Their other quantum numbers, like spin, (fractional) electric charge and weak isospin vary among models.
Leptoquarks are currently searched for in experiments ATLAS and CMS at the Large Hadron Collider in CERN.
In March 2021, there were some reports to hint at the possible existence of leptoquarks as an unexpected difference in how bottom quarks decay to create electrons or muons.
Nevertheless, most theories do not bring much of a theoretical motivation to believe that leptoquarks have only a single interaction and that the generation of the quark and lepton involved is the same.
These fields emerge in grand unification theories; for example, in the Georgi–Glashow SU(5) model, they are called X and Y bosons.
[3] However, later studies performed both at HERA and at the Tevatron with larger samples of data ruled out this possibility for masses of the leptoquark up to around 275–325 GeV/c2.