The <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e24330" altimg="si34.svg"> <mml:mrow> <mml:mi>X</mml:mi> <mml:mi>Y</mml:mi> <mml:mi>Z</mml:mi> </mml:mrow> </mml:math> states: Experimental and theoretical status and perspectives

Nora Brambilla, S.I. Eidelman, C. Hanhart, A. V. Nefediev, Cheng-Ping Shen, Christopher E. Thomas, Antonio Vairo, C. Z. Yuan