为FCHAMP加油？
Requiem for an FCHAMP?
摘要：
分数带电大质量粒子（FCHAMP）出现在标准模型的扩展中，特别是那些具有超弦结构的粒子。最轻的FCHAMP将是绝对稳定的，并且在宇宙早期演化过程中产生的任何物质都将存在于今天。本文讨论了质量为m_L、电荷为Q_L（正电子电荷单位）的强相互作用作用轻子L的产生、湮灭和存活。由于大质量带电粒子的行为类似于重子，原始核合成和宇宙背景辐射温度的各向异性限制了FCHAMP残余密度，从而限制了QL-mL关系。Z的不可见宽度和加速器对大质量带电粒子的搜索提供了进一步的限制。我们利用了这样一个事实，即在早期宇宙中，带负电荷的L将与α粒子和质子结合，形成紧密结合的带正电荷的状态。这些带正电荷的束缚态和自由L+之间的库仑势垒抑制了银河系和地球上的后期湮灭，限制了任何遗留FCHAMP对的后期还原。地球上幸存的FCHAMP丰度比地面搜索分数带电粒子的极限高出几个数量级，似乎关闭了FCHAMP的窗口。然而，当Q_L接近整数时，这些搜索变得越来越不敏感，在Q_L-m_L平面中留下一些“岛”，可以通过在宇宙射线中搜索FCHAMP来探索这些“岛”。
英文摘要：
Fractionally charged massive particles (FCHAMPs) appear in extensions of the standard model, especially those with superstring constructions. The lightest FCHAMP would be absolutely stable and any produced during the early evolution of the Universe would be present today. The production, annihilation, and survival of L, a lepton with electroweak but no strong interactions, of mass m_L and charge Q_L (in units of the positron charge) are explored. Since massive charged particles behave like baryons, primordial nucleosynthesis and the cosmic background radiation temperature anisotropies limit the FCHAMP relic density leading to constraints on the Q_L - m_L relation. Further constraints are provided by the invisible width of the Z and by accelerator searches for massive, charged particles. We exploit the fact that in the early Universe the negatively charged L will combine with alpha particles and protons forming tightly bound, positively charged states. The Coulomb barriers between these positively charged bound states and the free L+ suppress late time annihilation in the Galaxy and on Earth, limiting any late-time reduction of relic FCHAMP pairs. The surviving FCHAMP abundance on Earth is orders of magnitude higher than the limits from terrestrial searches for fractionally charged particles, appearing to close the window on FCHAMPs. However, as Q_L approaches an integer these searches become increasingly insensitive, leaving some "islands" in the Q_L - m_L plane which may be explored by searching for FCHAMPs in the cosmic rays.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
