arXiv subjects

Tatsuya Banno

Publications and source records attributed to Tatsuya Banno.

5 recordsLinked to original sources

arXiv2026

Full Three-Loop Electroweak Multiplet Contributions to the Electron Electric Dipole Moment

Experimental sensitivity to the electric dipole moment (EDM) of the electron has improved remarkably in recent years. Consequently, future prospects could probe new physics whose contribution to the electron EDM first arises at three-loop order. Additional SU(2)$_L$ multiplets with CP-violating Yukawa interactions, which contribute to the electron EDM at three-loop level, is one such testable new physics scenario. In this scenario, the electron EDM is radiatively induced from two contributions: the CP-odd trilinear $W$-boson coupling, called the electroweak-Weinberg operator, and the CP-odd dipole operator of electron. The former and the latter operators are generated at two-loop and three-loop levels, respectively, after integrating out the SU(2)$_L$ multiplets. Within the same models, according to an analysis based on the Standard Model Effective Field Theory (SMEFT), we previously found that the contribution to the electron EDM from the electroweak-Weinberg operator can be probed in future experiments. However, the one-loop matching condition between the electron EDM and the electroweak-Weinberg operator does not receive a large logarithmic enhancement because the associated anomalous dimension is zero. The CP-odd dipole operator of the electron would contribute to the electron EDM at the same three-loop order as the contribution through the electroweak-Weinberg operator. In this paper, we directly calculate the electron EDM induced by the CP-violating Yukawa interactions of the SU(2)$_L$ multiplets at full three-loop level. A central result is that the full three-loop calculation is a factor of three larger than that of the electroweak-Weinberg operator alone.

hep-ph↗

arXiv2026

Chasing the two-Higgs-doublet model via electroweak corrections at $e^+e^-$ colliders

We present a comprehensive study of Higgs boson production associated with a neutrino pair at $e^+e^-$ colliders ($e^+ e^- \to h \, ν\barν$) at next-to-leading-order accuracy in both the Standard Model and the two-Higgs-doublet model. We show that these new physics effects will be observable in total and differential cross sections when compared with theoretical predictions that include electroweak corrections, even in the Higgs alignment limit. This highlights the potential of precision studies at future $e^+e^-$ colliders for searching new physics.

hep-ph↗

arXiv2025

Two-loop corrections to QCD $θ$ angle from evanescent operator in the BMHV scheme

We study the renormalization of the QCD $θ$ angle at the two-loop level focusing on divergent and finite $CP$-violating contributions from evanescent operators, using dimensional regularization with the BMHV scheme. When one considers the Lagrangian in $d$-dimensional space-time instead of four dimensions in dimensional regularization, evanescent operators that break the chiral symmetry are induced. Consequently, $T$-odd and $P$-odd fermion loops in the BMHV scheme generate evanescent contributions to the QCD $θ$ angle. We carefully classify the evanescent contributions into two types: one originating from the evanescent operators at the one-loop level and the other directly produced by two-loop calculations. We show that renormalization of the parameters in the BMHV scheme keeps removing those unphysical contributions to the QCD $θ$ angle at any scale at the two-loop level. We also discuss how the rephasing invariance of the radiative correction to the QCD $θ$ angle is realized in the BMHV scheme.

hep-ph↗

arXiv2025

Impact of the Electroweak Weinberg Operator on the Electric Dipole Moment of Electron

Recent progresses in the measurements of the electric dipole moment (EDM) of the electron using the paramagnetic atom or molecule are remarkable. In this paper, we calculate a contribution to the electron EDM at three-loop level, introducing the CP-violating Yukawa couplings of new SU(2)$_L$ multiplets. At two-loop level, the Yukawa interactions generate a CP-violating dimension-six operator, composed of three SU(2)$_L$ field strengths, called the electroweak Weinberg operator. Another one-loop diagram with the operator inserted induces the electron EDM. We find that even if new SU(2)$_L$ particles have masses around TeV-scale, the electron EDM may be larger than the Standard Model contribution to the paramagnetic atom or molecule EDMs. We also discuss the relation between the Barr-Zee diagram contribution at two-loop level and the three-loop one, assuming that the SM Higgs has new Yukawa interactions with the SU(2)$_L$ multiplets.

hep-ph↗

arXiv2024

Closer look at the matching condition for radiative QCD $θ$ parameter

In this paper, we scrutinize a radiatively generated QCD $θ$ parameter at the two-loop level based on both full analytical loop functions with the Fock-Schwinger gauge method and the effective field theory approach, using simplified models. We observe that the radiatively generated $θ$ parameters at the low energy scale precisely match between them. It provides validity to perturbative loop calculations of the QCD $θ$ parameter with the Fock-Schwinger gauge method. Furthermore, it is also shown that the ordinary Fujikawa method for the radiative $θ$ parameter by using $\barθ= - arg det M_q^{loop}$ does not cover all contributions in the simplified models. But, we also find that when there is a scale hierarchy in $CP$-violating sector, evaluation of the Fujikawa method is numerically sufficient. As an application, we calculate the radiative $θ$ parameter at the two-loop level in a slightly extended Nelson-Barr model, where the spontaneous $CP$ violation occurs to solve the strong $CP$ problem. It is found a part of the radiative $θ$ parameters cannot be described by the Fujikawa method.

hep-ph↗