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arXiv 1506.04741hep-phastro-ph.COhep-th
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磁泡膨胀与单重态驱动的电弱重子生成的生存性

Bubble Expansion and the Viability of Singlet-Driven Electroweak Baryogenesis

Jonathan Kozaczuk

摘要:

电弱重子生成的标准图像需要缓慢膨胀的气泡。如果在电弱相变过程中,规范单重标量场的真空期望值发生了明显的变化,这就很难实现。在这种情况下,确定气泡壁速度是很重要的,因为预测的重子不对称性可以敏感地依赖于它的值。在这里,这个计算是讨论和说明在真正的单重扩展的标准模型。气泡壁面上的摩擦力采用动力学理论方法计算,并包括流体动力学效应。壁速度被发现是相当大的($v_w \gtrsim 0.2$),但在某些部分的参数空间与电弱重子生成兼容。然而,如果相变足够强,亚音速解可能不存在,从而完全排除了非定域电弱重子生成。这里给出的结果可以用于计算重子不对称性在各种单态驱动的情况下,以及其他功能相关的宇宙学相变在早期宇宙,如引力辐射的光谱。

英文摘要:

The standard picture of electroweak baryogenesis requires slowly expanding bubbles. This can be difficult to achieve if the vacuum expectation value of a gauge singlet scalar field changes appreciably during the electroweak phase transition. It is important to determine the bubble wall velocity in this case, since the predicted baryon asymmetry can depend sensitively on its value. Here, this calculation is discussed and illustrated in the real singlet extension of the Standard Model. The friction on the bubble wall is computed using a kinetic theory approach and including hydrodynamic effects. Wall velocities are found to be rather large ($v_w \gtrsim 0.2$) but compatible with electroweak baryogenesis in some portions of the parameter space. If the phase transition is strong enough, however, a subsonic solution may not exist, precluding non-local electroweak baryogenesis altogether. The results presented here can be used in calculating the baryon asymmetry in various singlet-driven scenarios, as well as other features related to cosmological phase transitions in the early Universe, such as the resulting spectrum of gravitational radiation.

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