The Constraint on FCNC Coupling of the Top Quark with a Gluon from ep Collisions

Abstract

Using the constraint on the single top production cross-section obtained at the HERA collider, $\sigma (ep\to etX)$, 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$(t\to gq)<13$

Comments: Latex, 3 figures, missed references were added