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引用次数: 0
摘要
我们提出了一种用于求解电弱重子发生的半经典玻尔兹曼方程的系统矩扩展。该扩展以绝热坐标速度的幂为单位展开,用于计算相变壁前端的违反 CP 的种子不对称性,它是宇宙重子不对称性(BAU)的最终来源。我们在一个基准模型中实施了这一方法,其违反 CP 的质量来自于费米子与单子标量场耦合的 5 维算子。我们发现,高矩数计算得出的 BAU 与常用的两矩数近似会有很大不同。我们详细讨论了力矩方法中的基本近似,并提出了一种新的扩展截断方案,与之前的方案相比,它似乎能给出数值上更稳健的结果。
Systematic moment expansion for electroweak baryogenesis
We present a systematic moment expansion for solving the semiclassical Boltzmann equations for electroweak baryogenesis. The expansion is developed in powers of adiabatic coordinate velocity, and it is used for computing the CP-violating seed asymmetry at the front of the phase transition wall, that sources the eventual baryon asymmetry of the universe (BAU). We implement the method in a benchmark model, with a CP-violating mass arising from a dimension-5 operator coupling the fermion to a singlet scalar field. We find that the higher moment calculations yield a BAU that can significantly differ from the commonly used two-moment approximation. We discuss in detail the underlying approximations in the moment method and propose a new truncation scheme for the expansion, that appears to give more numerically robust results than the previous schemes.
期刊介绍:
Journal of Cosmology and Astroparticle Physics (JCAP) encompasses theoretical, observational and experimental areas as well as computation and simulation. The journal covers the latest developments in the theory of all fundamental interactions and their cosmological implications (e.g. M-theory and cosmology, brane cosmology). JCAP''s coverage also includes topics such as formation, dynamics and clustering of galaxies, pre-galactic star formation, x-ray astronomy, radio astronomy, gravitational lensing, active galactic nuclei, intergalactic and interstellar matter.