Could quantum gravity slow down neutrinos?

TL;DR

This paper investigates how quantum spacetime might influence neutrino travel times, finding stronger evidence for neutrinos being slowed down by quantum gravity effects after updated IceCube data analysis.

Contribution

It revises previous analyses with new IceCube directional data, providing stronger evidence that quantum gravity may slow down neutrinos, and highlights the importance of this effect for future research.

Findings

No evidence for neutrinos sped up by quantum spacetime.

Stronger evidence for neutrinos slowed down by quantum spacetime.

False alarm probability less than 1% for slow neutrinos.

Abstract

In addition to its implications for astrophysics, the hunt for GRB neutrinos could also be significant in quantum-gravity research, since they are excellent probes of the microscopic fabric of spacetime. Some previous studies based on IceCube neutrinos had found intriguing preliminary evidence that some of them might be GRB neutrinos with travel times affected by quantum properties of spacetime, with the noticeable feature that quantum spacetime would slow down some of the neutrinos while others would be sped up. Recently the IceCube collaboration revised significantly the estimates of the direction of observation of their neutrinos, and we here investigate how the corrected directional information affects the results of the previous quantum-spacetime-inspired analyses. We find that there is now no evidence for neutrinos sped up by quantum-spacetime properties, whereas the evidence for neutrinos slowed down by quantum spacetime is even stronger than previously found. Our most conservative estimates find a false alarm probability of less than 1% for these "slow neutrinos", providing motivation for future studies on larger data samples.