Astrophysical implications of e⁺e^- measurements

Implications of the e⁺e^- measurements at LEP, in particular the determination of the number of neutrino flavors with m_ν ≲M_Z/2, on big bang nucleosynthesis and on dark matter are discussed. For the early Universe, the LEP measurements fix N_ν = 3. This together with recent measurements of the neutron half-life and new observations of ⁴He and ⁷Li determine the baryon-to-photon ratio η = 3 × 10^-10 implying that baryons provide only 1-8% of the closure density. In addition the determination that N_ν ≤ 3.14 (95% C.L.) indicates that certain dark matter candidates such as Dirac and Majorana neutrinos are excluded. The supersymmetric parameter space is somewhat restricted but still easily allows for candidates supplying the missing mass in the Universe.