Abreu Luciano M, Brandão Pedro C S, de Montigny Marc, Ouimet Pierre-Philippe A
Instituto de Física, Universidade Federal da Bahia, Campus Ondina, Salvador, Bahia 40170-115 Brazil.
Faculté Saint-Jean, University of Alberta, Edmonton, AB T6C 4G9 Canada.
Eur Phys J C Part Fields. 2022;82(10):880. doi: 10.1140/epjc/s10052-022-10864-2. Epub 2022 Oct 6.
We revisit the thermal production and annihilation of magnetic monopoles and their relic abundance in order to gain a deeper physical interpretation on the monopole phenomenology predicted from the Baines et al.'s effective field theory, recently proposed in the description of monopole pair production via Drell-Yan and photon fusion processes. In this sense, we use of the vacuum cross sections for the Drell-Yan reactions derived within the mentioned framework to evaluate the cross section averaged over the thermal distribution associated to other particles that constitute the hot medium where the monopoles propagate. In the considered range of monopole mass with spin-zero and spin-half, our findings suggest that the thermally averaged cross sections for the pair production are highly suppressed, while at higher temperatures those for the annihilation of lighter pairs reach larger magnitudes. Besides, we observe that smaller temperature leads to a rate of annihilation for scalar monopoles smaller than the one for fermionic monopoles, which might be interpreted as a theoretical evidence of a more pronounced stability for spin-zero and heavier monopoles. Then we input these thermally averaged cross sections into the kinetic equation that describes the evolution of the monopole abundance via an extension of a freeze-out theory. Our results infer that heavier monopoles achieve the equilibrium at earlier stages of the expansion, and consequently at higher temperatures. In addition, larger monopole masses produce higher values of the relic abundance. Besides, the results indicate that the abundance does not behave differently for spin-zero and spin-half relic monopoles.
我们重新审视磁单极子的热产生、湮灭及其遗迹丰度，以便对从贝恩斯等人的有效场论预测的磁单极子现象学有更深入的物理解释，该有效场论最近被用于描述通过德雷尔 - 扬和光子融合过程产生的磁单极子对。从这个意义上说，我们使用在上述框架内推导的德雷尔 - 扬反应的真空截面，来评估与构成磁单极子传播的热介质的其他粒子的热分布相关的平均截面。在考虑的自旋为零和自旋为二分之一的磁单极子质量范围内，我们的研究结果表明，对产生的热平均截面受到高度抑制，而在较高温度下，较轻磁单极子对湮灭的截面达到更大的值。此外，我们观察到较低的温度导致标量磁单极子的湮灭速率小于费米子磁单极子的湮灭速率，这可能被解释为自旋为零且较重的磁单极子具有更显著稳定性的理论证据。然后，我们将这些热平均截面输入到通过扩展冻结理论来描述磁单极子丰度演化的动力学方程中。我们的结果推断，较重的磁单极子在膨胀的早期阶段达到平衡，因此是在较高温度下。此外，更大的磁单极子质量产生更高的遗迹丰度值。此外，结果表明，对于自旋为零和自旋为二分之一的遗迹磁单极子，丰度的表现没有差异。
