3 research outputs found
Upper Bounds on the Neutrino-Nucleon Inelastic Cross Section
Extraterrestrial neutrinos can initiate deeply developing air showers, and
those that traverse the atmosphere unscathed may produce cascades in the ice or
water. Up to now, no such events have been observed. This can be translated
into upper limits on the diffuse neutrino flux. On the other hand, the
observation of cosmic rays with primary energies > 10^{10} GeV suggests that
there is a guaranteed flux of cosmogenic neutrinos, arising from the decay of
charged pions (and their muon daughters) produced in proton interactions with
the cosmic microwave background. In this work, armed with these cosmogenic
neutrinos and the increased exposure of neutrino telescopes we bring up-to-date
model-independent upper bounds on the neutrino-nucleon inelastic cross section.
Uncertainties in the cosmogenic neutrino flux are discussed and taken into
account in our analysis. The prospects for improving these bounds with the
Pierre Auger Observatory are also estimated. The unprecedented statistics to be
collected by this experiment in 6 yr of operation will probe the
neutrino-nucleon inelastic cross section at the level of Standard Model
predictions.Comment: To be published in JCA
The Particle Physics Reach of High-Energy Neutrino Astronomy
We discuss the prospects for high-energy neutrino astronomy to study particle
physics in the energy regime comparable to and beyond that obtainable at the
current and planned colliders. We describe the various signatures of
high-energy cosmic neutrinos expected in both neutrino telescopes and air
shower experiments and discuss these measurements within the context of
theoretical models with a quantum gravity or string scale near a TeV,
supersymmetry and scenarios with interactions induced by electroweak
instantons. We attempt to access the particle physics reach of these
experiments.Comment: Mini-review article for New Journal of Physics, "Focus on Neutrinos"
issue. 27 pages, 11 figure
Composition of UHECR and the Pierre Auger Observatory Spectrum
We fit the recently published Pierre Auger ultra-high energy cosmic ray
spectrum assuming that either nucleons or nuclei are emitted at the sources. We
consider the simplified cases of pure proton, or pure oxygen, or pure iron
injection. We perform an exhaustive scan in the source evolution factor, the
spectral index, the maximum energy of the source spectrum Z E_{max}, and the
minimum distance to the sources. We show that the Pierre Auger spectrum agrees
with any of the source compositions we assumed. For iron, in particular, there
are two distinct solutions with high and low E_{max} (e.g. 6.4 10^{20} eV and 2
10^{19} eV) respectively which could be distinguished by either a large
fraction or the near absence of proton primaries at the highest energies. We
raise the possibility that an iron dominated injected flux may be in line with
the latest composition measurement from the Pierre Auger Observatory where a
hint of heavy element dominance is seen.Comment: 19 pages, 6 figures (33 panels)- Uses iopart.cls and iopart12.clo- In
version 2: addition of a few sentences and two reference