( g -2) μ versus Flavor Changing Neutral Current Induced by the Light (B-L) μτ Boson Yoshihiro Shigekami Huazhong University of Science and Technology ( 华 中科技大学) with Zhaofeng Kang (HUST) Based on arXiv:1905.11018 [hep-ph] 基研研究会 PPP2019 @ 京都大学 基礎物理学研究所
Introduction • Standard Model (SM): gauge G SM = SU(3) C × SU(2) L × U(1) Y http://higgstan.com/ Y. Shigekami (HUST) 1
Introduction • We should solve and explain some mysteries ex. neutrino masses: massless in SM (no right-handed neutrinos) Extended model is needed • Neutrino masses are confirmed in some experiments Key: neutrino oscillation P ( ν e → ν μ ) • Super-Kamiokande à Neutrinos are oscillated! Nobel Prize (2015): T. Kajita, A. B. McDonald • Tiny neutrino masses Planck Collab., arXiv:1807.06209 [astro-ph.CO] Y. Shigekami (HUST) 2
Introduction • One of the interesting models à B-L model charges: +1 (+1/3) for Baryons (quarks), -1 for Leptons • New U(1) gauge sym. Note: U(1) B-L3 also cancels -6 × 1/3+3 × 1/3+3 × 1/3-2 × (-1)+1 × (-1) = 1 Figure from Peskin, Schroeder -6 × 1/3+3 × 1/3+3 × 1/3-2 × (-1)+1 × (-1)+1 × (-1) = 0 • RH ν is needed for gauge anomaly • It appears from some high-energy theories ex. Grand Unified Theory ： SO(10) → G SM × U(1) B-L Y. Shigekami (HUST) 3
Introduction • New terms with RH ν Φ: new scalar (charge 2) <H 0 > ≠ 0 à Dirac mass term, m <Φ> ≠ 0 à Majorana mass term, M Seesaw mechanism: Minkowski, PLB 67 , 421 (1977); m M Gell-Mann, Ramond, Slansky (proceedings) (1979); Yanagida (proceedings) (1979); Glashow, “Quarks and Leptons ”; Mohapatra, Senjanovic, PRL 44 , 912 (1980) • New gauge boson: Z’ interactions with fermions: Contributes to some predictions tree-level process Y. Shigekami (HUST) 4
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Introduction • New physics explanation: B-L model, L μ -L τ model, … • There is favored parameter space in light Z’ mass region M Z’ 〜 10-400 MeV & g ’ 〜 (3-15) × 10 -4 main focus of this work W. Altmannshofer et al ., PRL 113 , 091801 (2014) Y. Shigekami (HUST) 6
Introduction K. Zhaofeng and YS, arXiv:1905.11018 [hep-ph] • Our setup: 2 nd and 3 rd generations have U(1) B-L charges Z’ interactions: • In mass basis, elements of diagonalizing matrix for Yukawas à Flavor Violating Couplings (FVCs) • New contributions: t → q Z’, P 1 → P 2 Z’ (Z’ → νν ) light Z’ à decays to νν tree-level process! Y. Shigekami (HUST) 7
Contents ü done! • Introduction (7) à • Model details (4) • ( g -2) μ (3) • Quark FCNCs (6) • Summary (1) + which New Physics? → Light Z’! Y. Shigekami (HUST)
Model details K. Zhaofeng and YS, arXiv:1905.11018 [hep-ph]
Model details • We consider G SM × U(1) B-L • 2 nd and 3 rd generations are charged under U(1) B-L • Contents ( i = 2, 3): need for realization of CKM right-handed neutrinos tiny ν mass via seesaw mechanism 〈 Φ 〉 breaks U(1) B-L Y. Shigekami (HUST) 8
<latexit sha1_base64="X3Zd5q5xzcyQ3Rcm0J5mSLCrGU=">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</latexit> Model details • Yukawa couplings for quarks à No Yukawas between 1 st and the other generations: CKM • Vector-like quarks : Integrate out a = 1, 2, 3; i = 2, 3 • If we introduce doublet flavons with U(1) B-L charge +1/3, − L ⊃ e 1 i Q 1 e H µ τ u R,i + e Y u Y d i 1 Q i H µ τ d R, 1 + h.c. à vector-like quarks are not needed Y. Shigekami (HUST) 9
<latexit sha1_base64="t2jUOx8iTSGybzFdGVqCoNn4qw4=">ADY3ichVFLa9VAFD658VFTtdfqQhBh8NLiQi4niVARhKIbl314+6CpIY/pdWheTSYXr+H+gW4VXLhSEBF/hv/gIv+ABfisoIbEc9N0gbqhMm853vnG/ONzNuEohMIu4pLfXU6TNnJ85pk+cvXJxqX5peyeI89XjPi4M4XOdjAci4j0pZMDXkpQ7oRvwVXf7wTi/OuBpJuLokRwmfDN0+pHYEp4jibLbv9btnN1jlsv7IiqS0JGpeDrSho9zu9D1EZtlFTQaI6YZWl4EBtNyjiSMpuUWaUsHvmHXW4xayd3fLZu+yda8A8sYDlJXnJGbctvevuHvUtsNhVmU3GSBbvdwS6Wgx0Heg06UI+FuP0OLPAhBg9yCIFDBJwA5k9G2ADgJcZtQEJcSEmWewg0uZUxanCIXab/n2KNmo2oni8Z1aqPeoS0ExJyWAGP+N73MdP+AG/4s+/7lWUe4y9DGl1Ky1P7Kndq8s/qsKaZXwpFH907OELbhTehXkPSmZ8Sm8Sj949nJ/+e7STDGLb/Ab+X+Ne/iRThANvntvF/nSK9DoAfSj130crBhd3ewai7c78/frp5iAa3ADbtJ9z8E8PIQF6IGn+Mqu8lx50fqiTqrT6pWqtKXUmsvwx1Cv/wbkPN0H</latexit> Model details • Z’ couplings of quarks mass basis from flavor one: U q , W q : diagonalizing matrices for Yukawa : Flavor violating couplings (FVCs) Note: our FVCs are related to (1, i )-element of U q and W q • Different type of quark FCNC: Ø Singlet flavon case à only up sector Ø Doublet flavon case à up and down sectors y u y u y u y d 0 0 11 11 12 13 y u y u , y d y d y d Y u = 0 Y d = 22 23 21 22 23 y u y u y d y d y d 0 32 33 31 32 33 Y. Shigekami (HUST) 10
Model details • The size of FVCs: depend on g B-L and U q , W q • g B-L à determine from ( g -2) μ • U q à size from CKM matrix: • No cancellation means and diagonal element ～ 1 • For W q , there are no concrete bound, but if U q ～ W q , similar inequalities are applied Y. Shigekami (HUST) 11
( g -2) μ
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