The purpose of this paper is to define a rational orbitally ( Θ , δ b )-contraction and prove some new results in the context id="M3"> -metric spaces. Our extend, generalize, unify known literature. As application our main result, we investigate solution Fredholm i...

Motivated by the latest discovery of a new tetraquark $T_{cc}^+$ with two charm quarks and light antiquarks LHCb Collaboration, we investigated $DD^*$ hadronic molecule interpretation $T_{cc}^+$. By calculation, mass decay width this structure can be understood in one-meson exchange potential model. The binding energies for these molecules $J^P=1^+$ are around $1MeV$. Besides, also studied poss...