Speaker
Summary
The spectrum of the lowest-lying glueballs are investigated on the lattice with two flavors
of degenerate quarks. We generate large ensembles of gauge configurations on anisotropic
lattices at two pion masses, $m_\pi\sim650~MeV$ and $m_\pi\sim938~MeV$. We focus on the ground
states of the scalar, pseudoscalar and tensor glueballs, which are measured by gluonic
operators constructed from different prototypes of Wilson loops. We also investigate the pseudoscalar channel using the topological charge density as
the interpolation field operator, which are defined through Wilson loops and smeared by
the Wilson flow technique. The masses of the lowest state derived in this way are much
lighter (around 1GeV) and compatible with the expected masses of the flavor singlet $q\bar{q}$
meson. This provides a strong hint that the operator $\epsilon_{ijk}TrB_iD_jB_k$ and the topological
charge density (proportional to $Tr\mathbf{E}\cdot\mathbf{B}$) couple very differently to the glueball states and $q\bar{q}$ mesons.
