Search results for "Particle physics"
showing 10 items of 6826 documents
Sterile neutrinos with secret interactions—lasting friendship with cosmology
2015
Sterile neutrinos with mass ~1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A'. However, even this scenario is restricted by structure formation constraints when A'-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such "secret" interactions. We carefully dissect their evolution in the early Univers…
Future $\nu_\tau$ Oscillation Experiments and Present Data
1995
Our goal in this paper is to examine the discovery potential of laboratory experiments searching for the oscillation $\nu_\mu(\nu_e) \rightarrow \nu_\tau$, in the light of recent data on solar and atmospheric neutrino experiments, which we analyse together with the most restrictive results from laboratory experiments on neutrino oscillations. In order to explain simultaneously $all$ present results we use a four-neutrino framework, with an additional sterile neutrino. Our predictions are rather pessimistic for the upcoming experiments NOMAD and CHORUS, which, we find, are able to explore only a small area of the oscillation parameter space. On the other hand, the discovery potential of futu…
Sterile Neutrinos, Non-Standard Neutrino Oscillations and Tests of Lorentz Invariance
2020
Type-II Supernovae and Neutrino Magnetic Moment
1998
The present solar and atmospheric neutrino data together with the LSND results and the presence of hot dark matter (HDM) suggest the existence of a sterile neutrino at the eV scale. We have reanalysed the effect of resonant {\sl sterile} neutrino conversions induced by neutrino magnetic moments in a type-II supernova. We analyse the implications of $\nu_e-\nu_s$ and $\bar{\nu}_e-\bar{\nu}_s$ ($\nu_s$ denotes sterile neutrino) conversions for the supernova shock re-heating, the detected $\bar\nu_e$ signal from SN1987A and the $r$-process nucleosynthesis hypothesis. Using reasonable magnetic field profiles we determine the sensitivity of these three arguments to the relevant neutrino paramete…
Relic neutrinos, thermal axions, and cosmology in early 2014
2014
We present up to date cosmological bounds on the sum of active neutrino masses as well as on extended cosmological scenarios with additional thermal relics, as thermal axions or sterile neutrino species. Our analyses consider all the current available cosmological data in the beginning of year 2014, including the very recent and most precise Baryon Acoustic Oscillation (BAO) measurements from the Baryon Oscillation Spectroscopic Survey. In the minimal three active neutrino scenario, we find Sum m_nu < 0.22 eV at 95% CL from the combination of CMB, BAO and Hubble Space Telescope measurements of the Hubble constant. A non zero value for the sum of the three active neutrino masses of about …
Cosmological limits on neutrino unknowns versus low redshift priors
2015
Recent Cosmic Microwave Background (CMB) temperature and polarization anisotropy measurements from the Planck mission have significantly improved previous constraints on the neutrino masses as well as the bounds on extended models with massless or massive sterile neutrino states. However, due to parameter degeneracies, additional low redshift priors are mandatory in order to sharpen the CMB neutrino bounds. We explore here the role of different priors on low redshift quantities, such as the Hubble constant, the cluster mass bias, and the reionization optical depth $\tau$. Concerning current priors on the Hubble constant and the cluster mass bias, the bounds on the neutrino parameters may di…
Effects of degenerate sterile neutrinos on the supernova neutrino flux
2004
We consider the possibility that there exist sterile neutrinos which are closely degenerate in mass with the active neutrinos and mixed with them. We investigate the effects of this kind of active-sterile neutrino mixing on the composition of supernova neutrino flux at the Earth. If an adiabatic MSW-transition between active and sterile neutrinos takes place, it could dramatically diminish the electron neutrino flux.
Helicitogenesis: WIMPy baryogenesis with sterile neutrinos and other realizations
2014
We propose a mechanism for baryogenesis from particle decays or annihilations that can work at the TeV scale. Some heavy particles annihilate or decay into a heavy sterile neutrino N (with M > 0.5 TeV) and a "light" one ��(with m << 100 GeV), generating an asymmetry among the two helicity degrees of freedom of ��. This asymmetry is partially transferred to Standard Model leptons via fast Yukawa interactions and reprocessed into a baryon asymmetry by the electroweak sphalerons. We illustrate this mechanism in a WIMPy baryogenesis model where the helicity asymmetry is generated in the annihilation of dark matter. This model connects the baryon asymmetry, dark matter, and neutrino mas…
Impact of New Physics on CP-Asymmetries at Long Baselines
2018
We study the impact of new physics on CP-asymmetries using different oscillation channels at long baseline experiments.
Probing light sterile neutrino signatures at reactor and Spallation Neutron Source neutrino experiments
2017
We investigate the impact of a fourth sterile neutrino at reactor and Spallation Neutron Source neutrino detectors. Specifically, we explore the discovery potential of the TEXONO and COHERENT experiments to subleading sterile neutrino effects through the measurement of the coherent elastic neutrino-nucleus scattering event rate. Our dedicated $\chi^2$-sensitivity analysis employs realistic nuclear structure calculations adequate for high purity sub-keV threshold Germanium detectors.