Three loop top quark contributions to the ρ parameter

Abstract

We present results for the three-loop top quark contributions to the ρ parameter in the limit of large top quark mass. The simultaneous dependence on the mass of the Higgs boson M H and the mass of the top quark m t is obtained from expansions in the range of M H around m t and in the limit M H ≫ m t . In combination with the previous result for M H = 0 the dependence of the ρ parameter on the leading Yukawa contributions, i.e. on m t and M H , is well under control for all mass values of practical importance. The effects lead to a shift in the W mass in the order of 5 MeV and are relevant for precision measurements at TESLA.

The m W − m Z interdependence in the Standard Model: a new scrutiny

“…The latter turned out to be comparatively large and allowed for a drastic reduction of the scheme dependence. Leading three and four-loop effects related to δρ, in particular the O(α 3 M 6 t /m 6 W ), O(α 2 α s M 4 t /m 4 W ) [17,18] and the O(αα 3 s M 2 t /m 2 W ) [19,20] contributions, were also investigated. The complete calculation of ∆r at the two-loop level was accomplished in several steps.…”

Precise prediction forMWin the MSSM

“…Within the SM, the complete one-loop [11] and two-loop [12][13][14][15][16] results are known as well as leading higher-order contributions [17][18][19][20][21].…”

Precise prediction for theW-boson mass in the standard model

“…The contributions ∆r (G 2 µ αsm 4 t ) and ∆r (G 3 µ m 6 t ) have been obtained from the leading three-loop contributions to ∆ρ given in Ref. [12].…”