分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： Measuring the deviation from scale invariance of the primordial power spectrum is a critical test of inflation. In this paper we reconstruct the shape of the primordial power spectrum of curvature perturbations from the cosmic microwave background data, including the 7-year Wilkinson Microwave Anisotropy Probe data and the Atacama Cosmology Tele-scope 148 GHz data, by using a binning method of a cubic spline interpolation in log-log space. We find that the power-law spectrum is preferred by the data and that the Harrison-Zel’dovich spectrum is disfavored at 95% confidence level. These conclusions hold with and without allowing for tensor modes, however the simpler model without tensors is preferred by the data. We do not find evidence for a feature in the primordial power spectrum – in full agreement with generic predictions from cosmological inflation.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： Determining the energy scale of inflation is crucial to understand the nature of inflation in the early Universe. Assuming a power-law power spectrum of primordial curvature perturbations, we place observational constraints on the energy scale of the observable part of the inflaton potential by combining the 7-year Wilkinson Microwave Anisotropy Probe data with distance measurements from the baryon acoustic oscillations in the distribution of galaxies and the Hubble constant measurement. Our analysis provides an upper limit on this energy scale, 2.3 �1016 GeV at 95% confidence level. Moreover, we forecast the sensitivity and constraints achievable by the Planck experiment by per-forming Monte Carlo studies on simulated data. Planck could significantly improve the constraints on the energy scale of inflation and on the shape of the inflaton potential.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： We consider slow-roll inflation for a single scalar field with an arbitrary potential and an arbitrary nonminimal coupling to the Gauss-Bonnet term. By introducing a combined hierarchy of Hubble and Gauss-Bonnet flow functions, we analytically derive the power spectra of scalar and tensor perturbations. The standard consistency relation between the tensor-to-scalar ratio and the spectral index of tensor perturbations is broken. We apply this formalism to a specific model with a monomial potential and an inverse monomial Gauss-Bonnet coupling and constrain it by the 7-year Wilkinson Microwave Anisotropy Probe data. The Gauss-Bonnet term with a positive (or negative) coupling may lead to a reduction (or enhancement) of the tensor-to-scalar ratio and hence may revive the quartic potential ruled out by recent cosmological data.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： We consider power-law inflation with a Gauss-Bonnet correction inspired by string theory. We analyze the stability of cosmological perturbations and obtain the allowed parameter space. We find that for GB-dominated inflation ultra-violet instabilities of either scalar or tensor perturbations show up on small scales. The Gauss-Bonnet correction with a positive (or negative) coupling may lead to a reduction (or enhancement) of the tensor-to-scalar ratio in the potential-dominated case. We place tight constraints on the model parameters by making use of the WMAP 5-year data.
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