LIMITS ON ACTIVE-STERILE NEUTRINO MIXING AND THE PRIMORDIAL DEUTERIUMABUNDANCE

Studies of limits on active-sterile neutrino mixing derived from big b ang nucleosynthesis (BBN) considerations are extended to consider the dependence of these constraints on the primordial deuterium abundance. This study is motivated by recent measurements of D/H in quasar absor ption systems, which at present yield discordant results. Limits on ac tive-sterile mixing are somewhat relaxed for high D/H (approximate to 2X 10(-4)). For low D/H (approximate to 2X10(-5)), no active-sterile n eutrino mixing is allowed by currently popular upper limits on the pri mordial He-+ abundance Y. For such low primordial D/H values, the obse rvational inference of active-sterile neutrino mixing by upcoming sola r neutrino experiments would imply that Y has been systematically unde restimated, unless there is new physics not included in standard BBN.