G. Abbiendi et al., Two Higgs Doublet Model and model independent interpretation of neutral Higgs boson searches, EUR PHY J C, 18(3), 2001, pp. 425-445
Searches for the neutral Higgs bosons h(0) and A(0) are used to obtain limi
ts on the Type II Two Higgs Doublet Model (2HDM(II)) with no CP-violation i
n the Higgs sector and no additional particles besides the five Higgs boson
s. The analysis combines approximately 170 pb(-1) of data collected with th
e OPAL detector at roots approximate to 189 GeV with previous runs at roots
approximate to m(Z) and roots approximate to 183 GeV. The searches are sen
sitive to the h(0), A(0) --> q (q) over bar, gg. tau (+)tau (-) and h(0) --
> A(0)A(0) decay modes of the Higgs bosons. For the first time, the 2HDM(II
) parameter space is explored in a detailed scan, and new flavour independe
nt analyses are applied to examine regions in which the neutral Higgs boson
s decay predominantly into light quarks or gluons. Model-independent limits
are also given.