Constraints on two-lepton, two quark operators

TL;DR

This paper updates constraints on four-fermion operators involving two leptons and two quarks from various experimental data and suggests rare Kaon decays as promising probes for new physics beyond the Standard Model.

Contribution

It provides updated flavor-dependent bounds on two-lepton, two-quark operators and offers naive estimates of their possible magnitudes in theoretical models.

Findings

Collider and meson decay data constrain these operators.

Rare Kaon decays could be sensitive to such operators.

Estimated coefficients suggest potential for new physics detection.

Abstract

Physics from beyond the Standard Model, such as leptoquarks, can induce four fermion operators involving a quark, an anti-quark, a lepton and an anti-lepton. We update the (flavour dependent) constraints on the coefficients of such interactions, arising from collider searches for contact interactions, meson decays and other rare processes. We then make naive estimates for the magnitude of the coefficients, as could arise in texture models or from inverse hierarchies in the kinetic term coefficients. These estimates suggest that rare Kaon decays could be a good place to look for such operators.