Speaker
Description
We propose an $E_6$-inspired Pati-Salam (PS) model that naturally accommodates multi-TeV leptoquark gauge bosons, $X_\mu$, while incorporating an unbroken discrete $Z_2$ symmetry. In this model, Standard Model (SM) fermions are $Z_2$-even, while exotic fermions in the PS multiplets are $Z_2$-odd. A notable feature is that the PS gauge bosons are $Z_2$-odd, resulting in their coupling exclusively between ordinary and exotic fermions. This prevents flavor-violating meson decays at the tree level, with such effects arising only at the one-loop level, allowing for a lower PS breaking scale. The most stringent constraint arises from meson decays, particularly $K_L \to \mu e$, allowing PS gauge boson masses as low as $m_X \gtrsim \mathcal{O}$(few) TeV. This relatively low PS scale offers exciting collider prospects for probing leptoquark gauge bosons as well as vector-like fermions. Additionally, we explore compelling mechanisms for generating small neutrino masses via either a tree-level seesaw or one-loop scotogenic realization. The unbroken $Z_2$ symmetry also allows for a dark matter (DM) candidate, which could be either a singlet-doublet fermionic DM or a singlet scalar DM.
