Sensitivities to neutrino electromagnetic properties at the TEXONO experiment

Abstract

The possibility of measuring neutral-current coherent elastic neutrino-nucleus scattering (CENNS) at the TEXONO experiment has opened high expectations towards probing exotic neutrino properties. Focusing on low threshold Germanium-based targets with kg-scale mass, we find a remarkable efficiency not only for detecting CENNS events due to the weak interaction, but also for probing novel electromagnetic neutrino interactions. Specifically, we demonstrate that such experiments are complementary in performing precision Standard Model tests as well as in shedding light on sub-leading effects due to neutrino magnetic moment and neutrino charge radius. This work employs realistic nuclear structure calculations based on the quasi-particle random phase approximation (QRPA) and takes into consideration the crucial quenching effect corrections. Such a treatment, in conjunction with a simple statistical analysis, shows that the attainable sensitivities are improved by one order of magnitude as compared to previous studies.

COHERENT constraints to conventional and exotic neutrino physics

“…An improved determination of the weak mixing angle as well as stronger constraints on NSI and sterile neutrino parameters are expected after the upgrade of the CO-HERENT program with ton-scale detectors [32], while the advanced ultra low-threshold technologies being developed may provide more severe constraints on neutrino EM properties, complementary to existing neutrinoelectron data. Further improvements on the current limits are expected in the next phase of the COHERENT program for both Z and φ mediator fields, enabling validation of the neutrino-floor and detector-response models relevant to DM searches, while Z can be subject to other low-energy constraints such as atomic parity violation and neutrino-electron scattering [70].…”

“…The measurement of CEνNS is widely considered as an important tool for testing fundamental parameters in the electroweak sector at low energies [31,32,43]. At this stage, we are interested in extracting constraints on the weak mixing angle from the recent COHERENT data through a pull test.…”

Updating neutrino magnetic moment constraints

“…Indeed, different experiments have set constraints coming mainly from reactor neutrino studies [22,23] as well as from solar neutrino data [16,17]. Future tests from experiments measuring coherent neutrino-nucleus scattering are expected to improve the current bounds on neutrino electromagnetic properties [24][25][26][27][28]. Most of the constraints reported by the experiments refer to the case of a Dirac neutrino magnetic moment, despite the fact that Majorana neutrinos are better motivated from the theoretical point of view [29].…”

Revisiting large neutrino magnetic moments

“…Therefore the above estimate shows that generating large NMM while simultaneously keeping the radiative mass correction δm ν low, requires a significant amount of fine-tuning. To reach values µ ν 10 −12 µ B , which will be probed in future experiments [10][11][12][13], fine-tuning of seven orders of magnitude is required.…”