Is Doublet-Triplet Splitting Necessary?

Abstract

We demonstrate that it is not necessary to substantially break the mass degeneracy between the Standard Model Higgs boson doublet and the corresponding scalar leptoquark, where these two fields comprise a single five-dimensional $SU(5)$ representation. More precisely, we show that the experimental data on partial proton decay lifetimes cannot place any meaningful bound on the mass of the scalar leptoquark, a.k.a. the color triplet, if one includes effects of higher-dimensional operators within the Georgi-Glashow model. We also point out that the complete suppression of proton decay via the scalar leptoquark mediation is compatible with the partial suppression of the gauge mediated two-body proton decay signatures. Finally, we derive a proper limit on the cutoff scale of the aforementioned higher-dimensional operators and outline how this scenario could be tested.