QCD Corrections to Decay Distributions of Neutral Higgs Bosons with (In)definite CP Parity

Abstract

We compute the order ${\alpha }_s$ QCD corrections to the density matrix for the decay of a neutral Higgs boson $\varphi$ with (in)definite CP parity into a quark antiquark pair, respectively the QED corrections for the decay into a pair of charged leptons. We classify and calculate single spin asymmetries and spin-spin correlations which are generated by the scalar and pseudoscalar Yukawa couplings. These spin effects can be traced in $\varphi \to {\tau }^{-}{\tau }^{+}$ and, for heavy Higgs bosons, in $\varphi \to t\bar{t}$. We also calculate resulting correlations among the final states and estimate, for the respective decay modes, the number of events needed to measure the Yukawa couplings with these correlations at the 3 sigma level.

Comments: 32 pages, REVTeX, uses: psfig,amssym,aps,preprint 14 ps figures