Dark Matter Searches with DarkSide-20k: Solar Neutrinos and Ar-39 backgrounds

Arguably, one of the most important problems in fundamental physics today concerns the nature of dark matter (DM). The experimental quest for non-gravitational signatures of dark matter has ramped up over the past decades. This contribution will focus on the search for Weakly Interacting Massive Particles (WIMPs) with the DarkSide-20k experiment, the next generation of liquid argon (LAr) dual-phase time projection chamber (TPC), presently in construction at INFN Laboratori Nazionali del Gran Sasso in Italy. The detector is specifically designed for the direct detection of WIMPs with masses exceeding $10\;\rm{GeV}/c^2$. Moreover, as demonstrated with the previous DarkSide-50 detector, the experiment has a significant potential for discovering lighter dark-matter particles $(m_\chi\sim1-10\;\rm{GeV}/c^2)$. The search for low-mass dark matter particles with LAr presents many experimental challenges, such as the loss of background discrimination power, the presence of few-electron events and thus the need to have control over the various background components. Among them, the signals due to solar neutrino interactions and the beta decay of argon-39, an unstable argon isotope, are relevant and must be well characterized. In this contribution, I will discuss the latest calculations of the expected coherent elastic neutrino-nucleus scattering (CE$\nu$NS) and neutrino-electron ($\nu$ES) event rates for the DarkSide-20k searches as well as the importance of reducing the argon-39 content. Finally, perspectives for the measurement of core-collapse supernovae signals in the DarkSide-20k detector will be given.