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Ma PX, Feng X, Gorchtein M, Jin LC, Liu KF, Seng CY, Wang BG, Zhang ZL. Lattice QCD Calculation of Electroweak Box Contributions to Superallowed Nuclear and Neutron Beta Decays. PHYSICAL REVIEW LETTERS 2024; 132:191901. [PMID: 38804936 DOI: 10.1103/physrevlett.132.191901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/23/2024] [Accepted: 04/16/2024] [Indexed: 05/29/2024]
Abstract
We present the first lattice QCD calculation of the universal axial γW-box contribution □_{γW}^{VA} to both superallowed nuclear and neutron beta decays. This contribution emerges as a significant component within the theoretical uncertainties surrounding the extraction of |V_{ud}| from superallowed decays. Our calculation is conducted using two domain wall fermion ensembles at the physical pion mass. To construct the nucleon four-point correlation functions, we employ the random sparsening field technique. Furthermore, we incorporate long-distance contributions to the hadronic function using the infinite-volume reconstruction method. Upon performing the continuum extrapolation, we arrive at □_{γW}^{VA}=3.65(7)_{lat}(1)_{PT}×10^{-3}. Consequently, this yields a slightly higher value of |V_{ud}|=0.973 86(11)_{exp}(9)_{RC}(27)_{NS}, reducing the previous 2.1σ tension with the CKM unitarity to 1.8σ. Additionally, we calculate the vector γW-box contribution to the axial charge g_{A}, denoted as □_{γW}^{VV}, and explore its potential implications.
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Affiliation(s)
- Peng-Xiang Ma
- School of Physics, Peking University, Beijing 100871, China
| | - Xu Feng
- School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Center for High Energy Physics, Peking University, Beijing 100871, China
| | - Mikhail Gorchtein
- Institut für Kernphysik, Johannes Gutenberg-Universität, J.J. Becher-Weg 45, 55128 Mainz, Germany
- PRISMA+ Cluster of Excellence, Johannes Gutenberg-Universität, Mainz, Germany
| | - Lu-Chang Jin
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
- RIKEN-BNL Research Center, Brookhaven National Laboratory, Building 510, Upton, New York 11973
| | - Keh-Fei Liu
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Chien-Yeah Seng
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Bi-Geng Wang
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Plattner P, Wood E, Al Ayoubi L, Beliuskina O, Bissell ML, Blaum K, Campbell P, Cheal B, de Groote RP, Devlin CS, Eronen T, Filippin L, Garcia Ruiz RF, Ge Z, Geldhof S, Gins W, Godefroid M, Heylen H, Hukkanen M, Imgram P, Jaries A, Jokinen A, Kanellakopoulos A, Kankainen A, Kaufmann S, König K, Koszorús Á, Kujanpää S, Lechner S, Malbrunot-Ettenauer S, Müller P, Mathieson R, Moore I, Nörtershäuser W, Nesterenko D, Neugart R, Neyens G, Ortiz-Cortes A, Penttilä H, Pohjalainen I, Raggio A, Reponen M, Rinta-Antila S, Rodríguez LV, Romero J, Sánchez R, Sommer F, Stryjczyk M, Virtanen V, Xie L, Xu ZY, Yang XF, Yordanov DT. Nuclear Charge Radius of ^{26m}Al and Its Implication for V_{ud} in the Quark Mixing Matrix. PHYSICAL REVIEW LETTERS 2023; 131:222502. [PMID: 38101341 DOI: 10.1103/physrevlett.131.222502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/09/2023] [Indexed: 12/17/2023]
Abstract
Collinear laser spectroscopy was performed on the isomer of the aluminium isotope ^{26m}Al. The measured isotope shift to ^{27}Al in the 3s^{2}3p ^{2}P_{3/2}^{○}→3s^{2}4s ^{2}S_{1/2} atomic transition enabled the first experimental determination of the nuclear charge radius of ^{26m}Al, resulting in R_{c}=3.130(15) fm. This differs by 4.5 standard deviations from the extrapolated value used to calculate the isospin-symmetry breaking corrections in the superallowed β decay of ^{26m}Al. Its corrected Ft value, important for the estimation of V_{ud} in the Cabibbo-Kobayashi-Maskawa matrix, is thus shifted by 1 standard deviation to 3071.4(1.0) s.
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Affiliation(s)
- P Plattner
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- Universität Innsbruck, Innrain 52, 6020 Innsbruck, Austria
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - E Wood
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - L Al Ayoubi
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - O Beliuskina
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - M L Bissell
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - K Blaum
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - P Campbell
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - B Cheal
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - R P de Groote
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - C S Devlin
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - T Eronen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - L Filippin
- Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), Université libre de Bruxelles, 1050 Brussels, Belgium
| | - R F Garcia Ruiz
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, USA
| | - Z Ge
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - S Geldhof
- Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
| | - W Gins
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - M Godefroid
- Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), Université libre de Bruxelles, 1050 Brussels, Belgium
| | - H Heylen
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - M Hukkanen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - P Imgram
- Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
| | - A Jaries
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - A Jokinen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - A Kanellakopoulos
- Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
| | - A Kankainen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - S Kaufmann
- Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
| | - K König
- Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
| | - Á Koszorús
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
- Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
| | - S Kujanpää
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - S Lechner
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
| | - S Malbrunot-Ettenauer
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - P Müller
- Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
| | - R Mathieson
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - I Moore
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - W Nörtershäuser
- Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
| | - D Nesterenko
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - R Neugart
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
- Institut für Kernchemie, Universität Mainz, Fritz-Straßmann-Weg 2, 55128 Mainz, Germany
| | - G Neyens
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
| | - A Ortiz-Cortes
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - H Penttilä
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - I Pohjalainen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - A Raggio
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - M Reponen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - S Rinta-Antila
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - L V Rodríguez
- ISOLDE, CERN Experimental Physics Department, Geneva 23, 1211 Genevè, Switzerland
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
- IJCLab, CNRS/IN2P3, Université Paris-Saclay, 91400 Orsay, France
| | - J Romero
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - R Sánchez
- GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany
| | - F Sommer
- Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
| | - M Stryjczyk
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - V Virtanen
- Department of Physics, University of Jyväskylä, P.O. Box 35 FI-40014, Jyväskylä, Finland
| | - L Xie
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Z Y Xu
- Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
| | - X F Yang
- Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
- School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, 209 Chengfu Road, 100871 Beijing, China
| | - D T Yordanov
- IJCLab, CNRS/IN2P3, Université Paris-Saclay, 91400 Orsay, France
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Seng CY. Model-Independent Determination of Nuclear Weak Form Factors and Implications for Standard Model Precision Tests. PHYSICAL REVIEW LETTERS 2023; 130:152501. [PMID: 37115885 DOI: 10.1103/physrevlett.130.152501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/22/2023] [Indexed: 06/19/2023]
Abstract
We analyze the recoil corrections in superallowed beta decays of T=1, J^{P}=0^{+} nuclei by fixing the mean square charged weak radius model independently using the data of multiple charge radii across the nuclear isotriplet. By comparing to model estimations, we argue that the existing theory uncertainty in the statistical rate function f might have been substantially underestimated. We discuss the implications of our proposed strategy for precision tests of the standard model, including a potential alleviation of the first-row CKM unitarity deficit, and motivate new experiments for charge radii measurements.
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Affiliation(s)
- Chien-Yeah Seng
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA and Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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4
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New UTfit analysis of the unitarity triangle in the Cabibbo–Kobayashi–Maskawa scheme. RENDICONTI LINCEI. SCIENZE FISICHE E NATURALI 2023. [DOI: 10.1007/s12210-023-01137-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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5
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Cirigliano V, de Vries J, Hayen L, Mereghetti E, Walker-Loud A. Pion-Induced Radiative Corrections to Neutron β Decay. PHYSICAL REVIEW LETTERS 2022; 129:121801. [PMID: 36179200 DOI: 10.1103/physrevlett.129.121801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/10/2022] [Accepted: 08/03/2022] [Indexed: 06/16/2023]
Abstract
We compute the electromagnetic corrections to neutron β decay using a low-energy hadronic effective field theory. We identify new radiative corrections arising from virtual pions that were missed in previous studies. The largest correction is a percent-level shift in the axial charge of the nucleon proportional to the electromagnetic part of the pion-mass splitting. Smaller corrections, comparable to anticipated experimental precision, impact the β-ν angular correlations and the β asymmetry. We comment on implications of our results for the comparison of the experimentally measured nucleon axial charge with first-principles computations using lattice QCD and on the potential of β decay experiments to constrain beyond-the-standard-model interactions.
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Affiliation(s)
- Vincenzo Cirigliano
- Los Alamos National Laboratory, Theoretical Division T-2, Los Alamos, New Mexico 87545, USA
- Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550, USA
| | - Jordy de Vries
- Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
- Nikhef, Theory Group, Science Park 105, 1098 XG Amsterdam, Netherlands
| | - Leendert Hayen
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - Emanuele Mereghetti
- Los Alamos National Laboratory, Theoretical Division T-2, Los Alamos, New Mexico 87545, USA
| | - André Walker-Loud
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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6
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Suh JM, Jun YS, Kim HC. Axial-vector transition form factors of the baryon octet to the baryon decuplet with flavor SU(3) symmetry breaking. Int J Clin Exp Med 2022. [DOI: 10.1103/physrevd.105.114040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Kotwal AV, Matias J, Mauri A, Tong T, Varnhorst L. Round table on Standard Model Anomalies. EPJ WEB OF CONFERENCES 2022. [DOI: 10.1051/epjconf/202227401006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This contribution to “The XVth Quark confinement and the Hadron spectrum conference" covers a description, both theoretical and experimental, of the present status of a set of very different anomalies. The discussion ranges from the long standing b → sℓℓ anomalies, (g − 2) and the new MW anomaly.
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Chen S, Olsen SL. New physics searches at the BESIII experiment. Natl Sci Rev 2021; 8:nwab189. [PMID: 35382348 PMCID: PMC8972910 DOI: 10.1093/nsr/nwab189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 11/17/2022] Open
Abstract
The standard model (SM) of particle physics, comprised of the unified electroweak and
quantum chromodynamic theories, accurately explains almost all experimental results
related to the micro-world, and has made a number of predictions for previously unseen
particles, most notably the Higgs scalar boson, that were subsequently discovered. As a
result, the SM is currently universally accepted as the theory of the fundamental
particles and their interactions. However, in spite of its numerous successes, the SM has
a number of apparent shortcomings, including: many free parameters that must be supplied
by experimental measurements; no mechanism to produce the dominance of matter over
antimatter in the universe; and no explanations for gravity, the dark matter in the
universe, neutrino masses, the number of particle generations, etc. Because of these
shortcomings, there is considerable incentive to search for evidence for new, non-SM
physics phenomena that might provide important clues about what a new, beyond the SM
theory (BSM) might look like. Although the center-of-mass energies that BESIII can access
are far below the energy frontier, searches for new, BSM physics are an important
component of its research program. This report reviews some of the highlights from
BESIII’s searches for signs of new, BSM physics by: measuring rates for processes that the
SM predicts to be forbidden or very rare; searching for non-SM particles such as dark
photons; performing precision tests of SM predictions; and looking for violations of the
discrete symmetries C and CP in processes for which the
SM expectations are immeasurably small.
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Affiliation(s)
- Shenjian Chen
- School of Physics, Nanjing University, Nanjing 210093, China
- Nanjing Proton Source Research and Design Center, Nanjing 210093, China
| | - Stephen Lars Olsen
- University of Chinese Academy of Sciences, Beijing 100049, China
- Institute for Basic Science, Daejeon 34126, South Korea
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Crivellin A, Hoferichter M, Manzari CA. Fermi Constant from Muon Decay Versus Electroweak Fits and Cabibbo-Kobayashi-Maskawa Unitarity. PHYSICAL REVIEW LETTERS 2021; 127:071801. [PMID: 34459644 DOI: 10.1103/physrevlett.127.071801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
The Fermi constant G_{F} is extremely well measured through the muon lifetime, defining one of the key fundamental parameters in the standard model (SM). Therefore, to search for physics beyond the SM (BSM) via G_{F}, the constraining power is determined by the precision of the second-best independent determination of G_{F}. The best alternative extractions of G_{F} proceed either via the global electroweak (EW) fit or from superallowed β decays in combination with the Cabibbo angle measured in kaon, τ, or D decays. Both variants display some tension with G_{F} from muon decay, albeit in opposite directions, reflecting the known tensions within the EW fit and hints for the apparent violation of Cabibbo-Kobayashi-Maskawa unitarity, respectively. We investigate how BSM physics could bring the three determinations of G_{F} into agreement using SM effective field theory and comment on future perspectives.
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Affiliation(s)
- Andreas Crivellin
- Theory Division, CERN, CH-1211 Geneva 23, Switzerland
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Martin Hoferichter
- Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Claudio Andrea Manzari
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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Wingate M. Quark flavor physics and lattice QCD. THE EUROPEAN PHYSICAL JOURNAL. A, HADRONS AND NUCLEI 2021; 57:239. [PMID: 34305446 PMCID: PMC8287851 DOI: 10.1140/epja/s10050-021-00547-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
For a long time, investigation into the weak interactions of quarks has guided us toward understanding the Standard Model we know today. Now in the era of high precision, these studies are still one of the most promising avenues for peering beyond the Standard Model. This is a large-scale endeavour with many tales and many protagonists. In these pages I follow a few threads of a complex story, those passing through the realm of lattice gauge theory.
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Affiliation(s)
- Matthew Wingate
- DAMTP, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA UK
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11
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Li G, Ramsey-Musolf MJ, Vasquez JC. Left-Right Symmetry and Leading Contributions to Neutrinoless Double Beta Decay. PHYSICAL REVIEW LETTERS 2021; 126:151801. [PMID: 33929232 DOI: 10.1103/physrevlett.126.151801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/08/2021] [Indexed: 06/12/2023]
Abstract
We study the impact of the mixing (LR mixing) between the standard model W boson and its hypothetical, heavier right-handed parter W_{R} on the neutrinoless double beta decay (0νββ decay) rate. Our study is done in the minimal left-right symmetric model assuming a type-II dominance scenario with charge conjugation as the left-right symmetry. We then show that the 0νββ decay rate may be dominated by the contribution proportional to this LR mixing, which at the hadronic level induces the leading-order contribution to the interaction between two pions and two charged leptons. The resulting long-range pion exchange contribution can significantly enhance the decay rate compared to previously considered short-range contributions. Finally, we find that even if future cosmological experiments rule out the inverted hierarchy for neutrino masses, there are still good prospects for a positive signal in the next generation of 0νββ decay experiments.
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Affiliation(s)
- Gang Li
- Amherst Center for Fundamental Interactions, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Michael J Ramsey-Musolf
- Amherst Center for Fundamental Interactions, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Tsung-Dao Lee Institute and School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - Juan Carlos Vasquez
- Amherst Center for Fundamental Interactions, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Crivellin A, Hoferichter M. β Decays as Sensitive Probes of Lepton Flavor Universality. PHYSICAL REVIEW LETTERS 2020; 125:111801. [PMID: 32976005 DOI: 10.1103/physrevlett.125.111801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 08/14/2020] [Indexed: 06/11/2023]
Abstract
Nuclear β decays as well as the decay of the neutron are well-established low-energy probes of physics beyond the standard model (SM). In particular, with the axial-vector coupling of the nucleon g_{A} determined from lattice QCD, the comparison between experiment and SM prediction is commonly used to derive constraints on right-handed currents. Further, in addition to the CKM element V_{us} from kaon decays, V_{ud} from β decays is a critical input for the test of CKM unitarity. Here, we point out that the available information on β decays can be reinterpreted as a stringent test of lepton flavor universality (LFU). In fact, we find that the ratio of V_{us} from kaon decays over V_{us} from β decays (assuming CKM unitarity) is extremely sensitive to LFU violation (LFUV) in W-μ-ν couplings thanks to a CKM enhancement by (V_{ud}/V_{us})^{2}∼20. From this perspective, recent hints for the violation of CKM unitarity can be viewed as further evidence for LFUV, fitting into the existing picture exhibited by semileptonic B decays and the anomalous magnetic moments of muon and electron. Finally, we comment on the future sensitivity that can be reached with this LFU violating observable and discuss complementary probes of LFU that may reach a similar level of precision, such as Γ(π→μν)/Γ(π→eν) at the PEN and PiENu experiments or even direct measurements of W→μν at an FCC-ee.
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Affiliation(s)
- Andreas Crivellin
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Martin Hoferichter
- Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
- Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550, USA
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13
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Coutinho AM, Crivellin A, Manzari CA. Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly. PHYSICAL REVIEW LETTERS 2020; 125:071802. [PMID: 32857580 DOI: 10.1103/physrevlett.125.071802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 05/05/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Recently, discrepancies of up to 4σ between the different determinations of the Cabibbo angle were observed. In this context, we point out that this "Cabibbo-angle anomaly" can be explained by lepton flavor universality violating new physics in the neutrino sector. However, modified neutrino couplings to standard model gauge bosons also affect many other observables sensitive to lepton flavor universality violation, which have to be taken into account in order to assess the viability of this explanation. Therefore, we perform a model-independent global analysis in a Bayesian approach and find that the tension in the Cabibbo angle is significantly reduced, while the agreement with other data is also mostly improved. In fact, nonzero modifications of electron and muon neutrino couplings are preferred at more than 99.99% C.L. (corresponding to more than 4σ). Still, since constructive effects in the muon sector are necessary, simple models with right-handed neutrinos (whose global fit we update as a by-product) cannot fully explain data, pointing towards more sophisticated new physics models.
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Affiliation(s)
| | - Andreas Crivellin
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland and Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Claudio Andrea Manzari
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland and Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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14
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Feng X, Gorchtein M, Jin LC, Ma PX, Seng CY. First-Principles Calculation of Electroweak Box Diagrams from Lattice QCD. PHYSICAL REVIEW LETTERS 2020; 124:192002. [PMID: 32469584 DOI: 10.1103/physrevlett.124.192002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 04/30/2020] [Indexed: 06/11/2023]
Abstract
We present the first realistic lattice QCD calculation of the γW-box diagrams relevant for beta decays. The nonperturbative low-momentum integral of the γW loop is calculated using a lattice QCD simulation, complemented by the perturbative QCD result at high momenta. Using the pion semileptonic decay as an example, we demonstrate the feasibility of the method. By using domain wall fermions at the physical pion mass with multiple lattice spacings and volumes, we obtain the axial γW-box correction to the semileptonic pion decay, □_{γW}^{VA}|_{π}=2.830(11)_{stat}(26)_{syst}×10^{-3}, with the total uncertainty controlled at the level of ∼1%. This study sheds light on the first-principles computation of the γW-box correction to the neutron decay, which plays a decisive role in the determination of |V_{ud}|.
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Affiliation(s)
- Xu Feng
- School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Center for High Energy Physics, Peking University, Beijing 100871, China
- State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
| | - Mikhail Gorchtein
- Helmholtz Institute Mainz, Mainz 55128, Germany
- GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt 55128, Germany
- Johannes Gutenberg University, Mainz 55128, Germany
| | - Lu-Chang Jin
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
- RIKEN-BNL Research Center, Brookhaven National Laboratory, Building 510, Upton, New York 11973, USA
| | - Peng-Xiang Ma
- School of Physics, Peking University, Beijing 100871, China
| | - Chien-Yeah Seng
- Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, 53115 Bonn, Germany
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15
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Gou B, Arvieux J, Aulenbacher K, Ríos DB, Baunack S, Becker D, Capozza L, Deconinck W, Diefenbach J, Frascaria R, Gorchtein M, Gläser B, von Harrach D, Imai Y, Kabuß EM, Kothe R, Kowalski S, Kunne R, Maas FE, Merkel H, Espí MCM, Morlet M, Müller U, Ong S, Schilling E, Weinrich C, van de Wiele J, Zambrana M, Zimmermann I. Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range. PHYSICAL REVIEW LETTERS 2020; 124:122003. [PMID: 32281834 DOI: 10.1103/physrevlett.124.122003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, A_{⊥}^{ep}, at five beam energies from 315.1 to 1508.4 MeV and at a scattering angle of 30°<θ<40°. The covered Q^{2} values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c)^{2}. The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-Q^{2} kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and πN inelastic intermediate states, suggests that there are other inelastic intermediate states such as ππN, KΛ, and ηN. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.
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Affiliation(s)
- B Gou
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - J Arvieux
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - K Aulenbacher
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - D Balaguer Ríos
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - S Baunack
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - D Becker
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - L Capozza
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - W Deconinck
- Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Diefenbach
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - R Frascaria
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - M Gorchtein
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - B Gläser
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - D von Harrach
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - Y Imai
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - E-M Kabuß
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - R Kothe
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - S Kowalski
- Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R Kunne
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - F E Maas
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - H Merkel
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - M C Mora Espí
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - M Morlet
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - U Müller
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - S Ong
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - E Schilling
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - C Weinrich
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
| | - J van de Wiele
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, F-91406 Orsay Cedex, France
| | - M Zambrana
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
| | - I Zimmermann
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.J. Becherweg 45, D-55099 Mainz, Germany
- Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz, Staudingerweg 18, D-55099 Mainz, Germany
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16
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Fry J, Alarcon R, Baeßler S, Balascuta S, Palos LB, Bailey T, Bass K, Birge N, Blose A, Borissenko D, Bowman J, Broussard L, Bryant A, Byrne J, Calarco J, Caylor J, Chang K, Chupp T, Cianciolo T, Crawford C, Ding X, Doyle M, Fan W, Farrar W, Fomin N, Frlež E, Gericke M, Gervais M, Glück F, Greene G, Grzywacz R, Gudkov V, Hamblen J, Hayes C, Hendrus C, Ito T, Jezghani A, Li H, Makela M, Macsai N, Mammei J, Mammei R, Martinez M, Matthews D, McCrea M, McGaughey P, McLaughlin C, Mueller P, Petten DV, Penttilä S, Perryman D, Picker R, Pierce J, Počanić D, Qian Y, Ramsey J, Randall G, Riley G, Rykaczewski K, Salas-Bacci A, Samiei S, Scott E, Shelton T, Sjue S, Smith A, Smith E, Stevens E, Wexler J, Whitehead R, Wilburn W, Young A, Zeck B. The Nab experiment: A precision measurement of unpolarized neutron beta decay. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201921904002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, λ = gA/gV, through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter a with a precision of δa/a = 10−3 and the Fierz interference term b to δb = 3 × 10−3 in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio λ with a precision of δλ/λ = 0.03% that will allow an evaluation of Vud and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.
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17
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Wang X, Ziener C, Abele H, Bodmaier S, Dubbers D, Erhart J, Hollering A, Jericha E, Klenke J, Fillunger H, Heil W, Klauser C, Konrad G, Lamparth M, Lauer T, Klopf M, Maix R, Märkisch B, Mach W, Mest H, Moser D, Pethoukov A, Raffelt L, Rebrova N, Roick C, Saul H, Schmidt U, Soldner T, Virot R, Zimmer O. Design of the magnet system of the neutron decay facility PERC. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201921904007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The PERC (Proton and Electron Radiation Channel) facility is currently under construction at the research reactor FRM II, Garching. It will serve as an intense and clean source of electrons and protons from neutron beta decay for precision studies. It aims to contribute to the determination of the Cabibbo-Kobayashi-Maskawa quark-mixing element Vud from neutron decay data and to search for new physics via new effective couplings. PERC's central component is a 12 m long superconducting magnet system. It hosts an 8 m long decay region in a uniform field. An additional high-field region selects the phase space of electrons and protons which can reach the detectors and largely improves systematic uncertainties. We discuss the design of the magnet system and the resulting properties of the magnetic field.
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18
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Moser D, Abele H, Bosina J, Fillunger H, Soldner T, Wang X, Zmeskal J, Konrad G. NoMoS: An R × B drift momentum spectrometer for beta decay studies. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201921904003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The beta decay of the free neutron provides several probes to test the Standard Model of particle physics as well as to search for extensions thereof. Hence, multiple experiments investigating the decay have already been performed, are under way or are being prepared. These measure the mean lifetime, angular correlation coefficients or various spectra of the charged decay products (proton and electron). NoMoS, the neutron decay products mo___mentum spectrometer, presents a novel method of momentum spectroscopy: it utilizes the R ×B drift effect to disperse charged particles dependent on their momentum in an uniformly curved magnetic field. This spectrometer is designed to precisely measure momentum spectra and angular correlation coefficients in free neutron beta decay to test the Standard Model and to search for new physics beyond. With NoMoS, we aim to measure inter alia the electron-antineutrino correlation coefficient a and the Fierz interference term b with an ultimate precision of Δa/a < 0.3% and Δb < 10−3 respectively. In this paper, we present the measurement principles, discuss measurement uncertainties and systematics, and give a status update.
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19
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Gorchtein M. γW Box Inside Out: Nuclear Polarizabilities Distort the Beta Decay Spectrum. PHYSICAL REVIEW LETTERS 2019; 123:042503. [PMID: 31491248 DOI: 10.1103/physrevlett.123.042503] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/05/2019] [Indexed: 06/10/2023]
Abstract
I consider the γW-box correction to superallowed nuclear β decays in the framework of dispersion relations. I address a novel effect of a distortion of the emitted electron energy spectrum by nuclear polarizabilities and show that this effect, while neglected in the literature, is sizable. The respective correction to the β^{+} spectrum is estimated to be Δ_{R}(E)=(1.6±1.6)×10^{-4}E/MeV assuming a conservative 100% uncertainty. The effect is positive definite and can be observed if a high-precision measurement of the positron spectrum is viable. If only the full rate is observed, it should be included in the calculated Ft values of nuclear decays. I argue that this novel effect should be included in the analyses of nuclear beta decay experiments to ensure the correct extraction of V_{ud} from decay rates, and of the Fierz interference term from precision measurements of decay spectra.
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Affiliation(s)
- Mikhail Gorchtein
- Helmholtz-Institut Mainz, Mainz, Germany PRISMA Cluster of Excellence, Johannes Gutenberg-Universität, 55128 Mainz, Germany
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20
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Märkisch B, Mest H, Saul H, Wang X, Abele H, Dubbers D, Klopf M, Petoukhov A, Roick C, Soldner T, Werder D. Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam. PHYSICAL REVIEW LETTERS 2019; 122:242501. [PMID: 31322367 DOI: 10.1103/physrevlett.122.242501] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Indexed: 06/10/2023]
Abstract
We present a precision measurement of the axial-vector coupling constant g_{A} in the decay of polarized free neutrons. For the first time, a pulsed cold neutron beam was used for this purpose. By this method, leading sources of systematic uncertainty are suppressed. From the electron spectra we obtain λ=g_{A}/g_{V}=-1.27641(45)_{stat}(33)_{sys}, which confirms recent measurements with improved precision. This corresponds to a value of the parity violating beta asymmetry parameter of A_{0}=-0.11985(17)_{stat}(12)_{sys}. We discuss implications on the Cabibbo-Kobayashi-Maskawa matrix element V_{ud} and derive a limit on left-handed tensor interaction.
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Affiliation(s)
- B Märkisch
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - H Mest
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - H Saul
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
- Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Wien, Austria
- Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstraße 1, 85748 Garching, Germany
| | - X Wang
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
- Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Wien, Austria
| | - H Abele
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
- Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Wien, Austria
| | - D Dubbers
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - M Klopf
- Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Wien, Austria
| | - A Petoukhov
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - C Roick
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - T Soldner
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - D Werder
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
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21
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Klopf M, Jericha E, Märkisch B, Saul H, Soldner T, Abele H. Constraints on the Dark Matter Interpretation n→χ+e^{+}e^{-} of the Neutron Decay Anomaly with the PERKEO II Experiment. PHYSICAL REVIEW LETTERS 2019; 122:222503. [PMID: 31283271 DOI: 10.1103/physrevlett.122.222503] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Indexed: 06/09/2023]
Abstract
Discrepancies from in-beam- and in-bottle-type experiments measuring the neutron lifetime are on the 4σ standard deviation level. In a recent publication Fornal and Grinstein proposed that the puzzle could be solved if the neutron would decay on the one percent level via a dark decay mode, one possible branch being n→χ+e^{+}e^{-}. With data from the Perkeo II experiment we set limits on the branching fraction and exclude a one percent contribution for 95% of the allowed mass range for the dark matter particle.
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Affiliation(s)
- M Klopf
- Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Wien, Austria
| | - E Jericha
- Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Wien, Austria
| | - B Märkisch
- Physik-Department ENE, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - H Saul
- Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Wien, Austria
- Physik-Department ENE, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - T Soldner
- Institut Laue-Langevin, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - H Abele
- Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Wien, Austria
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22
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Seng CY, Meißner UG. Toward a First-Principles Calculation of Electroweak Box Diagrams. PHYSICAL REVIEW LETTERS 2019; 122:211802. [PMID: 31283352 DOI: 10.1103/physrevlett.122.211802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/15/2019] [Indexed: 06/09/2023]
Abstract
We derive a Feynman-Hellmann theorem relating the second-order nucleon energy shift resulting from the introduction of periodic source terms of electromagnetic and isovector axial currents to the parity-odd nucleon structure function F_{3}^{N}. It is a crucial ingredient in the theoretical study of the γW and γZ box diagrams that are known to suffer from large hadronic uncertainties. We demonstrate that for a given Q^{2} one only needs to compute a small number of energy shifts in order to obtain the required inputs for the box diagrams. Future lattice calculations based on this approach may shed new light on various topics in precision physics including the refined determination of the Cabibbo-Kobayashi-Maskawa matrix elements and the weak mixing angle.
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Affiliation(s)
- Chien-Yeah Seng
- Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, 53115 Bonn, Germany
| | - Ulf-G Meißner
- Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, 53115 Bonn, Germany
- Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, 52425 Jülich, Germany
- Tbilisi State University, 0186 Tbilisi, Georgia
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23
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Pattie R, Callahan N, Cude-Woods C, Adamek E, Adams M, Barlow D, Blatnik M, D. B, Broussard L, Clayton S, Currie S, Dees E, Ding X, Fellers D, Fox W, Fries E, Gonzalez F, Geltenbort P, Hickerson K, Hoffbauer M, Hoffman K, Holley A, Howard D, Ito T, Komives A, Liu C, M. M, Medina J, Morley D, Morris C, O'Connor T, Penttilä S, Ramsey J, Roberts A, Salvat D, Saunders A, Seestrom S, Sharapov E, Sjue S, Snow W, Sprow A, Vanderwerp J, Vogelaar B, P.L. W, Wang Z, Weaver H, Wexler J, Womack T, Young A, Zeck B. Status of the UCN τ experiment. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201921903004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics beyond the standard model. Measurements of neutron lifetime and β-decay correlation coefficients with precisions of 0.02% and 0.1%, respectively, would allow for stringent constraints on new physics. The UCNτ experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime, τn = 877.7s (0.7s)stat (+0.4/−0.2s)sys. We discuss the recent result from UCNτ, the status of ongoing data collection and analysis, and the path toward a 0.25 s measurement of the neutron lifetime with UCNτ.
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24
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Abstract
Free neutron decay is a fundamental process in particle and nuclear physics. It is the prototype for nuclear beta decay and other semileptonic weak particle decays. Neutron decay played a key role in the formation of light elements in the early universe. The precise value of the neutron mean lifetime, about 15 min, has been the subject of many experiments over the past 70 years. The two main experimental methods, the beam method and the ultracold neutron storage method, give average values of the neutron lifetime that currently differ by 8.7 s (4 standard deviations), a serious discrepancy. The physics of neutron decay, implications of the neutron lifetime, previous and recent experimental measurements, and prospects for the future are reviewed.
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