Positive parity $D_s$ mesons

Abstract

We study the positive parity charmed strange mesons using lattice QCD, the only reliable ab initio method to study QCD at low energies. Especially the experimentally observed $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ have challenged theory for quite some time. The dynamical lattice QCD simulations are performed at two distinct pion masses, $m_{\pi }$ = 266 MeV and 156 MeV, using both $\bar{c}s$ as well as $DK$ and $D^{\ast }K$ scattering operators in the construction of the correlation matrix in order to take into the account threshold effects. While the $J^P=0^{+}$ channel benefited most from the inclusion of scattering operators, it was also crucial for the case of the $D_{s1}(2460)$. Using the Lüscher method, which relates the finite volume spectrum to the infinite volume scattering matrix, we were able to determine the near threshold behavior of the scattering amplitude. From it we extracted the binding momenta and the masses of the below-threshold bound states $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ by determining the pole positions of the scattering amplitudes. Our results compare well with experiment, resolving a long standing discrepancy between theory and experiment.

Comments: 5 pages, 1 figure, Contribution to the International Symposium on Lepton Photon Interactions at High Energies 2015, minor corrections to text