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arXiv 0811.1503hep-thastro-ph
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轴向D3-D7膨胀

Axionic D3-D7 Inflation

C. P. Burgess, J. M. Cline, M. Postma

摘要:

本文研究了在K3 × T_2/Z_2上紧化为4D的IIB型弦真空中D3膜在D 7和O 7平面存在下的运动。我们的工作在有效的4D超重力描述如何移动D3相互作用的最轻的体积模量的紧化,包括模量稳定通量的影响。我们寻求由此产生的方程的通货膨胀的解决方案,执行我们的搜索数值,以避免诉诸近似参数化的低能量的潜力。我们考虑从D项和反D3膜的超对称性破坏效应中提升。我们发现了慢卷膨胀(反膜隆起)的例子,移动的D3沿着环形方向移动,从对跖点开始朝D 7-O 7堆叠下降。暴胀子是膜位置和K3体积模的轴子的线性组合,沿暴胀子方向的势与跑道暴胀方向的势的相似性导致谱指数n_s \le 0.95的预测.慢滚对有效超势的大多数特征不敏感,需要十分之一的调谐来确保环面接近正方形。我们还考虑了D-长期通货膨胀与D3接近有吸引力的D 7,但发现,对于广泛的(但不详尽)类参数的条件,慢滚往往不稳定的体积模量。与轴子的情况相反,这类最好的暴胀例子需要精细地调整势参数(比千分之一的水平要多得多),并且只在势的拐点处给出暴胀(因此需要对初始条件进行额外的微调,以避免过冲问题)。

英文摘要:

We study the motion of a D3 brane moving within a Type IIB string vacuum compactified to 4D on K3 x T_2/Z_2 in the presence of D7 and O7 planes. We work within the effective 4D supergravity describing how the mobile D3 interacts with the lightest bulk moduli of the compactification, including the effects of modulus-stabilizing fluxes. We seek inflationary solutions to the resulting equations, performing our search numerically in order to avoid resorting to approximate parameterizations of the low-energy potential. We consider uplifting from D-terms and from the supersymmetry-breaking effects of anti-D3 branes. We find examples of slow-roll inflation (with anti-brane uplifting) with the mobile D3 moving along the toroidal directions, falling towards a D7-O7 stack starting from the antipodal point. The inflaton turns out to be a linear combination of the brane position and the axionic partner of the K3 volume modulus, and the similarity of the potential along the inflaton direction with that of racetrack inflation leads to the prediction n_s \le 0.95 for the spectral index. The slow roll is insensitive to most of the features of the effective superpotential, and requires a one-in-10^4 tuning to ensure that the torus is close to square in shape. We also consider D-term inflation with the D3 close to the attractive D7, but find that for a broad (but not exhaustive) class of parameters the conditions for slow roll tend to destabilize the bulk moduli. In contrast to the axionic case, the best inflationary example of this kind requires the delicate adjustment of potential parameters (much more than the part-per-mille level), and gives inflation only at an inflection point of the potential (and so suffers from additional fine-tuning of initial conditions to avoid an overshoot problem).

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