Two-loop electroweak top corrections: are they under control?

The assumption that two-loop top corrections are well approximated by the O(G_mu^2 mt^4) contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the O(G_mu^2 mt^2 M_Z^2) terms are numerically comparable to the m_t^4 cont...

Descripción completa

Detalles Bibliográficos
Autores principales: Degrassi, G., Fanchiotti, S., Feruglio, F., Gambino, P., Vicini, A.
Lenguaje:eng
Publicado: 1994
Materias:
Particle Physics - Phenomenology
Acceso en línea:https://dx.doi.org/10.1016/0370-2693(95)00268-P
http://cds.cern.ch/record/274401
_version_ 1780887377786437632
author Degrassi, G.
Fanchiotti, S.
Feruglio, F.
Gambino, P.
Vicini, A.
author_facet Degrassi, G.
Fanchiotti, S.
Feruglio, F.
Gambino, P.
Vicini, A.
author_sort Degrassi, G.
collection CERN
description The assumption that two-loop top corrections are well approximated by the O(G_mu^2 mt^4) contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the O(G_mu^2 mt^2 M_Z^2) terms are numerically comparable to the m_t^4 contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.
id cern-274401
institution Organización Europea para la Investigación Nuclear
language eng
publishDate 1994
record_format invenio
spelling cern-2744012023-03-14T18:56:27Zdoi:10.1016/0370-2693(95)00268-Phttp://cds.cern.ch/record/274401engDegrassi, G.Fanchiotti, S.Feruglio, F.Gambino, P.Vicini, A.Two-loop electroweak top corrections: are they under control?Particle Physics - PhenomenologyThe assumption that two-loop top corrections are well approximated by the O(G_mu^2 mt^4) contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the O(G_mu^2 mt^2 M_Z^2) terms are numerically comparable to the m_t^4 contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.The assumption that two-loop top corrections are well approximated by the $O(G_mu~2 mt~4)$ contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the $O(G_mu~2 mt~2 M_Z~2)$ terms are numerically comparable to the $m_t~4$ contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.The assumption that two-loop top corrections are well approximated by the $O(G_mu~2 mt~4)$ contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the $O(G_mu~2 mt~2 M_Z~2)$ terms are numerically comparable to the $m_t~4$ contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.The assumption that two-loop top corrections are well approximated by the $O(G_mu~2 mt~4)$ contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the $O(G_mu~2 mt~2 M_Z~2)$ terms are numerically comparable to the $m_t~4$ contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.The assumption that two-loop top corrections are well approximated by the $O(G_mu~2 mt~4)$ contribution is investigated. It is shown that in the case of the ratio neutral-to-charged current amplitudes at zero momentum transfer the $O(G_mu~2 mt~2 M_Z~2)$ terms are numerically comparable to the $m_t~4$ contribution for realistic values of the top mass. An estimate of the theoretical error due to unknown two-loop top effect is presented for a few observables of LEP interest.The top quark contribution to two-loop, purely electroweak radiative corrections is investigated in the case of the ϱ parameter, extracted from the ratio of neutral to charged current amplitudes in low-energy neutrino-lepton scattering. It is shown that the order O ( G μ 2 m t 2 m z 2 ) contribution is numerically comparable and shares the same sign with the leading O ( G μ 2 m t 4 ) term, for realistic values of the top and Higgs masses. The result raises doubts on the reliability of the heavy top approximation in the two-loop contributions to electroweak observables. A naive extrapolation of this result to LEP observables would suggest an overall two-loop electroweak contribution close to the ultimate experimental sensitivity.hep-ph/9412380DFPD-94-TH-60NYU-TH-94-11-03DFPD-94-TH-60oai:cds.cern.ch:2744011994-12-28
spellingShingle Particle Physics - Phenomenology
Degrassi, G.
Fanchiotti, S.
Feruglio, F.
Gambino, P.
Vicini, A.
Two-loop electroweak top corrections: are they under control?
title Two-loop electroweak top corrections: are they under control?
title_full Two-loop electroweak top corrections: are they under control?
title_fullStr Two-loop electroweak top corrections: are they under control?
title_full_unstemmed Two-loop electroweak top corrections: are they under control?
title_short Two-loop electroweak top corrections: are they under control?
title_sort two-loop electroweak top corrections: are they under control?
topic Particle Physics - Phenomenology
url https://dx.doi.org/10.1016/0370-2693(95)00268-P
http://cds.cern.ch/record/274401
work_keys_str_mv AT degrassig twoloopelectroweaktopcorrectionsaretheyundercontrol
AT fanchiottis twoloopelectroweaktopcorrectionsaretheyundercontrol
AT ferugliof twoloopelectroweaktopcorrectionsaretheyundercontrol
AT gambinop twoloopelectroweaktopcorrectionsaretheyundercontrol
AT vicinia twoloopelectroweaktopcorrectionsaretheyundercontrol

Ejemplares similares