标题： WMAP数据限制非高斯性 显示英文标题

标题： Limits on non-Gaussianities from WMAP data

摘要： 我们提出了一种方法来限制密度扰动非高斯性的程度，当三点函数属于“等边”类型时。 这种形式的非高斯性偏离由单场模型（例如幽灵或DBI暴胀）产生，并且一般由暴胀子有效拉格朗日中存在高阶导数算符引起。 我们表明，诱导的三线函数形状可以很好地用可分解的形式近似，使分析变得实用。 我们还表明，除非有一个全天空图并且噪声均匀分布，否则为了达到三线函数振幅误差的Cramer-Rao界，估计器必须包含一个与数据线性相关的部分。 我们将此技术应用于WMAP数据，得到对“等边”非高斯性的振幅f_NL^equil的限制：在95%置信水平下，-366 < f_NL^equil < 238。 我们还应用此技术约束所谓的“局部”形状，例如由曲率子和变化衰变宽度模型预测。 我们表明，在估计器中加入线性项可以改进约束，比WMAP团队获得的结果更好，在95%置信水平下，-27 < f_NL^local < 121。 显示英文摘要

摘要： We develop a method to constrain the level of non-Gaussianity of density perturbations when the 3-point function is of the "equilateral" type. Departures from Gaussianity of this form are produced by single field models such as ghost or DBI inflation and in general by the presence of higher order derivative operators in the effective Lagrangian of the inflaton. We show that the induced shape of the 3-point function can be very well approximated by a factorizable form, making the analysis practical. We also show that, unless one has a full sky map with uniform noise, in order to saturate the Cramer-Rao bound for the error on the amplitude of the 3-point function, the estimator must contain a piece that is linear in the data. We apply our technique to the WMAP data obtaining a constraint on the amplitude f_NL^equil of "equilateral" non-Gaussianity: -366 < f_NL^equil < 238 at 95% C.L. We also apply our technique to constrain the so-called "local" shape, which is predicted for example by the curvaton and variable decay width models. We show that the inclusion of the linear piece in the estimator improves the constraint over those obtained by the WMAP team, to -27 < f_NL^local < 121 at 95% C.L.