Speaker
Philipp Gubler
(RIKEN)
Description
Quarkonia spectral functions at finite temperature are studied
using QCD sum rules in combination with the maximum entropy
method. This approach enables us to directly obtain the spectral
function from the sum rules, without having to introduce any
specific assumption about its functional form [1].
QCD sum rules incorporate finite temperature effects in form
of changing values of the various gluonic condensates that appear
in the operator product expansion. These changes depend on the
energy density and pressure at finite temperature, which we extract
from lattice QCD.
As a result, we find that the charmonium states J/\psi, \eta_c, \chi_{c0}
and \chi_{c1} dissolve into the continuum already at temperatures
around or slightly above the critical temperature T_c [2].
As for bottomonium, it is found that \Upsilon(1S) and \eta_b survive in
quark-gluon matter of temperature up to 2.5 -3.0 T_c, while \chi_{b0}
and \chi_{b1} dissociate at 2.0 -2.5 T_c [3]. Furthermore, we find
evidence for the melting of the excited states \Upsilon(2S) and
\Upsilon(3S) in the region of T=1.5 -2.0 T_c [3].
[1] P. Gubler and M. Oka, Prog. Theor. Phys. 124, 995 (2010).
[2] P. Gubler, K. Morita and M. Oka, Phys. Rev. Lett. 107, 092003 (2011).
[3] K. Suzuki, P. Gubler, K. Morita and M. Oka, arXiv:1204.1173 [hep-ph].
Primary author
Philipp Gubler
(RIKEN)
Co-authors
Mr
Kei Suzuki
(Tokyo Institute of Technology)
Kenji Morita
(Kyot University)
Prof.
Makoto Oka
(Tokyo Institute of Technology)
