[Paper Review] Confronting Recent Neutrino Oscillation Data with Sterile Neutrinos

G. Karagiorgi|Research Explorer (The University of Manchester)|Oct 17, 2011

Neutrino Physics Research3 citations

TL;DR

This paper investigates the viability of sterile neutrino models to explain anomalies in short-baseline neutrino oscillation data, particularly the LSND and MiniBooNE excesses. It combines data from MiniBooNE and reactor antineutrino experiments, finds tension between neutrino and antineutrino data incompatible with standard CP violation, and proposes a matter-like potential for sterile neutrinos to reconcile the anomalies, with future high-precision experiments critical for validation.

ABSTRACT

Recent neutrino oscillation results have evoked renewed interest in sterile neutrino oscillation models. This paper reviews the data from MiniBooNE and short-baseline reactor antineutrino experiments within the context of sterile neutrinos. The results are incorporated into combined fits to test the viability of sterile neutrino oscillation models, which are later expanded to address matter effects. Finally, future experiments that can resolve the questions that have been raised are discussed.

Motivation & Objective

• To assess the compatibility of recent short-baseline neutrino oscillation data with sterile neutrino models.
• To resolve the tension between LSND's antineutrino excess and MiniBooNE's neutrino/antineutrino data under sterile neutrino frameworks.
• To explore non-standard effects such as matter-like potentials that could explain discrepancies without invoking CPT violation.
• To identify future experiments capable of definitively testing sterile neutrino hypotheses.

Proposed method

• Uses two-neutrino and three-neutrino oscillation formalisms to model sterile neutrino mixing, with probabilities derived from mixing angles and mass splittings.
• Applies the standard oscillation formulae: P(να → να) = 1 - sin²2θαα sin²(1.27Δm²₄₁L/E) and P(να → νβ) = sin²2θαβ sin²(1.27Δm²₄₁L/E) for disappearance and appearance.
• Incorporates CP-violating phases via interference terms in the three-neutrino mixing framework, particularly for two sterile neutrinos.
• Performs global fits to MiniBooNE, LSND, and reactor antineutrino disappearance data to constrain sterile neutrino parameters.
• Introduces a phenomenological matter-like potential Vs = ±As that affects only sterile neutrinos to explain the neutrino-antineutrino data tension.
• Evaluates sensitivity of upcoming experiments like MicroBooNE and reactor-based short-baseline searches to test the proposed model.

Experimental results

Research questions

• RQ1 Can sterile neutrino oscillations simultaneously explain the LSND antineutrino excess and the MiniBooNE low-energy neutrino excess?
• RQ2 Why is there a significant discrepancy between neutrino and antineutrino data in short-baseline experiments under the sterile neutrino hypothesis?
• RQ3 Can CP-violating phases in a three-neutrino sterile model resolve the observed data tension?
• RQ4 Do non-standard interactions or matter-like potentials provide a viable explanation for the observed anomalies without violating CPT symmetry?
• RQ5 Which upcoming experiments can achieve a definitive test of the sterile neutrino hypothesis with >5σ sensitivity?

Key findings

• The LSND 3.8σ excess for ν̄μ → ν̄e oscillations is consistent with a sterile neutrino model at Δm²₄₁ ~ 1 eV² and sin²2θμe ~ 0.005.
• MiniBooNE found no excess above 475 MeV, excluding the LSND parameters at 98% CL under CPT-conserving two-state oscillation.
• A 3.0σ low-energy excess in MiniBooNE νμ → νe appearance is inconsistent with a single sterile neutrino model.
• The combined data from MiniBooNE and reactor antineutrino disappearance experiments show increasing tension between neutrino and antineutrino results that cannot be explained by CP violation in the standard sterile neutrino framework.
• A phenomenological model with a matter-like potential Vs = ±As for sterile neutrinos provides a good fit to the data, though it requires a large effective potential that invites theoretical scrutiny.
• Future experiments such as MicroBooNE and high-statistics reactor-based searches are expected to test the model with >5σ sensitivity, particularly for single-electron and single-photon event identification.