A standard approach to investigate the non-perturbative QCD dynamics is through vacuum models which emphasize the role played by specific gauge field fluctuations, such as instantons, monopoles or vortexes. The effective Hamiltonian describing the dynamics of the low-energy degrees of freedom in such approaches is usually postulated phenomenologically, or obtained through uncontrolled approximations. In a recent paper, we have shown how lattice field theory simulations can be used to rigorously compute the effective Hamiltonian of arbitrary vacuum models by stochastically performing the path integral over all the vacuum field fluctuations which are not explicitly taken into account. In this work, we present the first illustrative application of such an approach to a gauge theory and we use it to compute the instanton size distribution in SU(2) gluon-dynamics in a fully model independent and parameter-free way.
InQubator for Quantum Simulation (IQuS), Department of Physics, University of Washington（华盛顿大学量子模拟创新中心）；Center for Nuclear Theory, Department of Physics and Astronomy, Stony Brook University（纽约州立大学石溪分校核理论中心）；Energy and Photon Sciences Directorate, Condensed Matter and Materials Sciences Division, Brookhaven National Laboratory（布鲁克海文国家实验室凝聚态与材料科学部能源与光子科学司）
一些众所周知的影响，关于真空下的形式主义的时间场论重新审视。根据这些效应，它们可能意味着在不同的情况下存在一个热真空。真空的瞬时哈密顿量不仅能为Casimir效应和Van der Waals力的计算提供精确的分布函数，而且还能提供截止函数。温鲁效应的热浴是由时间格林函数构造的。从弯曲时空的场论出发，根据不同的真空态定义了场量子化，并导出了霍金辐射，引入的共形不变性与弯曲时空场论的形式一致.弯曲时空中的感生格林函数与热真空中的感生格林函数是一致的。
