Search for magnetic monopoles produced via the Schwinger mechanism
Search for magnetic monopoles produced via the Schwinger mechanism
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DOI：
10.1038/s41586-021-04298-1
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发表时间：
2022-02-03
期刊：
影响因子：
64.8
通讯作者：
Vives, O.
中科院分区：
文献类型：
--
作者：
Acharya, B.;Alexandre, J.;Vives, O.
带电粒子可以通过足够强的电场的衰减产生，这种现象被称为Schwinger机制（1）。根据电磁对偶性，如果磁单极子存在的话，一个足够强的磁场同样会产生磁单极子（2）。磁单极子是一种假想的基本粒子，在标准模型（3-7）之外的几种理论中都有预测，但从未被实验检测到。通过施温格机制寻找磁单极子的存在还没有尝试过，但它是有利的，因为可以通过半经典技术计算其速率而无需微扰理论，以及磁单极子的产生应该通过其有限的尺寸（8，9）和与光子的强耦合（2，10）来增强。在这里，我们提出了在大型强子对撞机的Pb-Pb重离子碰撞中通过Schwinger机制产生磁共振的研究，产生了当前宇宙中已知的最强磁场（11）。它是由MoEDAL实验进行的，该实验的捕获探测器在2018年11月暴露于每纳米线0.235或约1.8 x 10（9）的Pb-Pb碰撞，每次碰撞的质量中心能量为5.02太电子伏。超导量子干涉仪（SQUID）磁强计扫描MoEDAL的捕获探测器，以寻找磁荷的存在，这将在SQUID中感应出持续电流。在95%的置信水平下，分析排除了具有整数狄拉克电荷为1、2和3，质量高达75千兆电子伏/光速平方的磁单极子。这为对撞机搜索的有限大小磁单极子提供了一个较低的质量限制，并大大扩展了以前的质量界限。
Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism(1). By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist(2). Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model(3-7) but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size(8,9) and strong coupling to photons(2,10). Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe(11). It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 x 10(9), of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.