Search results for "Sterile neutrino"
showing 10 items of 151 documents
Calculation of the local density of relic neutrinos
2017
Nonzero neutrino masses are required by the existence of flavour oscillations, with values of the order of at least 50 meV. We consider the gravitational clustering of relic neutrinos within the Milky Way, and used the $N$-one-body simulation technique to compute their density enhancement factor in the neighbourhood of the Earth with respect to the average cosmic density. Compared to previous similar studies, we pushed the simulation down to smaller neutrino masses, and included an improved treatment of the baryonic and dark matter distributions in the Milky Way. Our results are important for future experiments aiming at detecting the cosmic neutrino background, such as the Princeton Tritiu…
Sterile Neutrinos in Light of Recent Cosmological and Oscillation Data: a Multi-Flavor Scheme Approach
2008
Light sterile neutrinos might mix with the active ones and be copiously produced in the early Universe. In the present paper, a detailed multi-flavor analysis of sterile neutrino production is performed. Making some justified approximations allows us to consider not only neutrino interactions with the primeval medium and neutrino coherence breaking effects, but also oscillation effects arising from the presence of three light (mostly-active) neutrino states mixed with two heavier (mostly-sterile) states. First, we emphasize the underlying physics via an analytical description of sterile neutrino abundances that is valid for cases with small mixing between active and sterile neutrinos. Then,…
A White Paper on keV sterile neutrino Dark Matter
2017
We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved - cosmology, astrophysics, nuclear, and particle physics - in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrin…
Dark radiation sterile neutrino candidates after Planck data
2013
Recent Cosmic Microwave Background (CMB) results from the Planck satellite, combined with previous CMB data and Hubble constant measurements from the Hubble Space Telescope, provide a constraint on the effective number of relativistic degrees of freedom 3.62(-0.48)(+0.50) at 95% CL. New Planck data provide a unique opportunity to place limits on models containing relativistic species at the decoupling epoch. We present here the bounds on sterile neutrino models combining Planck data with galaxy clustering information. Assuming N-eff active plus sterile massive neutrino species, in the case of a Planck+WP+HighL+HST analysis we find m(nu,sterile)(eff) < 0.36 eV and 3.14 < N-eff < 4.15 at 95% …
Probing secret interactions of eV-scale sterile neutrinos with the diffuse supernova neutrino background
2020
Sterile neutrinos with mass in the eV-scale and large mixings of order $\theta_0\simeq 0.1$ could explain some anomalies found in short-baseline neutrino oscillation data. Here, we revisit a neutrino portal scenario in which eV-scale sterile neutrinos have self-interactions via a new gauge vector boson $\phi$. Their production in the early Universe via mixing with active neutrinos can be suppressed by the induced effective potential in the sterile sector. We study how different cosmological observations can constrain this model, in terms of the mass of the new gauge boson, $M_\phi$, and its coupling to sterile neutrinos, $g_s$. Then, we explore how to probe part of the allowed parameter spa…
Abelian realization of phenomenological two-zero neutrino textures
2014
In an attempt at explaining the observed neutrino mass-squared differences and leptonic mixing, lepton mass matrices with zero textures have been widely studied. In the weak basis where the charged lepton mass matrix is diagonal, various neutrino mass matrices with two zeros have been shown to be consistent with the current experimental data. Using the canonical and Smith normal form methods, we construct the minimal Abelian symmetry realizations of these phenomenological two-zero neutrino textures. The implementation of these symmetries in the context of the seesaw mechanism for Majorana neutrino masses is also discussed.
Search for sterile neutrino mixing using three years of IceCube DeepCore data
2017
Physical review / D 95(11), 112002(2017). doi:10.1103/PhysRevD.95.112002
Heavy sterile neutrinos in stellar core-collapse
2018
We perform spherically symmetric simulations of the core collapse of a single progenitor star of zero age main sequence mass $M_{\rm ZAMS} = 15 \, M_{\odot}$ with two models of heavy sterile neutrinos in the mass range of hundred MeV$/c^2$. According to both models, these hypothetical particles are copiously produced in the center, stream outwards a subsequently decay releasing energy into final states (including neutrinos) of the Standard Model. We find that they can lead to a successful explosion in otherwise non-exploding progenitors. Depending on their unknown parameters (e.g., mass and coupling constants with matter), we obtain either no explosion or an explosion of one of two types, i…
Sterile neutrinos and flavor ratios in IceCube
2017
The flavor composition of astrophysical neutrinos observed in neutrino telescopes is a powerful discriminator between different astrophysical neutrino production mechanisms and can also teach us about the particle physics properties of neutrinos. In this paper, we investigate how the possible existence of light sterile neutrinos can affect these flavor ratios. We consider two scenarios: (i) neutrino production in conventional astrophysical sources, followed by partial oscillation into sterile states; (ii) neutrinos from dark matter decay with a primary flavor composition enhanced in tau neutrinos or sterile neutrinos. Throughout the paper, we constrain the sterile neutrino mixing parameters…
Production of keV sterile neutrinos in supernovae: New constraints and gamma-ray observables
2019
We study the production of sterile neutrinos in supernovae, focusing in particular on the keV--MeV mass range, which is the most interesting range if sterile neutrinos are to account for the dark matter in the Universe. Focusing on the simplest scenario in which sterile neutrinos mixes only with muon or tau neutrino, we argue that the production of keV--MeV sterile neutrinos can be strongly enhanced by a Mikheyev--Smirnov--Wolfenstein (MSW) resonance, so that a substantial flux is expected to emerge from a supernova, even if vacuum mixing angles between active and sterile neutrinos are tiny. Using energetics arguments, this yields limits on the sterile neutrino parameter space that reach do…