we assume that all the events of Z → hA are recorded as Z → b ¯ b due to the softness of tau jets. The exact fraction of events which is included in A b FB needs a detailed information of the events. Here we consider the most optimistic case in which all the events generated from Z → hA are included in A b FB measurement. Thus the estimation here would work as the maximum correction we can expect from this scenario. Let a = Γ( Z → hA ) Γ( Z → b ¯ b ) . For very small a ≪ 1, Therefore, if one loop correction decreases ( g b $_{L}$) 2 by one percent, R$_{b}$ remains to be the same if a = 0 . 012. When there is no change in ( g b $_{L}$) $^{2}$, a = 0 . 012 will increase R$_{b}$ by one percent which is the correction allowed by 2 σ of R$_{b}$ measurement. Total Z width is precisely measured and should be kept within 0 . 1%. a = 0 . 012 gives 0 . 15% increasement of total Z width which is in 1 . 5 σ range. The same a enters in A b FB ( A b FB = 3 $_{4}$A$_{e}$ A$_{b}$ ). Therefore, a = 0 . 012 will reduce A$_{b}$ (and thus A b $_{FB}$) by 1 . 2% which will make the difference between the prediction to be 0.0033 which is within 2 σ (1.8 σ ). Here we simply assumed that hA production is isotropic and appears only in the denominator and cancels in the numerator. Whether 1 − a is the right dependence depends on the fitting method of angular distribution. The actual change to A$_{b}$ from a can be smaller than what is estimated here. Note that changing g b L can not change A$_{b}$ very much since it dominates in the numerator and denominator at the same time. 14 A$_{b}$ = Γ( Z → b$_{L}$ ¯ b$_{L}$ ) − Γ( Z → b$_{R}$ ¯ b$_{R}$ ) Γ( Z → b$_{L}$ ¯ b$_{L}$ ) + Γ( Z → b$_{R}$ ¯ b$_{R}$ ) + Γ( Z → hA ) (16) = $^{(}$Γ( Z → b$_{L}$ ¯ b$_{L}$ ) − Γ( Z → b$_{R}$ ¯ b$_{R}$ ) Γ( Z → b$_{L}$ ¯ b$_{L}$ ) + Γ( Z → b$_{R}$ ¯ b$_{R}$ )$^{)}$ (1 − a ) . (17) R$_{b}$ = Γ( Z → b ¯ b ) Γ( Z → hadrons) (1 + (1 − R$_{b}$ ) a ) . (15) R$_{b}$ = Γ( Z → b ¯ b ) + Γ( Z → hA ) Γ( Z → hadrons) + Γ( Z → hA ) . (14)