Neutrino Velocity and the Variability of Fundamental Constants

TL;DR

This paper explores how neutrino speed measurements and deep underground clock experiments can test for depth-dependent variations in fundamental constants, potentially revealing new physics beyond the Standard Model.

Contribution

It introduces a model where fundamental constants vary with depth, proposing new experimental tests using neutrino speed and atomic clock comparisons to detect such effects.

Findings

Neutrino experiments can constrain depth-dependent fundamental constant variations.

Deep underground atomic clock experiments may surpass neutrino tests in sensitivity.

Depth-dependent tensor backgrounds could cause measurable clock frequency shifts.

Abstract

Neutrino speed experiments could be viewed not only as tests of Lorentz invariance but also as measurements of limiting propagation speed for all standard model species below certain depth where no direct metrological information is available. The latter option, hypothetically caused by some chameleon-type background, could be tested in the next installment of the neutrino speed experiments. We also show that that complementary constraints on the same class of models can be obtained with experiments testing clock universality in deep underground/underwater experiments. By considering the explicit QED model with particle-universal modification of propagation speed by a depth-dependent tensor background, we show that in general one should expect larger-than-GR shifts of the clock frequencies and clock non-universality. This can be tested by comparison of the narrow transitions in atomic clocks, which for a generic model could deliver a superior accuracy compared to the neutrino speed experiments.