Related papers: Large Nc and Chiral Dynamics
The Thirring model is an interacting fermion theory with current-current interaction. The model in $1+2$ dimensions has applications in condensed-matter physics to describe the electronic excitations of Dirac materials. Earlier…
Recent attempts to detect the pion polarizability via analysis of $\gamma\gamma\rightarrow\pi\pi$ measurements are examined. The connection between calculations based on dispersion relations and on chiral perturbation theory is established…
We show how the unitarized description of pion nucleon scattering within Heavy Baryon Chiral Perturbation Theory can be considerably improved, by a suitable reordering of the expansion over the nucleon mass. Within this framework, the…
By using unitarized two-loop Chiral Perturbation Theory partial waves to describe pion-pion scattering we find that the dominant component of the lightest scalar meson does not follow the q-qbar dependence on the number of colors that, in…
We develop a "variational mass" expansion approach, recently introduced in the Gross--Neveu model, to evaluate some of the order parameters of chiral symmetry breakdown in QCD. The method relies on a reorganization of the usual perturbation…
We extend from operators with one derivative to operators with three derivatives the analysis of two-body hadronic parity violation in a combined pionless effective field theory (EFT$_{\pi\!/}$) and large-$N_c$ expansion, where $N_c$ is the…
An explicitly crossing-symmetric decomposition of the pion-pion scattering amplitudes into low- and high-energy components is established. The high-energy components are entirely determined by absorptive parts at high energies. With the…
A detailed investigation of the low-energy chiral expansion is presented within a model truncation of QCD. The truncation allows for a phenomenological description of the quark-quark interaction in a framework which maintains the global…
We study supersymmetric QCD with N_f<N_c in the limit of small supersymmetry-breaking masses and smaller quark masses using the weak-coupling Kahler potential. We calculate the full spectrum of this theory, which manifests a chiral symmetry…
We explore potential explanations for why using large-$N_c$ ($N_c$ is the number of colors) scaling to determine the relative size of few-nucleon low-energy operators agrees with experiment even when dynamical $\Delta$'s are not explicitly…
A recently proposed set of sum rules, based on the pion-Kaon scattering amplitudes and their crossing-symmetric conjugates are analysed in detail. A key role is played by the $l=0$ $\pi\pi\to K\overline K$ amplitude which requires an…
It was recently conjectured that, in SU(3) gauge theories with fundamental quarks, valence spontaneous chiral symmetry breaking is equivalent to condensation of local dynamical chirality and appearance of chiral polarization scale…
The near-threshold n p -> d pi0 cross section is calculated in chiral perturbation theory to next-to-leading order in the expansion parameter sqrt{M m_pi}/Lambda_chi. At this order irreducible pion loops contribute to the relevant…
We study Quantum Chromodynamics in the chiral large $N_c$ limit which contains a left-handed Weyl fermion in the fundamental representation, a left-handed Weyl fermion in the two index antisymmetric representation and $(N_c-3)$ left-handed…
We use a variational procedure to study finite density QCD in an approximation in which the interaction between quarks is modelled by that induced by instantons. We find that uniform states with conventional chiral symmetry breaking have…
We study pi eta scattering in a model which starts from the tree diagrams of a non-linear chiral Lagrangian including appropriate resonances. Previously, models of this type were applied to pi pi and pi K scattering and were seen to require…
For five different electron and hole systems in two dimensions (Si MOSFET's, p-GaAs, p-SiGe, n-GaAs and n-AlAs), the critical density, $n_c$ that marks the onset of strong localization is shown to be a single power-law function of the…
As a first result of two new partial-wave analyses, one of the pp and another one of the np scattering data below 500 MeV, we report a study of the long-range chiral two-pion exchange interaction which contains the chiral coupling constants…
It is commonly believed that ${\pi}^0 \to 2 \gamma$ decay shows that there are three colours in Quantum Chromodynamics (QCD). It is shown here that this is not correct. When correct colour dependent charges of the quarks are considered then…
Positivity constraints are derived on pion-nucleon scattering amplitudes and their even-order derivatives inside the Mandelstam Triangle with the help of dispersion relations. Fairly interesting constraints are obtained on some of the low…