Time-reversal violating interactions in hydrogen-like atoms
Figure 1: Matter-antimatter asymmetry.
Mentors:
Wouter Dekens (INSPIRE-HEP, email: wdekens@uw.edu)
Vincenzo Cirigliano (INSPIRE-HEP, email: cirigv@uw.edu)
Prerequisites:
Basic knowledge of quantum mechanics and basic coding skills, which will be refined during the project.
What Students Will Learn:
The student will learn the basics of CP violation in and beyond the Standard Model, and the connection to Electric Dipole Moments. The student will become familiar with so-called Schiff screening [1], an effect that partially screens CP-violating interactions in atoms and molecules, and how to compute the remaining measurable CP-violating effects. Investigating the latter will require the student to compute the wavefunctions of hydrogen-like atoms.
Expected Project Length:
One year
Project Description:
The Standard Model of particle physics (SM) is a very successful theory that has so far passed all experimental tests. However, the theory has a number of shortcomings, among which is its inability to explain the observed asymmetry between matter and antimatter in the universe. Any explanation of this asymmetry has to meet several requirements, the so-called Sakharov conditions, one of which is a need for new interactions that violate charge-parity (CP), or equivalently Time-reversal (T), symmetry. This has motivated a large number of beyond-the- SM (BSM) scenarios that propose new CP-violating interactions, as well as experiments aiming to find signals of them. The most sensitive of these experiments are searches for Electric Dipole Moments (EDMs), especially those using molecular systems, which have seen a rapid improvement in sensitivity in recent years. Although there have also been recent theoretical developments [2, 3, 4], there currently is no description that connects the proposed BSM interactions to EDM measurements in a systematic way. Given the projected improvements on the experimental side, it is becoming more and more important to develop a theoretical description to interpret future EDM searches. As a first step towards this goal, this project will investigate the effects of BSM CP violation in hydrogen-like systems.
References:
[1] L. I. Schiff, Measurability of Nuclear Electric Dipole Moments, Phys. Rev. 132 (1963) 2194–2200.
[2] V. V. Flambaum, M. Pospelov, A. Ritz and Y. V. Stadnik, Sensitivity of EDM experiments in paramagnetic atoms and molecules to hadronic CP violation, Phys. Rev. D 102 (2020) 035001, [arXiv:1912.13129].
[3] H. Mulder, R. Timmermans and J. de Vries, Probing the QCD θ term with paramagnetic molecules, JHEP 07 (2025) 232, [arXiv:2502.06406].
[4] W. Dekens, J. de Vries, L. Gialidi, J. Menéndez, H. Mulder and B. Romeo, Nucleon Electric Dipole Moments in Paramagnetic Molecules through Effective Field Theory, arXiv:2510.14933.