2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/206325Using the constraint on the single top production cross-section obtained at the HERA collider, $σ(ep \to e t X)$, we evaluate an upper limit on oupling constant of the anomalous top quark interaction with a gluon via flavor-changing neutral current: $|κ_{tgq}/Λ| \le 0.4 {TeV}^{-1}$, BR$(t \to gq) < 13 % $Latex, 3 figures, missed references were addedHigh Energy Physics - Phenomenologytext