We evaluate the next-to-leading-order QCD corrections of O( αs2GFMt2) to the Standard-Model ℓ +ℓ -H, ZZH, and W+W-H couplings in the heavy-top-quark limit. Exploiting these results together with knowledge of Δπ to the same order, we analyze a variety of production and decay processes of low-mass Higgs bosons at e+e- colliders. Specifically, we consider H → ℓ +ℓ -, H → ℓ +ℓ -ℓ' +ℓ' -, e +e - → ZH, Z → f overlinefH , and e +e - → f overlinefH , with f = ℓ, ν. We work in the electroweak on-shell scheme formulated with GF and employ both the on-shell and overlineMS definitions of the top-quark mass in QCD. As expected, the scheme and scale dependences are greatly reduced when the next-to-leading-order corrections are taken into account. In the on-shell scheme of top-quark mass renormalization, the O( αs2GFMt2) corrections act in the same direction as the O( αsGFMt2) ones and further increase the screening of the O( GFMt2) terms. The coefficients of ( αs/ π) 2 range from -6.847 for the ZZH coupling to -16.201 for the ℓ +ℓ -H coupling. This is in line with the value -14.594 recently found for Δπ.
Nuclear Physics B
- Pub Date:
- February 1995
- High Energy Physics - Phenomenology
- 22 pages (Latex), 3 figures (uuencoded compressed tarred Postscript). The complete paper, including figures, is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/, or via www at http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints/