We present a new amplitude analysis of the $\eta\pi$ $D$-wave in $\pi^- p\to \eta\pi^- p$ measured by COMPASS. Employing an analytical model based on the principles of the relativistic $S$-matrix, we find two resonances that can be identified with the $a_2(1320)$ and th...

Comment: 37 pages, 31 figures. Angles of the photocouplings at the pole adapted to the convention of Phys. Rev. C 87, 068201 (2013)

We apply an extension of the Weinberg compositeness condition on partial waves of L = 1 and resonant states to determine the weight of the meson-baryon component in the Δ(1232) resonance and the other members of the \( J^P= \frac{3}{2}^{+}\) baryon decuplet. We obtain a...

Comment: 7 Pages, 5 Figures

Comment: 12 pages, 6 figures

Using gauge invariant quark Green's functions, defined with path-ordered gluon field phase factors along polygonal lines, and functional relations among them, two compatible bound state equations of the Dirac type are established for quark-antiquark systems, each relati...

The Wess-Zumino-Witten structure is supplemented by a simple vector-meson Lagrangian where the vector mesons are described by antisymmetric tensor fields. With the \( \rho\) -\( \omega\) -\( \pi\) coupling as the only parameter in the sector of odd intrinsic parity, i.e...

The $\eta N$ final state is isospin-selective and thus provides access to the spectrum of excited nucleons without being affected by excited $\Delta$ states. To this end, the world database on eta photoproduction off the proton up to a center-of-mass energy of $E\sim 2....

A model for S-wave eta pi scattering is proposed which could be realistic in an energy range from threshold up to above 1 GeV, where inelasticity is dominated by the K (K) over bar channel. The T-matrix, satisfying two-channel unitarity, is given in a form which matches...

The first two non-trivial moments of the distribution of the topological charge (or gluonic winding number), i.e., the topological susceptibility and the fourth cumulant, can be computed in lattice QCD simulations and exploited to constrain the pattern of chiral symmetr...