In lepton-proton collisions, a natural area of searches for physics
beyond the Standard Model is the search for leptoquarks, that are bound
states between a lepton and a quark. No sign for the production of such
particles was found in the data.
The figure shows limits for the production
of leptoquarks from positron-d-quark and positrons-u-quark processes. The
limits reach mass values of the leptoquarks up to about m_LQ = 250 GeV.
The reduced strength of the limits at mass values slightly above m_LQ =
200 GeV reflects the excess events that were found in neutral current events
at high Q2 (see poster high Q2). At small values of the branching ratio
beta(LQ -> positron quark) for the decay of the leptoquark, the H1 data
are significantly more sensitive compared to the data of other accelerators.
This demonstrates the discovery potential for new physics at HERA.
