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First full Dalitz plot measurement in neutron 𝛽 decay using the Nab spectrometer and implications for new physics

Gonzalez, Francisco M. [Oak Ridge National Laboratory] (ORCID:0000000259544155)·Choi, Jin Ha [North Carolina State University; Duke University] (ORCID:0000000237681634)·Acharya, Himal [University of Kentucky] (ORCID:0009000022198511)·Clymer, Skylar [Arizona State University] (ORCID:0009000388774990)·Hagemeier, Andrew [University of Virginia]·Mathews, David G. [Oak Ridge National Laboratory; University of Kentucky] (ORCID:0000000248974379)·Mendelsohn, August [University of Manitoba] (ORCID:0000000248472133)·Nelsen, Austin [University of Kentucky] (ORCID:0000000309130496)·Rahangdale, Hitesh [University of Tennessee] (ORCID:0000000270664318)·Richburg, Love [University of Tennessee] (ORCID:0000000286213036)·Alarcon, Ricardo [Arizona State University] (ORCID:000000027882403X)·Atencio, Ariella [Drexel University] (ORCID:0009000986337467)·Baeßler, Stefan [University of Virginia; Oak Ridge National Laboratory] (ORCID:0000000177329873)·Bailey, Thomas [North Carolina State University; Duke University] (ORCID:0000000179154333)·Barrón Palos, Libertad [Universidad Nacional Autónoma de México] (ORCID:0000000330823676)·Birge, Noah [University of Tennessee] (ORCID:0000000318945494)·Borissenko, Dennis [University of Virginia]·Bowler, Michael [University of Virginia] (ORCID:0000000294685850)·Broussard, Leah J. [Oak Ridge National Laboratory] (ORCID:0000000191822808)·Bryant, Albert T. [University of Virginia]·Caylor, Jimmy [University of Tennessee] (ORCID:0000000324127076)·Chupp, Tim [University of Michigan] (ORCID:0000000162939409)·Crawford, Christopher [University of Kentucky] (ORCID:0000000219324334)·Croley, R. Alston [University of Kentucky] (ORCID:0000000319105382)·Cruz, Micah [University of Tennessee]·Cude-Woods, Chris [North Carolina State University] (ORCID:0000000305578189)·Dodson, George [Massachusetts Institute of Technology] (ORCID:0000000325044862)·Fan, Wenjiang [University of Virginia]·Fellers, Deion [Lawrence Berkeley National Laboratory] (ORCID:0000000207319562)·Fomin, Nadia [University of Tennessee] (ORCID:0000000248373223)·Frlež, Emil [University of Virginia] (ORCID:0000000165333998)·Frost, Matthew [Oak Ridge National Laboratory] (ORCID:000000016821170X)·Fry, Jason [Eastern Kentucky University] (ORCID:0000000304370108)·Fuehne, Duncan [University of Chicago]·Gericke, Michael T. [University of Manitoba] (ORCID:0000000289768192)·Gervais, Michelle [University of Kentucky]·Gilbert, Corey [Oak Ridge National Laboratory] (ORCID:0000000217192171)·Glück, Ferenc [Karlsruhe Institute of Technology] (ORCID:0000000204878289)·Godri, Rebecca [University of Tennessee] (ORCID:000000020904753X)·Greene, Geoff L. [University of Tennessee; Oak Ridge National Laboratory]·Greene, William [University of Tennessee] (ORCID:0000000172312407)·Hamblen, Josh [University of Tennessee at Chattanooga] (ORCID:0009000660211995)·Harmston, Paul [University of Tennessee] (ORCID:0000000287859293)·Harrison, David [University of Manitoba]·Hayen, Leendert [Université de Caen; North Carolina State University] (ORCID:0000000294710964)·Hedinger, Carter [University of Virginia]·Hendrus, Chelsea [University of Michigan] (ORCID:0000000247567317)·Hollander, Sean [Oak Ridge National Laboratory] (ORCID:0009000102732008)·Imam, Kavish [University of Tennessee] (ORCID:0000000194273197)·Iverson, Erik B. [Oak Ridge National Laboratory] (ORCID:000000027920705X)·Jezghani, Aaron [Partnership for an Advanced Computing Environment] (ORCID:0000000243024227)·Jiang, Chenyang [Oak Ridge National Laboratory] (ORCID:0000000263213164)·Klassen, Wolfgang [University of Manitoba] (ORCID:0009000132947771)·Li, Huangxing [University of Virginia] (ORCID:0000000337269663)·Macsai, Nick [University of Manitoba]·Makela, Mark [Los Alamos National Laboratory] (ORCID:0000000305923683)·Mammei, Russell [University of Winnipeg] (ORCID:0009000534814832)·Marshall, Ricky [University of Virginia]·Martinez, Madelyn [Arizona State University]·McCrea, Mark [University of Kentucky] (ORCID:0009000982001472)·McGaughey, Pat [Los Alamos National Laboratory] (ORCID:000000030020716X)·McGovern, Sean [University of Virginia] (ORCID:0000000299027785)·McLaughlin, David [University of Virginia] (ORCID:0000000211357369)·Mirabal, Jacqueline [Los Alamos National Laboratory] (ORCID:0000000165894832)·Mueller, Paul [Oak Ridge National Laboratory] (ORCID:0000000203346889)·Mullins, Andrew [University of Kentucky] (ORCID:0009000208983155)·Musk, William [University of Virginia]·O'Kronley, Jordan [University of Tennessee] (ORCID:0000000175671800)·Penttilä, Seppo I. [Oak Ridge National Laboratory] (ORCID:0000000168881084)·Perryman, D. Elliot [University of Tennessee] (ORCID:0000000176254873)·Pierce, Josh [Oak Ridge National Laboratory] (ORCID:0000000232344989)·Pioquinto, Jason A. [University of Virginia] (ORCID:000000021497336X)·Počanić, Dinko [University of Virginia] (ORCID:0000000256610591)·Presley, Hunter [University of Tennessee] (ORCID:0000000276728052)·Ramsey, John Clinton [Oak Ridge National Laboratory] (ORCID:0000000164913288)·Randall, Glenn [Arizona State University]·Raney, Zachary [University of Virginia]·Ricketts, Jackson [University of Tennessee at Chattanooga]·Riley, Grant [Los Alamos National Laboratory; University of Tennessee] (ORCID:0000000173238448)·Salas-Bacci, Americo [University of Virginia]·Samiei, Sepehr [University of Virginia]·Saunders, Alexander [Oak Ridge National Laboratory] (ORCID:0009000404681410)·Schreyer, Wolfgang [Oak Ridge National Laboratory] (ORCID:0000000324134700)·Scott, E. Mae [University of Tennessee] (ORCID:0000000330911772)·Shelton, Thomas [University of Kentucky] (ORCID:000000032440597X)·Singh, Aryaman [University of Virginia]·Smith, Alexander [University of Virginia]·Smith, Erick [Los Alamos National Laboratory] (ORCID:0000000321525546)·Stevens, Eric [University of Virginia]·Taylor, R. J. [North Carolina State University; Duke University] (ORCID:0000000267067969)·Tinius, Leonard [University of Virginia]·Wallace, Isaiah [University of Tennessee]·Wexler, Jonathan [North Carolina State University; Duke University]·Wilburn, W. Scott [Los Alamos National Laboratory]·Young, A. R. [North Carolina State University; Duke University] (ORCID:0000000273267414)·Zeck, B. [North Carolina State University; Duke University]
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Abstract

Precision measurements of observables in neutron 𝛽 decay are used to test the standard model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accurately reconstruct the proton momentum and electron energy for each 𝛽 decay. This work describes the detection of neutron 𝛽-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron 𝛽 decay for all electrons >100 keV. In addition, new constraints are placed on a possible excited neutron state, hypothesized to explain the disagreement between the appearance and disappearance neutron lifetime techniques.

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73 NUCLEAR PHYSICS AND RADIATION PHYSICSBeta decayNeutron decay timeNeutron physicsNuclear tests of fundamental interactions

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Gonzalez, Francisco M. [Oak Ridge National Laboratory] (ORCID:0000000259544155), Choi, Jin Ha [North Carolina State University; Duke University] (ORCID:0000000237681634), Acharya, Himal [University of Kentucky] (ORCID:0009000022198511), Clymer, Skylar [Arizona State University] (ORCID:0009000388774990), Hagemeier, Andrew [University of Virginia], Mathews, David G. [Oak Ridge National Laboratory; University of Kentucky] (ORCID:0000000248974379), Mendelsohn, August [University of Manitoba] (ORCID:0000000248472133), Nelsen, Austin [University of Kentucky] (ORCID:0000000309130496), Rahangdale, Hitesh [University of Tennessee] (ORCID:0000000270664318), Richburg, Love [University of Tennessee] (ORCID:0000000286213036), Alarcon, Ricardo [Arizona State University] (ORCID:000000027882403X), Atencio, Ariella [Drexel University] (ORCID:0009000986337467), Baeßler, Stefan [University of Virginia; Oak Ridge National Laboratory] (ORCID:0000000177329873), Bailey, Thomas [North Carolina State University; Duke University] (ORCID:0000000179154333), Barrón Palos, Libertad [Universidad Nacional Autónoma de México] (ORCID:0000000330823676), Birge, Noah [University of Tennessee] (ORCID:0000000318945494), Borissenko, Dennis [University of Virginia], Bowler, Michael [University of Virginia] (ORCID:0000000294685850), Broussard, Leah J. [Oak Ridge National Laboratory] (ORCID:0000000191822808), Bryant, Albert T. [University of Virginia], Caylor, Jimmy [University of Tennessee] (ORCID:0000000324127076), Chupp, Tim [University of Michigan] (ORCID:0000000162939409), Crawford, Christopher [University of Kentucky] (ORCID:0000000219324334), Croley, R. Alston [University of Kentucky] (ORCID:0000000319105382), Cruz, Micah [University of Tennessee], Cude-Woods, Chris [North Carolina State University] (ORCID:0000000305578189), Dodson, George [Massachusetts Institute of Technology] (ORCID:0000000325044862), Fan, Wenjiang [University of Virginia], Fellers, Deion [Lawrence Berkeley National Laboratory] (ORCID:0000000207319562), Fomin, Nadia [University of Tennessee] (ORCID:0000000248373223), Frlež, Emil [University of Virginia] (ORCID:0000000165333998), Frost, Matthew [Oak Ridge National Laboratory] (ORCID:000000016821170X), Fry, Jason [Eastern Kentucky University] (ORCID:0000000304370108), Fuehne, Duncan [University of Chicago], Gericke, Michael T. [University of Manitoba] (ORCID:0000000289768192), Gervais, Michelle [University of Kentucky], Gilbert, Corey [Oak Ridge National Laboratory] (ORCID:0000000217192171), Glück, Ferenc [Karlsruhe Institute of Technology] (ORCID:0000000204878289), Godri, Rebecca [University of Tennessee] (ORCID:000000020904753X), Greene, Geoff L. [University of Tennessee; Oak Ridge National Laboratory], Greene, William [University of Tennessee] (ORCID:0000000172312407), Hamblen, Josh [University of Tennessee at Chattanooga] (ORCID:0009000660211995), Harmston, Paul [University of Tennessee] (ORCID:0000000287859293), Harrison, David [University of Manitoba], Hayen, Leendert [Université de Caen; North Carolina State University] (ORCID:0000000294710964), Hedinger, Carter [University of Virginia], Hendrus, Chelsea [University of Michigan] (ORCID:0000000247567317), Hollander, Sean [Oak Ridge National Laboratory] (ORCID:0009000102732008), Imam, Kavish [University of Tennessee] (ORCID:0000000194273197), Iverson, Erik B. [Oak Ridge National Laboratory] (ORCID:000000027920705X), Jezghani, Aaron [Partnership for an Advanced Computing Environment] (ORCID:0000000243024227), Jiang, Chenyang [Oak Ridge National Laboratory] (ORCID:0000000263213164), Klassen, Wolfgang [University of Manitoba] (ORCID:0009000132947771), Li, Huangxing [University of Virginia] (ORCID:0000000337269663), Macsai, Nick [University of Manitoba], Makela, Mark [Los Alamos National Laboratory] (ORCID:0000000305923683), Mammei, Russell [University of Winnipeg] (ORCID:0009000534814832), Marshall, Ricky [University of Virginia], Martinez, Madelyn [Arizona State University], McCrea, Mark [University of Kentucky] (ORCID:0009000982001472), McGaughey, Pat [Los Alamos National Laboratory] (ORCID:000000030020716X), McGovern, Sean [University of Virginia] (ORCID:0000000299027785), McLaughlin, David [University of Virginia] (ORCID:0000000211357369), Mirabal, Jacqueline [Los Alamos National Laboratory] (ORCID:0000000165894832), Mueller, Paul [Oak Ridge National Laboratory] (ORCID:0000000203346889), Mullins, Andrew [University of Kentucky] (ORCID:0009000208983155), Musk, William [University of Virginia], O'Kronley, Jordan [University of Tennessee] (ORCID:0000000175671800), Penttilä, Seppo I. [Oak Ridge National Laboratory] (ORCID:0000000168881084), Perryman, D. Elliot [University of Tennessee] (ORCID:0000000176254873), Pierce, Josh [Oak Ridge National Laboratory] (ORCID:0000000232344989), Pioquinto, Jason A. [University of Virginia] (ORCID:000000021497336X), Počanić, Dinko [University of Virginia] (ORCID:0000000256610591), Presley, Hunter [University of Tennessee] (ORCID:0000000276728052), Ramsey, John Clinton [Oak Ridge National Laboratory] (ORCID:0000000164913288), Randall, Glenn [Arizona State University], Raney, Zachary [University of Virginia], Ricketts, Jackson [University of Tennessee at Chattanooga], Riley, Grant [Los Alamos National Laboratory; University of Tennessee] (ORCID:0000000173238448), Salas-Bacci, Americo [University of Virginia], Samiei, Sepehr [University of Virginia], Saunders, Alexander [Oak Ridge National Laboratory] (ORCID:0009000404681410), Schreyer, Wolfgang [Oak Ridge National Laboratory] (ORCID:0000000324134700), Scott, E. Mae [University of Tennessee] (ORCID:0000000330911772), Shelton, Thomas [University of Kentucky] (ORCID:000000032440597X), Singh, Aryaman [University of Virginia], Smith, Alexander [University of Virginia], Smith, Erick [Los Alamos National Laboratory] (ORCID:0000000321525546), Stevens, Eric [University of Virginia], Taylor, R. J. [North Carolina State University; Duke University] (ORCID:0000000267067969), Tinius, Leonard [University of Virginia], Wallace, Isaiah [University of Tennessee], Wexler, Jonathan [North Carolina State University; Duke University], Wilburn, W. Scott [Los Alamos National Laboratory], Young, A. R. [North Carolina State University; Duke University] (ORCID:0000000273267414), Zeck, B. [North Carolina State University; Duke University]. 2026-03-04. First full Dalitz plot measurement in neutron 𝛽 decay using the Nab spectrometer and implications for new physics. https://doi.org/10.1103/ksmp-zxsl

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