Identifying and studying tetraquarks and pentaquarks helps physicists to better understand how the strong force binds quarks together. This force also binds protons and neutrons in atomic nuclei.
Physicists are still divided as to the nature of these exotic hadrons. Some models suggest that their quarks are tightly bound via the strong force, so making these hadrons compact objects. Others say that the quarks are only loosely bound. To confuse things further, there is evidence that in some exotic hadrons, the quarks might be both tightly and loosely bound at the same time.
Now, new findings from the CMS Collaboration suggest that tetraquarks are tightly bound, but they do not completely rule out other models.
