Large mass expansion versus small momentum expansion of Feynman diagrams
Abstract
The method of the large mass expansion (LME) has the technical advantage that twoloop integrals occur only as bubbles with large masses. In many cases only one large mass occurs. In such cases these integrals are expressible in terms of Γfunctions, i.e. they can be handled completely analytically avoiding even recursions and therefore this approach may find a wide field of application. We consider it necessary to investigate the precision of this method and test it for several twoloop vertex functions ocurring in the Z>bb¯ decay by comparing it with the small momentum expansion. It turns out that in general high order approximants have to be taken into account for a sufficient accuracy. © 1998
 Publication:

Physics Letters B
 Pub Date:
 May 1998
 DOI:
 10.1016/S03702693(98)003128
 arXiv:
 arXiv:hepph/9802262
 Bibcode:
 1998PhLB..427..141F
 Keywords:

 STANDARD MODEL;
 FEYNMAN DIAGRAM;
 TWOLOOP DIAGRAM;
 VERTEX DIAGRAM;
 High Energy Physics  Phenomenology
 EPrint:
 LaTeX, 8 pages including 5 eps figures, uses epsf.sty