  The W boson mass measurement is sensitive to QED radiative corrections due to
virtual photon loops and real photon emission. The largest shift in the
measured mass, which depends on the transverse momentum spectrum of the charged
lepton from the boson decay, is caused by the emission of real photons from the
final-state lepton. There are a number of calculations and codes available to
model the final-state photon emission. We perform a detailed study, comparing
the results from the Horace and Photos implementations of the final-state
multi-photon emission in the context of a direct measurement of the W boson
mass at the Tevatron. Mass fits are performed using a simulation of the CDF II
detector.
