Constraining Scalar Doublet and Triplet Leptoquarks with Vacuum Stability and Perturbativity

Understand

We investigate the constraints on the leptoquark Yukawa couplings and Higgs-leptoquark quartic couplings for scalar doublet leptoquark $\tilde{R}_2$, scalar triplet leptoquark $\vec S_3$ and their combination with both three generations and one generation from perturbative unitarity and vacuum stability.

• Perturbative unitarity of all the dimensionless couplings have been studied via one- and two-loop beta-functions.
• Introduction of new $SU(2)$ multiplets in terms of these leptoquarks fabricate Landau poles at two-loop level in the gauge coupling $g_2$ at $10^{19.7}$ GeV and $10^{14.4}$ GeV, respectively for $\vec S_3$ and $\tilde{R}_2+\vec S_3$ models with three generations.
• However, such Landau pole ceases to exist for $\tilde{R}_2$ and any of these extensions with both one and two generations till Planck scale.