Precision Measurements of Particle Masses using Jets at LEP2

How massive elementary particles get their mass is one of the greatest open questions in physics. Two of the major goals of the current LEP2 physics program that help to address this question are (a) to measure as precisely as possible the W Boson mass mW and (b) to exclude or discover the Higgs Boson within the available kinematic region. The reconstruction of invariant masses with jets from 4-jet channels (e.g. WW -> q qbar q qbar and HZ -> b bbar q qbar) and missing energy channels (e.g WW -> e nu q qbar and e+e- -> H nu nubar) is discussed. The emphasis is on the determination of mW, from which the role of calorimetry in such a precision measurement is emphasised.