标题： Jordan 帧超出标量-张量理论 显示英文标题

标题： Jordan frame beyond scalar-tensor theories

摘要： 我们研究了标量 - 张量理论广义形式的Jordan框架表述，这些广义形式通过用其他场（如矢量）替换标量来构思。 这一族中的通用理论在Jordan框架作用量中包含高阶时间导数项，这表明其不适定性。 然而，我们证明只要原始Einstein框架表述适定，运动方程总可以化为二阶时间形式。 从Jordan框架回到Einstein框架的逆变换在所有理论的所有场值下并非总是可行，但我们通过对矢量场重新定义，得到了矢量 - 张量理论的完全可逆变换。 我们的主要动机是对自发标量化及其广义形式有更深入的理解，但我们的结论适用于广泛的理论。 Jordan框架传统上被用于某些引力标量 - 张量理论的计算，我们的结果将帮助研究人员推广这些结果，从而与观测数据进行比较。 显示英文摘要

摘要： We study the Jordan frame formulation of generalizations of scalar-tensor theories conceived by replacing the scalar with other fields such as vectors. The generic theory in this family contains higher order time derivative terms in the Jordan frame action which is indicative of ill-posedness. However, we show that equations of motion can always be reduced to a second-order-in-time form as long as the original Einstein frame formulation is well posed. The inverse transformation from the Jordan frame back to the Einstein frame is not possible for all field values in all theories, but we obtain a fully invertible transformation for vector-tensor theories by a redefinition of the vector field. Our main motivation is a better understanding of spontaneous scalarization and its generalizations, however our conclusions are applicable to a wide class of theories. Jordan frame has been traditionally used for certain calculations in scalar-tensor theories of gravitation, and our results will help researchers generalize these results, enabling comparison to observational data.