论文标题
AD/CFT对应的非平衡系统中的Nambu-Goldstone模式
Nambu-Goldstone modes in non-equilibrium systems from AdS/CFT correspondence
论文作者
论文摘要
我们研究了通过ADS/CFT对应关系实现的耗散系统中Nambu-Goldstone模式的分散关系。我们采用代表$ {\ cal n} = 4 $超对称的Yang-Mills理论的D3/D7模型，耦合到$ {\ cal n = 2} $风味领域。如果我们在存在外部磁场的情况下考虑无质量的夸克，则该系统表现出与手性对称性的自发对称性断裂相关的相变。我们发现，Nambu-Goldstone模式在分散关系中显示出扩散的行为，这与有效的现场理论方法相符。我们还研究了一个非平衡稳态，该稳态在存在外电场的情况下具有恒定的电流。在非平衡稳态中，我们发现Nambu-Goldstone模式除了扩散行为外，在频率的实际部分中显示了线性分散体。此外，我们分析了流体动力近似中Nambu-Goldstone模式的线性分散。结果，我们发现线性色散可以写为双场理论中数量的分析函数。我们的结果表明，这种线性分散体是Nambu-Goldstone模式在非平衡稳态下的特征行为。
We investigate dispersion relation of Nambu-Goldstone modes in a dissipative system realized by the AdS/CFT correspondence. We employ the D3/D7 model which represents ${\cal N} = 4$ supersymmetric Yang-Mills theory coupled to ${\cal N = 2}$ flavor fields. If we consider massless quarks in the presence of an external magnetic field, the system exhibits the phase transition associated with the spontaneous symmetry breaking of the chiral symmetry. We find that the Nambu-Goldstone modes shows a diffusive behavior in the dispersion relation, which agrees with that found with the effective field theory approach. We also study a non-equilibrium steady state which has a constant current flow in the presence of an external electric field. In a non-equilibrium steady state, we find that the Nambu-Goldstone modes shows a linear dispersion in the real part of the frequency in addition to the diffusive behavior. Moreover, we analyze the linear dispersion of the Nambu-Goldstone modes in the hydrodynamic approximation. As a result, we find that the linear dispersion can be written as the analytic functions of quantities in the dual field theory. Our results imply that such a linear dispersion is a characteristic behavior of Nambu-Goldstone modes in a non-equilibrium steady state.
