2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46438Assuming that the actual values of $m_t$ and the data set ($Γ_b$, $Γ_h$, $Γ_Z$, $R_b$, $R_c$, $R_l$) are within their $1-σ$ errors as reported by CDF, D0 and by LEP Collaborations, the parameter $Δ^{new}_b$ which measures the nonoblique corrections on the $Zb\overline{b}$ vertex from new physics can be determined experimentally. According to the precision data one can obtain updated constraints on the parameters $ξ$ and the masses of the charged PGBs.10 pages, Latex, no macros, no figures, hard copy is available upon request. to appear in Commun.Theor.PhysHigh Energy Physics - Phenomenologytext