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Dispersive evaluation of the inner radiative correction in neutron and nuclear β decay

Seng, Chien-Yeah and Gorchtein, Mikhail and Ramsey-Musolf, Michael J. (2019) Dispersive evaluation of the inner radiative correction in neutron and nuclear β decay. Physical Review D, 100 (1). Art. No. 013001. ISSN 2470-0010.

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We propose a novel dispersive treatment of the so-called inner radiative correction to the neutron and nuclear β decay. We show that it requires knowledge of the parity-violating structure function F^((0))_3 that arises from the interference of the axial vector charged current and the isoscalar part of the electromagnetic current. By isospin symmetry, we relate this structure function to the charged current inelastic scattering of neutrinos and antineutrinos. Applying this new data-driven analysis we obtain a new, more precise evaluation for the universal radiative correction Δ^(V,new)_R=0.02467(22) that supersedes the previous estimate by Marciano and Sirlin, Δ^V_R=0.02361(38). The substantial shift in the central value of Δ^V_R reflects in a respective shift of V_(ud) and a considerable tension in the unitarity constraint on the first row of the Cabibbo-Kobayashi-Maskawa matrix which is used as one of the most stringent constraints on new physics contributions in the charged current sector. We also point out that dispersion relations offer a unifying tool for treating hadronic and nuclear corrections within the same framework. We explore the potential of the dispersion relations for addressing the nuclear structure corrections absorbed in the Ft values, a crucial ingredient alongside Δ^V_R in extracting V_(ud) from superallowed nuclear decays. In particular, we estimate the quenching of the free neutron Born contribution in the nuclear environment, corresponding to a quasielastic single-nucleon knockout, and find a significantly stronger quenching effect as compared to currently used estimates based on the quenching of spin operators in nuclear transitions. This observation suggests that the currently used theoretical uncertainties of Ft values might be underestimated and require a renewed scrutiny, while emphasizing the importance of new, more precise measurements of the free neutron decay where nuclear corrections are absent.

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Ramsey-Musolf, Michael J.0000-0001-8110-2479
Additional Information:© 2019 American Physical Society. Received 6 March 2019; published 16 July 2019. We are grateful to Hiren H. Patel for his participation at the early stages of this calculation. We acknowledge helpful discussions with Bill Marciano, John Hardy, Vincenzo Cirigliano, Peter Blunden, Emmanuel Paschos, Cheng-Pang Liu, Chung-Wen Kao, Hubert Spiesberger and Jens Erler. Significant progress was made during the scientific program “Bridging the Standard Model to New Physics with the Parity Violation Program at MESA” hosted by MITP Mainz. M. G. acknowledges support by the Deutsche Forschungsgemeinschaft under the personal Grant No. GO 2604/2-1 and by the German-Mexican research collaboration Grant No. SP 778/4–1 (DFG) and No. 278017 (CONACyT). C.-Y. S.’s work is supported in part by the National Natural Science Foundation of China (NSFC) under Grants No. 11575110, No. 11655002, and No. 11735010, Natural Science Foundation of Shanghai under Grants No. 15DZ2272100 and No. 15ZR1423100, by Shanghai Key Laboratory for Particle Physics and Cosmology, by Key Laboratory for Particle Physics, Astrophysics and Cosmology, Ministry of Education, and by the DFG (Grant No. TRR110) and the NSFC (Grant No. 11621131001) through the funds provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD” and also appreciates the support through the Recruitment Program of Foreign Young Talents from the State Administration of Foreign Expert Affairs, China. M. J. R.-M. was supported in part by U.S. Department of Energy Contract No. DE-SC0011095.
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)GO 2604/2-1
Deutsche Forschungsgemeinschaft (DFG)SP 778/4-1
Consejo Nacional de Ciencia y Tecnología (CONACYT)278017
National Natural Science Foundation of China11575110
National Natural Science Foundation of China11655002
National Natural Science Foundation of China11735010
Natural Science Foundation of Shanghai15DZ2272100
Natural Science Foundation of Shanghai15ZR1423100
Shanghai Key Laboratory for Particle Physics and CosmologyUNSPECIFIED
Ministry of Education (Taipei)UNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)TRR110
National Natural Science Foundation of China11621131001
Collaborative Research Center (CRC)CRC 110
State Administration of Foreign Expert Affairs (China)UNSPECIFIED
Department of Energy (DOE)DE-SC0011095
Issue or Number:1
Record Number:CaltechAUTHORS:20190716-104707744
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97170
Deposited By: Tony Diaz
Deposited On:16 Jul 2019 18:40
Last Modified:03 Oct 2019 21:28

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