Top Mass Measurements from Jets and the Tevatron Top-Quark Mass

Theoretical issues are discussed for the measurement of the top-mass using jets, including perturbative and non-perturbative effects that relate experimental observables to the Lagrangian mass, and appropriate choices for mass schemes. Full account for these issues is given for e+e-→tt-bar using a factorization theorem for event shapes for massive quarks. Implications for the Tevatron top-mass measurement are discussed. A mass-scheme, the 'MSR-mass', is introduced which allows for a precise description of observables sensitive to scales R<<m, but at the same time does not introduce perturbative matching uncertainties in conversion to the MS-bar mass