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Title: Neutron Lifetime and Axial Coupling Connection

Abstract

Here, experimental studies of neutron decay, n→pe¯ν, exhibit two anomalies. The first is a 8.6(2.1) s, roughly 4σ difference between the average beam measured neutron lifetime, τbeamn = 888.0(2.0) s, and the more precise average trapped ultracold neutron determination, τtrapn = 879.4(6) s. The second is a 5σ difference between the pre2002 average axial coupling, gA, as measured in neutron decay asymmetries gpre2002A = 1.2637(21), and the more recent, post2002, average gpost2002A = 1.2755(11), where, following the UCNA Collaboration division, experiments are classified by the date of their most recent result. In this Letter, we correlate those τn and gA values using a (slightly) updated relation τn(1+3g2A) = 5172.0(1.1) s. Consistency with that relation and better precision suggest τfavoredn = 879.4(6) s and gfavoredA = 1.2755(11) as preferred values for those parameters. Comparisons of gfavoredA with recent lattice QCD and muonic hydrogen capture results are made. A general constraint on exotic neutron decay branching ratios, <0.27%, is discussed and applied to a recently proposed solution to the neutron lifetime puzzle.

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP)
OSTI Identifier:
1437339
Alternate Identifier(s):
OSTI ID: 1439292
Report Number(s):
BNL-205699-2018-JAAM
Journal ID: ISSN 0031-9007; PRLTAO; 202002
Grant/Contract Number:  
SC0012704
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Name: Physical Review Letters Journal Volume: 120 Journal Issue: 20; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; neutron; anomalies; decay; asymmetry; coupling; PDG; cosmology; axial; astrophysics; particle physics

Citation Formats

Czarnecki, Andrzej, Marciano, William J., and Sirlin, Alberto. Neutron Lifetime and Axial Coupling Connection. United States: N. p., 2018. Web. doi:10.1103/PhysRevLett.120.202002.
Czarnecki, Andrzej, Marciano, William J., & Sirlin, Alberto. Neutron Lifetime and Axial Coupling Connection. United States. https://doi.org/10.1103/PhysRevLett.120.202002
Czarnecki, Andrzej, Marciano, William J., and Sirlin, Alberto. 2018. "Neutron Lifetime and Axial Coupling Connection". United States. https://doi.org/10.1103/PhysRevLett.120.202002.
@article{osti_1437339,
title = {Neutron Lifetime and Axial Coupling Connection},
author = {Czarnecki, Andrzej and Marciano, William J. and Sirlin, Alberto},
abstractNote = {Here, experimental studies of neutron decay, n→pe¯ν, exhibit two anomalies. The first is a 8.6(2.1) s, roughly 4σ difference between the average beam measured neutron lifetime, τbeamn = 888.0(2.0) s, and the more precise average trapped ultracold neutron determination, τtrapn = 879.4(6) s. The second is a 5σ difference between the pre2002 average axial coupling, gA, as measured in neutron decay asymmetries gpre2002A = 1.2637(21), and the more recent, post2002, average gpost2002A = 1.2755(11), where, following the UCNA Collaboration division, experiments are classified by the date of their most recent result. In this Letter, we correlate those τn and gA values using a (slightly) updated relation τn(1+3g2A) = 5172.0(1.1) s. Consistency with that relation and better precision suggest τfavoredn = 879.4(6) s and gfavoredA = 1.2755(11) as preferred values for those parameters. Comparisons of gfavoredA with recent lattice QCD and muonic hydrogen capture results are made. A general constraint on exotic neutron decay branching ratios, <0.27%, is discussed and applied to a recently proposed solution to the neutron lifetime puzzle.},
doi = {10.1103/PhysRevLett.120.202002},
url = {https://www.osti.gov/biblio/1437339}, journal = {Physical Review Letters},
issn = {0031-9007},
number = 20,
volume = 120,
place = {United States},
year = {Wed May 16 00:00:00 EDT 2018},
month = {Wed May 16 00:00:00 EDT 2018}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1103/PhysRevLett.120.202002

Citation Metrics:
Cited by: 76 works
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Figures / Tables:

Table I Table I: Input data used for the τ$$trap\atop{n}$$ , τ$$beam\atop{n}$$ , g$$post2002\atop{A}$$ and g$$pre2002\atop{A}$$ averages. Values and methodology were based on PDG2016 but with updates from [12–15]. The error in τ$$trap\atop{n}$$ average was scaled by a factor of 1.5 in accordance with PDG protocol. Statistical and systematic uncertainties were addedmore » in quadrature and kept to two significant figures before averaging. Averages have not been sanctioned by the PDG.« less

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Works referencing / citing this record:

Neutron lifetime puzzle and neutron–mirror neutron oscillation
journal, June 2019


Neutron lifetime puzzle and neutron–mirror neutron oscillation
journal, June 2019


NoMoS: An R×B drift momentum spectrometer for beta decay studies
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Neutron disappearance inside the nucleus
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The neutron lifetime anomaly and charge exchange collisions of trapped protons
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Nucleon axial radius and muonic hydrogen—a new analysis and review
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Big-Bang Nucleosynthesis after Planck
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Neutron Star Stability in Light of the Neutron Decay Anomaly
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Figures / Tables found in this record:

Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.