two directions. A simpler energy versus wave vector curve for a 1%
La-doped crystal is discussed more briefly.
