Scalar mesons and tetraquarks from twisted mass lattice QCD

Understand

We study light scalar mesons with particular focus on the a_0(980) using lattice QCD with 2+1+1 dynamical quark flavors.

• To investigate the structure of these scalar mesons and to identify, whether a sizeable tetraquark component is present, we use a large set of operators, including diquark-antidiquark, mesonic molecule and two-meson operators.
• We find that the low-lying states overlap essentially exclusively with two-meson states.
• This indicates that in the channels investigated no tightly bound four-quark states of either molecular or diquark-antidiquark type exist.