Relativistic impulse approximation in the atomic ionization process induced by millicharged particles

Area of Science:

• Particle Physics
• Beyond Standard Model Physics
• Direct Detection Experiments

Background:

• Millicharged particles are key to exploring physics beyond the Standard Model.
• Atomic ionization processes offer a method to constrain millicharged particle parameters in direct detection experiments.

Purpose of the Study:

• To develop and apply the relativistic impulse approximation (RIA) for atomic ionization by millicharged particles.
• To investigate atomic ionizations induced by millicharged dark matter and neutrinos in High-Purity Germanium (HPGe) and Liquid Xenon (LXe) detectors.

Main Methods:

• Formulation and derivation of the relativistic impulse approximation (RIA) for millicharged particle-induced atomic ionization.
• Numerical calculations and comparisons with Free Electron Approximation (FEA) and Equivalent Photon Approximation (EPA).
• Estimation of differential cross sections, reaction event rates, and detection sensitivities in HPGe and LXe detectors.

Main Results:

• The relativistic impulse approximation (RIA) effectively accounts for atomic many-body effects.
• Next-generation experiments are predicted to enhance sensitivity to dark matter particle millicharge by 2-3 orders of magnitude.
• Sensitivity to neutrino millicharge is expected to improve by a factor of 2-3 in future experiments.

Conclusions:

• The developed RIA approach provides a robust framework for studying millicharged particle interactions.
• Next-generation HPGe and LXe experiments hold significant potential for advancing the search for millicharged dark matter and neutrinos.
• This work establishes new benchmarks for constraining millicharge parameters in beyond Standard Model physics searches.