NEUTRINOS AS A PROBE

Neutrinos are a unique probe of many aspects of physics and astrophysics, on scales ranging from $10^{-33}$ to $10^{+28}$ cm. Particle physics applications include:

• $\nu N, \mu N, e N$ scattering: existence/ properties of quarks, QCD
• Weak decays ( $n \rightarrow p e^- \bar{\nu}_e, \mu^- \rightarrow e^- \nu_\mu \bar{\nu}_e$): Fermi theory, parity violation, mixing
• Neutral current, $Z$-pole, atomic parity: electroweak unification, field theory, $m_t$; severe constraint on physics to TeV scale
• Neutrino mass: constraint on TeV physics, grand unification, superstrings, extra dimensions

Similarly, their relevance to astrophysics and cosmology includes

• Core of Sun
• Supernova dynamics
• Atmospheric neutrinos (cosmic rays)
• Violent events: GRBs, AGNs, cosmic rays
• Large scale structure (dark matter)
• Nucleosynthesis (big bang: small $A$; stellar: to iron; supernova: large $A$)
• Baryogenesis

Astrophysical applications are especially challenging, because one must often simultaneously disentagle the properties of the neutrinos and of the astrophysical sources.