121037160
The high-energy behavior of the Feynman amplitude and gauge invariance
15252744
Precise Numerical Evaluation of the Scalar One-Loop Integrals with the Infrared Divergence
We present a new approach for obtaining very precise integration results for infrared vertex and box diagrams, where the integration is carried out directly without performing any analytic integration of Feynman parameters. Using an appropriate numerical integration routine with an extrapolation method, together with a multi-precision lib rary, we have obtained integration results which agree with the analytic results to 10 digits even for such a very small photon mass as 10 150 GeV in the infrared vertex diagram.
15312798
Monte Carlo Approach to Radiative Corrections in Bhabha Scattering
§ 1. lntroduction It has become a common understanding that detailed theoretical predictions for e+ e- experiments should include the radiative corrections with multi-photon contribu­ tion. A well-known example is the significant modification of the apparent cross section around the Z-boson pole at LEP.ll The study of inclusive processes with multi-photon emission has led some authors to propose several kinds of Monte Carlo generators. 2 l In a pre~ious paper 3 l we have reported a new method for the Monte Carlo generator of multi-photon and have shown some results obtained via a computer progam written for muon pair production in e+ e- annihilation. This is a QED version of the parton shower model which has been studied extensively in QCD. In this paper we generalize this method to the Bhabha scattering by employing essen­ tially the same algorithm as that for muon pair production. It will be convenient to summarize the main features of the algorithm to generate photons. We rely on the technique to sum up all the collinear singularities, which plays an essential role in the parton shower model. 4 J The present model is limited to the leading logarithmic approximation, though there is no difficulty in principle to include the next-to-leading corrections. 5 l This approximation is reasonable as the QED coupling a is very small compared with that in QCD. Another remarkable feature is that the transverse momentum distribution of produced photons is derived correctly once one imposes the four-momentum conservation at each of branching vertices. 4 l This is a consequence of the branching, e±--> e±y, being aprocess of 1--> 2 bodies.
118595829
Full $\mathcal{O}(\alpha)$ electroweak radiative corrections to $e^+e^- \rightarrow e^+e^- \gamma$ at the ILC with GRACE-Loop
By using the GRACE-Loop system, we calculate the full $\mathcal{O}(\alpha)$ electroweak radiative corrections to the process $e^+e^- \rightarrow e^+e^- \gamma$, which is important for future investigations at the International Linear Collider (ILC). With the GRACE-Loop system, the calculations are checked numerically by three consistency tests: ultraviolet finiteness, infrared finiteness, and gauge-parameter independence. The results show good numerical stability when quadruple precision is used. In the phenomenological results, we find that the electroweak corrections to the total cross section range from $\sim -4\%$ to $\sim -21\%$ when $\sqrt{s}$ varies from $250$ GeV to $1$ TeV. The corrections also significantly affect the differential cross sections, which are a function of the invariant masses and angles and the final-particle energies. Such corrections will play an important role for the high-precision program at the ILC.
123615884
Automation of loop amplitudes in numerical approach
Abstract An automatic calculating system GRACE-L1 of one-loop Feynman amplitude is reviewed. This system can be applied to 2 to 2-body one-loop processes. A sample calculation of 2 to 3-body one-loop amplitudes is also presented.
54183358
Calculation of Single Top Quark Production in Electron-Positron Scattering
96097660
Laser-cooled radioactive francium factory at CYRIC
Abstract A factory of laser-cooled francium (Fr) atoms is being developed to search for the electric dipole moment (EDM) of the electron. The factory has achieved the production of Fr ions of 9 × 10 5  particles/s and transport with a transmission efficiency of 2%. In pilot experiments, the magneto-optical trapping of rubidium (Rb) has been performed using a new ion-to-atom converter. To achieve the Fr trap, the development and design of each of the factory’s components are in progress.
453979
S4 Flavor Model of Quarks and Leptons
We present an S4 flavor model to unify quarks and leptons in the framework of the SU(5) GUT. Three generations of 5-plets in SU(5) are assigned to be 31 of S4 while the first and the second generations of 10-plets in SU(5) are assigned to be 2 of S4 ,a nd the third generation of 10-plet is to be 11 of S4. Right-handed neutrinos are also assigned to be 2 for the first and second generations and 11 for the third generation, respectively. Taking vacuum alignments of relevant gauge singlet scalars, we predict the quark mixing as well as the tri-bimaximal mixing of neutrino flavors. Especially, the Cabbibo angle is predicted to be 15 ◦ in the limit of the vacuum alignment. We can improve the model to predict observed CKM mixing angles.
119213142
Pairing fluctuations and gauge symmetry restoration in rotating superfluid nuclei
Rapidly rotating nuclei provide us good testing grounds to study the pairing correlations; in fact, the transition from the superfluid to the normal phase is realized at high-spin states. The role played by the pairing correlations is quite different in these two phases: The static (BCS like mean-field) contribution is dominant in the superfluid phase, while the dynamic fluctuations beyond the mean-field approximation are important in the normal phase. The influence of the pairing fluctuations on the high-spin rotational spectra and moments of inertia is discussed.
116955892
Realisability of SUSY discrete flavour symmetry in our universe
We study the realisation of supersymmetric discrete flavour symmetry models to the thermal history of our universe. We focus on the evolution of the pseudo moduli field among the flavons by taking into account finite temperature corrections. We show that the pseudo moduli flavon dominates the energy density of our universe and this domination makes crucially difficult to realise the flavour symmetry models in our universe. We also discuss possible extensions of the supersymmetric discrete flavour symmetry models which can ensure the consistency of the models with the thermal history of our universe. Finally, we show an extension to realise the thermal inflation by the flavon domination.
118633837
Like-Sign Dimuon Asymmetry of B0 Meson and LFV in SU(5) SUSY GUT with S4 Flavor Symmetry
The like-sign dimuon charge asymmetry of the B meson, which was reported in the DO Collaboration, is studied in the SU(5) SUSY GUT model with S4 flavor symmetry. Additional CP violating effects from the squark sector are discussed in Bs- ¯ Bs mixing process. The predicted like-sign charge asymmetry is in the 2σ range of the combined result of DO and CDF measurements. Since the SUSY contributions in the quark sector affect to the lepton sector because of the SU(5) GUT relation, two predictions are given in the leptonic processes: (i) both BR(μ → eγ) and the electron EDM are close to the present upper bound, (ii) the decay ratios of τ decays, τ → μγ and τ → eγ, are related to each other via the Cabibbo angle λc :B R( τ → eγ)/BR(τ → μγ) � λ 2. These are testable at future experiments. Subject Index: 142, 151, 152, 154, 158