We propose the possibility of using the near detector at reactor neutrino experiments to probe the renormalization group (RG) running effect on the leptonic Dirac CP phase $\delta_D$. Although the reactor neutrino oscillation cannot directly measure $\delta_D$, it can probe the deviation $\Delta \delta \equiv \delta_D(Q^2_d) - \delta_D(Q^2_p)$ caused by the RG running. Being a key element, the mismatched momentum transfers at neutrino production ($Q^2_p$) and detection ($Q^2_d$) processes can differ by two orders. We illustrate this concept with the upcoming Taishan Antineutrino Observatory (TAO, also known as JUNO-TAO) experiment and obtain the projected sensitivity to the CP RG running beta function $\beta_\delta$.
Categories: hep-ph hep-ex