The quark-lepton portal beyond leptoquarks

We explore models where single new exotic states interact with the Standard Model through an asymmetric Standard Model portal with couplings to at least one quark and one lepton. All effective operators up to dimension six where such interactions couple the SM to spin 0 and spin 1/2 particles are written down, and the exotic states accessible through the portal are identified. We note interactions that couple the SM to new particles with exotic combinations of baryon and lepton numbers, states of higher electric charge, and particles with unusual SM charge, including states in higher-dimensional representations of both SU(3) and SU(2). Finally, we discuss the phenomenology of these interactions, including novel particle decays, and we classify some of the collider production modes for exotic states at the LHC, LHeC and muon colliders.

💡 Research Summary

The paper introduces a systematic framework for exploring new exotic particles that couple simultaneously to a Standard Model (SM) quark and lepton through a non‑symmetric “quark‑lepton portal.” The authors work within an effective field theory called LEX‑EFT (Light Exotic Effective Field Theory), in which higher‑dimensional operators of the form
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