arXiv subjects

Cyprien Beaufort

Publications and source records attributed to Cyprien Beaufort.

3 recordsLinked to original sources

arXiv2023

New solar X-ray constraints on keV Axion-Like Particles

The decay of Axion-Like Particles (ALPs) trapped in the solar gravitational field would contribute to the observed solar X-ray flux, hence constraining ALP models. We improve by one order of magnitude the existing limits in the parameter space $(g_{aγγ}, m)$ by considering ALPs production via photon coalescence. For $g_{ae} \neq 0$, we demonstrate that trapped ALPs can be Compton-absorbed while crossing the Sun, resulting in two regimes in the exclusion limits, with a transition triggered by $g_{ae}$. Out of the transitional region, the solar X-ray constraints on ALPs are exclusively governed by $g_{aγγ}$.

hep-ph↗

arXiv2022

Directionality and head-tail recognition in the keV-range with the MIMAC detector by deconvolution of the ionic signal

Directional detection is the only strategy for the unambiguous identification of galactic Dark Matter (DM) even in the presence of an irreducible background such as beyond the neutrino floor. This approach requires measuring the direction of a DM-induced nuclear recoil in the keV-range. To probe such low energies, directional detectors must operate at high gain where 3D track reconstruction can be distorted by the influence of the numerous ions produced in the avalanches. The article describes the interplay between electrons and ions during signal formation in a Micromegas. It introduces SimuMimac, a simulation tool dedicated to high gain detection that agrees with MIMAC measurements. This work proposes an analytical formula to deconvolve the ionic signal induced on the grid from any measurements, with no need for prior nor ad hoc parameter. This deconvolution is experimentally tested and validated, revealing the fine structure of the primary electrons cloud and consequently leading to head-tail recognition in the keV-range. Finally, the article presents how this deconvolution can be used for directionality by reconstructing the spectra of mono-energetic $27~\mathrm{keV}$ and $8~\mathrm{keV}$ neutrons with an angular resolution better than $15^\circ$. This novel approach for directionality appears as complementary to the standard one from 3D tracks reconstruction and offers redundancy for improving directional performances at high gain in the keV region.

physics.ins-det↗

arXiv2021

Solar axions in large extra dimensions

The axion could be used as a probe for extra dimensions. In large extra dimensions, besides the QCD axion one obtains an infinite tower of massive Kaluza-Klein (KK) states. We describe the processes of KK axions production in the Sun via the axion-photon coupling, $g_{aγγ}$, and we derive the number density of KK axions that get trapped into the solar gravitational field and then accumulate over cosmic times. The large multiplicity of states, as well as their masses in the keV-range, deeply alter the phenomenology of the axion. This scenario leads us to propose the presence of KK axions as an interpretation of the non-thermal distribution of the solar X-rays. In this work, we dedicate special attention on the astrophysical and cosmological bounds that apply on the model. In particular, we show how the KK axions may escape the EBL limit that constrains standard ALPs in the same mass range. Present searches for KK axions make use of the decay channel, $a\rightarrowγγ$, for which we revise the event rate; our value lies orders of magnitude below the rate usually quoted in the literature. This major conclusion stems from recent measurements of the luminosity of the quiet Sun which acts as an irreducible limit. The revised model remains a viable and an attractive explanation for multiple astrophysical observations, and we propose several approaches to search for solar KK axions in the near future.

hep-ph↗