jats:titleAbstract</jats:title>jats:pIn this paper, we generalize Coleman–Weinberg (CW) inflation in grand unified theories (GUTs) such as jats:inline-formulajats:alternativesjats:tex-math$$\text {SU}(5)$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:mtextSU</mml:mtext>mml:mo(</mml:mo>mml:mn5</mml:mn>mml:mo)</mml:mo></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> and jats:inline-formulajats:alternativesjats:tex-math$$\text {SO}(10)$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:mtextSO</mml:mtext>mml:mo(</mml:mo>mml:mn10</mml:mn>mml:mo)</mml:mo></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> by means of considering two complex singlet fields with conformal invariance. In this framework, inflation emerges from a spontaneously broken conformal symmetry. The GUT symmetry implies a potential with a CW form, as a consequence of radiative corrections. The conformal symmetry flattens the above VEV branch of the CW potential to a Starobinsky plateau. As a result, we obtain jats:inline-formulajats:alternativesjats:tex-math$$n_{s}\sim 1-\frac{2}{N}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:msubmml:min</mml:mi>mml:mis</mml:mi></mml:msub>mml:mo∼</mml:mo>mml:mn1</mml:mn>mml:mo-</mml:mo>mml:mfracmml:mn2</mml:mn>mml:miN</mml:mi></mml:mfrac></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> and jats:inline-formulajats:alternativesjats:tex-math$$r\sim \frac{12}{N^2}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:mir</mml:mi>mml:mo∼</mml:mo>mml:mfracmml:mn12</mml:mn>mml:msupmml:miN</mml:mi>mml:mn2</mml:mn></mml:msup></mml:mfrac></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> for jats:inline-formulajats:alternativesjats:tex-math$$N\sim $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:miN</mml:mi>mml:mo∼</mml:mo></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> 50–60 e-foldings. Furthermore, this framework allow us to estimate the proton lifetime as jats:inline-formulajats:alternativesjats:tex-math$$\tau {p}\lesssim 10^{40}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:msubmml:miτ</mml:mi>mml:mip</mml:mi></mml:msub>mml:mo≲</mml:mo>mml:msupmml:mn10</mml:mn>mml:mn40</mml:mn></mml:msup></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> years, whose decay is mediated by the superheavy gauge bosons. Moreover, we implement a type I seesaw mechanism by weakly coupling the complex singlet, which carries two units of lepton number, to the three generations of singlet right handed neutrinos (RHNs). The spontaneous symmetry breaking of global lepton number amounts to the generation of neutrino masses. We also consider non-thermal leptogenesis in which the inflaton dominantly decays into heavy RHNs that sources the observed baryon asymmetry. We constrain the couplings of the inflaton field to the RHNs, which gives the reheating temperature as jats:inline-formulajats:alternativesjats:tex-math$$10^{6}\text { GeV}\lesssim T{R}<10^{9}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:msupmml:mn10</mml:mn>mml:mn6</mml:mn></mml:msup><mml:mspace />mml:mtextGeV</mml:mtext>mml:mo≲</mml:mo>mml:msubmml:miT</mml:mi>mml:miR</mml:mi></mml:msub>mml:mo<</mml:mo>mml:msupmml:mn10</mml:mn>mml:mn9</mml:mn></mml:msup></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> GeV.</jats:p>