Minimal Realistic SU(5) Scenario

We present phenomenological aspects of the simplest realistic SU(5) grand unified theory--the theory with the 5, 15, and 24 dimensional representations in the Higgs sector. We show that a successful gauge coupling unification sets experimentally accessible upper bound on the total proton decay lifetime. It also relates proton decay lifetime to scalar leptoquark mass in an experimentally testable manner. We also discuss an addition of gauge singlets--both fermions and bosons--to the simplest scenario and comment on relevant phenomenological consequences of such modifications