On the Origin of the Enhancementof CP-violating Charge Asymmetries in K→3πK \rightarrow 3\pi Decays Predicted from Chiral Theory

We present an analysis of the enhancement of CP-violating charge asymmetries in $K \rightarrow 3\pi$ decays. Calculations of decay amplitudes are performed on the basis of bosonized strong and weak Lagrangians derived from QCD-motivated quark Lagrangians. We show that the interplay of fourth-order contributions of chiral Lagrangians for strong interactions and penguin operators in weak interactions significantly enhances the charge asymmetries.Comment: DESY 92-106, 15

Reduction of Vector and Axial--Vector Fields in a Bosonized Nambu--Jona--Lasinio Model

We derive the effective action for pseudoscalar mesons by integrating out vector and axial--vector collective fields in the generating functional of the bosonized NJL--model. The corresponding modifications of the nonlinear effective Lagrangian and the bosonized currents, arising at $O(p^4)$, are discussed.Comment: 30p. 1 fig. on reques

Radiative Kaon Decays and CPCP Violation

The amplitudes of $K \rightarrow \pi \gamma^* \rightarrow \pi e^+e^-$ and $K \rightarrow \pi \pi \gamma$ decays have been calculated within chiral Lagrangian approach including higher-order derivative terms and meson loops. The selfconsistency of the simultaneous description of the experimental data on the nonleptonic and radiative kaon decays have been demonstrated. We estimate the effects of ``indirect'' and ``direct'' $CP$-violation in $K^0_L \rightarrow \pi^0 e^+e^-$ decays and discuss $CP$-violating charge asymmetries in $K^{\pm} \rightarrow \pi^{\pm} \pi^0 \gamma$ decays.Comment: 25 p., DESY 93-06

On the p4p^4--corrections to K→3πK \to 3\pi decay amplitudes in nonlinear and linear chiral models

The calculations of isotopic amplitudes and their results for the direct $CP$--violating charge asymmetry in $K^\pm \to 3\pi$ decays within the nonlinear and linear ($\sigma$--model) chiral Lagrangian approach are compared with each other. It is shown, that the latter, taking into account intermediate scalar resonances, does not reproduce the $p^4$--corrections of the nonlinear approach introduced by Gasser and Leutwyler, being saturated mainly by vector resonance exchange. The resulting differences concerning the $CP$ violation effect are traced in some detail.Comment: 14 page

Calculation of Heat-Kernel Coefficients and Usage of Computer Algebra

The calculation of heat-kernel coefficients with the classical DeWitt algorithm has been discussed. We present the explicit form of the coefficients up to $h_5$ in the general case and up to $h_7^{min}$ for the minimal parts. The results are compared with the expressions in other papers. A method to optimize the usage of memory for working with large expressions on universal computer algebra systems has been proposed.Comment: 12 pages, LaTeX, no figures. Extended version of contribution to AIHENP'95, Pisa, April 3-8, 199

Heat-Kernel Calculation of Quark Determinant and Computer Algebra

In this paper there we describe the calculational background of deriving a strong meson Lagrangian from the Nambu--Jona-Lasinio quark model using the computer algebra systems FORM and REDUCE in recursive algorithms, based on the heat-kernel method for the calculation of the quark determinant.Comment: LATEX, 11 p., DESY 92-15

The pi N -> pi pi N reaction around the N(1440) energy

We study the pi N -> pi pi N reaction around the N(1440) mass-shell energy. Considering the total cross sections and invariant mass distributions, we discuss the role of N(1440) and its decay processes. The calculation is performed by extending our previous approach [Phys. Rev. C 69, 025206 (2004)] to this reaction, in which only the nucleon and Delta(1232) were considered as intermediate baryon states. The characteristics observed in the recent data for the pi- p -> pi0 pi0 n reaction obtained by Crystal Ball Collaboration (CBC), can be understood as a strong interference between the two decay processes: N(1440) -> pi Delta(1232) and N(1440) -> N(pi pi)_S. It is also found that the scalar-isoscalar pi pi rescattering effect in the NN*(pi pi)_S vertex, which corresponds to the propagation of sigma meson, seems to be necessary for explain ing the several observables of the pi N -> pi pi N reaction: the large asymmetric shape in the pi0-pi0 invariant mass distributions of the pi- p -> pi0 pi0 n reaction and the pi+ p -> pi+ pi+ n total cross section.Comment: 28 pages, 13 figures. Version to appear in Phys. Rev.