Relative $P$-wave excitations of $D^{(*)}\bar D^{(*)}$ configurations in QCD sum rules

We investigate the relative $P$-wave excitations of the $D^{(*)}\bar D^{(*)}$ systems using the QCD sum rule method. By introducing a covariant derivative between two ground-state charmed meson fields, we construct color-singlet interpolating currents to describe the relative orbital excitation betw