Impact of form factor uncertainties on interpretations of coherent elastic neutrino-nucleus scattering data

Abstract

The standard model coherent elastic neutrino-nucleus scattering (CEνNS) cross section is subject to nuclear form factor uncertainties, mainly driven by the root-mean-square radius of the neutron density distribution. Motivated by COHERENT phases I-III and future multi-ton direct detection dark matter searches, we evaluate these uncertainties in cesium iodide, germanium, xenon and argon detectors. We find that the uncertainties become relevant for momentum transfers q 20 MeV and are essentially independent of the form factor parameterization. Consequently, form factor uncertainties are not important for CEνNS induced by reactor or solar neutrinos. Taking into account these uncertainties, we then evaluate their impact on measurements of CEνNS at COHERENT, the diffuse supernova background (DSNB) neutrinos and sub-GeV atmospheric neutrinos. We also calculate the relative uncertainties in the number of COHERENT events for different nuclei as a function of recoil energy. For DSNB and atmospheric neutrinos, event rates at a liquid argon detector can be uncertain to more than 5%. Finally, we consider the impact of form factor uncertainties on searches for nonstandard neutrino interactions, sterile neutrinos and neutrino generalized interactions. We point out that studies of new physics using CEνNS data are affected by neutron form factor uncertainties, which if not properly taken into account may lead to the misidentification of new physics signals. The uncertainties quantified here are also relevant for dark matter direct detection searches. * daristizabal@ulg.ac.be †

Nuclear structure uncertainties in coherent elastic neutrino-nucleus scattering

“…These changes of the neutrino energy distributions produce effects of about 10%, at least one order of magnitude larger than those induced by the nuclear structure uncertainties. Our results agree with those obtained using other simpler, analytical, nucleon densities and/or form factors [25,47].…”

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

“…The uncertainties of the nuclear form factors are explored in Ref. [35] where it is pointed out that studies looking for physics beyond the SM can be seriously affected by the uncertainty of the neutron form factor [80]. It is therefore important to treat with special care the nuclear form factors since new physics could be claimed or missed, if their uncertainties are not properly taken into account.…”

“…Future precision measurements at such rare-event facilities may become sensitive to nuclear structure effects which in principle can be explored by experiments looking for CEνNS. Therefore precise information on the nuclear form factors becomes very relevant for DM detectors especially for those involving multi-ton mass scale [35]. For example, alterations are expected at high recoil energies of neutrino-induced interactions at direct DM detection searches [39] which on the other hand may be limited by the current uncertainties of the Atmospheric and DSNB neutrinos.…”

New physics from COHERENT data with an improved quenching factor

“…[38] was R n = 5.5 +0.9 −1.1 fm, which is consistent within 1σ. One can show that the small difference arises from different form factors [20]. However, the significant contribution is still caused by the improved QF.…”