Measuring properties of a Heavy Higgs boson in the Hto toverline{t}to b{W}^{+}overline{b}{W}^{-} decay

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Suppose a heavy neutral Higgs or scalar boson H is discovered at the LHC, it is important to investigate its couplings to the standard model particles as much as possible. Here in this work we attempt to probe the CP-even and CP-odd couplings of the heavy Higgs boson to a pair of top quarks, through the decay Hto toverline{t}to b{W}^{+}overline{b}{W}^{-} . We use the helicity-amplitude method to write down the most general form for the angular distributions of the final-state b quarks and W bosons. We figure out that there are 6 types of angular observables and, under mathrm{C}mathrm{P}tilde{mathrm{T}} conservation, one-dimensional angular distributions can only reveal two of them. Nevertheless, the H couplings to the toverline{t} pair can be fully determined by exploiting the one-dimensional angular distributions. A Higgs-boson mass of 380 GeV not too far above the toverline{t} threshold is illustrated with full details. With a total of 104 events of Hto toverline{t}to b{W}^{+}overline{b}{W}^{+} , one can determine the couplings up to 10-20% uncertainties.