Study of conventional and non-conventional scalar and vector mesons

Abstract

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' $q\bar{q}$ 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 $q\bar{q}$ 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 $s\bar{s}$ state in $1$ ${}^3{D}_1$ nonet. Some non-conventional mesons can be understood by the mechanism of dynamical generation. We show that the inclusion of a single conventional $q\bar{q}$ 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 $K_0^{\ast }(700)$ emerges as a companion pole of the $q\bar{q}$ meson $K_0^{\ast }(1430)$. Moreover, we show that the enigmatic resonance $X(3872)$ in the charmonium sector can be interpreted as the (virtual) companion pole of the $c\bar{c}$ state ${\chi }_{c1}(2P)$. Then, we study the $c\bar{c}$ meson $\psi (4040)$. 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 $\psi (4040)$ to the $D^{\ast }D$ channel.

PhD thesis at the Jan Kochanowski University, Kielce, Poland (2021). 139 pages, 35 tables, 32 figures

References in corpus (30)

• Heavy quarkonium: progress, puzzles, and opportunities
• Exotics: Heavy Pentaquarks and Tetraquarks
• Measurement of e^+e^- to pi^+pi^-J/psi Cross Section via Initial State Radiation at Belle
• Higher Charmonia and X,Y,Z states with Screened Potential
• The Z(4430) and a New Paradigm for Spin Interactions in Tetraquarks
• Precise measurement of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}J/\psi$ cross section at center-of-mass energies from 3.77 to 4.60 GeV
• Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation?
• Nature of the f_0(600) from its N_c dependence at two loops in unitarized Chiral Perturbation Theory
• Isoscalar meson spectroscopy from lattice QCD
• Reconciling the X(3872) with the near-threshold enhancement in the D^0\bar{D}^{*0} final state
• Resonances in coupled πK,ηK scattering from quantum chromodynamics
• The K^*_0(800) scalar resonance from Roy-Steiner representations of pi K scattering
• Identification of a Scalar Glueball
• Estimate for the X(3872) to gamma J/psi decay width
• Line Shapes of the X(3872)
• X(3872) as a hadronic molecule and its decays to charmonium states and pions
• The nature of $\sigma$, $\kappa$, $a_0(980)$ and $f_0(980)$
• On the spectral functions of scalar mesons
• What can radiative decays of the X(3872) teach us about its nature?
• Strong and electromagnetic decays of the light scalar mesons interpreted as tetraquark states
• Measurements of $\psi (2S)$ and $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ production in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
• B_{s1}(5830) and B_{s2}^*(5840)
• Charmonium resonances in the 3.9 GeV/$c^2$ energy region and the $X(3915)/X(3930)$ puzzle
• An improved study of the kappa resonance and the non-exotic $s$ wave $\pi K$ scatterings up to $\sqrt{s}=2.1$GeV of LASS data
• Strange resonance poles from $K\pi$ scattering below 1.8 GeV
• Strong and radiative decays of excited vector mesons and predictions for a new $\varphi (1930)$ resonance
• The origin of light $0^{+}$ scalar resonances
• Unquenched quark-model calculation of X(3872) electromagnetic decays
• Measurement of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0\eta$ cross section below $\sqrt{s}=2$ GeV
• The role of the next-to-leading order triangle-shaped diagram in two-body hadronic decays