Price for Environmental Neutrino-Superluminality

TL;DR

This paper explores whether the OPERA neutrino superluminality results can be explained by a planetary-scale environmental effect involving a new spin-2 field, without violating fundamental Poincaré invariance.

Contribution

It proposes a novel environmental explanation involving a massive spin-2 field coupled asymmetrically to matter, which could cause superluminal neutrino propagation.

Findings

The model passes key phenomenological tests.

Predicts a testable long-range fifth force.

Identifies the massive graviton as the only viable environmental explanation.

Abstract

We ask whether the recent OPERA results on neutrino superluminality could be an environmental effect characteristic of the local neighborhood of our planet, without the need of violation of the Poincar\'e-invariance at a fundamental level. This explanation requires the existence of a new spin-2 field of a planetary Compton wave-length that is coupled to neutrinos and the rest of the matter asymmetrically, both in the magnitude and in the sign. Sourced by the earth this field creates an effective metric on which neutrinos propagate superluminally, whereas other species are much less sensitive to the background. Such a setup, at an effective field theory level, passes all immediate phenomenological tests and its natural prediction is an inevitable appearance of a testable long-range gravity-type fifth force. We then prove that under the assumption of the weakly-coupled Poincar\'e-invariant physics, the asymmetrically-coupled second massive graviton is the only possible environmental explanation. Despite phenomenological viability, the sign asymmetry of the coupling we identify as the main potential obstacle for a consistent UV-completion. We also discuss the possible identification of this field with a Kaluza-Klein state of an extra dimension in which neutrino can propagate.