Scalar mesons in lattice QCD

Abstract

We explore whether ''f 0 (600) or '' exists as a pole in QCD, by a full lattice QCD simulation on the 8 3 ϫ16 lattice using the plaquette action and Wilson fermions. It is shown that there exists a pole, whose mass is as low as that of the , owing to the disconnected diagram of the meson propagator. A discussion is given on the physical content of the .

Scalar glueball, scalar quarkonia, and their mixing

“…With the lowest one corresponding to m π as low as 180 MeV, it is found that, when the quark mass is smaller than that of the strange, a 0 mass levels off, in contrast to those of a 1 and other hadrons that have been calculated on the lattice. This confirms the trend that has been observed in earlier works at higher quark masses in both the quenched and unquenched calculations [7,8,9,10]. The chiral extrapolated mass a 0 = 1.42 ± 0.13 GeV suggests that a 0 (1450) is a qq state.…”

“…[20] seriously. We shall rely on the conclusion from the other calculations in both the quenched and unquenched calculations [6,7,8,9,10]. light scalar nonet is known to have a reversed ordering, namely, the scalar strange meson κ is lighter than the non-strange one such as f 0 (980), it has been proposed in [25] to consider the mixing of the qq heavy scalar nonet with the light nonet to make a 0 (1450) and K * 0 (1430) closer.…”

“…However, there are several serious problems with this scenario. First, the isovector scalar meson a 0 (1450) is confirmed to be a qq meson in lattice calculations [6,7,8,9, 10] which will be discussed later. As such, the degeneracy of a 0 (1450) and K * 0 (1430), which has a strange quark, cannot be explained if M S is larger than M N by ∼ 250 MeV.…”

Light scalar mesons in 2+1 flavor full QCD

“…Early two-flavor dynamical simulations [3,4] reported values at or above 1.5 GeV, but later two-flavor dynamical calculations [6,7,8] obtained a ground state near 1 GeV. But is this the a 0 or πη ′ 2 ?…”

Scalar mesons in a finite volume

“…Indeed, recent years have seen considerable activity, concerning the calculation of the spectrum of the scalar mesons on the lattice (see, e.g., [25][26][27][28][29][30][31][32][33][34][35][36][37][38]). However, alone the calculations of the excited spectrum do not answer the question.…”