Testing Fundamental QED and BSM Physics Theories in Leptonic and Hadronic Processes

*This Special Issue is dedicated to Dr. Eliahu Comay*

Dear Colleagues,

The aim of this Special Issue is to collect research articles focused on the current and future directions of electro-Weak, strong, and beyond the standard model (SM) Processes. In particular, the recent advances in beta and double beta decay modes, related processes in neutrino-nucleus (neutral current and charged current) reactions, as well as dark matter physics are welcome. Also, we welcome the submission of works focused on precision physics in purely leptonic atoms combined with accurate predictions deriving from advanced solutions of relevant fundamental differential equations.

Today, thanks to accumulated experimental and theoretical experience, it is widely known that a great portion of leptonic and hadronic processes cannot be fully interpreted within the standard model of electro-weak and strong interactions. Experimental verifications point to the necessity of going beyond the SM and investigating BSM processes. Towards achieving this aim, several double beta Decay experiments have taken data with enriched isotopes as the detection medium. The designed experiments plan to use ton-scale detectors of several isotopes and employ various detection techniques. Such experiments require the prediction of nuclear matrix elements with appreciable reliability and accuracy.

We aim for this Special Issue to include the complementary scientific areas of rare electroweak decays, neutrino properties, coherent elastic neutrino-nucleus scattering (CEvNS), and dark matter detection. BSM physics is searched through the lepton flavor violation (LFV) and charged-LFV (cLFV) with powerful probes as μ- to e^±, etc.

This Special Issue invites contributions which focus on precision measurements in purely leptonic atoms as, e.g., the 1S-2S energy interval in the leptonic atom Mu (μ+e-), and the decay of the Ps (e+e-) atom capable of testing discrete symmetries.

Finally, since the wealth of available data in the above physics topics necessitate accurate predictions from physical theories (QED, BSM, etc.) governed by fundamental partial differential equations (PDEs), Schrödinger, Dirac, etc., research works on advanced solutions of these equations (physics-informed neural networks, etc.) are welcome.

Prof. Dr. Theocharis Kosmas
Prof. Dr. Hiroyasu Ejiri
Prof. Dr. John Vergados
Guest Editors

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• standard model of electroweak and strong interactions
• beyond the standard model physics theories
• beta and double beta decay modes
• spectroscopy of purely leptonic atoms
• the positronium as a probe of discrete symmetries
• the muonium bound spectrum (theory and experiments)
• neutral current neutrino-nucleus scattering (coherent and incoherent channel)
• charge changing neutrino nucleus reactions
• direct detection of dark matter
• Physics Informed Neural Networks (PINNs) in Particle Physics