Spheres, deficit angles and the cosmological constant
Spheres, deficit angles and the cosmological constant
复制标题
DOI：
10.1088/0264-9381/20/16/306
复制
发表时间：
2003-05
影响因子：
3.5
通讯作者：
I. Navarro
中科院分区：
文献类型：
--
作者：
I. Navarro
我们考虑在四维闵可夫斯基或德西特空间乘以二维球面S2中的六维引力的紧化。正如最近所指出的，在这些背景中引入具有任意张力的3膜而不影响有效的四维宇宙学常数是可能的，因为它的唯一作用是在球体中引起亏角。我们证明，如果使用6D U(1)规范场的单极态来产生球体中两个额外维度的自发紧化，一旦考虑规范场的量子化条件，就会重新引入膜和体参数之间的微调，因此4D宇宙学常数取决于膜张力。如果我们不考虑单极子，而是考虑体中的四形式场强来获得所需的能量-动量张量，则不存在这个问题。同时，利用4形域，我们将解推广到任意维数（≥6），在n维球面上始终保持4个非紧化维数，其余的紧化维数。我们证明了在这种背景下可以引入具有任意张力的（n + 1）膜而不影响有效四维宇宙学常数。
We consider compactifications of six-dimensional gravity in four-dimensional Minkowski or de Sitter space times a two-dimensional sphere, S2. As has been pointed out recently, it is possible to introduce 3-branes in these backgrounds with arbitrary tension without affecting the effective four-dimensional cosmological constant, since its only effect is to induce a deficit angle in the sphere. We show that if a monopole-like configuration of a 6D U(1) gauge field is used to produce the spontaneous compactification of the two extra dimensions in a sphere, a fine-tuning between brane and bulk parameters is reintroduced once the quantization condition for the gauge field is taken into account, so the 4D cosmological constant depends on the brane tension. This problem is absent if instead of the monopole we consider a 4-form field strength in the bulk to obtain the required energy–momentum tensor. Also, making use of the 4-form field, we generalize the solution to an arbitrary number of dimensions (≥6), keeping always four noncompact dimensions and compactifying the rest in an n-dimensional sphere. We show that an (n + 1)-brane with arbitrary tension can be introduced in this background without affecting the effective 4D cosmological constant.