arXiv subjects

Nodoka Yamanaka

Publications and source records attributed to Nodoka Yamanaka.

At least 19 recordsLinked to original sources

arXiv2026

Irrelevance of Anomalous Breaking of Axial U(1) Symmetry and the U(1) Problem

The eta and eta' mesons are conventionally known to receive contribution from the anomalous breaking of axial U(1) symmetry, and they are considered to not be the Nambu-Goldstone (NG) bosons of the spontaneous chiral SU(3)_L x SU(3)_R symmetry breaking of QCD. However, it has recently been shown that this axial U(1) anomaly is not actually physical. In this contribution, we first review this statement and then propose a mechanism in which eta and eta' mesons are indeed NG bosons while being consistent with the axial U(1) problem.

hep-ph↗

arXiv2026

Quantification of the Flavor Diagonal Hadronic CP Violation

The flavor diagonal CP violation of elementary particle physics contributes to the atomic, nuclear, and nucleon electric dipole moments (EDMs), T-violating neutron optics, and to the angular correlations of beta decay. In this contribution, we review the basics and the importance of CP violation in the search for new physics beyond the standard model, the recent progress in the quantification of the hadron level CP violation contributing to the aforementioned observables, and finally the current attempt to solve the strong CP problem without additional interactions and fields.

hep-ph↗

arXiv2026

Higher-order QCD and electroweak corrections for $t{\bar t}H$ production

We calculate higher-order soft-gluon corrections for the associated production of a top-antitop quark pair and a Higgs boson ($t{\bar t}H$ production) using resummation in one-particle-inclusive (1PI) kinematics. By adding these corrections to NLO QCD and NLO electroweak (EW) results, we present cross sections through approximate N$^3$LO (aN$^3$LO) in QCD and NLO in EW for $t{\bar t}H$ production at LHC energies. These aN$^3$LO QCD + NLO EW results provide significant enhancements over lower orders and a reduced scale dependence. Based on our results and current experimental data, we derive a constraint on the deviation of the top quark Yukawa coupling from the Standard Model value which is a probe of new physics beyond it. We also calculate top-quark differential distributions in transverse momentum and rapidity.

hep-ph↗

arXiv2025

Light nuclei under magnetic field and the lithium problem

We analyze the effect of the magnetic field on the proton and neutron density distributions of the nuclei 2H, 3H, 3He, which are calculated ab initio, and the 6Li nucleus in the alpha-cluster model. It is found that the asymptotic exponential damp of the probability density at long distance is modified, and that the linear component of the exponent with respect to the magnetic field yields the leading contribution, while those of the second derivative and the confining magnetic force are subleading. Due to the linear dependence of the exponent, fluctuating magnetic fields always enhance the tunneling rate, i.e. the cross section of low energy nuclear reactions which occur at large separation across the Coulomb barrier. While this mechanism cannot suppress the production of 7Be in the early Universe, it has the potential to resolve the lithium problem either by increasing the reaction rate of 7Be + p -> 8B at the bigbang nucleosynthesis era if the magnetic field at this time was sufficiently strong, or by correcting the systematically enlarged 4He + 3He -> 7Be cross section by the unwanted magnetic field generated in the nuclear experimental setup, which was so far used as the input of the simulation of bigbang nucleosynthesis.

nucl-th↗

arXiv2024

Sketch of the resolution of the axial U(1) problem without chiral anomaly

We propose a mechanism which explains the masses of $η$ and $η'$ mesons without invoking the explicit violation of $U(1)_A$ symmetry by the chiral anomaly. It is shown that the U(1) problem, the problem for which the prediction of $η$ and $η'$ masses in the simple chiral perturbation theory largely deviates from the experimental values, is actually resolved by considering the first order contribution of the disconnected meson correlator with respect to the quark mass. The bound of Weinberg $m_η^2 \le 3 m_π^2$ is fulfilled by considering the negative squared mass of $η$ or $η'$ which is just the saddle point of the QCD effective potential, and 20% level agreements with experimental data are obtained by just fitting one low energy constant. We provide the leading chiral Lagrangian due to the disconnected contribution in 3-flavor QCD, and also discuss the 2- and 4-flavor cases as well as the consistency of our mechanism with the chiral restoration at high temperature found in lattice calculations.

hep-ph↗

arXiv2023

R-parity violating two-loop level rainbowlike contribution to the fermion electric dipole moment

We analyze the two-loop level $R$-parity violating supersymmetric contribution to the electric and chromoelectric dipole moments of fermions with a lepton and a gaugino in the intermediate state. It is found that this contribution can be sufficiently enhanced with large $\tan β$ and that it can have comparable size with the currently known $R$-parity violating Barr-Zee type process within TeV scale supersymmetry breaking. We also give new upper limits on $R$-parity violating couplings given by the atomic electric dipole moment and molecular beam experiments.

hep-ph↗

arXiv2023

Quantification of the electric dipole moment generated by hadronic CP violation: resolution of the strong CP problem

The atomic, nuclear, and nucleon electric dipole moments (EDMs) have significant sensitivity to the CP violation of elementary particle physics, but its quantification has for long been obstructed by the nonperturbative physics of quantum chromodynamics. Quite recently, there were significant progresses in this field, notably the quantification of hadron level CP violation and the resolution of the strong CP problem. In this proceedings contribution, we summarize this attempt by focussing on the latter topic, the resulting new paradigm of baryogenesis, and the modifications that have to be applied in the evaluation of the EDMs.

hep-ph↗

arXiv2023

Revisiting Theoretical Analysis of Electric Dipole Moment of $^{129}$Xe

Linear response approach to the relativistic coupled-cluster (RCC) theory has been extended to estimate contributions from the parity and time-reversal violating pseudoscalar-scalar (Ps-S) and scalar-pseudoscalar (S-Ps) electron-nucleus interactions along with electric dipole moments (EDMs) of electrons ($d_e$) interacting with internal electric and magnetic fields. Random phase approximation (RPA) is also employed to produce results to compare with the earlier reported values and demonstrate importance of the non-RPA contributions arising through the RCC method. It shows that contributions from the S-Ps interactions and $d_e$ arising through the hyperfine-induced effects are very sensitive to the contributions from the high-lying virtual orbitals. Combining atomic results with the nuclear shell-model calculations, we impose constraints on the pion-nucleon coupling coefficients, and EDMs of proton and neutron. These results are further used to constrain EDMs and chromo-EDMs of up- and down-quarks by analyzing particle physics models.

hep-ph↗

arXiv2023

Higher-order corrections for $tqZ$ production

We present theoretical results for the associated production of a single top quark and a $Z$ boson ($tqZ$ production) at LHC energies. We calculate higher-order corrections from soft-gluon emission for this process. We compute the approximate NNLO (aNNLO) cross section at LHC energies, including uncertainties from scale dependence and from parton distributions. We also calculate the top-quark rapidity distribution. The aNNLO corrections are significant and enhance the NLO cross section, and their inclusion provides a more precise theoretical prediction.

hep-ph↗

arXiv2022

Unobservability of the topological charge in nonabelian gauge theory: Ward-Takahashi identity and phenomenological aspects

We argue that the topological charge of nonabelian gauge theory is unphysical. To show this statement, we use the Adler-Bardeen theorem and the Becchi-Rouet-Stora-Tyutin symmetry which are warranted by the perturbative finiteness of the chiral anomaly, thus being free of Gribov ambiguity. In addition to the original argument using the unphysical gauge field component collinear to the spatial derivative of the gauge function, we show the unobservability of the topological charge using the Ward-Takahashi identity. We then present the consequences of this finding and show the consistency with many physical pictures and ideas that have been developed around the topology of nonabelian gauge theory. The most important ones are the resolution of the Strong CP problem, the unobservability of topological instantons, the physical relevance of the axial $U(1)$ symmetry, the independence of the vacuum energy on the vacuum angle, and the impossibility to realize the sphaleron induced baryogenesis and chiral magnetic effects. The axial $U(1)$ symmetry and the unphysical $θ$-term imply that the physical complex phase of the Cabibbo-Kobayashi-Maskawa matrix is the sole source of CP violation in the standard model. The unphysical sphaleron also means that the lepton number is phenomenologically free from the baryon number, and their violations may be modeled separately. We also comment on the consistency with the results of lattice calculations.

hep-ph↗

arXiv2022

Unobservability of topological charge in nonabelian gauge theory

We show that the topological charge of nonabelian gauge theory is unphysical by using the fact that it always involves the unphysical gauge field component proportional to the gradient of the gauge function. The removal of Gribov copies, which may break the Becchi-Rouet-Stora-Tyutin symmetry, is irrelevant thanks to the perturbative one-loop finiteness of the chiral anomaly. The unobservability of the topological charge immediately leads to the resolution of the Strong CP problem. We also present important consequences such as the physical relevance of axial $U(1)$ symmetry, the $θ$-independence of vacuum energy, the unphysicalness of topological instantons, and the impossibilities of realizing the sphaleron induced baryogenesis as well as the chiral magnetic effect. The unphysical vacuum angle and the axial $U(1)$ symmetry also imply that the CP phase of the Cabibbo-Kobayashi-Maskawa matrix is the sole source of CP violation of the standard model.

hep-th↗

arXiv2022

Quantification of the hadronic CP violation contribution to the atomic EDMs

CP violating interactions are required to realize the matter abundance of our Universe. It is however known that the standard model of particle physics does not contain sufficient CP violation. The electric dipole moment (EDM) of atomic systems is a very sensitive experimental probe of CP violation beyond the standard model, and it is very actively studied in experiments. The atomic EDM has a significant sensitivity to hadronic CP violation, but its quantification has for long been obstructed by the nonperturbative physics of quantum chromodynamics. Quite recently, the contribution of the Weinberg operator (CP violating three-gluon interaction) to the atomic EDM has been analyzed, and we are almost attaining the quantification era of the CP violating hadronic interaction in the leading order of standard model effective field theory. In this proceedings contribution, we summarize the current attempt to quantify the hadronic CP violation contribution to the EDM of atoms.

hep-ph↗

arXiv2022

Weinberg operator contribution to the CP-odd nuclear force in the quark model

The contribution of the CP violating three-gluon interaction, proposed by Weinberg, to the short-range CP-odd nuclear force is evaluated in the nonrelativistic quark model. We first show that the naive leading contribution generated by the quark exchange process vanishes at sufficiently short distance within the resonating group method, by considering the one-loop level gluon exchange CP-odd interquark potential induced by the Weinberg operator with massive quarks and gluons. We then estimate the true leading contribution by evaluating the gluonic correction to the CP-odd interquark potential in the closure approximation. It is found that the resulting irreducible CP-odd nuclear force is comparable to that generated by the chiral rotation of the CP-even short-range nuclear force, where the CP-odd mass calculated with QCD sum rules is used as input. The explicit calculation of the electric dipole moment (EDM) of the $^3$He nucleus yields $d_{^3{\rm He}}^{\rm (irr)} (w) = - 1.5 \, w\, e $ MeV. The total $^3$He EDM, accounting for the intrinsic nucleon EDM, the pion-exchange and the short-range CP-odd nuclear force, is $d_{^3{\rm He}}^{\rm (tot)} (w) = 20_{-11}^{+14} \, w\, e $ MeV, with the dominant effect coming from the intrinsic nucleon EDM.

nucl-th↗

arXiv2022

Soft-gluon corrections for $tqZ$ production

We study soft-gluon corrections for the associated production of a single top quark and a $Z$ boson ($tqZ$ production) at hadron colliders. We find that the radiative corrections are dominated by soft-gluon emission. We calculate the approximate NNLO (aNNLO) cross section at LHC energies, including uncertainties from scale dependence and from parton distributions. We also calculate differential distributions in top-quark rapidity. We show that the aNNLO corrections are significant and they enhance the NLO cross section while decreasing theoretical uncertainties.

hep-ph↗

arXiv2022

Interglueball potential in lattice SU(N) gauge theories

The dynamics of the glueballs is important in the context of the experimental search as well as for understanding the non-Abelian gauge theory. The glueballs of the dark $SU(N_c)$ Yang-Mills theory are also good candidates of dark matter. In this proceedings contribution, we report on the result of the lattice calculation of the interglueball potential of the Yang-Mills theory with the color numbers $N_c=2,3,4$, with a detailed inspection of the systematics due to the discretization.

hep-lat↗

arXiv2022

Weinberg Operator Contribution to the Hadronic CP Violation

The CP violating Weinberg operator (or the gluon chromo-electric dipole moment) is generated in many candidates of new physics beyond the standard model, and it contributes to observables such as the electric dipole moments (EDM) of the neutron, nuclei and atoms. In this proceedings contribution, we review the present understanding of the Weinberg operator as well as the result of the estimation of its effect to the EDM of $^3$He nucleus through the contact CP-odd nuclear force.

nucl-th↗

arXiv2022

QCD corrections in $tqγ$ production at hadron colliders

We study QCD corrections for the associated production of a single top quark and a photon ($tqγ$ production) at hadron colliders. We calculate the NLO cross section at LHC and future collider energies for a variety of kinematical cuts, and we estimate uncertainties from scale dependence and from parton distributions. We also calculate differential distributions in top-quark transverse-momentum and rapidity as well as photon energy. Finally, we study higher-order corrections from soft-gluon emission for this process, and we provide approximate NNLO (aNNLO) results for the cross section and top-quark differential distributions. We also compare our calculations with recent measurements from CMS and ATLAS at the LHC and find that the aNNLO corrections improve the comparison between the data and the Standard Model predictions.

hep-ph↗

arXiv2022

Contribution of the Weinberg-type Operator to atomic and nuclear electric dipole moments

The contribution of the CP violating three-gluon Weinberg operator, $\frac{1}{3!} w f^{abc} ε^{νραβ} G^a_{μν} G^b_{αβ} G^{c μ}_ρ$, to the atomic and nuclear EDMs is estimated using QCD sum rules. After calculating the transition matrix element between the pion and the vacuum through the Weinberg operator, we obtain the long-range CP-odd nuclear force by determining the isovector CP-odd pion-nucleon vertex, using chiral perturbation theory at NLO. The EDMs of $^{199}$Hg, $^{129}$Xe, $^{225}$Ra, $^2$H, and $^3$He are finally given including comprehensive uncertainty analysis. While the leading contribution of the $^{199}$Hg EDM is given by the intrinsic nucleon EDM, that of $^{129}$Xe atom may be dominated by the one-pion exchange CP-odd nuclear force generated by the Weinberg operator. From current experimental data of the $^{199}$Hg atomic EDM, we obtain an upper limit on the Weinberg operator magnitude of $\left|w \right| < 4 \times 10^{-10} {\rm GeV}^{-2}$ if we assume that it is the only source of CP violation at the scale $μ=1$ TeV.

hep-ph↗