Daily modulations and broadband strategy in axion searches. An application with CAST-CAPP detector

TL;DR

This paper explores the potential of daily modulation and broadband detection strategies in axion searches, motivated by the AQN dark matter model predicting relativistic axions with significant daily flux variations, using CAST-CAPP data.

Contribution

It introduces the concept of using daily modulations and broadband strategies in axion detection, applying it to CAST-CAPP data, and discusses the challenges faced due to experimental factors.

Findings

No conclusive detection of daily modulation due to gain drifts

Demonstrated the feasibility of using broadband strategies for relativistic axion searches

Provided a reference procedure for future modulation-based axion detection studies

Abstract

It has been previously advocated that the presence of the daily and annual modulations of the axion flux on the Earth's surface may dramatically change the strategy of the axion searches. The arguments were based on the so-called Axion Quark Nugget (AQN) dark matter model which was originally put forward to explain the similarity of the dark and visible cosmological matter densities $\Omega_{\rm dark}\sim \Omega_{\rm visible}$. In this framework, the population of galactic axions with mass $ 10^{-6} {\rm eV}\lesssim m_a\lesssim 10^{-3}{\rm eV}$ and velocity $\langle v_a\rangle\sim 10^{-3} c$ will be accompanied by axions with typical velocities $\langle v_a\rangle\sim 0.6 c$ emitted by AQNs. Furthermore, in this framework, it has also been argued that the AQN-induced axion daily modulation (in contrast with the conventional WIMP paradigm) could be as large as $(10-20)\%$, which represents the main motivation for the present investigation. We argue that the daily modulations along with the broadband detection strategy can be very useful tools for the discovery of such relativistic axions. The data from the CAST-CAPP detector have been used following such arguments. Unfortunately, due to the dependence of the amplifier chain on temperature-dependent gain drifts and other factors, we could not conclusively show the presence or absence of a dark sector-originated daily modulation. However, this proof of principle analysis procedure can serve as a reference for future studies.