The Top Mass in Hadronic Collisions

There is something strange about the current status of top mass measurements t hadron colliders. Regarding the most precise measurements, performed by kinematic reconstruction of the full t¯t event, and commonly referred to as “Standard Measurements”, often it is not stated clearly what is measured, in contrast with the very small error that is proudly quoted by the experimental collaborations. In some circumstances, it is claimed that what is measured is a “Monte Carlo” mass, i.e. just a parameter in the generator used to perform the analysis. But yet extensive variations of Monte Carlo parameters are performed in order to estimate errors, in a clear effort to reach something more fundamental. Other measurements, for example from the total cross section, or from some kinematic distributions, are presented collectively as “Pole Mass Measurement”, that is (in the context of perturbation theory) a theoretically well defined parameter. No attempt is made to combine these pole mass measurements with the direct measurements.