Doubly charm tetraquark channel with isospin 1 from lattice QCDMeng, Lu (Avtor) Ortiz Pacheco, Emmanuel (Avtor) Baru, Vadim (Avtor) Epelbaum, Evgeny (Avtor) Padmanath, M. (Avtor) Prelovšek, Saša (Avtor) physics of elementary particleslattice QCDExperimentally, the doubly charm tetraquark channel $cc\bar{q}\bar{q}$ with $q=u$, $d$ features an exotic hadron, $T_{cc}$, with isospin $I=0$ near the $DD^*$ threshold, while no peak was observed for $I=1$. We present a lattice QCD study of this channel with $I=1$, $J^P=1^+$,and $m_{\pi} \simeq 280$ MeV. Finite-volume energies calculated across five charm quark masses consistently feature a positive energy shift with respect to noninteracting energies, indicating repulsive interaction at energies near the threshold. These energies are used to compute the $DD^*$ scattering amplitude using both the standard Lüscher method and the recently proposed effective field theory-based approach in the plane wave basis, which incorporates the long-range interactions and the left-hand cut. Both analyses render a small negative scattering length and a scattering amplitude that does not feature any poles in the energy region near the $DD^*$ threshold, in line with the LHCb results. We identify that the Wick contraction, resembling $t$-channel isovector-vector meson exchanges between $D$ and $D^*$, plays a key role in distinguishing between the $I=0$ and $I=1$ channels, leading to repulsion in the $I=1$ and attraction in the $I=0$ channel.20252025-03-05 16:30:18Članek v reviji167666UDK: 539.120.811ISSN pri članku: 2470-0010DOI: 10.1103/PhysRevD.111.034509COBISS_ID: 228099075sl