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SUMMARY:Wave function and CKM renormalization in the Standard Model and be
 yond
DTSTART;VALUE=DATE-TIME:20020625T103000Z
DTEND;VALUE=DATE-TIME:20020625T113000Z
DTSTAMP;VALUE=DATE-TIME:20261109T043157Z
UID:indico-event-1268@indico.ific.uv.es
DESCRIPTION:We clarify some aspects of the LSZ formalism and wave function
  renormalisation for unstable particles in the presence of electroweak int
 eractions when mixing and CP violation are considered. We also analyse the
  renormalisation of the CKM mixing matrix which is closely related to wave
  function renormalisation. We critically review earlier attempts to define
  a set of "on-shell" wave function renormalisation constants. With the aid
  of an extensive use of the Nielsen identities complemented by explicit ca
 lculations we corroborate that the counter term for the CKM mixing matrix 
 must be explicitly gauge independent and demonstrate that the commonly use
 d prescription for the wave function renormalisation constants leads to ga
 uge parameter dependent amplitudes\, even if the CKM counter term is gauge
  invariant as required. We show that a proper LSZ-compliant prescription l
 eads to gauge independent amplitudes. The resulting wave function renormal
 isation constants necessarily possess absorptive parts\, but we verify tha
 t they comply with the expected requirements concerning CP and CPT. The re
 sults obtained using this prescription are different (even at the level of
  the modulus squared of the amplitude) from the ones neglecting the absorp
 tive parts in the case of top decay. The difference is numerically relevan
 t.\n\nhttps://indico.ific.uv.es/event/1268/
LOCATION:Dpto. de Física Teórica (UVEG) Sala Seminarios
URL:https://indico.ific.uv.es/event/1268/
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