Remarks on pole trajectories for resonances

We discuss in general terms pole trajectories of resonances coupling to a continuum channel as some strength parameter is varied. It is demonstrated that, regardless of the underlying dynamics, the trajectories of poles that couple to the continuum in a partial wave higher than s -wave are qualitatively the same, while in case of s -waves the pole trajectory can reveal important information on the internal structure of the resonance. In addition we show that only molecular (or extraordinary) states appear near thresholds naturally, while more compact structures need a significant fine tuning in the parameters

Analysis Tools for Next-Generation Hadron Spectroscopy Experiments

The series of workshops on {\it New Partial-Wave Analysis Tools for Next-Generation Hadron Spectroscopy Experiments} was initiated with the\break ATHOS 2012 meeting, which took place in Camogli, Italy, June 20--22, 2012. It was followed by ATHOS~2013 in Kloster Seeon near Munich, Germany, May 21--24, 2013. The third, ATHOS3, meeting is planned for April 13--17, 2015 at The George Washington University Virginia Science and Technology Campus, USA. The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the INT-JLab Workshop on Hadron Spectroscopy in Seattle in 2009, the International Workshop on Amplitude Analysis in Hadron Spectroscopy at the ECT*-Trento in 2011, the School on Amplitude Analysis in Modern Physics in Bad Honnef in 2011, the Jefferson Lab Advanced Study Institute Summer School in 2012, and the School on Concepts of Modern Amplitude Analysis Techniques in Flecken-Zechlin near Berlin in September 2013. The aim of this document is to summarize the discussions that took place at the ATHOS~2012 and ATHOS~2013 meetings. We do not attempt a comprehensive review of the field of amplitude analysis, but offer a collection of thoughts that we hope may lay the ground for such a document. The material presented in the article was edited by the following Editorial Board: Marco Battaglieri, Bill J.~Briscoe, Su-Urk Chung, Michael D\"oring, JĂłzef Dudek, Geoffrey Fox, Christoph Hanhart, Martin Hoferichter, David G.~Ireland, Bernhard Ketzer, Bastian Kubis, Vincent Mathieu, Ryan Mitchell, Jos\'e R.~Pel\'aez, Elena Santopinto, Adam Szczepaniak