Work

Unfolding the low-energy reactor neutrino flux from CE$ν$NS data with a finite Dirac sum

Year: 2026

Type: preprint

Abstract: We present a novel method to analyze coherent elastic neutrino--nucleus scattering (CE$ν$NS) data to extract the reactor antineutrino spectrum below the inverse beta decay threshold of 1.8 MeV, where it remains unmeasured. Adapting halo-independent analysis techniques developed for direct dark matter detection, we show how to obtain a best-fit and a pointwise confidence band for the integrated neutrino flux, without assuming a parametric form or smoothness prior for the spectrum. In our approach, which follows from convex geometry arguments, the differential neutrino rate is written as a linear combination of Dirac delta functions -- a finite Dirac sum (FDS) -- with a maximum number of terms determined by the number of data points. We apply our "FDS method" to mock CE$ν$NS data for a low-threshold Ge detector and compare it with Tikhonov-regularized unfolding.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2608.16107

Authors: Chen, Muping, Gelmini, Graciela, Marfatia, Danny, Yasuda, Koichiro

Institutions: High Energy Accelerator Research Organization, International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles, University of California, Los Angeles, University of Hawaiʻi at Mānoa

Language: English

Topic: Neutrino Physics Research

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: CERN

OpenAlex ID: W7203716943

Cites: 3

Cited by:

Related to: 10