Physical Review D
We present the first lattice QCD study of coupled isoscalar pi pi, K (K) over bar, eta eta S- and D-wave scattering extracted from discrete finite-volume spectra computed on lattices which have a value of the light quark mass corresponding to m(pi) similar to 391 MeV. In the J(P) = 0(+) sector we find analogues of the experimental sigma and f(0)(980) states, where the sigma appears as a stable bound-state below pi pi threshold, and, similar to what is seen in experiment, the f(0)(980) manifests itself as a dip in the pi pi cross section in the vicinity of the K (K) over bar threshold. For J(P) = 2(+) we find two states resembling the f(2)(1270) and f'(2)(1525), observed as narrow peaks, with the lighter state dominantly decaying to pi pi and the heavier state to K (K) over bar. The presence of all these states is determined rigorously by finding the pole singularity content of scattering amplitudes, and their couplings to decay channels are established using the residues of the poles.
Briceno, Raul A.; Dudek, Jozef J.; Edwards, Robert G.; and Wilson, David J., Isoscalar pi pi, K(K)over-bar, eta eta scattering and the sigma, f(0),f(2) mesons from QCD (2018). Physical Review D, 97(5), 054513-1-054513-24.