  We investigate baryon number fluctuations for finite temperature and density
in two-flavor QCD. This is done within a QCD-improved low-energy effective
theory in an extension of the approach put forward in [1,2]. In the present
work we aim at improving the predictive power of this approach for large
temperatures and density, that is, for small collision energies. This is
achieved by taking into account the full frequency dependence of the quark
dispersion. This ensures the necessary Silver Blaze property of finite density
QCD for the first time, which so far was only implemented approximately.
Moreover, we show that Polyakov loop fluctuations have a sizeable impact at
large temperatures and density. The results for the kurtosis of baryon number
fluctuations are compared to previous effective theory results, lattice results
and recent experimental data from STAR.
