Neutrino oscillations as a probe of macrorealism

The correlations between successive measurements of a quantum system can violate a family of Leggett-Garg Inequalities (LGIs) that are analogous to the violation of Bell’s inequalities of measurements performed on spatially separated quantum systems. These LGIs follow from a point of view, imposing that a classical system is at all times in a definite state and that a measurement can, at least in principle, leave this state undisturbed. Violations of LGIs can be probed by neutrino flavor oscillations if the correlators of consecutive flavor measurements are approximately stationary. We discuss here several improvements of the methodology used in previous analyses based on accelerator and reactor neutrino data. We argue that the strong claims of LGI violations made in previous studies are based on an unsuitable modeling of macrorealistic systems in statistical hypothesis tests. We illustrate our improved methodology via the example of the MINOS muon-neutrino survival data, where we find revised statistical evidence for violations of LGIs at the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mo stretchy="false">(</a:mo> <a:mn>2</a:mn> <a:mi>–</a:mi> <a:mn>3</a:mn> <a:mo stretchy="false">)</a:mo> <a:mi>σ</a:mi> </a:math> level, depending on macrorealistic background models.