Parity violation and new physics in superconductors

TL;DR

This paper introduces a novel method using Andreev reflection in superconductors to detect parity violation effects from the Standard Model and potential new physics, providing a new experimental approach to constrain such effects.

Contribution

It proposes a new experimental technique based on Andreev reflection to measure tiny parity-violating effects in superconductors caused by the electroweak theory and beyond.

Findings

Parity-violating effects in superconductors are estimated to be tiny but measurable.

The proposed method could set bounds on new physics models coupling to electrons.

Spin polarization effects during Andreev reflection could be comparable to atomic parity violation.

Abstract

We propose a new method, using the Andreev reflection at superconductors, to measure parity violation induced by the standard electroweak theory, which in turn constrains the possible parity-violating effects of new physics. The weak neutral currents induce parity-violating, marginal effective operators, though quite tiny, in superconductors. We estimate their effects on superconducting gaps and propose a method to measure the parity-violation from the spin polarization effect, when electrons or holes get Andreev-reflected at the interface between normal metal and a superconductor. Such polarization effects might be comparable to the atomic parity violation and thus naturally give an interesting bound on certain models of new physics, that couples to electrons, such as Majorana mass of active neutrinos or doubly charged Higgs.