2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46099In this article we show that the $\rb -\als $ crisis of the SM can be resolved in a commuting TC scenario with sideways gauge bosons only if the ETC representation contains mirror technifermions. For a toy ETC model we estimate the value of $ξ^2_t={\gel/ \guer}$ that is needed to produce the observed LEP excess in $\rb$. It is also shown that the same value of $ξ^2_t$ resolvs the $\als$ crisis of the SM but produces a $δρ_{new}$ which is barely within the present experimental bound.TeX, 8 pages, no figuresHigh Energy Physics - Phenomenologytext