Probing nonstandard interactions with reactor neutrinos

Abstract

New limits on the weak mixing angle and on the electron neutrino effective charge radius in the low energy regime, below 100 MeV, are obtained from a combined fit of all electron-(anti)neutrino electron elastic scattering measurements. We have included the recent TEXONO measurement with a CsI (Tl) detector. Only statistical error of this measurement has been taken into account. Weak mixing angle is found to be sin 2 θW = 0.255 +0.022 −0.023 . The electron neutrino effective charge radius squared is bounded to be r 2 νe = (0.9 +0.9 −1.0 ) × 10 −32 cm 2 . The sensitivity of future low energy neutrino experiments to nonstandard interactions of neutrinos with quarks is also discussed.

Flavor-dependent radiative corrections in coherent elastic neutrino-nucleus scattering

“…Liquid argon is used as a common liquid noble detector material all of whose stable isotopes ( 40 Ar, 38 Ar, and 36 Ar) are spin-0, and silicon is the main material in Skipper-CCDs [5,19,129,130], two of whose stable isotopes ( 28 Si and 30 Si) are spin-0 and compose 95% of silicon's natural abundance. Moreover, because a detailed understanding of 40 Ar's nuclear physics is essential for the DUNE physics program [131,132], we are optimistic that the theoretical nuclear uncertainties relevant for CEνNS will be steadily improved in coming years.…”

“…An alternative to this is the bottom-up approach based on the extraction of relevant form factors, F ch (Q 2 ) and F W (Q 2 ), directly from experiments. In fact, F ch (Q 2 ) is already well determined with high precision for a number of nuclei [169,170], including 40 Ar [171], through decades of elastic electron scattering experiments. For instance, the charge radius of 208 Pb extracted from experiment is known to about 0.02% precision [169].…”

“…In this section, we evaluate CEνNS cross sections and provide a complete error budget for the case of 40 Ar nucleus. 9 We focus on three benchmark energies relevant for a CEνNS experiment whose neutrino flux is sourced by pion decay at rest (πDAR).…”

“…9 See [183][184][185] for a recent discussion of neutrino neutral-current cross sections on 40 Ar producing an excited state of the nucleus.…”

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We calculate coherent elastic neutrino-nucleus scattering cross sections on spin-0 nuclei (e.g. 40 Ar and 28 Si) at energies below 100 MeV within the Standard Model and account for all effects of permille size. We provide a complete error budget including uncertainties at nuclear, nucleon, hadronic, and quark levels separately as well as perturbative error.

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