2019 Impact factor 4.389
Particles and Fields

Eur. Phys. J. C 16, 253-267
DOI 10.1007/s100520000400

Search for resonances decaying to e+-jet
e+p interactions at HERA

The ZEUS Collaboration

J. Breitweg - et al.

Received: 15 February 2000 / Published online: 18 May 2000 - © Springer-Verlag 2000

The e+-jet invariant mass spectrum produced in the reaction $e^+ p \rightarrow e^+ X$ has been studied at a center-of-mass energy of 300 GeV. The data were collected using the ZEUS detector operating at the HERA collider, and correspond to an integrated luminosity of 47.7 pb-1. The observed mass spectrum is in good agreement with Standard Model expectations up to an e+-jet mass of 210 GeV. Above this mass, some excess is seen. The angular distribution of these events is typical of high-Q2 neutral current events and does not give convincing evidence for the presence of a narrow scalar or vector state. Limits are presented on the product of cross section and branching ratio for such a state and are interpreted as limits on leptoquark or R-parity-violating squark production. Specific leptoquark types are ruled out at 95% confidence level for coupling strength $\lambda=0.3$for masses between 150 and 280 GeV.

Copyright Società Italiana di Fisica, Springer-Verlag 2000