标题： 微扰约化有效场论中的导数阶数 显示英文标题

标题： Perturbative reduction of derivative order in EFT

摘要： 高阶导数修正在有效场论中无处不在，这似乎在相继的阶次中引入了新的自由度。 这实际上是由定义有效场论的隐含局部导数展开所造成的伪像。 我们认为，那些引入额外自由度的高阶导数修正应该被移除，并且它们的影响要么通过低阶导数修正来捕捉，要么通过不传播额外自由度的特殊高阶导数修正组合来捕捉。 考察了三种适用于此任务的方法，发现场重新定义是最合适的选择。 在标量张量理论中，通过场重新定义去除了第一阶的高阶导数修正，并发现它们的影响由Horndeski理论的一个子集捕获。 提出了原则上应将有效场论展开限制为仅包含不引入额外自由度的项的观点。 显示英文摘要

摘要： Higher derivative corrections are ubiquitous in effective field theories, which seemingly introduces new degrees of freedom at successive order. This is actually an artefact of the implicit local derivative expansion defining effective field theories. We argue that higher derivative corrections that introduce additional degrees of freedom should be removed and their effects captured either by lower derivative corrections, or special combinations of higher derivative corrections not propagating extra derees of freedom. Three methods adapted for this task are examined and field redefinitions are found to be most appropriate. First order higher derivative corrections in a scalar tensor theory are removed by field redefinition and it is found that their effects are captured by a subset of Horndeski theories. A case is made for restricting the effective field theory expansions in principle to only terms not introducing additional degrees of freedom.