arXiv subjects
Publications and source records attributed to Nodoka Yamanaka.
The electric dipole moment (EDM) is an excellent probe of new physics beyond the standard model of particle physics. The EDM of light nuclei is particularly interesting due to the high sensitivity to the hadron level CP violation. In this proceedings contribution, we investigate the mechanism of the generation of the EDM for several light nuclei and the prospect for the discovery of new physics.
The electric dipole moment (EDM) is a very sensitive probe of CP violation beyond the standard model, and it as been measured in many systems such as atoms, neutrons, etc. The EDM of composite systems may be sensitive to several elementary level CP violating processes, but the theoretical evaluations of the CP violation at different physical (atomic, nuclear, hadronic, elementary) hierarchies are required to unveil them. In this context, we are particularly interested in which CP violating processes are enhanced in a given system, or vice versa. In this proceedings contribution, we will give an overview of the enhancement and suppression of CP violation in processes contributing to the EDMs of composite systems.
Quarkonium production in proton-proton (pp) collision provides interesting means to study the parton content and their correlations in the proton. Recent LHC and Tevatron data of J/psi + Z, J/psi + W and J/psi +J/psi production suggest the relevance of double parton scatterings (DPSs) as opposed to single parton scatterings (SPSs). In this proceedings contribution, we review the corresponding SPS contributions and discuss their upper limits set up by quark-hadron duality. These allow us to perform an improved extraction of the DPS yields and of their implications.
The measurement of the electric dipole moment (EDM) is an excellent test of the standard model of particle physics, and the detection of a finite value is signal of a new source of CP violation beyond it. Among systems for which the EDM can be measured, light nuclei are particularly interesting due to their high sensitivity to new physics. In this proceedings contribution, we examine the sensitivity of the EDM of several light nuclei to the CP-odd one pion-exchange nucleon-nucleon interaction within the cluster model. We suggest an approximate sum rule for the nuclear EDM.
We calculate the scalar and tensor charges of the nucleon in 2+1-flavor lattice QCD, for which the systematics of the renormalization of the disconnected diagram is well controlled. Numerical simulations are performed at a single lattice spacing a = 0.11 fm. We simulate four pion masses, which cover a range of $m_π\sim$ 290 - 540 MeV, and a single strange quark mass close to its physical value. The statistical accuracy is improved by employing the so-called low-mode averaging technique and the truncated solver method. We study up, down, and strange quark contributions to the nucleon charges by calculating disconnected diagrams using the all-to-all quark propagator. Chiral symmetry is exactly preserved by using the overlap quark action to avoid operator mixing among different flavors, which complicates the renormalization of scalar and tensor matrix elements and leads to possibly large contamination to the small strange quark contributions. We also study the nucleon axial charge with contribution from the disconnected diagram. Our results are in reasonable agreement with experiments and previous lattice studies.
The production process of quarkonia in proton-proton (pp) collision is a very good probe of the parton structure of the proton. Recent experimental data of the production of J/psi+vector boson or quarkonium pairs at the LHC and Tevatron suggest the relevance of double parton scatterings (DPS). We discuss here the single parton scattering (SPS) contribution to the J/psi +Z, J/psi +W, and J/psi +J/psi productions in hadron collisions. By revisiting the computations of the SPS contributions to the J/psi+Z and J/psi +W productions, we demonstrate that the ATLAS data in fact show evidence for DPS.
In this proceeding, we present the results of the theoretical evaluations of the electric dipole moment (EDM) of light nuclei, including the preliminary value for the 11B nucleus. From the data, we can infer an approximate counting rule, and predict the EDM of other light nuclei.
We evaluate the frame-independent gluon and charm parton-distribution functions (PDFs) of the deuteron utilizing light-front quantization and the impulse approximation. We use a nuclear wave function obtained from solving the nonrelativistic Schroedinger equation with the realistic Argonne v18 nuclear force, which we fold with the proton PDF. The predicted gluon distribution in the deuteron (per nucleon) is a few percent smaller than that of the proton in the domain x_{bj} = Q^2 / (2 p_N \cdot q) \sim 0.4, whereas it is strongly enhanced for x_{bj} larger than 0.6. We discuss the applicability of our analysis and comment on how to extend it to the kinematic limit x_{bj} \to 2. We also analyze the charm distribution of the deuteron within the same approach by considering both the perturbatively and non-perturbatively generated (intrinsic) charm contributions. In particular, we note that the intrinsic-charm content in the deuteron will be enhanced due to 6-quark "hidden-color" QCD configurations.
We re-analyse the associated production of a prompt J/psi and a W boson in pp collisions at the LHC following the results of the ATLAS Collaboration. We perform the first study of the Single-Parton-Scattering (SPS) contributions at the Next-to-Leading Order (NLO) in alpha_s in the Colour-Evaporation Model (CEM), an approach based on the quark-hadron-duality. Our study provides clear indications for Double-Parton-Scattering (DPS) contributions, in particular at low transverse momenta, since our SPS CEM evaluation, which can be viewed as a conservative upper limit of the SPS yields, falls short compared to the ATLAS experimental data by 3.1 standard deviations. We also determine a finite allowed region for sigma_eff, inversely proportional to the size of the DPS yields, corresponding to the otherwise opposed hypotheses, namely our NLO CEM evaluation and the LO direct Colour-Singlet (CS) Model contribution. In both cases, the resulting DPS yields are significantly larger than that initially assumed by ATLAS based on jet-related analyses but is consistent with their observed raw-yield azimuthal distribution and with their prompt J/psi+J/psi and Z + prompt J/psi data.
The electric dipole moment is a very sensitive probe of CP violation beyond the standard model. Light nuclei are particularly interesting since the CP violation may be enhanced by nuclear many-body effects. In this proceeding, we present the current status of the theoretical evaluations of the electric dipole moment of light nuclei in the ab initio approach and in the cluster model. We add the preliminary result of the evaluation of the electric dipole moment of $^7$Li which is treated in a cluster model with a triton.
We calculate for the first time the electric dipole moment (EDM) of $^{13}$C generated by the isovector CP-odd pion exchange nuclear force in the $α$-cluster model, which describes well the structures of low lying states of the $^{13}$C nucleus. The linear dependence of the EDM of $^{13}$C on the neutron EDM and the isovector CP-odd nuclear coupling is found to be $d_{^{13}{\rm C}} = -0.33 d_n - 0.0020 \bar G_π^{(1)}$. The linear enhancement factor of the CP-odd nuclear coupling is smaller than that of the deuteron, due to the difference of the structure between the $1/2^-_1$ state and the opposite parity ($1/2^+$) states. We clarify the role of the structure played in the enhancement of the EDM. This result provides good guiding principles to search for other nuclei with large enhancement factor. We also mention the role of the EDM of $^{13}$C in determining the new physics beyond the standard model.
We calculate the electric dipole moment (EDM) of the deuteron in the standard model with $|ΔS| =1$ interactions by taking into account the $NN - ΛN - ΣN$ channel coupling, which is an important nuclear level systematics. The two-body problem is solved with the Gaussian Expansion Method using the realistic Argonne $v18$ nuclear force and the $YN$ potential which can reproduce the binding energies of $^3_Λ$H, $^3_Λ$He, and $^4_Λ$He. The $|ΔS| =1$ interbaryon potential is modeled by the one-meson exchange process. It is found that the deuteron EDM is modified by less than 10\%, and the main contribution to this deviation is due to the polarization of the hyperon-nucleon channels. The effect of the $YN$ interaction is small, and treating $ ΛN$ and $ ΣN$ channels as free is a good approximation for the EDM of the deuteron.
In this review, we summarize the theoretical development on the electric dipole moment of light nuclei. We first describe the nucleon level CP violation and its parametrization. We then present the results of calculations of the EDM of light nuclei in the ab initio approach and in the cluster model. The analysis of the effect of several models beyond standard model is presented, together with the prospects for its discovery. The advantage of the electric dipole moment of light nuclei is focused in the point of view of the many-body physics. The evaluations of the nuclear electric dipole moment generated by the $θ$-term and by the CP phase of the Cabibbo-Kobayashi-Maskawa matrix are also reviewed.
The nuclear electric dipole moment is a very sensitive probe of CP violation beyond the standard model, and for light nuclei, it can be evaluated accurately using the few-body calculational methods. In this talk, we present the result of the evaluation of the electric dipole moment of 3-body and 4-body systems using the Gaussian expansion method in the ab initio approach and in the cluster model. We also give the future prospects for the discovery of new physics beyond it within the sensitivity of prepared experiments.
The nuclear electric dipole moment is a very sensitive probe of CP violation beyond the standard model, and for light nuclei, it can be evaluated accurately using few-body calculational methods. In this talk, we present the deuteron, $^3$He, $^3$H, $^6$Li, and $^9$Be electric dipole moments calculated using the Gaussian expansion method with a realistic nuclear force, and assuming the one-meson exchange model for the P, CP-odd nuclear force. We then give future prospects for models beyond the standard model such as the supersymmetry.
We calculate for the first time the electric dipole moment (EDM) of the deuteron, $^3$H, and $^3$He nuclei generated by the one-meson exchange CP-odd nuclear force in the standard model. The effective $|ΔS| = 1$ four-quark operators are matched to the $|ΔS| = 1$ standard model processes involving the CP phase of the Cabibbo-Kobayashi-Maskawa matrix at the electroweak scale and run down to the hadronic scale $μ= 1$ GeV according to the renormalization group evolution in the next-to-leading logarithmic order. At the hadronic scale, the hadron matrix elements are modeled in the factorization approach. We then obtain the one-meson (pion, eta meson, and kaon) exchange CP-odd nuclear force, which is the combination of the $|ΔS| = 1$ meson-baryon vertices which issue from the penguin operator and the hyperon-nucleon transition. From this CP-odd nuclear force, the nuclear EDM is calculated with the realistic Argonne $v18$ interaction and the CP-odd nuclear force using the Gaussian expansion method. It is found that the EDMs of light nuclear systems are of order $O(10^{-31}) e $ cm. We also estimate the standard model contribution to other hadronic CP violating observables such as the EDMs of $^6$Li, $^9$Be nuclei, and the atomic EDMs of $^{129}$Xe, $^{199}$Hg, $^{211}$Rn, and $^{225}$Ra generated through the nuclear Schiff moment. We then analyze the source of theoretical uncertainties and show some possible ways to overcome them.
We discuss the dark matter in the hidden gauge theory. We propose a scenario where the mini-inflation dilutes the dark matter density. This scenario is consistent with the current baryon number asymmetry.
We calculate for the first time the electric dipole moment (EDM) of the $^6$Li nucleus within the alpha + p + n three-body cluster model using the Gaussian expansion method, assuming the one meson exchange P, CP-odd nuclear forces. It is found that the EDM of the $^6$Li is 2 times more sensitive on the isovector pion exchange P, CP-odd nuclear force than the deuteron EDM, due to the CP-odd interaction between the nucleons and the alpha cluster. The $^9$Be EDM is also calculated in the same framework as an alpha + alpha + n three-body system. We also test the ab initio calculation of the EDM of the deuteron, $^3$H and $^3$He nuclei using the realistic Argonne $v18$ nuclear force. In the ab initio calculations, good agreements with previous studies are obtained. We finally discuss the prospects for the new physics beyond the standard model.