feynlag.pheno.loop.higgs_gg_width¶
- feynlag.pheno.loop.higgs_gg_width(m_h, m_t, v, alpha_s, qcd=False, n_flavors=5)[source]¶
$Gamma(hto gg)=frac{alpha_s^2 m_h^3}{72pi^3 v^2} big|tfrac34 A_{1/2}(tau_t)big|^2$ (leading order).
With
qcd=Truemultiply by the NLO $K$-factor $K=1+frac{alpha_s}{pi}left(frac{95}{4}-frac{7}{6}N_fright)$ [Spira95] ($approx1.64$ for $N_f=5$), which brings the LO ~0.20 MeV up to the measured ~0.34 MeV (8.2% branching ratio).