Testing for Large Extra Dimensions with Neutrino Oscillations

TL;DR

This paper investigates how large extra dimensions could affect neutrino oscillations and uses experimental data to set upper bounds on the size of these dimensions, finding no significant improvement in fit quality but establishing new limits.

Contribution

It introduces a model where sterile neutrinos propagate in extra dimensions and uses experimental data to constrain the size of these dimensions.

Findings

Upper bounds on extra dimension size ~1 micrometer from current experiments.

No significant improvement in oscillation fit quality with extra dimensions.

Future experiments could improve sensitivity to extra dimension size.

Abstract

We consider a model where sterile neutrinos can propagate in a large compactified extra dimension giving rise to Kaluza-Klein (KK) modes and the standard model left-handed neutrinos are confined to a 4-dimensional spacetime brane. The KK modes mix with the standard neutrinos modifying their oscillation pattern. We examine former and current experiments such as CHOOZ, KamLAND, and MINOS to estimate the impact of the possible presence of such KK modes on the determination of the neutrino oscillation parameters and simultaneously obtain limits on the size of the largest extra dimension. We found that the presence of the KK modes does not essentially improve the quality of the fit compared to the case of the standard oscillation. By combining the results from CHOOZ, KamLAND and MINOS, in the limit of a vanishing lightest neutrino mass, we obtain the stronger bound on the size of the extra dimension as ~ 1.0(0.6) micrometer at 99% C. L. for normal (inverted) mass hierarchy. If the lightest neutrino mass turn out to be larger, 0.2 eV, for example, we obtain the bound ~ 0.1 micrometer. We also discuss the expected sensitivities on the size of the extra dimension for future experiments such as Double CHOOZ, T2K and NOvA.