1211.3156 (William Detmold et al.)

Quarkonium at non-zero isospin density    [PDF]

William Detmold, Stefan Meinel, Zhifeng Shi

We calculate the energies of quarkonium bound states in the presence of a medium of nonzero isospin density using lattice QCD. The medium, created using a canonical (fixed isospin charge) approach, induces a reduction of the quarkonium energies. As the isospin density increases, the energy shifts first increase linearly and then saturate at an isospin density where a qualitative change in the behaviour of the energy density of the medium has been previously observed. This provides further support to the conjecture that the medium undergoes a transition from a pion gas to a Bose-Einstein condensed phase at this point. The reduction of the quarkonium energies becomes more pronounced as the heavy-quark mass is decreased, similar to the behaviour seen in two-colour QCD at non-zero quark chemical potential. In the process of our analysis, the Upsilon-pi and eta_b-pi scattering phase shifts are determined at low momentum and found to be small.

View original: http://arxiv.org/abs/1211.3156