Shuzhe SHI (Tsinghua University)
The conserved charge fluctuations, as quantified by the corresponding susceptibilities, provide important information about the charge-carriers and their dynamical correlations in strongly interacting matter such as the quark-gluon plasma. Using the gauge-gravity correspondence approach, we study the patterns of conserved charge fluctuations in two types of holographic models for QCD, the D4/D8 and the D3/D7 models. We compute and compare the quark number susceptibilities in both models and find an interesting common feature of the two: at very strong coupling higher order susceptibilities are suppressed and the conserved charge fluctuations become purely Gaussian. In light of the state-of-the-art lattice QCD results we also discuss what we can learn from these susceptibilities about the underlying degrees of freedom in the $1\sim 2 T_c$ quark-gluon plasma and examine the viability of different ideas such as holography, quasi-particles, as well as bound states. From analysis of second order cross-flavor susceptibilities we conclude that the bound states exist and are important in the $1\sim 2 T_c$ region. Based on that we have further constructed model with predictions for several ratios of fourth-order susceptibilities that are in good agreement with lattice QCD results. Reference: Shuzhe Shi and Jinfeng Liao, JHEP06(2013)104[arXiv:1304.7752].
|On behalf of collaboration:||None|
Jinfeng Liao (Indiana University) Shuzhe SHI (Tsinghua University)