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arXiv · 1711.09815

Lattice QCD investigation of the structure of the $a_0(980)$ meson

Constantia Alexandrou·Joshua Berlin·Mattia Dalla Brida·Jacob Finkenrath·Theodoros Leontiou·Marc Wagner
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Abstract

We investigate the quark content of the scalar meson $a_0(980)$ using lattice QCD. To this end we consider correlation functions of six different two- and four-quark interpolating fields. We evaluate all diagrams, including diagrams, where quarks propagate within a timeslice, e.g. with closed quark loops. We demonstrate that diagrams containing such closed quark loops have a drastic effect on the final results and, thus, may not be neglected. Our analysis shows that in addition to the expected spectrum of two-meson scattering states there is an additional energy level around the two-particle thresholds of $K + \bar{K}$ and $\eta + \pi$. This additional state, which is a candidate for the $a_0(980)$ meson, couples to a quark-antiquark as well as to a diquark-antidiquark interpolating field, indicating that it is a superposition of an ordinary $\bar{q} q$ and a tetraquark structure. The analysis is performed using AMIAS, a novel statistical method based on the sampling of all possible spectral decompositions of the considered correlation functions, as well as solving standard generalized eigenvalue problems.

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Constantia Alexandrou, Joshua Berlin, Mattia Dalla Brida, Jacob Finkenrath, Theodoros Leontiou, Marc Wagner. 2017-11-27. Lattice QCD investigation of the structure of the $a_0(980)$ meson. https://doi.org/10.1103/physrevd.97.034506

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