arXiv subjects
Publications and source records attributed to Toru Sato.
We analyze the current status of three P-wave baryon states $N(1710){1/ 2}^+$, $N(1900){3/2}^+$, and $Δ(1600){3/2}^+$ as given in the Review of Particles Physics (RPP). Since the evidence for a particle's existence is linked to its RPP "star" rating, we discuss its subjective present definition. We also present the accumulating evidence supporting these states and give our new "star" rating recommendations.
We examine how the signature of the strange dibaryon resonances shows up in scattering amplitudes and observables of the three-body $\bar{K}NN$-$πY N (Y=Σ, Λ)$ system on the physical real energy axis. The so-called point method is applied to handle logarithmic singularities that appear in solving the Alt-Grassberger-Sandhas equations for the real scattering energies. By taking two different kinds of models for the two-body $\bar{K}N$-$πΣ$ subsystem, both of which reproduce the available data equally well but give quite a different resonance-pole structure for $Λ(1405)$, we also investigate whether the strange-dibaryon production reactions can be used for disentangling the nature of $Λ(1405)$.
The contribution of the R-parity violating trilinear couplings in the supersymmetric model to the fermion electric dipole moment is analyzed at the two-loop level. We show that in general, the Barr-Zee type contribution to the fermion electric dipole moment with the exchange of W and Z bosons is not small compared to the currently known photon exchange one with R-parity violating interactions. We will then give new upper bounds on the imaginary parts of R-parity violating couplings from the experimental data of the electric dipole moments of the electron and of the neutron. The effect due to bilinear R-parity violating couplings, which needs to be investigated separately, is not included in our analyses.
The contribution of the R-parity violating minimal supersymmetric standard model to the neutron beta decay at the one-loop level is investigated. It is found that the baryon number and R-parity violating interactions contribute to the D correlation through one-loop corrections, while the tree level prediction is vanishing. The Fierz interference term is also investigated at the one-loop level by considering the lepton number and R-parity violating interactions. We show that future experimental progress can provide us with better constraints on some of the combinations of R-parity violating couplings.
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.
We examine how the signature of the strange-dibaryon resonances in the barKNN-piSigmaN system shows up in the scattering amplitude on the physical real energy axis within the framework of Alt-Grassberger-Sandhas (AGS) equations. The so-called point method is applied to handle the three-body unitarity cut in the amplitudes. We also discuss the possibility that the strange-dibaryon production reactions can be used for discriminating between existing models of the two-body barKN-piSigma system with Lambda(1405).
The scattering length and effective range of the piSigma channel are studied in order to characterize the strangeness S=-1 meson-baryon scattering and the Lambda(1405) resonance. We examine various off-shell dependence of the amplitude in dynamical chiral models to evaluate the threshold quantities with the constraint at the KbarN threshold. We find that the piSigma threshold parameters are important to the structure of the Lambda(1405) resonance and provide further constraints on the subthreshold extrapolation of the KbarN interaction.
Minimal supersymmetric standard model with R-parity violation (RPVMSSM) contributes to the P-, CP-odd four-quark interaction. The P-, CP-odd four-quark interaction is constrained by the new 199Hg EDM experimental data. It is then possible to constrain R-parity violating (RPV) couplings from the 199Hg EDM data. In this talk, we analyze the RPV contribution to the P-, CP-odd four- quark interaction at the one-loop level to give constraints on RPV parameters.
We present first results on the axial and pseudoscalar $Δ$ form factors. The analysis is carried out in the quenched approximation where statistical errors are small and the lattice set-up can be investigated relatively quickly. We also present an analysis with a hybrid action using staggered sea quarks and domain-wall valence fermions.
The contribution in the R-parity violating (RPV) Minimal Supersymmetric Standard Model (MSSM) to the electric dipole moment (EDM) of $^{199}$Hg at the one-loop level is evaluated. At the one-loop level, the $^{199}$Hg EDM receives RPV contribution whose couplings are of a different type from the tree level analysis. This contribution is shown to be constrained by using the limit to the CP-odd electron-nucleon (e-N) interaction given by the recent result of $^{199}$Hg EDM experiment.
We study the resonance energy of the strange dibaryons using two models with the energy-independent and energy-dependent potentials for the s-wave barKN interaction, both of which are derived by certain reductions from the leading order term of the effective chiral Lagrangian. These potential models produce rather different off-shell behaviors of the two-body barKN - piSigma amplitudes in I=0 channel, i.e., the model with energy-independent (energy-dependent) potential predicts one (two) resonance pole in the Lambda(1405) region, while they describe the available data equally well. We find that the energy-independent potential model predicts one resonance pole of the strange dibaryons, whereas the energy-dependent potential model predicts two resonance poles: one is the shallow quasi-bound state of the barKNN, and another is the resonance of the piYN with large width. An investigation of the binding energy of the strange dibaryons will make a significant contribution to clarify resonance structure of s-wave barKN - piSigma around the Lambda(1405) region.
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 effective scalar interaction of the neutron beta decay is constructed by making use of the relation between isospin asymmetries and the proton-neutron 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. We also point out the existence of new types of angular correlations which are sensitive to the RPV interactions.
We comment on the assertion made by Caselle et al., J. Stat. Mech. 0603, P008 (2006), that the confining (string) potential for three quarks "makes a smooth cross-over transition from the Delta-string to the Y-string configuration at interquark distances of around 0.8 fm". We study the functional dependence of the three-quark confining potentials due to a Y-string, and the Delta-string and show that they have different symmetries, which lead to different constants of the motion (i.e. they belong to different "universality classes" in the parlance of the theory of phase transitions). This means that there is no "smooth cross-over" between the two, when their string tensions are identical, except at the vanishing hyper-radius. We also comment on a certain two-body potential approximation to the Y-string potential.
In this paper we explore the time-reversal-odd triple-correlation coefficient in neutron beta decay, the so-called "D coefficient", using heavy-baryon effective field theory with photon degrees of freedom. We find that this framework allows us to reproduce the known results for the contribution which comes from final-state interactions, and also to discuss higher-order corrections. In particular we are able to show that in the heavy-baryon limit all electromagnetic contributions vanish. By calculating the leading correction to the known result, we give a final expression which is accurate to better than 1%. Hence we extend downwards the range over which the D coefficient could be used to explore time-violation from new physics.
The resonance energies of strange dibaryons are investigated with the use of the \bar{K}NN-πY N coupled-channels Faddeev equation. It is found that the pole positions of the predicted three-body amplitudes are significantly modified when the three-body coupled-channels dynamics is approximated, as is done in the literature, by the effective two-body \bar{K}N interactions.
KNN three body resonance has been studied by KNN-pi Sigma N coupled channel Faddeev equation. The S-matrix pole has been investigated using the analytically continued scattering amplitude on the unphysical Riemann sheet. As a result we found a three-body resonance of strange dibaryon system with the binding energy and width B=76MeV and Γ=54MeV.
Recently the so-called $Θ^+$ resonance has been reported first from SPring8\cite{nakano} and many following experiments showed apparent confirmation of the state. Since $Θ^+$ exclusively decays into either $K^+ n$ or $K^0 p$, it is explained as the predicted pentaquark state which includes $ u u d d \bar{s}$ quarks. However, one yet has to obtain consistent picture of $Θ^+$ and its quantum numbers. We try to explain $Θ^+$ in a conventional picture and show that such picture leads to new predictions on kaon and pion system.