254 research outputs found
The Diffuse Supernova Neutrino Background
The Diffuse Supernova Neutrino Background (DSNB) is the weak glow of MeV
neutrinos and antineutrinos from distant core-collapse supernovae. The DSNB has
not been detected yet, but the Super-Kamiokande (SK) 2003 upper limit on the
electron antineutrino flux is close to predictions, now quite precise, based on
astrophysical data. If SK is modified with dissolved gadolinium to reduce
detector backgrounds and increase the energy range for analysis, then it should
detect the DSNB at a rate of a few events per year, providing a new probe of
supernova neutrino emission and the cosmic core-collapse rate. If the DSNB is
not detected, then new physics will be required. Neutrino astronomy, while
uniquely powerful, has proven extremely difficult -- only the Sun and the
nearby Supernova 1987A have been detected to date -- so the promise of
detecting new sources soon is exciting indeed.Comment: Submitted to Annual Review of Nuclear and Particle Science, Volume
60. 25 pages with 7 figures
Theoretically palatable flavor combinations of astrophysical neutrinos
The flavor composition of high-energy astrophysical neutrinos can reveal the
physics governing their production, propagation, and interaction. The IceCube
Collaboration has published the first experimental determination of the ratio
of the flux in each flavor to the total. We present, as a theoretical
counterpart, new results for the allowed ranges of flavor ratios at Earth for
arbitrary flavor ratios in the sources. Our results will allow IceCube to more
quickly identify when their data imply standard physics, a general class of new
physics with arbitrary (incoherent) combinations of mass eigenstates, or new
physics that goes beyond that, e.g., with terms that dominate the Hamiltonian
at high energy.Comment: 13 pages, 12 figures. Matches published versio
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