Hints of theta_13>0 from global neutrino data analysis

TL;DR

This paper performs a comprehensive global analysis of neutrino oscillation data, revealing hints that the mixing angle theta_13 is greater than zero with about 90% confidence, based on combined atmospheric, solar, and reactor data.

Contribution

It provides the first combined global estimate of theta_13 indicating a preference for a non-zero value, integrating recent experimental results.

Findings

Hints of theta_13>0 at ~1sigma from atmospheric data

Hints of theta_13>0 at ~1sigma from solar and reactor data

Combined analysis suggests sin^2(theta_13)=0.016±0.010, favoring theta_13>0

Abstract

Nailing down the unknown neutrino mixing angle theta_13 is one of the most important goals in current lepton physics. In this context, we perform a global analysis of neutrino oscillation data, focusing on theta_13, and including recent results [Neutrino 2008, Proceedings of the XXIII International Conference on Neutrino Physics and Astrophysics, Christchurch, New Zealand, 2008 (unpublished)]. We discuss two converging hints of theta_13>0, each at the level of ~1sigma: an older one coming from atmospheric neutrino data, and a newer one coming from the combination of solar and long-baseline reactor neutrino data. Their combination provides the global estimate sin^2(theta_13) = 0.016 +- 0.010 (1sigma), implying a preference for \theta_13>0 with non-negligible statistical significance (~90% C.L.). We discuss possible refinements of the experimental data analyses, which might sharpen such intriguing indication.