The Glashow resonance at E_ν=6.3 PeV is a measure of the \barν_e content of the astrophysical neutrino flux. The fractional \barν_e content depends on the neutrino production model at the cosmic neutrino source, and the environment at the source. Thus, the strength of the Glashow resonance event rate is a potential window into astrophysical sources. We quantify the "Glashow resonometer" and comment on the significance that no Glashow events are observed in the IceCube three-year data.
Discovering neutrino decay would be strong evidence of physics beyond the Standard Model. Presently, there are only lax lower limits on the lifetime $τ$ of neutrinos, of $τ/m \sim 10^{-3}$ s eV$^{-1}$ or worse, where $m$ is the unknown neutrino mass. High-energy cosmic neutrinos, with TeV-PeV energies, offer superior sensitivity to decay due to their cosmological-scale baselines. To tap into it, we employ a promising method, recently proposed, that uses the Glashow resonance $\barν_e + e \to W$, triggered by $\barν_e$ of 6.3 PeV, to test decay with only a handful of detected events. If most of…
The Glashow resonance as a discriminator of UHE cosmic neutrinos originating from p-gamma and p-p collisions
We re-examine the interesting possibility of utilizing the Glashow resonance (GR) channel nu_ebar + e^- to W^- to anything to discriminate between the UHE cosmic neutrinos originating from p-gamma and pp collisions in an optically thin source of cosmic rays . We propose a general parametrization of the initial neutrino flavor composition by allowing the ratios Phi^{p gamma}_{pi^-}/Phi^{p gamma}_{pi^+} and Phi^{pp}_{pi^-}/Phi^{pp}_{pi^+} to slightly deviate from their conventional values. A relationship between the typical source parameter kappa = (Phi^{p gamma}_{pi^+} + Phi^{p gamma}_{pi^-})/(…
The IceCube neutrino discovery was punctuated by three showers with $E_ν$ ~ 1-2 PeV. Interest is intense in possible fluxes at higher energies, though a marked deficit of $E_ν$ ~ 6 PeV Glashow resonance events implies a spectrum that is soft and/or cutoff below ~few PeV. However, IceCube recently reported a through-going track event depositing 2.6 $\pm$ 0.3 PeV. A muon depositing so much energy can imply $E_{ν_μ} \gtrsim$ 10 PeV. We show that extending the soft $E_ν^{-2.6}$ spectral fit from TeV-PeV data is unlikely to yield such an event. Alternatively, a tau can deposit this much energy, tho…
We discuss the spectrum of the different components in the astrophysical neutrino flux reaching the Earth and the possible contribution of each component to the high-energy IceCube data. We show that the diffuse flux from cosmic ray interactions with gas in our galaxy implies just 2 events among the 54 event sample. We argue that the neutrino flux from cosmic ray interactions in the intergalactic (intracluster) space depends critically on the transport parameter $δ$ describing the energy dependence in the diffusion coefficient of galactic cosmic rays. Our analysis motivates a E^{-2.1} neutrino…
We review the peculiarities that make neutrino a very special cosmic messenger in high-energy astrophysics, and, in particular, to provide possible indications of deviations from special relativity, as it is suggested theoretically by quantum gravity models. In this respect, we examine the effects that one could expect in the production, propagation, and detection of neutrinos, not only in the well-studied scenario of Lorentz Invariance Violation, but also in models which maintain, but deform, the relativity principle, such as those considered in the framework of Doubly Special Relativity. We …
PeV neutrinos from the propagation of ultra-high energy cosmic rays
本文讨论了IceCube最近观测到的PeV中微子是河外宇宙射线在穿过辐射背景时相互作用产生的可能性。我们发现，从宇宙射线质子与CMB背景的相互作用中产生的中子衰变产生的通量被抑制（$E_ν^2$ d $Φ_ν/$ d $E< 10^{-10}$ GeV/cm $^2$ s sr），与那些从与UV/光学/IR背景的相互作用中产生的π介子衰变产生的是在PeV能量占主导地位的。由重核与CMB光子的光致衰变产生的中子衰变所产生的反中微子通量也被证明是相当抑制的（$E_ν^2$ d $Φ_ν/$ d $E< 10^{-11}$ GeV/cm $^2$ s sr），而由具有UV/光学/IR背景的光子π过程产生的反中微子通量可能更大，尽管它们预计不会高于纯质子情况下可实现的通量。混合成分和低截止刚度的情况下，可以导致PeV中微子通量增强相对于那些在纯铁的情况下。我们还讨论了可能的影响，为检测这些情况下，显示出它起着温和的作用的marthow共振。
We study an effective theory beyond the standard model (SM) where either of two additional gauge singlets, a Majorana fermion and a real scalar, constitutes all or some fraction of dark matter. In particular, we focus on the masses of the two singlets in the range of O(10) MeV-O(10) GeV, with a neutrino portal interaction which plays important roles not only in particle physics but also in cosmology and astronomy. We point out that the dark matter abundance can be thermally explained with (co)annihilation, where the dark matter with a mass greater than 2 GeV can be tested in future lepton coll…
Weakly interacting neutrinos are ideal astronomical messengers because they travel through space without deflection by magnetic fields and, essentially, without absorption. Their weak interaction also makes them notoriously difficult to detect, with observation of high-energy neutrinos from distant sources requiring kilometer-scale detectors. The IceCube project transformed a cubic kilometer of natural Antarctic ice at the geographic South Pole into a Cherenkov detector. It discovered a flux of cosmic neutrinos in the energy range from 10 TeV to 10 PeV, predominantly extragalactic in origin. T…
High energy neutrinos can be produced by interactions of ultra-high energy cosmic rays (UHECRs) in the dense radiation fields of their sources as well as off the cosmic backgrounds when they propagate through the universe. Multi-messenger interpretations of current measurements deeply rely on the understanding of these interactions. In order to efficiently produce neutrinos in the sources of UHECRs, at least a moderate level of interactions is needed, which means that a nuclear cascade develops if nuclei are involved. On the other hand, the available cross-section data and interaction models t…
The recent detection of the gravitational wave event GW170817, produced by the coalescence of two neutron stars, and of its optical-infrared counterpart, powered by the radioactive decay of r-process elements, has opened a new window to gamma-ray astronomy: the direct detection of photons coming from such decays. Here we calculate the contribution of kilonovae to the diffuse gamma-ray background in the MeV range, using recent results on the spectra of the gamma-rays emitted in individual events, and we compare it with that from other sources. We find that the contribution from kilonovae is not…
The IceCube Neutrino Observatory has recently found compelling evidence for a particular blazar producing high-energy neutrinos and $\mathrm{PeV}$ cosmic rays, however the sources of cosmic rays above several $\mathrm{EeV}$ remain unidentified. It is believed that the same environments that accelerate ultra-high-energy cosmic rays (UHECRs) also produce high-energy neutrinos via hadronic interactions of lower-energy cosmic rays. Two out of three joint analyses of the IceCube Neutrino Observatory, the Pierre Auger Observatory and the Telescope Array yielded hints for a possible directional corre…
