  Starting from the coordinate system used by Einstein to find the bending of
light rays by gravitational fields we calculate the effect of the Earth
gravitational energy along a hypothetical photon null path on the geoid non
inertial system. There is an energy term, relative to an inertial system, which
may be interpreted as a small time-relative "dressed" physical rest mass
correction to the photon null mass. This relative gravitational potential
energy determines a proper time delay proportional to the laboratory non
inertial flying time interval along the trajectory with a small factor
5.276x10-5. We also use a geometric technique based on Ehresmann connections to
compare the parallel transport of the photon vector and the neutrino spinor on
null trajectories. The result is that there is a theoretical neutrino time
delay from its inertial path which is half the delay of the photon. Applying
these delays to a hypothetical particle trajectory from the CERN SPS/CNGS
target to the LNGS OPERA detector we find that the difference between the
experimental and theoretical results falls within the reported experimental
errors. The delayed neutrino is faster than the delayed photon but its speed is
smaller than the fundamental constant c. The results also indicate that
neutrino trajectories, as photon trajectories, are affected by gravitational
fields but with smaller effects.
