The Constraint on FCNC Coupling of the Top Quark with a Gluon from ep   Collisions
  Using the constraint on the single top production cross-section obtained at the HERA collider, $\sigma(ep \to e t X)$, we evaluate an upper limit on oupling constant of the anomalous top quark interaction with a gluon via flavor-changing neutral current: $|\kappa_{tgq}/\Lambda| \le 0.4 {TeV}^{-1}$, BR$(t \to gq) < 13 % $ 
A.A. Ashimova (1) and S.R. Slabospitsky (2) ((1) Moscow State   University, Moscow, Russia, (2) IHEP, Protvino, Russia)