Radiative corrections to the Z b anti-b vertex and constraints on extended Higgs sectors
Radiative corrections to the Z b anti-b vertex and constraints on extended Higgs sectors
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DOI：
10.1103/physrevd.62.015011
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发表时间：
1999-09
影响因子：
5
通讯作者：
H. Haber;H. Logan
中科院分区：
文献类型：
--
作者：
H. Haber;H. Logan
We explore the radiative corrections to the process Z → bb in models with ex- tended Higgs sectors. The observables Rb and Ab are sensitive to these corrections. Rb is the hadronic branching fraction of Z bosons to bb, Rb = ( Z → b ¯)/( Z → hadrons). Ab is the b quark asymmetry, Ab = (g 2 L − g 2 )/(g 2 + g 2 R ) where gL and gR are the left and right handed couplings of Z to b quarks. We find that in models containing only dou- blets, singlets, or larger multiplets constrained by a custodial SU(2)c symmetry so that MW = MZ cos θW at tree level, the corrections involving charged Higgs bosons always worsen agreement with experiment. The Rb measurement can be used to set lower bounds on the charged Higgs masses in such models. Corrections involving light neutral Higgs bosons in models with enhanced H 0 bcoupling (large tan β) can improve agreement with experiment over the Standard Model. We present general formulas for the corrections to Rb and Ab in an arbitrary extended Higgs sector, and derive explicit results for a number of specific models.
