Contact Interaction Explanation of HERA Events and $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ Invariance

Abstract

We reexamine the contact interaction hypothesis for excess high-$Q^2$ events seen at HERA in $e^{+}p\to e^{+}X$ scattering. We consider the most general structure of contact interactions insisting on $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ invariance. Apart from constraints for $e^{+}{e}^{-}\to q\bar{q}$ , Drell-Yan and atomic parity violation experiments, we find stringent constraints from neutrino deep inelastic data. A possible choice of contact terms that escape present bounds is still possible, althought new data from FERMILAB and LEP should further constrain such a possibility.

Comments: 13 pages(Latex), 2 PS Figures. A few changes have been made in the text and in the reference