Neutrino Constraints and the ATOMKI X17 Anomaly

Article
Report number	arXiv:2304.09877 ; CERN-TH-2023-053
Title	Neutrino Constraints and the ATOMKI X17 Anomaly
Author(s)	Denton, Peter B. (Brookhaven Natl. Lab.) ; Gehrlein, Julia (CERN)
Publication	2023-07-01
Imprint	2023-04-19
Number of pages	11
In:	Phys. Rev. D 108 (2023) 015009
DOI	10.1103/PhysRevD.108.015009 (publication)
Subject category	hep-ph ; Particle Physics - Phenomenology
Abstract	Recent data from the ATOMKI group continues to confirm their claim of the existence of a new $\sim17$ MeV particle. We review and numerically analyze the data and then put into context constraints from other experiments, notably neutrino scattering experiments such as the latest reactor anti-neutrino coherent elastic neutrino nucleus scattering data and unitarity constraints from solar neutrino observations. We show that minimal scenarios are disfavored and discuss the model requirements to evade these constraints.
Copyright/License	publication: © 2023-2024 authors (License: CC BY 4.0), sponsored by SCOAP³ preprint: (License: CC BY 4.0)

$Measured opening angles of the $e^+e^-$ pairs using the mass differences between different excited states and the ground state of He (blue), Be (orange), C (green). We show contours of different $m_X$ using the relation $\theta_{e^+e^-}^{\text{min}}\approx 2\arcsin(m_x/(m_{N^*}-m_N))$ \cite{Feng:2020mbt}.$ $The parameter estimation at 1, 2, 3$\sigma$ of $m_X$, $\varepsilon_n$, and $\varepsilon_p$ using 11 separate angular measurements and the three latest width measurements from ATOMKI in addition to a prior on $\varepsilon_p$ from $\pi^0\to\gamma X$ constraints for three separate treatments of the Be nuclear physics: no isospin effects (top left), isospin mixing (top right), and both isosopin mixing and breaking (bottom). The not shown parameter is minimized over in each panel. The colors correspond to the preferred parameters from individual ATOMKI measurements and the black curves are the result of the combined fit. We assume that BR($X\to e^+e^-$)${}=1$.$ $The parameter estimation at 1, 2, 3$\sigma$ of $m_X$, $\varepsilon_n$, and $\varepsilon_p$ using 11 separate angular measurements and the three latest width measurements from ATOMKI in addition to a prior on $\varepsilon_p$ from $\pi^0\to\gamma X$ constraints. The single ellipses on the left two panels are the $3\sigma$ ellipses. The not shown parameter is minimized over in each panel. The colors correspond to the preferred parameters from individual ATOMKI measurements and the black curves are the result of the combined fit. The red cross shows the SM value of $\varepsilon_{n,p}=0$. We assume that BR($X\to e^+e^-$)${}=1$. The data prefers $m_X=16.83$ MeV, $\varepsilon_n=\pm0.0058$, and $\varepsilon_p=\pm0.0024$ (correlated signs), and has only a modest internal tension at the $2.9\sigma$ level ($\Delta\chi^2/dof=27.9/11$).$ Show more plots

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記錄創建於2023-04-22，最後更新在2023-07-13

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