Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCosmic neutrino cascades from secret neutrino interactions
106
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The first detection of high-energy astrophysical neutrinos by IceCube provides new opportunities for tests of neutrino properties. The long baseline through the Cosmic Neutrino Background (C$ u$B) is particularly useful for directly testing secret neutrino interactions ($ u$SI) that would cause neutrino-neutrino elastic scattering at a larger rate than the usual weak interactions. We show that IceCube can provide competitive sensitivity to $ u$SI compared to other astrophysical and cosmological probes, which are complementary to laboratory tests. We study the spectral distortions caused by $ u$SI with a large s-channel contribution, which can lead to a dip, bump, or cutoff on an initially smooth spectrum. Consequently, $ u$SI may be an exotic solution for features seen in the IceCube energy spectrum. More conservatively, IceCube neutrino data could be used to set model-independent limits on $ u$SI. Our phenomenological estimates provide guidance for more detailed calculations, comparisons to data, and model building.
rate research
Read More
Neutrinos offer a window to physics beyond the Standard Model. In particular, high-energy astrophysical neutrinos, with TeV-PeV energies, may provide evidence of new, secret neutrino-neutrino interactions that are stronger than ordinary weak interactions. During their propagation over cosmological distances, high-energy neutrinos could interact with the cosmic neutrino background via secret interactions, developing characteristic energy-dependent features in their observed energy distribution. For the first time, we look for signatures of secret neutrino interactions in the diffuse flux of high-energy astrophysical neutrinos, using 6 years of publicly available IceCube High Energy Starting Events (HESE). We find no significant evidence for secret neutrino interactions, but place competitive upper limits on the coupling strength of the new mediator through which they occur, in the mediator mass range of 1-100 MeV.
Gamma-ray bursts (GRBs) have long been held as one of the most promising sources of ultra-high energy (UHE) neutrinos. The internal shock model of GRB emission posits the joint production of UHE cosmic ray (UHECRs, above 10^8 GeV), photons, and neutrinos, through photohadronic interactions between source photons and magnetically-confined energetic protons, that occur when relativistically-expanding matter shells loaded with baryons collide with one another. While neutrino observations by IceCube have now ruled out the simplest version of the internal shock model, we show that a revised calculation of the emission, together with the consideration of the full photohadronic cross section and other particle physics effects, results in a prediction of the prompt GRB neutrino flux that still lies one order of magnitude below the current upper bounds, as recently exemplified by the results from ANTARES. In addition, we show that by allowing protons to directly escape their magnetic confinement without interacting at the source, we are able to partially decouple the cosmic ray and prompt neutrino emission, which grants the freedom to fit the UHECR observations while respecting the neutrino upper bounds. Finally, we briefly present advances towards pinning down the precise relation between UHECRs and UHE neutrinos, including the baryonic loading required to fit UHECR observations, and we will assess the role that very large volume neutrino telescopes play in this.
We report on the first search for extra-terrestrial neutrino-induced cascades in IceCube. The analyzed data were collected in the year 2007 when 22 detector strings were installed and operated. We will discuss the analysis methods used to reconstruct cascades and to suppress backgrounds. Simulated neutrino signal events with a E-2 energy spectrum, which pass the background rejection criteria, are reconstructed with a resolution dlogE ~ 0.27 in the energy range from ~20 TeV to a few PeV. We present the range of the diffuse flux of extra-terrestrial neutrinos in the cascade channel in IceCube within which we expect to be able to put a limit.
We perform a new, detailed calculation of the flux and energy spectrum of Earth-emerging $tau$-leptons generated from the interactions of tau neutrinos and antineutrinos in the Earth. A layered model of the Earth is used to describe the variable density profile of the Earth. Different assumptions regarding the neutrino charged- and neutral-current cross sections as well as the $tau$-lepton energy loss models are used to quantify the systematic uncertainty from these on the results. A baseline simulation is then used to generate the optical Cherenkov signal from upward-moving extensive air showers generated by the $tau$-lepton decay in the atmosphere, applicable to a range of space-based instruments. We use this simulation to determine the neutrino sensitivity for $E_ u>$ 10 PeV for a space-based experiment with performance similar to that for the Probe of Extreme MultiMessenger Astrophysics (POEMMA) mission currently under study.
We investigate neutrino processes for conditions reached in simulations of core-collapse supernovae. Where neutrino-matter interactions play an important role, matter is partially degenerate, and we extend earlier work that addressed the degenerate regime. We derive expressions for the spin structure factor in neutron matter, which is a key quantity required for evaluating rates of neutrino processes. We show that, for essentially all conditions encountered in the post-bounce phase of core-collapse supernovae, it is a very good approximation to calculate the spin relaxation rates in the nondegenerate limit. We calculate spin relaxation rates based on chiral effective field theory interactions and find that they are typically a factor of two smaller than those obtained using the standard one-pion-exchange interaction alone.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
