2021/05/18 by Milena Piotrowska, Piotrowska, Milena
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2105.08557
openalex publication_date 2021/05/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Enormous progress in physics enriched our knowledge about the particles which build matter. Among them there are mesons, to which this thesis is entirely devoted. The overwhelming majority of mesons is made of `conventional' qq pairs, but nowadays there is mounting evidence for `non-conventional' mesons, such as tetraquarks, glueballs, hybrids, and molecules. The main aim of this thesis is to understand the nature of some scalar and vector mesonic states which still remain puzzling. In this thesis we investigate two nonets of qq excited vector mesons. Within an effective QFT model we evaluate various decay channels of these states and compare the results with experimental data from PDG. Moreover, we make predictions for a not-yet observed ss state in 1 3D1 nonet. Some non-conventional mesons can be understood by the mechanism of dynamical generation. We show that the inclusion of a single conventional qq seed in the relativistic QFT Lagrangian may cause the appearance of an additional associated state as a dynamically generated companion pole. Along this line, we show that light scalar kaon K^*0(700) emerges as a companion pole of the qq meson K0^*(1430). Moreover, we show that the enigmatic resonance X(3872) in the charmonium sector can be interpreted as the (virtual) companion pole of the cc state χc1(2P). Then, we study the cc meson ψ(4040). We show that an additional companion pole appears on the complex plane. At first sight one may identify it with the enhancement Y(4008) observed by the Belle Collaboration. A detailed analysis reveals that different mechanism is responsible for the creation of Y(4008). Hence, the bump associated with Y(4008) should not be interpreted as an independent resonance, but rather as a manifestation of the strong coupling of ψ(4040) to the D^*D channel.