Quintessential inflation eff=v(o) Q To 0e、NV T=3P eff=v(o)+ awm Q Gumjudpai et al WDE JcAP0506(2005) Q+ eff 1/26/2021 BRICS 201/1/26/2021 BRICS_2017 Quintessential inflation Gumjudpai et al JCAP0506(2005)