Yoshimitsu Shimizu

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We describe the main building blocks of a generic automated package for the calculation of Feynman diagrams. These blocks include the generation and creation of a model file, the graph generation, the symbolic calculation at an intermediate level of the Dirac and tensor algebra, implementation of the loop integrals, the generation of the matrix elements or(More)
We demonstrate applications of numerical integration and visualization algorithms in diverse fields including psychological modeling (biometrics); in high energy physics for the study of collisions of elementary particles; and in medical physics for regulating the dosage of proton beam radiation therapy. We discuss the problems and solution methods, as(More)
Automatic calculation of 1-loop diagrams in the electroweak theory with gauge parameter independence checks Abstract A general non-linear gauge condition is implemented into GRACE, an automated system for the calculation of physical processes in high-energy physics. These new gauge-fixing conditions are used as a very efficient means to check the results of(More)
We have examined the relationship between the anisotropy of the triangular lattice and the electronic states of κ-(BEDT-TTF) 2 X. We have found the spin-liquid behavior in a Mott insulator κ-(BEDT-TTF) 2 Cu 2 (CN) 3 which has nearly regular triangular lattice. The 1 H-NMR study confirmed that this compound shows no magnetic ordering down to 32mK, indicating(More)
We discuss a new approach for the numerical evaluation of loop integrals. The fully numerical calculations of an infrared one-loop vertex and a box diagram are demonstrated. To perform these calculations, we apply an extrapolation method based on the-algorithm. In our approach, the super high precision control in the numerical manipulation is essential to(More)
Extending the method successful for one-loop integrals, the computation of two-loop diagrams with general internal masses is discussed. For the two-loop vertex of non-planar type, as an example, we show a calculation related to Z 0 → t ¯ t vertex. The calculation of loop integrals is essential to obtain the precise theoretical prediction for high-energy(More)