Abstract
Since few years, a new family of exotic states has been appearing above the
open-heavy meson thresholds: the so-called $XYZ$ states. BESIII at the BEPCII
$e^+e^-$ collider plays a unique role in the study of those particles in the
charmonium sector. Changing the beam energy, BESIII can collect large data
samples by means of scans of the resonant region, accessing directly to all
vector states. As part of a larger upgrade program, BESIII has planned to
increase the center of mass energy to reach $4.7$ GeV: this will allow BESIII
to investigate the nature of the $Y(4660)$, that was at first observed by Belle
and BaBar after Initial State Radiation only in $\pi\psi(2s)$ and
$Łambda_c$ $Łambda_c$ final states. The relative branching ratio seems
to point toward a baryonium interpretation of the resonance, as expected in
Rossi-Veneziano model. BESIII can directly measure the cross sections around
the expected peak position and verify this prediction. In this presentation,
the status of the $XYZ$ searches at BESIII will be presented, with a focus also
on the plans for the newest data taking and for the $Y(4660)$ studies.
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