Speaker
Description
The doubly charmed tetraquark $T_{cc}^+$ recently discovered by the LHCb collaboration is studied on the basis of (2 + 1)-flavor lattice QCD simulations of $D^*D$ system with nearly physical pion mass $m_\pi = 146$ MeV. The interaction of $D^* D$ in the isoscalar and $S$-wave channel, derived from the hadronic spacetime correlation by the HAL QCD method, is attractive for all distances and leads to a near-threshold virtual state with a pole position $E_{\rm pole} = −38(73)(^{+20}_{−53})$ keV and a large scattering length $1/a_0 = −0.05(5)(^{+2}_{−2})$ fm$^{−1}$. The virtual state is shown to evolve into a loosely bound state as $m_\pi$ decreases to its physical value by using a potential modified to $m_\pi = 135$ MeV based on the pion-exchange interaction. Such a potential is found to give a semi-quantitative description of the LHCb data on the $D^0 D^0 \pi^+$ mass spectrum.
| Topical area | Hadronic and Nuclear Spectrum and Interactions |
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