1301.0881 (S. Groote et al.)

Fully analytical O(α_s) results for on-shell and off-shell
polarized W-boson decays into massive quark pairs    [PDF]

S. Groote, J. G. Körner, P. Tuvike

We provide analytical O(\alpha_s) results for the three polarized decay structure functions H_{++}, H_{00} and H_{--} that describe the decay of a polarized W boson into massive quark-antiquark pairs. As an application we consider the decay t -> b + W^+ involving the helicity fractions \rho_{mm} of the W^+ boson followed by the polarized decay W^+(\uparrow) -> q_1 \bar{q}_2 described by the polarized decay structure functions H_{mm}. We thereby determine the O(\alpha_s) polar angle decay distribution of the cascade decay process t -> b + W^+ (-> q_1 \bar{q}_2). As a second example we analyze quark mass and off-shell effects in the cascade decays H -> W^- + W^{*+} (-> q_1 \bar{q}_2) and H -> Z + Z^* (-> q \bar{q}). For the decays H -> W^- + W^{*+} (-> c \bar b) and H -> Z + Z^* (-> b \bar{b}) we find substantial deviations from the mass-zero approximation in particular in the vicinity of the threshold region.

View original: http://arxiv.org/abs/1301.0881