2024/10/24 by Ghosh, Mitrajyoti, Grossman, Yuval, Sieng, Chinhsan +1 · 4 citations
#Atomic Physics (physics.atom-ph) #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2410.19059
The Standard Model predicts a long-range force mediated by a pair of neutrinos, known as ``the neutrino force". It scales as GF2/r5, where GF is the Fermi constant. However, as r \lesssim √(GF), the four-Fermi theory breaks down and the neutrino force no longer has the 1/r5 scaling. For the first time, we derive a complete expression for the neutrino force that is valid at all distances. For r ≫ √(GF), the result reduces to the known GF2/r5; for r ≪ √(GF), it scales as 1/r. We explore the implications of this result for atomic parity violation (APV) experiments. A key feature of the neutrino force is that it is a long-range effect compared to the atomic length scale. Thus, in general, it cannot be simply treated as a correction to the tree-level Z-exchange diagram without considering the atomic wavefunctions. We calculate the effects in muonium and positronium, finding that the neutrino force contributes about 4% and 16%, respectively, compared to the leading Z exchange. This indicates a significant impact on APV, with important implications for detecting the neutrino force and measuring the weak mixing angle in APV experiments.