TeV Scale Leptoquarks as a Signature of Standard--like Superstring Models

Abstract

We show that there can be TeV scale scalar and fermionic leptoquarks with very weak Yukawa couplings in a generic standard--like superstring model. Leptoquark--(down--like) quark mixing though present, is not large enough to violate the unitarity bounds on the CKM matrix. The constraints on leptoquark masses and couplings from FCNCs are easily satisfied whereas those from baryon number violation may cause problems. The leptoquarks of the model are compared to the ones in $E_6$ Calabi--Yau and flipped $SU(5) \times U(1)$ models.