Constraints on light singlet fermion interactions from coherent elastic neutrino-nucleus scattering

In this work we study the current bounds from the CEνNS process and meson invisible decays on generic neutrino interactions with sterile neutrinos in effective field theories. The interactions between quarks and left-handed SM neutrinos and/or right-handed neutrinos are first described by the low-energy effective field theory (LNEFT) between the electroweak scale and the chiral symmetry breaking scale. We complete the independent operator basis for the LNEFT up to dimension-6 by including both the lepton-number-conserving (LNC) and lepton-number-violating (LNV) operators involving right-handed neutrinos. We translate the bounds on the LNEFT Wilson coefficients from the COHERENT observation and calculate the branching fractions of light meson invisible decays. The bounds on LNEFT are then mapped onto the SM effective field theory with sterile neutrinos (SMNEFT) to constrain new physics above the electroweak scale. We find that the meson invisible decays can provide the only sensitive probe for τ neutrino flavor component and s quark component in the quark-neutrino interactions involving two (one) active neutrinos and for the effective operators without any active neutrino fields. The CEνNS process places the most stringent bound on all other Wilson coefficients. By assuming one dominant Wilson coefficient at a time in SMNEFT and negligible sterile neutrino mass, the most stringent limits on the new physics scale are 2.7–10 TeV from corresponding dipole operator in LNEFT and 0.5–1.5 TeV from neutrino-quark operator in LNEFT.

Section: Jhep07(2020)152mentioning

confidence: 99%

“…3 Coherent neutrino-nucleus scattering ν N → XN coherent scattering, where X ∈ {ν,ν, N,N } denotes a neutrino, is at leading order given by [9,13]…”

Section: Classmentioning

confidence: 99%

General neutrino interactions with sterile neutrinos in light of coherent neutrino-nucleus scattering and meson invisible decays

Schmidt

2020

“…Note that in order to produce a massive fermion χ in the scattering νN → χN , the energy of the incident neutrinos should be larger than a minimal energy [3,9]…”

Section: Jhep02(2021)099mentioning

confidence: 99%

“…Following ref. [9], we evaluate the statistical significance of BSM by defining 28) where N i meas and N i th denotes the number of measured (predicted) events per energy bin, respectively. α (β) represents the nuisance parameters for the signal rate (the beam- B SS being the steady-state background from the anti-coincident data, and B on the beam-on background mainly consists of prompt neutrons.…”

Section: Jhep02(2021)099mentioning

confidence: 99%

See 1 more Smart Citation

Loop effect in the coherent neutrino-nucleus scattering

Liao

2021

Self Cite

A connection between the neutrino and an exotic fermion is described in the general neutrino model. In this model the neutrinos can convert into the new fermion and thus the interaction leads to novel recoil spectrum in the neutrino scattering experiments. We study the general neutrino interaction by evaluating both the tree-level and loop-level contributions to the coherent elastic neutrino-nucleus scattering. We illustrate the scattering by taking the framework of a simplified neutrino model with a Dirac fermion χ and a spin-0 mediator. For the CP phase in the quark sector being 0 and π/2, the detection processes are dominated by the tree-level and loop-level contribution, respectively. We investigate the constraints on the couplings between the mediator and the new particle χ or the quarks by fitting to the COHERENT data. The parameter space with mχ larger than the maximal energy of incoming neutrinos can be also constrained by including the loop-level contribution.

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

Tomalak

Machado

Pandey

et al. 2021

We calculate coherent elastic neutrino-nucleus scattering cross sections on spin-0 nuclei (e.g. 40Ar and 28Si) 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. Our calculation starts from the four-fermion effective field theory to explicitly separate heavy-particle mediated corrections (which are absorbed by Wilson coefficients) from light-particle contributions. Electrons and muons running in loops introduce a non- trivial dependence on the momentum transfer due to their relatively light masses. These same loops, and those mediated by tau leptons, break the flavor universality because of mass-dependent electromagnetic radiative corrections. Nuclear physics uncertainties significantly cancel in flavor asymmetries resulting in subpercent relative errors. We find that for low neutrino energies, the cross section can be predicted with a relative precision that is competitive with neutrino-electron scattering. We highlight potentially useful applications of such a precise cross section prediction ranging from precision tests of the Standard Model, to searches for new physics and to the monitoring of nuclear reactors.