Related papers: U(3) chiral perturbation theory with infrared regu…
We match the results for the subthreshold parameters of pion-nucleon scattering obtained from a solution of Roy-Steiner equations to chiral perturbation theory up to next-to-next-to-next-to-leading order, to extract the pertinent low-energy…
We study the formation of resonances in terms of the chiral SU(3) Lagrangian. At leading order parameter-free predictions are obtained for the scattering of Goldstone bosons off any hadron once we insist on approximate crossing symmetry of…
In the framework of the effective field theory method, we use the experimental data and the perturbative unitarity bounds to determine the values and uncertainty of all the 11 chiral coefficients ($\al_i, i=0, ..., 10$) of the standard…
Positivity constraints on the pion-nucleon scattering amplitude are derived in this article with the help of general S-matrix arguments, such as analyticity, crossing symmetry and unitarity, in the upper part of Mandelstam triangle, R.…
We show that the magnetic moments of the octet baryons can be fitted to an accuracy of 1.5 percent by a phenomenological Lagrangian in which SU(3) breaking corrections appear only linearly. This is in contrast to conventional chiral…
We construct the most general low-energy effective lagrangian including local parity violating terms parametrized by an axial chemical potential or chiral imbalance $\mu_5$, up to ${\cal O}(p^4)$ order in the chiral expansion for two light…
Preliminary results for the Dalitz plot distribution of $\eta^\prime\to\eta\pi\pi$ decays in the frameworks of Large-$N_c$ Chiral Perturbation Theory and Resonance Chiral Theory are given. We hope our results to be of some relevance for the…
$\eta \rightarrow \pi^{0} \gamma \gamma$ and $\ggpipi$ are considered in $O(p^{6})$ chiral perturbation theory. In addition to the usual $\rho,\omega$ contributions, there are two $O(p^{6})$ operators (${\cal L}_{6,m}$) arising from…
The main elements and methods of chiral perturbation theory, the effective field theory of the Standard Model below the scale of spontaneous chiral symmetry breaking, are summarized. Applications to the interactions of mesons and baryons at…
We calculate the complete $T$-matrices of pion-nucleon ($\pi N$) scattering to the third order in heavy baryon SU(3) chiral perturbation theory. The baryon mass in the chiral limit $M_0$ and the low-energy constants are determined by…
In these proceedings we provide a brief summary of the findings of a previous article where we have studied the photon-photon scattering into longitudinal weak bosons within the context of the electroweak chiral Lagrangian with a light…
In this paper, we employ chiral effective field theory to study the process of electron-positron annihilation into four pions in the low energy region within $E_{c.m.}\leq 0.6$ GeV. The prediction of the cross section is obtained through…
These lectures give an introduction to baryon chiral perturbation theory. I show in detail how to construct the chiral effective pion-nucleon Lagrangian in the one loop approximation. Particular emphasis is put on the physics related to…
A successful effective field theory program requires besides the most general effective Lagrangian a perturbative expansion scheme for observables in terms of a consistent power counting method. We discuss a renormalization scheme for…
The Goldberger-Treiman discrepancy in SU(3) is analyzed in the framework of heavy baryon chiral perturbation theory (HBChPT). It is shown that the discrepancy at leading order is entirely given by counterterms from the order p^3 Lagrangian,…
We consider the scattering of Goldstone bosons in the range of intermediate energies, and in particular focus our attention on the scattering of pions in the $\rho$-resonance region. The chiral perturbation series is obtained to order $E^4$…
A general procedure for the calculation of a class of two-loop Feynman diagrams is described. These are two-point functions containing three massive propagators, raised to integer powers, in the denominator, and arbitrary polynomials of the…
There exist both continuum and lattice regularizations of gauge theories with fermions which preserve chiral U(1) invariance ("fermion number"). Such regularizations necessarily break gauge invariance but, in a covariant gauge, one recovers…
We calculate the T-matrices of pseudoscalar meson octet-baryon scattering to one-loop order in SU(3) heavy baryon chiral perturbation theory. The pertinent combinations of low-energy constants are determined by fitting to phase shifts of…
A $1/\N$ expansion of the chiral Lagrangian for baryons is formulated and used to study the low-energy dynamics of baryons interacting with the pion nonet $\pi$, $K$, $\eta$ and $\eta^\prime$ in a combined expansion in chiral symmetry…