Tokuzo Shimada

String based methods in perturbative gravity

Abstract String theory implies a relatively modest growth in computational complexity for perturbative gravity calculations as compared to gauge theory calculations, contrary to field theory expectations. An explicit string-based calculation, which would be extremely difficult using conventional techniques, is presented to illustrate this.

Electroweak corrections to muon pair production in electron-positron annihilation at high energy

Abstract The lowest-order radiative corrections to the reaction e + + e − → μ + + μ − are analyzed in the standard SU(2) × U(1) electroweak theory. The virtual corrections are calculated in the on-shell renormalization scheme. The masses of the recently discovered Z-boson and W-boson are used to fix the weak coupling constants. The decay width of the Z-boson is also taken into account. By including the cross section of hard photon emission, various kinds of distribution are obtained both analytically and numerically. The magnitude of the effective axial vector coupling is confirmed to be quite different from that previously taken in the calculations within QED. This difference, which is due to the genuine electroweak corrections, reaches about 10% in angular distribution at the energy around the Z-boson mass, even if the reasonable effect of a hard photon is included.

Periodicity manifestations in the turbulent regime of the globally coupled map lattice

We revisit the globally coupled map lattice. We show that in the so called turbulent regime various periodic cluster attractor states are formed, even though the coupling between the maps are very small relative to the nonlinearity in the element maps. Most outstanding is a maximally symmetric three cluster attractor in period-3 motion, due to the foliation of the period-3 window of the element logistic maps. An analytical approach is proposed which successfully explains the systematics of various periodicity manifestations in the turbulent regime. The linear stability of the period-3 cluster attractors is investigated.

Amplitude and natural-parity-exchange analysis of K±p → (Kπ)±p data at 10 GeV/c

Abstract High statistics data for the reactions K ± p → K S 0 π ± p at 10 GeV/ c are analysed. The K ∗ (1 − ), K ∗ (2 + ), and K ∗ (3 − ) resonance parameters and production cross sections are calculated. The Kπ production amplitudes are determined as a function of t and the produced Kπ mass. Isoscalar natural-parity-exchange (NPE) is dominant. The t dependence of the K ± NPE amplitudes have a cross-over at t = −0.3 (GeV/ c ) 2 for both K ∗ (890) and K ∗ (1420) production, being more pronounced for the K ∗ (1420). Natural-parity-exchange interference effects are isolated. The NPE amplitudes are decomposed into pomeron-, f-, and ω-exchange contributions. S-wave Kπ production is found to be consistent with the Kπ partial-wave analyses of charge-exchange reactions.

Incompatibility of torsion with the Gauss-Bonnet combination in the bosonic string

Abstract In general, either manifest unitary or the inclusion of the antisymmetric tensor field strength as torsion can be trivially implemented via field redefinitions in string theory low energy effective actions. However, requiring both simultaneously is explicitly shown to be incompatible in the bosonic string effective action. We also discuss the usefulness of the redefinition theorem as a technical tool.

The correlation between charge and energy flow within cascade models for quark and hadron jets

AbstractWe consider the ratio

A resolution of the question of ππ and Kπ “anomalies”

\frac{{\Delta Q}}{{\Delta \varepsilon }}

Periodicity manifestations in the non-locally coupled maps

of the charge and energy fraction carried by particles in the angular interval ΔΩ with respect to the jet axis, where we assume a recursive scheme for the hadron cascade. A measurement of this ratio inep andvp collisions determines the quark chargeQq at any angle ΔΩ and ine+e−-annihilations alsoQq4 can be obtained. In hadron hadron collisions this ratio discriminates in a very direct way between different production models. We consider the “stopping quark” model, the “two dual sheet” model, and finally a leading cluster model. More data on