Search for resonance decays to a (nu)over-bar plus jet in e(+)p scattering at DESY HERA

A study of the <(<nu>)over bar>-jet mass spectrum in e(+) p--><(<nu>)over bar>X events at a center-of-mass energy 300 GeV has been performed with the ZEUS detector at the HERA collider at DESY using an integrated luminosity of 47.7 pb(-1). The mass spectrum is in good agreement with that expected from standard model processes over the <(<nu>)over bar>-jet mass range studied. No significant excess attributable to the decay of a narrow resonance is observed. By using both e(+) p-->e(+) X and e(+) p--><(<nu>)over bar>X data, mass-dependent limits are set on the s-channel production of scalar and vector resonant states. Couplings to first-generation quarks are considered and limits are presented as a function of the e(+) q and <(<nu>)over bar>q branching ratios. These limits are used to constrain the production of leptoquarks and R-parity violating squarks.