Nodoka Yamanaka

Linear programming analysis of the R-parity violation within EDM-constraints

A bstractThe constraint on the R-parity violating supersymmetric interactions is discussed in the light of current experimental data of the electric dipole moment of neutron, 129Xe , 205Tl, and 199Hg atoms, and YbF and ThO molecules. To investigate the constraints without relying upon the assumption of the dominance of a particular combination of couplings over all the rest, an extensive use is made of the linear programming method in the scan of the parameter space. We give maximally possible values for the EDMs of the proton, deuteron, 3He nucleus, 211Rn, 225Ra, 210Fr, and the R-correlation of the neutron beta decay within the constraints from the current experimental data of the EDMs of neutron, 129Xe, 205Tl, and 199Hg atoms, and YbF and ThO molecules using the linear programming method. It is found that the R-correlation of the neutron beta decay and hadronic EDMs are very useful observables to constrain definite regions of the parameter space of the R-parity violating supersymmetry.

Quark tensor charge and electric dipole moment within the Schwinger-Dyson formalism

We calculate the tensor charge of the quark in the QCD-like theory in the Landau gauge using the Schwinger-Dyson formalism. It is found that the dressed tensor charge of the quark is significantly suppressed against the bare quark contribution, and the result agrees qualitatively with the analyses in the collinear factorization approach and lattice QCD. We also analyze the quark confinement effect with the phenomenological strong coupling given by Richardson, and find that this contribution is small. We show that the suppression of the quark tensor charge is due to the superposition of the spin flip of the quark arising from the successive emission of gluons which dress the tensor vertex. We also consider the relation between the quark and the nucleon electric dipole moments by combining with the simple constituent quark model.

Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism

We calculate the scalar, axial, and pseudoscalar charges of the quark in the Schwinger-Dyson formalism of Landau gauge QCD. It is found that the dressed quark scalar density of the valence quark is significantly enhanced against the bare quark contribution, and the result explains qualitatively the phenomenologically known value of the pion-nucleon sigma term and also that given by lattice QCD. Moreover, we show that the Richardsons interquark potential suppresses the quark scalar density in the Higashjima-Miransky approximation. This fact suggests that the quark scalar density is an observable that is sensitive to quark confinement. For the quark axial charge, we find that it is suppressed due to the gluon dynamics. The result of the quenched analysis agrees qualitatively with the experimental data of the isovector axial coupling constant

Two-loop level rainbowlike supersymmetric contribution to the fermion electric dipole moment

g_A

Standard model contribution to the electric dipole moment of the deuteron, 3H, and 3He nuclei

. We show that the suppression of the quenched axial charge is due to a mechanism similar to that of the quark tensor charge. In the Schwinger-Dyson equation with the leading unquenching quark-loop contribution the quark axial charge is more suppressed, due to the anomaly effect. The quark pseudoscalar density is found to be large, and is divergent as the bare quark becomes massless. This result is in agreement with the phenomenological current algebraic analysis, and explains well the dominance of the pion-pole contribution.

Sfermion loop contribution to the two-loop level fermion electric dipole moment in R-parity violating supersymmetric models

We calculate the two-loop level electric and chromo-electric dipole moments of the fermion involving fermion-sfermion inner loop, gaugino, and higgsino in the minimal supersymmetric standard model, and analyze the chromo-electric dipole moment with the top-stop inner loop. It is found that this contribution is comparable with, and even dominates in some situation over the Barr-Zee type diagram generated from the CP-violation of the top squark sector in TeV scale supersymmetry breaking.

R-parity violating supersymmetric contributions to the neutron beta decay

A bstractWe calculate for the first time the electric dipole moment (EDM) of the deuteron, 3H, and 3He 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 6Li, 9Be nuclei, and the atomic EDMs of 129Xe, 199Hg, 211Rn, and 225Ra generated through the nuclear Schiff moment. We then analyze the source of theoretical uncertainties and show some possible ways to overcome them.

A Reappraisal of two-loop contributions to the fermion electric dipole moments in R-parity violating supersymmetric models

The supersymmetric extension of the standard model is one of the favored candidates of new physics. It has many advantages which resolve theoretical and observational problems of the standard model (SM), and has been exhaustively studied over decades [1]. The supersymmetric SM allows also baryon number or lepton number violating interactions, known as the R-parity violating (RPV) interactions. The RPV effects have also been constrained from the analysis of various phenomena [2]. In searching for new physics beyond the SM, the electric dipole moment (EDM) plays a very important role. The EDM is an observable sensitive to the P and CP violations of the underlying theory, and provides excellent information about the new physics for many reasons. First, it can be measured in many systems and many accurate experimental data are available [3]. Second, it has a very small SM contribution [4], so that any observation of finite EDM will be a direct indication of new physics. Finally, the EDM is sensitive to many new physics, in particular the supersymmetry, and many supersymmetric models with [5–8] and without [9–16] the conservation of R-parity have been studied. In the RPV supersymmetric model with trilinear RPV interactions, it has been found that the fermion (quark or lepton) EDM does not receive any one-loop level contribution [10], and the two-loop level contribution has been analyzed in detail to give the Barr-Zee type diagram [17] with fermion loops as the leading contribution [12, 15]. In previous works however, Barr-Zee type process with sfermion loops has not been considered so far, although it involves the same set of coupling constants. In this paper we will evaluate the Barr-Zee type diagrams with sfermion loop generated by RPV interactions to clarify the relative size between the currently known fermion loop contribution. It is actually found that the sfermion loop effect acts destructively to the fermion loop one, and that it can be significant in some situation. The RPV interactions are generated by the following superpotential:

R-parity violating supersymmetric Barr-Zee type contributions to the fermion electric dipole moment with weak gauge boson exchange

We investigate the contribution to the angular correlation coefficients of the neutron beta decay within the R-parity violating (RPV) minimal supersymmetric standard model (MSSM). The RPV effects contribute to the scalar interaction at the tree level. The coefficient of the effective scalar interaction of the nucleon is determined in terms of the nucleon mass difference. On the basis of the recent update of the analyses of the superallowed Fermi transitions and the recent measurement of transverse polarization of the emitted electrons at PSI, we deduce new upper limits on the RPV couplings and compare them with those obtained through the pion decay and atomic electric dipole moment (EDM). We also give a comprehensive analysis of angular correlations sensitive to the RPV interactions.

R-parity violating supersymmetric contributions to the neutron beta decay at the one-loop level

We reexamine the R-parity violating contribution to the fermion electric and chromo-electric dipole moments (EDM and cEDM) in the two-loop diagrams. It is found that the leading Barr-Zee type two-loop contribution is smaller than the result found in previous works, and that EDM experimental data provide looser limits on RPV couplings.