Electroweak corrections uncertainties on the W mass measurement

The systematic uncertainty on the W mass and width measurement coming from the not perfect knowledge of electroweak radiative corrections is discussed. The intrinsic uncertainty in the 4-f generator used by DELPHI is studied following the guidelines of the YFSWW authors, on which its radiative corrections part is based. A comparison with the other available 4-f calculation implementing DPA O(fi) corrections, RacoonWW, is also presented. The uncertainty on the W mass is found to be below 10 MeV for all the WW decay channels used in the measurement.