  Convective core overshooting has a strong influence on the evolution of stars
of moderate and high mass. Studies of double-lined eclipsing binaries and
stellar oscillations have renewed interest in the possible dependence of
overshooting on stellar mass, which has been poorly constrained by observations
so far. Here we have used a sample of 29 well-studied double-lined eclipsing
binaries in key locations of the H-R diagram to establish the explicit
dependence of f(ov) on mass, where f(ov) is the free parameter in the diffusive
approximation to overshooting. Measurements of the masses, radii, and
temperatures of the binary components were compared against stellar evolution
calculations based on the MESA code to infer semi-empirical values of f(ov) for
each component. We find a clear mass dependence such that f(ov) rises sharply
from zero in the range 1.2--2.0 solar masses, and levels off thereafter up to
the 4.4 solar mass limit of our sample. Tests with two different element
mixtures indicate the trend is the same, and we find it is also qualitatively
similar to the one established in our previous study with the classical
step-function implementation of overshooting characterized by the free
parameter alpha(ov). Based on these measurements we infer an approximate
relationship between the two overshooting parameters of alpha(ov)/f(ov) = 11.36
+/- 0.22, with a possible dependence on stellar properties.

Solar and Stellar Astrophysics