The running coupling of a heavy quark-antiquark pair in the STU background

Employing holographic duality, we evaluate the running coupling of a heavy quark-antiquark ( Q Q ¯ ) pair in the STU black hole background by computing the Nambu-Goto action for a fundamental string, whose worldsheet is anchored to a rectangular Wilson loop. It is shown that an increase in the black hole charge leads to a reduction in both the free energy and the running coupling of the Q Q ¯ . This reduction implies a lowering of the free energy of Q Q ¯ , thereby enhancing their thermodynamic stability and strengthening the quark-antiquark attractive interaction, while also weakening the intrinsic short-range strong interaction between quarks by reducing the running coupling of Q Q ¯ .