Study of the electromagnetic transition form-factors in →µ + µ − and !→µ + µ − 0 decays with NA60

The NA60 experiment at the CERN SPS has studied low-mass muonpairs in 158A GeV In-In collisions. The mass and pT spectra associated with peripheral collisions can quantit atively be described by the known neutral meson decays. The high data quality has allowed to remeasure the electromagnetic transition form factors of the Dalitz decays �→µ + µ − and !→µ + µ − � 0 . Using the usual pole approximation F = (1− M 2 /� 2 ) −1 for the form factors, we