The anomalous chiral perturbation theory meson Lagrangian to order p6p^6 revisited

We present a revised and extended construction of the mesonic Lagrangian density in chiral perturbation theory (ChPT) at order $p^6$ in the anomalous (or epsilon) sector, ${\cal{L}}_{6,\epsilon}$. After improving several aspects of the strategy we used originally, i.e., a more efficient application of partial integration, the implementation of so-called Bianchi identities, and additional trace relations, we find the new monomial sets to include 24 $SU(N_f)$, 23 SU(3), and 5 SU(2) elements. Furthermore, we introduce 8 supplementary terms due to the extension of the chiral group to $SU(N_f)_L \times SU(N_f)_R \times U(1)_V$.Comment: 21 pages, Latex, using RevTe

Coherent \pi^0 threshold production from the deuteron at Q^2 = 0.1 GeV^2/c^2

First data on coherent threshold \pi^0 electroproduction from the deuteron taken by the A1 Collaboration at the Mainz Microtron MAMI are presented. At a four-momentum transfer of q^2=-0.1 GeV^2/c^2 the full solid angle was covered up to a center-of-mass energy of 4 MeV above threshold. By means of a Rosenbluth separation the longitudinal threshold s wave multipole and an upper limit for the transverse threshold s wave multipole could be extracted and compared to predictions of Heavy Baryon Chiral Perturbation Theory.Comment: 7 pages, 7 figures, latex2

Renormalization of relativistic baryon chiral perturbation theory and power counting

We discuss a renormalization scheme for relativistic baryon chiral perturbation theory which provides a simple and consistent power counting for renormalized diagrams. The method involves finite subtractions of dimensionally regularized diagrams beyond the standard $\bar{\rm MS}$ scheme of chiral perturbation theory to remove contributions violating the power counting. This is achieved by a suitable renormalization of the parameters of the most general effective Lagrangian. In addition to simplicity our method has the benefit that it can be easily applied to multiloop diagrams. As an application we discuss the mass and the scalar form factor of the nucleon and compare the results with the expressions of the infrared regularization of Becher and Leutwyler.Comment: 20 pages, RevTex, 1 figure, published version is shortene

Chiral effective field theories of the strong interactions

Effective field theories of the strong interactions based on the approximate chiral symmetry of QCD provide a model-independent approach to low-energy hadron physics. We give a brief introduction to mesonic and baryonic chiral perturbation theory and discuss a number of applications. We also consider the effective field theory including vector and axial-vector mesons.Comment: 22 pages, 9 figures, proceedings of "Many-Body Structure of Strongly Interacting Systems", Mainz, Germany, Feb. 23-25 201

Coherent pion electroproduction on the deuteron in the Δ(1232)\Delta(1232) resonance region

Coherent pion electroproduction on the deuteron is studied in the $\Delta(1232)$ resonance region in the impulse approximation, i.e., neglecting pion rescattering and two-body effects. The elementary reaction on the nucleon is described in the framework of an effective Lagrangian approach including the dominant $P_{33}(1232)$ resonance and the usual background terms of the Born contributions for $\pi^0$ production. We have studied the influence of these different contributions on the various structure functions which determine the unpolarized exclusive differential cross section in a variety of kinematic regions