mesonic molecule

{{Short description|Hypothetical particle in physics}}

A mesonic molecule is a set of two or more mesons bound together by the strong force.{{cite book |last1=Trutnev |first1=Yuri A. |title=In The Intermissions: Collected Works On Research Into The Essentials Of Theoretical Physics In R |date=1998 |publisher=World Scientific |isbn=978-981-4495-65-3 |page=106 |url=https://books.google.com/books?id=r37VCgAAQBAJ&pg=PA106 |access-date=23 June 2020 |language=en}}{{cite book |last1=Hughes |first1=Vernon |title=Muon Physics V3: Chemistry and Solids |date=2012 |publisher=Elsevier |isbn=978-0-323-15616-5 |page=189 |url=https://books.google.com/books?id=VW-huO047W4C&pg=PA189 |access-date=23 June 2020 |language=en}} Unlike baryonic molecules, which form the nuclei of all elements in nature save hydrogen-1, a mesonic molecule has yet to be definitively observed.{{cite book |last1=Jungmann |first1=Klaus |last2=Hughes |first2=Vernon W. |last3=Putlitz |first3=Gisbert zu |title=The Future of Muon Physics: Proceedings of the International Symposium on The Future of Muon Physics, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Federal Republic of Germany, 7–9 May, 1991 |date=2012 |publisher=Springer Science & Business Media |isbn=978-3-642-77960-2 |url=https://books.google.com/books?id=6avoCAAAQBAJ&pg=PA203 |language=en}} The X(3872) discovered in 2003 and the Z(4430) discovered in 2007 by the Belle experiment are the best candidates for such an observation.