9 research outputs found
Sterile Neutrinos or Flux Uncertainties? - Status of the Reactor Anti-Neutrino Anomaly
The discrepancy between the predicted and observed reactor
anti-neutrino flux, known as the reactor anti-neutrino anomaly, continues to
intrigue. The recent discovery of an unexpected bump in the reactor
anti-neutrino spectrum, as well as indications that the flux deficit is
different for different fission isotopes seems to disfavour the explanation of
the anomaly in terms of sterile neutrino oscillations. We critically review
this conclusion in view of all available data on electron (anti)neutrino
disappearance. We find that the sterile neutrino hypothesis cannot be rejected
based on global data and is only mildly disfavored compared to an individual
rescaling of neutrino fluxes from different fission isotopes. The main reason
for this is the presence of spectral features in recent data from the NEOS and
DANSS experiments. If state-of-the-art predictions for reactor fluxes are taken
at face value, sterile neutrino oscillations allow a consistent description of
global data with a significance close to relative to the
no-oscillation case. Even if reactor fluxes and spectra are left free in the
fit, a hint in favour of sterile neutrinos remains, with allowed
parameter regions consistent with an explanation of the anomaly in terms of
oscillations.Comment: 25 pages, 5 figures. 1 page and table 4 added. Published in JHE
Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic
This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic
Beta and Neutrinoless Double Beta Decays with KeV Sterile Fermions
International audienceMotivated by the capability of the KATRIN experiment to explore the existence of KeV neutrinos in the [1 â 18.5] KeV mass range, we explore the viability of minimal extensions of the Standard Model involving sterile neutrinos (namely the 3 + N frameworks) and study their possible impact in both the beta energy spectrum and the neutrinoless double beta decay effective mass, for the two possible ordering cases for the light neutrino spectrum. We also explore how both observables can discriminate between motivated low-scale seesaw realizations involving KeV sterile neutrinos. Our study concerns the prospect of a Type-I seesaw with two right-handed neutrinos, and a combination of the inverse and the linear seesaws where the Standard Model is minimally extended by two quasi-degenerate sterile fermions. We also discuss the possibility of exploring the latter case searching for double-kinks in KATRIN
Updated global analysis of neutrino oscillations in the presence of eV-scale sterile neutrinos
We discuss the possibility to explain the anomalies in short-baseline neutrino oscillation experiments in terms of sterile neutrinos. We work in a 3 + 1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the Îœ disappearance channel favour sterile neutrino oscillations at the 3Ï level with Îm âââ1.3 eV and |U| â 0.1, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the Îœ appearance channel (dominated by LSND) are in strong tension with improved bounds on Îœ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than 2.6 Ă 10. Therefore, an explanation of the LSND anomaly in terms of sterile neutrino oscillations in the 3 + 1 scenario is excluded at the 4.7Ï level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths |U| (α = e, ÎŒ, Ï ) of active neutrinos with a fourth neutrino mass state in the eV range.We discuss the possibility to explain the anomalies in short-baseline neutrino oscillation experiments in terms of sterile neutrinos. We work in a 3+1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the disappearance channel favour sterile neutrino oscillations at the level with eV and , even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the appearance channel (dominated by LSND) are in strong tension with improved bounds on disappearance, mostly driven by MINOS+ and IceCube. Under the sterile neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than . Therefore, an explanation of the LSND anomaly in terms of sterile neutrino oscillations in the 3+1 scenario is excluded at the level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths () of active neutrinos with a fourth neutrino mass state in the eV range