Partial UV completion of P(X) from a curved field space
Partial UV completion of P(X) from a curved field space
复制标题
来自弯曲场空间的 P(X) 的部分 UV 补全
DOI：
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发表时间：
2020
影响因子：
6.4
通讯作者：
R. Namba
中科院分区：
文献类型：
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作者：
S. Mukohyama;R. Namba
k-本质理论是一类典型的标量场模型，它已经提供了丰富的现象学，并且一直是宇宙学广泛研究的目标。众所周知，移对称 k 本质的一般形式会在平面对称构型中形成焦散，唯一的例外是规范和 DBI-/cuscuton 型动力学项。考虑到这一点，我们在本文中寻求一类通用的平移对称 k 本质模型的多场无碱完成。 UV 理论中的场空间自然是弯曲的，我们引入曲率尺度作为控制重场质量的参数，重场在 EFT 缩减过程中会被积分出来。通过数值方法，我们证明了重场的引入确实通过在可能的腐蚀形成附近调用重场的运动来解决腐蚀问题。我们进一步研究该模型的宇宙学应用。通过展开关于场空间曲率尺度的方程，我们证明通过对背景和扰动（包括重力）取无限曲率的极限，可以成功地减少 EFT。一致地进行下一个前导阶计算，并表明 EFT 降低在扰动消失声速的极限内失效。
The k-essence theory is a prototypical class of scalar-field models that already gives rich phenomenology and has been a target of extensive studies in cosmology. General forms of shift-symmetric k-essence are known to suffer from formation of caustics in a planar-symmetric configuration, with the only exceptions of canonical and DBI-/cuscuton-type kinetic terms. With this in mind, we seek for multi-field caustic-free completions of a general class of shift-symmetric k-essence models in this paper. The field space in UV theories is naturally curved, and we introduce the scale of the curvature as the parameter that controls the mass of the heavy field(s) that would be integrated out in the process of EFT reduction. By numerical methods, we demonstrate that the introduction of a heavy field indeed resolves the caustic problem by invoking its motion near the would-be caustic formation. We further study the cosmological application of the model. By expanding the equations with respect to the curvature scale of the field space, we prove that the EFT reduction is successfully done by taking the limit of infinite curvature, both for the background and perturbation, with gravity included. The next leading-order computation is consistently conducted and shows that the EFT reduction breaks down in the limit of vanishing sound speed of the perturbation.