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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, τ beam n = 888.0(2.0) s, and the more precise average trapped ultracold neutron determination, τ trap n = 879.4(6) s. The second is a 5σ difference between the pre2002 average axial coupling, gA, as measured in neutron decay asymmetries g pre2002 A = 1.2637(21), and the more recent, post2002, average g post2002 A = 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 τ n and g A values using a (slightly) updated relation τ n(1+3g 2 A) = 5172.0(1.1) s. Consistency with that relation and better precision suggest τ favored n = 879.4(6) s and g favored A = 1.2755(11) as preferred values for those parameters. Comparisons of g favored A 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:
 [1];  [2];  [3]
  1. Univ. of Alberta, Edmonton, AB (Canada)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. New York Univ., New York, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1437339
Alternate Identifier(s):
OSTI ID: 1439292
Report Number(s):
BNL-205699-2018-JAAM
Journal ID: ISSN 0031-9007; PRLTAO
Grant/Contract Number:  
SC0012704
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 120; Journal Issue: 20; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
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. doi:10.1103/PhysRevLett.120.202002.
Czarnecki, Andrzej, Marciano, William J., and Sirlin, Alberto. Wed . "Neutron Lifetime and Axial Coupling Connection". United States. doi: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},
journal = {Physical Review Letters},
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 10.1103/PhysRevLett.120.202002

Citation Metrics:
Cited by: 4 works
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