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We compute the static potential of a quark-antiquark pair in lattice QCD using a method which is not based on Wilson loops, but where the trial states are formed by eigenvector components of the covariant lattice Laplace operator. The computational effort of this method is significantly lower than the standard Wilson loop calculation, when computing the static potential not only for on-axis, but also for many off-axis quark-antiquark separations, i.e., when a fine spatial resolution is required, e.g., for string breaking calculations. We further improve the signal by using multiple eigenvector pairs, weighted with Gaussian profile functions of the eigenvalues, providing a basis for a generalized eigenvalue problem (GEVP), as it was recently introduced to improve distillation in meson spectroscopy. We show results from the new method for the static potential with dynamical fermions and demonstrate its efficiency compared to traditional Wilson loop calculations. [ABSTRACT FROM AUTHOR]

In this talk I reviewed the present status and recent progress on lightmeson scattering analyses, by means of dispersive or analytic methods. The recent application of these model independent techniques have settled the controversy about the existence and parameters of long debated light meson resonances. I will thus discuss here the state of the art and recent changes on our knowledge about the spectroscopy of light scalar mesons when observed from such scattering processes. [ABSTRACT FROM AUTHOR]

Diffractive production of π- π- π+ and π- π0 π0 final states is the subject of comprehensive studies performed recently by the VES and the COM-PASS experiments. COMPASS pioneered the application of novel methods of partial-wave analysis: mass-independent PWA inmultiple (m3π, t')-cells, mass-dependent analysis of spin-density matrices performed simultaneously in all measured t' bins, the analysis with freed shapes of π+ π- isobars. In addition, COMPASS observed a new narrow state: a1(1420). VES has world-leading data samples on π- π- π+ and π- π0 π0, that yield compatible results and show the potential for a detailed comparison of isospin relations between different decay channels, using the PWA methods with fixed and freed shapes of ππ isobars. [ABSTRACT FROM AUTHOR]

It is demonstrated that, if the lightest positive parity charm mesons are assumed to owe their existence to non-perturbative Goldstone boson-D/D∗ scattering, various puzzles in the charm meson spectrum get resolved. Most importantly the ordering of the lightest strange and non-strange scalars becomes natural. Furthermore, it is demonstrated that the amplitudes for Goldstone boson-D/D∗ scattering are fully consistent with the high quality data on decay B−→ D+π−π− provided by LHCb. It implies that the lowest positive-parity charm mesons are dynamically generated rather than quark-antiquark states. [ABSTRACT FROM AUTHOR]

The discovery of the ground state positive-parity charm-strange and charm-nonstrange mesons D s 0 * $ D_{s0}^* $ (2317), Ds1(2460), D 0 * $ D_0^* $ (2400) and D1(2430) in 2003 and 2004 brought up several mysteries related to their masses. Here I briefly review recent progresses from lattice calculations and analysis of the precise LHCb measurements of the B−→ D+π−π− in the framework of unitarized chiral perturbation theory. It turns out that all the mysteries can be understood in a picture consistent with both lattice results and the LHCb measurements. In this picture, the main components of D s 0 * $ D_{s0}^* $ (2317) and Ds1(2460) are DK and D∗K hadronic molecules, respectively. Furthermore, the resonance parameters of the ground state 0+ and 1+ charm-nonstrange mesons take values very different from the known ones of the D 0 * $ D_0^* $ (2400) and D1(2430), which were obtained by using an improper resonance parameterization. It is pointed out that there should be two D 0 * $ D_0^* $ and two D1 broad states in region relevant to the D 0 * $ D_0^* $ (2400) and D1(2430). Suggestions towards identifying the higher nonstrange resonances are given. [ABSTRACT FROM AUTHOR]

We present results on the measurement of the I=½ KπS-wave through a model independent partial wave analysis of ηc decays to K0sK+π− and K+K−π0 produced in two-photon interactions. We also perform Dalitz plot analyses of the J/Ψ decays to π+π−π0, K+K−π0 and K0sK±π∓ produced in the initial state radiation process. [ABSTRACT FROM AUTHOR]