Masayuki Wakayama, Chiho Nonaka
We study the possibility that the scalar mesons exist as four-quark states. The energy shift of two pseudoscalar mesons as a function of spatial lattice size makes a distinction between bound states and scattering states of four-quark states. We calculate the four-quark state in the quenched approximation, ignoring the two-quark annihilation diagrams and the vacuum channels. We perform a calculation of pseudoscalar meson scattering amplitudes, using N_f=2 Wilson fermion and plaquette/Iwasaki gauge actions. We obtain the indication that the four-quark states in the case of the isospin zero (I=0) and two (I=2) channels are no bound states. And we find that the bound energy depends strongly on pion mass rather than the ratio of pion mass to rho meson mass.
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http://arxiv.org/abs/1211.2072
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