论文标题
Keldysh场理论中的双轨变形
Double-trace deformation in Keldysh field theory
论文作者
论文摘要
Keldysh形式主义能够将开放量子系统的驱动驱动动力学描述为不一定是热力学的单身有效野外理论，因此经常表现出新的物理学。在这里，我们介绍了一般的Keldys诉讼，最大程度地遵守Weinbergian的约束，包括当地，Poincaré不变性和两个“ $ CPT $”约束：完全积极和痕迹保留和指控，Parity，Parity，Parity和时间逆转对称性。我们发现，在其中引入的驱动驱动性动态的扰动lindblad术语具有双跟踪变形的自然形式$ \ MATHCAL {O}^2 $，在大$ n $限制中，这可能导致新的非心电符号固定点。当$Δ<d/2 $或紫外线时，当$δ> d/2 $给定$ d $时空的尺寸和$δ$ $ \ mathcal {o} $的缩放维度时，该固定点为ir。 Weinbergian的约束不禁止这样的紫外线固定点，这可能暗示其存在甚至完成，这与常识始终是不相关的常识。该观察结果表明，驱动的动力学比热力学要丰富得多，不仅与热力学对称性的不符合（例如，波动 - 隔离关系）的不同之处也有所不同，而且其UV/IR相关性也有所不同。研究了包括$（0+1）$ - $ D $谐波振荡器在连续测量下的示例和$（4-ε）$ - $ d $ classic $ o（n）$ vector Model具有四分之一相互作用的模型。
The Keldysh formalism is capable of describing driven-dissipative dynamics of open quantum systems as nonunitary effective field theories that are not necessarily thermodynamical, thus often exhibiting new physics. Here, we introduce a general Keldysh action that maximally obeys Weinbergian constraints, including locality, Poincaré invariance, and two "$CPT$" constraints: complete positivity and trace preserving as well as charge, parity, and time reversal symmetry. We find that the perturbative Lindblad term responsible for driven-dissipative dynamics introduced therein has the natural form of a double-trace deformation $\mathcal{O}^2$, which, in the large $N$ limit, possibly leads to a new nonthermal conformal fixed point. This fixed point is IR when $Δ<d/2$ or UV when $Δ>d/2$ given $d$ the dimensions of spacetime and $Δ$ the scaling dimension of $\mathcal{O}$. Such a UV fixed point being not forbidden by Weinbergian constraints may suggest its existence and even completion of itself, in contrast to the common sense that dissipation effects are always IR relevant. This observation implies that driven-dissipative dynamics is much richer than thermodynamics, differing in not only its noncompliance with thermodynamic symmetry (e.g., the fluctuation-dissipation relation) but its UV/IR relevance as well. Examples including a $(0+1)$-$d$ harmonic oscillator under continuous measurement and a $(4-ε)$-$d$ classic $O(N)$ vector model with quartic interactions are studied.
