Physics Department, Stellenbosch University, Matieland 7602, South Africa.
Phys Rev Lett. 2011 Mar 11;106(10):101601. doi: 10.1103/PhysRevLett.106.101601.
We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18) m. The vacuum remains stable in our model, because neutral strings are not energetically favored.
我们研究了在标准模型的简化版本中，由重费米子偶子对宇宙弦的量子稳定化。我们表明，如果电弱玻色子与质量小于顶夸克两倍的费米子耦合，那么通过填充费米子束缚态能级得到的带电弦将变得稳定。这一结果表明，在标准模型中绑定宇宙弦并不需要非常大的费米子质量或不切实际的耦合。数值上，我们发现最有利的弦轮廓是半径约为 10^(-18)m 的希格斯真空期望值的简单槽。由于中性弦在能量上不占优势，所以在我们的模型中真空仍然稳定。
