Arman Esmaili

Are IceCube neutrinos unveiling PeV-scale decaying dark matter?

Recent observations by IceCube, notably two PeV cascades accompanied by events at energies ~ (30–400) TeV, are clearly in excess over atmospheric background fluxes and beg for an astroparticle physics explanation. Although some models of astrophysical accelerators can account for the observations within current statistics, intriguing features in the energy and possibly angular distributions of the events make worth exploring alternatives. Here, we entertain the possibility of interpreting the data with a few PeV mass scale decaying dark matter, with lifetime of the order of 1027 s. We discuss generic signatures of this scenario, including its unique energy spectrum distortion with respect to the benchmark Eν−2 expectation for astrophysical sources, as well as peculiar anisotropies. A direct comparison with the data show a good match with the above-mentioned features. We further discuss possible future checks of this scenario.

IceCube events and decaying dark matter: hints and constraints

In the light of the new IceCube data on the (yet unidentified) astrophysical neutrino flux in the PeV and sub-PeV range, we present an update on the status of decaying dark matter interpretation of the events. In particular, we develop further the angular distribution analysis and discuss the perspectives for diagnostics. By performing various statistical tests (maximum likelihood, Kolmogorov-Smirnov and Anderson-Darling tests) we conclude that currently the data show a mild preference (below the two sigma level) for the angular distribution expected from dark matter decay vs. the isotropic distribution foreseen for a conventional astrophysical flux of extragalactic origin. Also, we briefly develop some general considerations on heavy dark matter model building and on the compatibility of the expected energy spectrum of decay products with the IceCube data, as well as with existing bounds from gamma-rays. Alternatively, assuming that the IceCube data originate from conventional astrophysical sources, we derive bounds on both decaying and annihilating dark matter for various final states. The lower limits on heavy dark matter lifetime improve by up to an order of magnitude with respect to existing constraints, definitively making these events---even if astrophysical in origin---an important tool for astroparticle physics studies.

Probing the stability of superheavy dark matter particles with high-energy neutrinos

Two of the most fundamental properties of the dark matter particle, the mass and the lifetime, are only weakly constrained by the astronomical and cosmological evidence of dark matter. We derive in this paper lower limits on the lifetime of dark matter particles with masses in the range 10TeV−1015TeV from the non-observation of ultrahigh energy neutrinos in the AMANDA, IceCube, Auger and ANITA experiments. For dark matter particles which produce neutrinos in a two body or a three body leptonic decay, we find that the dark matter lifetime must be longer than (1026−1028)s for masses between 10 TeV and the Grand Unification scale. Finally, we also calculate, for concrete particle physics scenarios, the limits on the strength of the interactions that induce the dark matter decay.

KATRIN Sensitivity to Sterile Neutrino Mass in the Shadow of Lightest Neutrino Mass

The presence of light sterile neutrinos would strongly modify the energy spectrum of the tritium � electrons. We perform an analysis of the KArlsruhe TRItium Neutrino (KATRIN) experiment’s sensitivity by scanning almost all the allowed region of neutrino mass-squared difference and mixing angles of the 3 þ 1 scenario. We consider the effect of the unknown absolute mass scale of active neutrinos on the sensitivity of KATRIN to the sterile neutrino mass. We show that after 3 years of data-taking, the KATRIN experiment can be sensitive to mixing angles as small as sin 2 2� s � 10 � 2 . Particularly we show that for small mixing angles, sin 2 2� s & 0:1, the KATRIN experiment can give the strongest limit on active-sterile mass-squared difference.

Restricting the LSND and MiniBooNE sterile neutrinos with the IceCube atmospheric neutrino data

A bstractWe study oscillations of the high energy atmospheric neutrinos in the Earth into sterile neutrinos with the eV-scale mass. The MSW resonance and parametric enhancement of the

Probing non-standard interaction of neutrinos with IceCube and DeepCore

\overline{\nu}

Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints

μ →

Implications of the Pseudo-Dirac Scenario for Ultra High Energy Neutrinos from GRBs

\overline{\nu}

Exploring

s oscillations lead to distortion of the zenith angle distribution of the muon-track events which can be observed by IceCube. Due to matter effect, the IceCube signal depends not only on the mixing element Uμ4 relevant for LSND and MiniBooNE but also on Uτ4 and the CP-violating phase δ24. We show that the case with Uτ4 = δ24 = 0 leads to the weakest IceCube signal and therefore should be used to bound Uμ4. We compute the zenith angle distributions of the νμ − events for different energy intervals in the range (0.1 - 10) TeV and find that inclusion of the energy information (binning in energy) improves the sensitivity to νs drastically. We estimate that with already collected (during 3-4years) IceCube statistics thebound |Uμ4|2<0.01(99% C.L.)canbeestablished and the mixing required by LSND and MiniBooNE can be excluded at (4–6)σ confidence level.

\nu_\tau - \nu_s

A bstractWe consider effects of the Non-Standard Interactions (NSI) on oscillations of the high energy atmospheric neutrinos. The νμ-oscillograms are constructed and their dependence on the NSI strength parameters ϵαβ studied. We computed the zenith angle distributions of the νμ-events in the presence of NSI in different energy regions. The distributions are confronted with the IceCube-79 (high energy sample) and the DeepCore (low energy sample) data and constraints on the strength parameters |ϵμτ|≲ 6 × 10−3 and |ϵμμ − ϵττ| ≲ 3 × 10−2 (90% C.L.) have been obtained. Future measurements of the zenith angle distributions by DeepCore in several energy bins will allow to improve the bounds by factor 2–3. We discuss the signatures of NSI in the zenith angle and energy distributions of events which allow to discriminate them from the effects of sterile neutrinos.