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

A study of the ν -jet mass spectrum in e+pν 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 ν -jet mass range studied. No significant excess attributable to the decay of a narrow resonance is observed. By using both e+pe+X and e+pν 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 ν q branching ratios. These limits are used to constrain the production of leptoquarks and R-parity violating squarks.