0 v 2 1 0 N ov 1 99 7 Instantons , Spin Crisis and High Q 2 Anomaly at HERA

The contribution of the nonperturbative quark-gluon interaction induced by the instantons to g p 1 (x, Q 2) and F p 2 (x, Q 2) structure functions is estimated. It is shown that nontrivial Q 2 dependence of the instanton contribution to g p 1 (x, Q 2) allows us to explain the observed decreasing of the part of the proton spin carried by quarks without involving a large positive gluon polarization. It is demonstrated that the anomalous enhancement of the instanton contribution to F p 2 (x, Q 2) structure function, due to multiple emission of the gluons from instanton vertex, can be one of the reasons for the excess of the DIS events at HERA at high Q 2 and x.