SEMINARIO: "HADRON SPECTROSCOPY: FROM THE RHO MESON TO MULTIQUARK STATES WITH HEAVY QUARKS"
Impartido por: Raquel Molina Peralta, The George Washington University
Fecha y hora: Jueves, 12 de enero de 2017 a las 12:30 horas
Lugar: Sala Polivalente del Departamento de Física Aplicada, Facultad de Ciencias, Fase II
Quantum Chromodynamics (QCD) is the theory of the strong interaction, one of the fundamental forces of nature, which is responsible for the properties of microscopic matter as we know it. In the intermediate energy region, QCD manifests itself in a very rich and complex spectrum of resonances. Lattice QCD calculations have recently contributed signi_cantly to the extraction of resonance phase shifts from _rst principles of QCD. E_ective eld theories can be adapted to the conditions of the _nite volume and are useful to analyze the quark mass dependence and the e_ect of missing channels. In the _rst part of this talk, lattice QCD data on p-wave __ scattering are analyzed with Unitary Chiral Perturbation Theory. The analysis shows that the kaon channel pushes upward the __ scattering phase shift having an e_ect on the _-mass. Some examples of likely candidates for multiquark states in the light-quark sector are given. On the second part of the talk, charm spectroscopy is reviewed. The B factories, originally constructed to test CP violation, have discovered a plethora of states called XYZ di_cult to interpreted in terms of q_q. The charged charmonia Z observed by BESIII are clearly candidates to be tetraquarks or two-meson molecules. LHCb, has observed recently a pentaquark state decaying into J p. The need of understanding the strong interaction has motivated experiments to collect an unprecedented amount of data on hadron spectroscopy, and the spectrum is evolving into an extraordinary complexity, which urges the theory community to make e_orts to understand the nature of these new particles. Chiral lagrangians and hidden gauge approaches give us some clues on the nature of these exotic states near thresholds.