what is the predicted charge & mass of a leptoquark (theoreticaly)?
The most conservative limit on leptoquark mass is > 73 GeV by (Abreu 93J). There are a number of potential leptoquarks, and their possible charges and quantum numbers are listed and discussed in the Physical Review under the section on Gauge and Higgs Bosons. See the Review at http://pdg.lbl.gov/.
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