arXiv subjects

Kiyoto Ogawa

Publications and source records attributed to Kiyoto Ogawa.

5 recordsLinked to original sources

arXiv2026

Impact of dimension-8 SMEFT operators on baryogenesis via sphaleron decoupling

We investigate whether a baryogenesis mechanism known as sphalerogenesis can account for the observed baryon asymmetry of the Universe within the Standard Model effective field theory. In this scenario, the baryon asymmetry is generated through the $CP$-asymmetric decoupling of electroweak (EW) sphaleron-like transitions. We introduce seven $CP$-violating dimension-8 operators constructed from the Higgs doublet and the $SU(2)_L$ gauge fields and show that five of them can individually account for the observed baryon asymmetry with satisfying experimental constraints from colliders or electron electric dipole moment measurements. We further study their impact in the presence of a $CP$-violating dimension-6 operator. We find that the dimension-8 contributions can be comparable to the dimension-6 contribution when the dimension-8 operators are generated at one loop, demonstrating that loop-order counting can be as important as canonical mass-dimension counting in sphalerogenesis.

hep-ph↗

arXiv2026

Baryogenesis in $SU(2)_{L}$ multiplet models

We investigate baryogenesis in Standard Model (SM) extensions with new $SU(2)_L$ multiplet fields. We focus on sphalerogenesis, in which the baryon asymmetry of the Universe (BAU) is generated through the gradual decoupling of CP-violating electroweak sphaleron-like processes. We show that the observed BAU can be reproduced when the new fields possess CP-violating Yukawa interactions, which leave a CP-violating dimension-six operator involving the $SU(2)_L$ gauge fields at low energies. As representative examples, we study models with fermionic $SU(2)_L$ quintuplets and septuplets, and find that these field masses should be $\mathcal{O}(1)\,\mathrm{TeV}$ to explain the BAU. We also show that viable parameter regions for the BAU are consistent with current bounds on the electron electric dipole moment and thoroughly probed by future measurements such as ACME III and by mono-lepton searches at the HL-LHC. Our results provide a concrete and phenomenologically testable ultraviolet completion of sphalerogenesis.

hep-ph↗

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↗

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↗