[Paper Review] Neutrinos, DUNE and the world best bound on CPT violation

Gabriela Barenboim, M. Tórtola+1 more|arXiv (Cornell University)|Dec 5, 2017

Neutrino Physics Research6 citations

TL;DR

This paper proposes that neutrino oscillation experiments, particularly DUNE, can significantly improve the world's best bound on CPT violation by several orders of magnitude. Using current neutrino data and DUNE's sensitivity, it demonstrates that CPT violation could be detected at more than 3σ if T2K's recent results hold true, with DUNE improving bounds on Δ(Δm²₃₁) by at least one order of magnitude.

ABSTRACT

CPT symmetry, the combination of Charge Conjugation, Parity and Time reversal, is a cornerstone of our model building strategy and therefore the repercussions of its potential violation will severely threaten the most extended tool we currently use to describe physics, i.e. local relativistic quantum fields. However, limits on its conservation from the Kaon system look indeed imposing. In this work we will show that neutrino oscillation experiments can improve this limit by several orders of magnitude and therefore are an ideal tool to explore the foundations of our approach to Nature. In order to do that we calculate the current CPT bound on all the neutrino mixing parameters and study the sensitivity of the DUNE experiment to such a violation. After deriving the most updated bound on CPT from neutrino oscillation data, we show that, if the recent T2K results turn out to be the true values of neutrino and antineutrino oscillations, DUNE would measure CPT violation at more than 3$\sigma$. Then, we study the sensitivity of the experiment to measure CPT violation in general, finding that DUNE will be able to improve the current bounds on $\Delta(\Delta m^2_{31})$ by at least one order of magnitude. We also study the sensitivity to the other oscillation parameters. Finally we show that, if CPT is violated in nature, combining neutrino with antineutrino data in oscillation analysis will produce imposter solutions.

Motivation & Objective

• To improve the current world-best bound on CPT violation using neutrino oscillation data.
• To assess DUNE's sensitivity to CPT violation in neutrino mixing parameters.
• To investigate the impact of combining neutrino and antineutrino data when CPT is violated.
• To quantify the expected improvement in sensitivity to Δ(Δm²₃₁) and other oscillation parameters.

Proposed method

• Analysis of current neutrino oscillation data to derive the most updated bound on CPT violation.
• Use of the DUNE experiment's projected sensitivity to evaluate CPT violation in neutrino and antineutrino oscillations.
• Comparison of neutrino and antineutrino oscillation probabilities to detect CPT-violating differences in mixing parameters.
• Statistical evaluation of sensitivity to CPT violation using Δχ² analysis and confidence intervals.
• Simulation of imposter solutions arising from combined neutrino-antineutrino data when CPT is violated.

Experimental results

Research questions

• RQ1 Can neutrino oscillation experiments improve the current bound on CPT violation by several orders of magnitude?
• RQ2 What is the sensitivity of the DUNE experiment to detect CPT violation if T2K's recent results are correct?
• RQ3 How much can DUNE improve the bound on Δ(Δm²₃₁) compared to current limits?
• RQ4 What are the implications for oscillation analysis when CPT is violated and both neutrino and antineutrino data are combined?

Key findings

• DUNE would measure CPT violation at more than 3σ if the recent T2K results represent the true values of neutrino and antineutrino oscillations.
• DUNE is expected to improve the current bound on Δ(Δm²₃₁) by at least one order of magnitude.
• The sensitivity of DUNE to CPT violation in other oscillation parameters is also significantly enhanced.
• Combining neutrino and antineutrino data in the presence of CPT violation leads to the appearance of imposter solutions in the analysis.