Possible mixing of a diquark-antidiquark with a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mover accent="true"><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">¯

We discuss the possibility that the two nearby resonances observed by BESIII partially below the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>p</a:mi><a:mover accent="true"><a:mi>p</a:mi><a:mo stretchy="false">¯</a:mo></a:mover></a:math> threshold might be due to mixing between two metastable states with the same <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msup><e:mi>J</e:mi><e:mrow><e:mi>P</e:mi><e:mi>C</e:mi></e:mrow></e:msup><e:mo>=</e:mo><e:msup><e:mn>0</e:mn><e:mrow><e:mo>−</e:mo><e:mo>+</e:mo></e:mrow></e:msup></e:math> quantum numbers, but rather different internal structure. One is a <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>p</g:mi><g:mover accent="true"><g:mi>p</g:mi><g:mo stretchy="false">¯</g:mo></g:mover></g:math> hadronic molecule and the other a bound state of a light-quark diquark and an antidiquark, both with spin 1 and isospin 0, a composite color antitriplet and triplet, respectively. The doubling of resonances, one of which may be interpreted as a hadronic molecule, while the other arises from <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>q</k:mi><k:mover accent="true"><k:mi>q</k:mi><k:mo stretchy="false">¯</k:mo></k:mover></k:math> annihilation in a state with vacuum quantum numbers, may be a more general feature than the specific case considered here. Published by the American Physical Society 2024