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Title: Can nuclear physics explain the anomaly observed in the internal pair production in the Beryllium-8 nucleus?

Abstract

Recently the experimentalists in Krasznahorkay (2016) [1] announced observing an unexpected enhancement of the – pair production signal in one of the 8Be nuclear transitions. The subsequent studies have been focused on possible explanations based on introducing new types of particle. In this work, we improve the nuclear physics modeling of the reaction by studying the pair emission anisotropy and the interferences between different multipoles in an effective field theory inspired framework, and examine their possible relevance to the anomaly. The connection between the previously measured on-shell photon production and the pair production in the same nuclear transitions is established. These improvements, absent in the original experimental analysis, should be included in extracting new particle's properties from the experiment of this type. However, the improvements can not explain the anomaly. We then explore the nuclear transition form factor as a possible origin of the anomaly, and find the required form factor to be unrealistic for the 8Be nucleus. The reduction of the anomaly's significance by simply rescaling our predicted event count is also investigated.

Authors:
ORCiD logo [1];  [1]
  1. Univ. of Washington, Seattle, WA (United States)
Publication Date:
Research Org.:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1437722
Alternate Identifier(s):
OSTI ID: 1499270
Grant/Contract Number:  
FG02-97ER41014; FG02-97ER-41014
Resource Type:
Published Article
Journal Name:
Physics Letters B
Additional Journal Information:
Journal Volume: 773; Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Zhang, Xilin, and Miller, Gerald A. Can nuclear physics explain the anomaly observed in the internal pair production in the Beryllium-8 nucleus?. United States: N. p., 2017. Web. doi:10.1016/j.physletb.2017.08.013.
Zhang, Xilin, & Miller, Gerald A. Can nuclear physics explain the anomaly observed in the internal pair production in the Beryllium-8 nucleus?. United States. https://doi.org/10.1016/j.physletb.2017.08.013
Zhang, Xilin, and Miller, Gerald A. Wed . "Can nuclear physics explain the anomaly observed in the internal pair production in the Beryllium-8 nucleus?". United States. https://doi.org/10.1016/j.physletb.2017.08.013.
@article{osti_1437722,
title = {Can nuclear physics explain the anomaly observed in the internal pair production in the Beryllium-8 nucleus?},
author = {Zhang, Xilin and Miller, Gerald A.},
abstractNote = {Recently the experimentalists in Krasznahorkay (2016) [1] announced observing an unexpected enhancement of the – pair production signal in one of the 8Be nuclear transitions. The subsequent studies have been focused on possible explanations based on introducing new types of particle. In this work, we improve the nuclear physics modeling of the reaction by studying the pair emission anisotropy and the interferences between different multipoles in an effective field theory inspired framework, and examine their possible relevance to the anomaly. The connection between the previously measured on-shell photon production and the pair production in the same nuclear transitions is established. These improvements, absent in the original experimental analysis, should be included in extracting new particle's properties from the experiment of this type. However, the improvements can not explain the anomaly. We then explore the nuclear transition form factor as a possible origin of the anomaly, and find the required form factor to be unrealistic for the 8Be nucleus. The reduction of the anomaly's significance by simply rescaling our predicted event count is also investigated.},
doi = {10.1016/j.physletb.2017.08.013},
journal = {Physics Letters B},
number = C,
volume = 773,
place = {United States},
year = {2017},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1016/j.physletb.2017.08.013

Citation Metrics:
Cited by: 38 works
Citation information provided by
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Figures / Tables:

Fig. 1. Fig. 1. : The top shows the kinematics for the $e$+–$e$ pair production as well as the photon production (without the lepton line). The bottom plots the allowed phase space (shaded area) in terms of $M$+− and cos $θ$+− assuming $m$e = 0.

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Works referenced in this record:

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Works referencing / citing this record:

New results on the 8 Be anomaly
journal, July 2018


New physics via pion capture and simple nuclear reactions
journal, November 2019


X(16.7) production in electron–positron collision
journal, June 2018


Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN
text, January 2018


Dark forces coupled to non-conserved currents
text, January 2017


Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN
text, January 2018


New physics via pion capture and simple nuclear reactions
text, January 2019