Numerical approach to the onset of the electroweak phase transition
Numerical approach to the onset of the electroweak phase transition
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电弱相变开始的数值方法
DOI：
10.1103/physrevd.56.4544
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发表时间：
1997
影响因子：
5
通讯作者：
J. Yokoyama
中科院分区：
文献类型：
--
作者：
Masahide Yamaguchi;J. Yokoyama
通过对一个唯象朗之万方程的一系列数值模拟，我们研究了在弱一阶相变(如电弱相变)的临界温度下，宇宙是否均匀地处于伪真空态，该方程的噪声项来自有效作用，但耗散项被设置为满足涨落-耗散关系。由非平衡场理论给出的噪声项的关联函数如果起源于与玻色子或费米子的相互作用，则有一个明显的特征。无质量玻色子噪声的空间关联函数按幂定律衰减，而费米子噪声在逆温标度以上总是指数衰减。在希格斯场的单圈等效势的模拟中，后者对均匀场位形的扰动更为有效。由于这两种类型的噪声都存在于电弱相变中，我们的结果表明，传统的相变图景，即在均匀背景中临界气泡的成核，在标准模型中不适用，或者单圈近似被打破。{版权所有}{ITAL 1997}{ITAL The American Physitive Society}
We investigate whether the universe was homogeneously in the false vacuum state at the critical temperature of a weakly first-order phase transition such as the electroweak phase transition in terms of a series of numerical simulations of a phenomenological Langevin equation, whose noise term is derived from the effective action but the dissipative term is set so that the fluctuation-dissipation relation is met. The correlation function of the noise terms given by a nonequilibrium field theory has a distinct feature if it originates from interactions with a boson or with a fermion. The spatial correlation function of noises from a massless boson damps with a power law, while the fermionic noises always damp exponentially above the inverse-temperature scale. In the simulation with the one-loop effective potential of the Higgs field, the latter turns out to be more effective to disturb the homogeneous field configuration. Since noises of both types are present in the electroweak phase transition, our results suggest that the conventional picture of a phase transition, namely, nucleation of critical bubbles in a homogeneous background, does not apply or the one-loop approximation breaks down in the standard model. {copyright} {ital 1997} {ital The American Physical Society}