The fermionloop scheme for finitewidth effects in e^{+}e^{t } annihilation into four fermions
Abstract
We describe the gaugeinvariant treatment of the finitewidth effects of W and Z bosons in the fermionloop scheme and its application to the sixfermion (LEP2) processes e^{t }e^{+} → four fermions, with massless external fermions. The fermionloop scheme consists in including all fertnionic oneloop corrections in treelevel amplitudes and resumming the selfenergies. We give explicit results for the unrenormalized fermionic oneloop contributions to the gaugeboson selfenergies and the triple gaugeboson vertices, and perform the renormalization in a gauge invariant way by introducing complex pole positions and running couplings. A simple effective Born prescription is presented, which allows for a relatively straightforward implementation of the fermionloop scheme in LEP1 and LEP2 processes. We apply this prescription to typical LEP2 processes, i.e. e ^{t}e ^{+} → μ ^{t}overlineν_{μ}u overlined, e ^{t}e ^{+} → s overlinecu overlined, and e ^{t}e ^{+} → e ^{t}overlineν_{e}r overlined, and give numerical comparisons with other gaugeinvariancepreserving schemes in the energy range of LEP2, NLC and beyond.
 Publication:

Nuclear Physics B
 Pub Date:
 February 1997
 DOI:
 10.1016/S05503213(97)003167
 arXiv:
 arXiv:hepph/9612260
 Bibcode:
 1997NuPhB.500..255B
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 49 pages, LaTeX, 2 figures, uses amssymb, axodraw