The f0(1370)f_0(1370), f0(1710)f_0(1710), f2(1270)f_2(1270), f2′(1525)f_2'(1525), and K2∗(1430)K_2^*(1430) as dynamically generated states from vector meson - vector meson interaction

We report on some recent developments in understanding the nature of the low-lying mesonic resonances $f_0(1370)$, $f_0(1710)$, $f_2(1270)$, $f_2'(1525)$, and $K_2^*(1430)$. In particular we show that these five resonances can be dynamically generated from vector meson--vector meson interaction in a coupled-channel unitary approach, which utilizes the phenomenologically very successful hidden-gauge Lagrangians to produce the interaction kernel between two vector mesons, which is then unitarized by the Bethe-Salpeter-equation method. The data on the strong decay branching ratios, total decay widths, and radiative decay widths of these five states, and on related $J/\psi$ decay processes can all be well described by such an approach. We also make predictions, compare them with the results of earlier studies, and highlight observables that if measured can be used to distinguish different pictures of these resonances.Comment: 9 pages; Invited talk at workshop CHIRAL'10, Valencia (Spain), June 21-24, 201

Repercussion of the a0(1710)a_0(1710) [a0(1817)a_0(1817)] resonance and future developments

In this paper, we discuss the significance and prospect for the newly discovered a0(1710)[a0(1817)] resonance state at BESIII experiment, in which they reported the observation of a scalar meson of spin-parity $J^P=0^+$ with isospin $I=1$, branded as $a_0(1817)$. This state may be the same particle as the $a_0(1710)$ observed by the BaBar experiment earlier. As early as 2008, we found that f0(1710) can be regarded as a $K^* \bar{K}^*$ molecular state based on the chiral unitary theory, and there is a partner state $a_0(1710)$ with an isospin $I=1$. Our theoretical prediction based on this picture is in good agreement with the latest BESIII data, which further supports the molecular state picture of $a_0(1710)[a_0(1817)]$. If it is indeed the isospin partner state of $f_0(1710)$, this would rule out $f_0(1710)$ as a glueball candidate. This paper briefly reviews the relevant theoretical studies and suggests new experiments to further examine the nature of $a_0(1710)[a_0(1817)]$.Comment: typos corrected. 6 pages,4 figures, to be published as a "Perspective" in Science Bulleti

Role of the N∗N^*(1535) in the J/ψ→pˉηpJ/\psi\to \bar{p}\eta p and J/ψ→pˉK+ΛJ/\psi\to \bar{p}K^+\Lambda reactions

We study the $J/\psi\to \bar{p}\eta p$ and $J/\psi\to \bar{p}K^+\Lambda$ reactions with a unitary chiral approach. We find that the unitary chiral approach, which generates the $N^*(1535)$ dynamically, can describe the data reasonably well, particularly the ratio of the integrated cross sections. This study provides further support for the unitary chiral description of the $N^*(1535)$. We also discuss some subtle differences between the coupling constants determined from the unitary chiral approach and those determined from phenomenological studies.Comment: version to appear in PRC; certain features of the approach clarifie

Comments on the dispersion relation method to vector-vector interaction

We study in detail the method proposed recently to study the vector-vector interaction using the $N/D$ method and dispersion relations, which concludes that, while for $J=0$, one finds bound states, in the case of $J=2$, where the interaction is also attractive and much stronger, no bound state is found. In that work, approximations are done for $N$ and $D$ and a subtracted dispersion relation for $D$ is used, with subtractions made up to a polynomial of second degree in $s-s_\mathrm{th}$, matching the expression to $1-VG$ at threshold. We study this in detail for the $\rho - \rho$ interaction and to see the convergence of the method we make an extra subtraction matching $1-VG$ at threshold up to $(s-s_\mathrm{th})^3$. We show that the method cannot be used to extrapolate the results down to 1270 MeV where the $f_2(1270)$ resonance appears, due to the artificial singularity stemming from the "on shell" factorization of the $\rho$ exchange potential. In addition, we explore the same method but folding this interaction with the mass distribution of the $\rho$, and we show that the singularity disappears and the method allows one to extrapolate to low energies, where both the $(s-s_\mathrm{th})^2$ and $(s-s_\mathrm{th})^3$ expansions lead to a zero of $\mathrm{Re}\,D(s)$, at about the same energy where a realistic approach produces a bound state. Even then, the method generates a large $\mathrm{Im}\,D(s)$ that we discuss is unphysical.Comment: 8 pages, 10 figures, 1 tabl

Nature of the axial-vector mesons from their Nc behavior within the chiral unitary approach

By describing within the chiral unitary approach the s-wave interaction of the vector meson nonet with the octet of pseudoscalar Goldstone Bosons, we find that the main component of the axial vector mesons b_1(1235), h_1(1170), h_1(1380), a_1(1260), f_1(1285) and the two states associated to the K_1(1270) does not follow the QCD dependence on the number of colors for ordinary qqbar mesons.Comment: 18 pages, 5 figures, to be published in EPJ