Transverse polarisation of the positron from polarized muon decay? A new precision measurement and its implications for the Standard Model

por Wulf Fetscher (ETH Zurich)

viernes 25 jun. 1999 11:00 → 12:00 Europe/Madrid

Sala Seminarios (Dpto. de Fisica Teorica (UVEG))

Is the positron from polarized muon decay really transversely polarised? Only slightly in the case of the standard model with its lefthanded couplings, but maybe sizeably if additional exotic couplings contribute to muon decay. A new experiment at PSI is aiming to measure the two possible transverse polarization components P_T1 and P_T2 with a precision of 3 x 10^-3. The energy dependence of P_T1 yields an improved value for the low energy parameter eta that is the limiting quantity in the determination of the Fermi coupling constant G_F. The measurement of P_T2 is the only test of time reversal invariance so far in a purely leptonic interaction. I will present the experiment, show the results of our test measurements and discuss the implications of this experiment for our knowledge of the charged weak interaction.