scholarly journals Are the XYZ states unconventional states or conventional states with unconventional properties?

2020 ◽  
Vol 35 (05) ◽  
pp. 2050019
Author(s):  
Christoph Hanhart ◽  
Eberhard Klempt

We discuss three possible scenarios for the interpretation of mesons containing a heavy quark and its antiquark near and above the first threshold for a decay into a pair of heavy mesons in a relative [Formula: see text]-wave. View I assumes that these thresholds force the quark potential to flatten which implies that while in these energy ranges molecular states may be formed, there should not be any quark–antiquark states above these thresholds. View II assumes that the main part of the interaction between two mesons is due to the poles which originate from the [Formula: see text] interaction. The properties of the [Formula: see text] mesons are strongly influenced by opening thresholds but the number of states is given by the quark model. In View III, both types of mesons are admitted also near and above the open flavor thresholds: [Formula: see text] mesons and dynamically generated mesons. Experimental consequences of these different views are discussed.

2012 ◽  
Vol 27 (08) ◽  
pp. 1250039 ◽  
Author(s):  
B. EAKINS ◽  
W. ROBERTS

We discuss the extension of the superflavor symmetry of doubly heavy baryons to states which contain an excited heavy diquark and we examine some of the consequences of this symmetry for the spectra of doubly heavy baryons and heavy mesons. We explore the ramifications of a proposed symmetry that relates heavy diquarks to doubly heavy mesons. We present a method for determining how the excitation energy of a system containing two heavy quarks will scale as one changes the strength of the interactions and the reduced mass of the system. We use this to derive consequences of the heavy diquark-doubly heavy meson symmetry. We compare these consequences to the results of a quark model as well as the experimental data for doubly and singly heavy mesons. We also discuss the possibility of treating the strange quark as a heavy quark and apply the ideas developed here to strange hadrons.


2013 ◽  
Vol 54 (7-10) ◽  
pp. 1027-1031 ◽  
Author(s):  
Yoshiaki Koma ◽  
Miho Koma

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