title: Pseudo-dirac neutrinos: a challenge for neutrino telescopes.
abstract: Neutrinos may be pseudo-Dirac states, such that each generation is actually composed of two maximally mixed Majorana neutrinos separated by a tiny mass difference. The usual active neutrino oscillation phenomenology would be unaltered if the pseudo-Dirac splittings are deltam(2) less, similar 10(-12) eV(2); in addition, neutrinoless double beta decay would be highly suppressed. However, it may be possible to distinguish pseudo-Dirac from Dirac neutrinos using high-energy astrophysical neutrinos. By measuring flavor ratios as a function of L/E, mass-squared differences down to deltam(2) approximately 10(-18) eV(2) can be reached. We comment on the possibility of probing cosmological parameters with neutrinos.
authors.affiliation: NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Beacom
authors.forename: Nicole F
authors.initials: NF
authors.lastname: Bell
authors.forename: Dan
authors.initials: D
authors.lastname: Hooper
authors.forename: John G
authors.initials: JG
authors.lastname: Learned
authors.forename: Sandip
authors.initials: S
authors.lastname: Pakvasa
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Weiler