Springer LINK: The European Physical Journal C - Abstract Volume 4 Issue 2 (1998) pp 259-263

The European Physical Journal C

ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)

Table of Contents

Abstract Volume 4 Issue 2 (1998) pp 259-263
DOI 10.1007/s100529800772

theoretical physics:
Gauge invariance in the process $e^+e^-\rightarrow \bar \nu_e e^-W^+ \rightarrow\bar\nu_e e^-u\bar d$

Robin G. Stuart

Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120, USA

Received: 1 March 1997 / Revised version: 19 September 1997 / Published online: 26 February 1998

Abstract. The process $e^+e^-\rightarrow \bar \nu_e e^-W^+ \rightarrow\bar\nu_e e^-u\bar d$ is considered as an example of the problems associated with maintaining gauge invariance in matrix elements involving unstable particles. It is shown how to construct a matrix element that correctly treats width effects for the intermediate unstable $W$ boson and that is both $SU(2)_L$ and $U(1)_{\rm e.m.}$ gauge-invariant. $SU(2)_L$ gauge-invariance is maintained by Laurent expansion in kinematic invariants and $U(1)_{\rm e.m.}$ gauge-invariance is enforced by means of projection operator under which the exact matrix element is invariant.

Article in PDF-Format (220 KB)
Article in (gzipped) PS-Format (150 KB)

The European Physical Journal C

theoretical physics: Gauge invariance in the process $e^+e^-\rightarrow \bar \nu_e e^-W^+ \rightarrow\bar\nu_e e^-u\bar d$

theoretical physics:
Gauge invariance in the process $e^+e^-\rightarrow \bar \nu_e e^-W^+ \rightarrow\bar\nu_e e^-u\bar d$