Speaker
Dr
Francesco Giacosa
(Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, Frankfurt)
Description
A standard quark-antiquark state gets dressed by meson-meson clouds
corresponding to its decay product and its pole moves down in the complex
plane. If some conditions are met (coupling constant strong enough nearby
energy threshold(s)), additional. so-called companion poles may emerge, which
correspond to a type of dynamically generated states. For instance, the light
scalar states $K_{0}^{\ast}(800)$ and $a_{0}(980)$ can be interpreted as a
companion poles of the predominantly standard quark-antiquark state
$K_{0}^{\ast}(1430)$ and $a_{0}(1450)$. In the charmonium sector, the
predominately charm-anticharm resonance $\psi(3770)$ is also described by two
poles, a standard quark-antiquark pole and a companion one, the latter being
responsible for the peculiar form of the left part of its spectral function.
In the future, the mechanism of companion poles can be tested on other yet
unexplained $X$ and $Y$ resonances.
Primary author
Dr
Francesco Giacosa
(Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, Frankfurt)
