Speaker
Description
Low-energy neutrino-nucleus interactions are entering a precision era in which coherent elastic scattering, charged-current absorption, beta decay and electron capture should be treated as complementary probes of weak nuclear dynamics. CEvNS measures the diagonal neutral-current response of the nucleus and provides an approximately flavor-blind handle on the active neutrino flux. Charged-current absorption, beta decay and electron capture instead probe off-diagonal weak transition densities, with different sensitivity to nuclear structure, lepton wave functions and kinematic kernels.
I will discuss a non-factorized treatment of low-energy weak processes, motivated by recent work on the gallium anomaly, in which nuclear transition densities and lepton wave functions are retained inside the same radial matrix elements. In this framework, detailed balance and contact-limit approximation may fail: beta decay, electron capture and neutrino absorption can weight the same transition density differently, leading to unexpected observable signatures when nuclear dynamics and lepton kinematics are treated as inseparable.
This theoretical issue is becoming experimentally urgent. The SNO+ observation of solar 8B charged-current interactions on 13C, the DEAP-3600 program on 40Ar, and the expanding CEvNS program provide new benchmarks for weak nuclear response in the few-to-tens-of-MeV regime. Beyond its CEvNS measurements, COHERENT has measured charged-current interactions on 127I and neutrino-induced neutrons on Pb, and is developing a broader charged-current and inelastic program on Ar, O, Pb and heavy water.
Together with solar-8B CEvNS measurements in XENONnT, LZ and PandaX-4T, these data can help disentangle fluxes, oscillations and nuclear cross sections. This combined perspective is relevant for solar 8B and hep neutrinos, supernova-neutrino detection, and the control of neutrino backgrounds in future precision experiments.