CP violating effects in coherent elastic neutrino-nucleus scattering processes

Abstract

The presence of new neutrino-quark interactions can enhance, deplete or distort the coherent elastic neutrino-nucleus scattering (CEνNS) event rate. The new interactions may involve CP violating phases that can potentially affect these features. Assuming light vector mediators, we study the effects of CP violation on the CEνNS process in the COHERENT sodium-iodine, liquid argon and germanium detectors. We identify a region in parameter space for which the event rate always involves a dip and another one for which this is never the case. We show that the presence of a dip in the event rate spectrum can be used to constraint CP violating effects, in such a way that the larger the detector volume the tighter the constraints. Furthermore, it allows the reconstruction of the effective coupling responsible for the signal with an uncertainty determined by recoil energy resolution. In the region where no dip is present, we find that CP violating parameters can mimic the Standard Model CEνNS prediction or spectra induced by real parameters. We point out that the interpretation of CEνNS data in terms of a light vector mediator should take into account possible CP violating effects. Finally, we stress that our results are qualitatively applicable for CEνNS induced by solar or reactor neutrinos. Thus, the CP violating effects discussed here and their consequences should be taken into account as well in the analysis of data from multi-ton dark matter detectors or experiments such as CONUS, ν-cleus or CONNIE.

Recent Probes of Standard and Non-standard Neutrino Physics With Nuclei

“…[30,120]). Before closing our discussion it is important to note that, very recently CP violating effects have been also analyzed with the current and future COHERENT data in the context of light vector mediator scenarios [27]. The latter have been also found to be applicable to reactor or solar/atmospheric neutrino searches with important implications on multi-ton dark matter detectors.…”

“…The authors of Ref. [27] demonstrated how the intrinsic nuclear structure uncertainties may have a significant impact to searches beyond the SM such those regarding NSIs, sterile neutrinos and neutrino generalized interactions (GNIs). Starting from the form factor of Eq.…”

“…It is important to notice that theoretically the µ − → e − branching ratio depends on the nuclear form factor which can be probed from CEνNS measurements as discussed in Sect III. For the relevant nuclei such as 27 Al and 48 Ti the nuclear form factors at q ≈ m µ = 0.53 fm −1 have values 0.63 and 0.53 respectively i.e. well far from the approximation of point like nucleus (see Ref.…”

“…[12] for various applications). In particular, the recent works have concentrated on non-standard interactions (NSI) [13][14][15][16][17][18][19], electromagnetic properties [20][21][22][23], sterile neutrinos [24][25][26], CP-violation [27] and novel mediators [28][29][30][31]. Nuclear and atomic effects are explored in Refs.…”

Probing new neutral gauge bosons with CEνNS and neutrino-electron scattering

“…New constraints have been placed on non-standard and generalized interactions [26][27][28][29], nuclear physics parameters [30][31][32], neutrino electromagnetic properties [33,34] and sterile neutrinos [35][36][37]. It has been noted [38][39][40][41][42][43][44][45][46] that light mediators may be accessible to CEνNS experiments, providing information that is complementary to what can be achieved from high-energy and/or precision measurements. Constraints on the Z parameters from CEνNS have been reported in Refs.…”