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arXiv 2602.17620hep-phastro-ph.CO
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通过暗物质热衰变的轻暗物质领域：17 MeV粒子与电子耦合的案例

Light dark sector via thermal decays of Dark Matter: the case of a 17 MeV particle coupled to electrons

Facoltà di Scienze matematiche, fisiche e naturali（数学、物理和自然科学学院）

Marco Graziani

备注：
81 pages. Master's thesis defended on January 26 at Sapienza University of Rome, under the supervision of Drs. Ludovico Vittorio and Giacomo Landini. Acknowledgements are also extended to Dr Claudio Toni for his valuable support on X17 subject
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AI总结：

本研究探讨了一个17 MeV粒子作为标准模型与隐藏领域中介的可能性，旨在解决暗物质的本质和起源问题。

摘要：

最近的实验观测，特别是ATOMKI和POSITRON ANNIHILATION INTO DARK MATTER EXPERIMENT（PADME）合作组报告的观测，提示了一些异常，可能表明存在一个质量约为17 MeV的新共振态，可能与核子和电子相互作用。自2020年以来，ATOMKI在铍-8、氦-4和碳-12的激发态到基态转变中观测到了这个共振。更最近地，在2025年，PADME在弗拉斯卡蒂国家实验室运行时，也提示了一个类似的过剩，这种情况出现在正负电子对产生事件中，这些事件源于正电子湮灭在碳原子电子上。这种一致性加强了共同基础的案例，可能涉及一个新的规范玻色子，通常称为X17。尽管这些引人注目的发展，全球实验景观仍然高度动态，特别是考虑到最近的MEG II约束，对X17假说的确凿确认或排除仍然缺乏。在这一演变和令人兴奋的背景下，本论文探讨了一个假设的17 MeV粒子是否能作为标准模型和之前未探索的隐藏领域的中介。这种中介有可能提供一种新的途径来解决标准模型的主要未解问题：暗物质的性质和起源。

英文摘要：

Recent experimental observations, most notably those reported by the ATOMKI and Positron Annihilation into Dark Matter Experiment (PADME) collaborations, have hinted anomalies that may indicate the presence of a new resonance with a mass around $17\,\text{MeV}$, potentially interacting with both nucleons and electrons. Since 2020, ATOMKI has observed this resonance in nuclear transitions from excited to ground states in ${}^{8}\mathrm{Be}$, ${}^{4}\mathrm{He}$, and ${}^{12}\mathrm{C}$. More recently, in 2025, PADME, operating at the Laboratori Nazionali di Frascati, has also hinted a similar excess, in this case in the $e^{+}e^{-}$ final-state events originating from positron annihilation on fixed-target atomic electrons of Carbonium. This concordance strengthens the case for a common underlying origin, potentially involving a new boson, conventionally referred to as $X_{17}$. Despite these intriguing developments, the global experimental landscape remains highly dynamic, particularly in light of recent MEG~II constraints, and a definitive confirmation or exclusion of the $X_{17}$ hypothesis is still lacking. Within this evolving and exciting context, this thesis investigates whether a hypothetical $17\,\text{MeV}$ particle, coupled to electrons as suggested by the PADME observations, could function as a mediator between the Standard Model and previously unexplored hidden sectors. Such a mediator could, in principle, offer a novel pathway toward addressing one of the principal outstanding inconsistencies of the Standard Model: the nature and origin of dark matter.

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。

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