Related papers: Progress in the Partial-Wave Analysis Methods at C…
Applying the technique of partial-wave analysis, there are cases where more than one set of underlying complex-valued amplitudes can describe the measured observables. These ambiguities can sometimes be resolved using additional…
The aim of the COMPASS hadron programme is to study the light-quark hadron spectrum, and in particular, to search for evidence of hybrids and glueballs. COMPASS is a fixed-target experiment at the CERN SPS and features a two-stage…
We develop a theoretical framework to quantify the structure of unstable hadron resonances. With the help of the corresponding system in a finite volume, we define the compositeness of resonance states which can be interpreted as a…
Scattering resonances play a crucial role in understanding wave behavior in various physical systems. While significant progress has been made in analyzing resonances in high-contrast and nonlinear media, a general characterization of…
The COMPASS experiment at the CERN SPS investigates the structure and spectrum of hadrons by scattering high energetic hadrons and polarised muons off various fixed targets. During the years 2002-2007, COMPASS focused on nucleon spin…
In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic $\pi N$ scattering, however, usually the partial waves of the SAID or other groups are fitted,…
The observables in a single-channel $2$-body scattering problem remain invariant once the amplitude is multiplied by an overall energy- and angle-dependent phase. This invariance is known as the continuum ambiguity. Also, mostly in…
We present a determination of the isospin-1/2 elastic $\pi K$ scattering amplitudes in S and P partial waves using lattice Quantum Chromodynamics. The amplitudes, constrained for a large number of real-valued energy points, are obtained as…
Structures in the invariant mass distribution are often linked to unstable intermediate states or resonances. In experiments, many signals are detected which have broad, overlapping or intricate profiles, which makes their characterization…
The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the pi- pi- pi+ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of…
The last two decades have witnessed the discovery of a myriad of new and unexpected hadrons. The future holds more surprises for us, thanks to new-generation experiments. Understanding the signals and determining the properties of the…
A partial-wave analysis of the decay $J/\psi \to K^+K^-\pi^0$ has been made using $(223.7\pm1.4)\times 10^{6}$ $J/\psi$ events collected with the BESIII detector in 2009. The analysis, which is performed within the isobar-model approach,…
Heavy flavour decay to light hadrons is the key to understanding many aspects of the SM from CP violation to strong dynamics. It is often presumed in line with the simple quark spectator model of D decay to Kpipi that the Kpi system has…
One of the remaining challenges within the standard model is to gain a good understanding of QCD in the non-perturbative regime. One key step toward this aim is baryon spectroscopy, investigating the spectrum and the properties of baryon…
We address the problem of completely characterizing multi-particle states including loss of information to unobserved degrees of freedom. In systems where non-classical interference plays a role, such as linear-optics quantum gates, such…
A problem of amplitude reconstruction in terms of the given angular distribution is considered. Solution of this problem is not unique. A class of amplitudes, correspondent to one and the same angular distribution, forms a region in…
The COmmon Muon and Proton Apparatus for Structure and Spectroscopy (COMPASS) is a multi-purpose fixed-target experiment at the CERN Super Proton Synchrotron (SPS) aimed at studying the structure and spectrum of hadrons. In the naive…
The COMPASS collaboration at CERN has measured diffractive dissociation of 190 GeV/$c$ pions into the $\pi^-\pi^-\pi^+$ final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of $3\pi$ mass and…
We present results of meson and baryon spectroscopy using the Chirally Improved Dirac operator on lattices of size 16**3 x 32 with two mass-degenerate light sea quarks. Three ensembles with pion masses of 322(5), 470(4) and 525(7) MeV and…
We consider the reaction dynamics of bosons with negative parity and spin $0$ or $1$ and fermions with positive parity and spin $\frac{1}{2}$ or $\frac{3}{2}$. Such systems are of central importance for the computation of the baryon…