Constraints on the charged currents in general neutrino interactions with sterile neutrinos
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Springer
Received: August 3, 2020 Accepted: September 18, 2020 Published: October 19, 2020
Tong Li,a Xiao-Dong Mab and Michael A. Schmidtc a
School of Physics, Nankai University, Tianjin 300071, China b Department of Physics, National Taiwan University, Taipei 10617, Taiwan c School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
E-mail: [email protected], [email protected], [email protected] Abstract: In this work we investigate the implication of low-energy precision measurements on the quark-lepton charged currents in general neutrino interactions with sterile neutrinos in effective field theories. The physics in low-energy measurements is described by the low-energy effective field theory extended with sterile neutrinos (LNEFT) defined below the electroweak scale. We also take into account renormalization group running and match the LNEFT onto the Standard Model (SM) effective field theory with sterile neutrinos (SMNEFT) to constrain new physics (NP) above the electroweak scale. The most sensitive low-energy probes are from leptonic decays of pseudoscalar mesons and hadronic tau lepton decays in terms of precise decay branching fractions, the lepton flavor universality and the Cabibbo-Kobayashi-Maskawa (CKM) unitarity. We also consider other constraints including nuclear beta decay. The constraints on charged current operators are generally stronger than the ones for quark-neutrino neutral current operators. We find that the most stringent bounds on the NP scale of lepton-number-conserving and leptonnumber-violating operators in SMNEFT are 74 (110) TeV and 9.8 (13) TeV, respectively, for the operators with down (strange) quark. Keywords: Beyond Standard Model, Effective Field Theories, Neutrino Physics ArXiv ePrint: 2007.15408
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP10(2020)115
JHEP10(2020)115
Constraints on the charged currents in general neutrino interactions with sterile neutrinos
Contents 1 Introduction
1
2 General neutrino interactions with RH neutrinos 2.1 General lepton-quark charged current operators in LNEFT basis 2.2 Matching to the SMNEFT
2 3 5 7 9 12 12 14
4 Numerical results
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5 Other constraints and vector meson decays
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6 Conclusions
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A The complete operator basis involving RH neutrinos N in the LNEFT
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B The SMNEFT operator basis at dim-6 and dim-7
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C The decay matrix elements of meson and tau lepton
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D β decay
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1
Introduction
The absence of any signal for new physics (NP) beyond the Standard Model (BSM) at the Large Hadron Collider (LHC) has sparked a renaissance in the search for the BSM physics at low-energy experiments. The hints for BSM physics, however, may hide in deviations from the SM in low-energy precision measurements. The precision era in neutrino physics sheds light on possible new dynamical degrees of freedom such as right-handed (RH) neutrinos and non-standard neutrino interactions. The results of low-energy precision measurements can guide our dir
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