Can a protophobic vector boson explain the ATOMKI anomaly?
Can a protophobic vector boson explain the ATOMKI anomaly?
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DOI：
10.1016/j.physletb.2021.136061
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发表时间：
2020-08
影响因子：
4.4
通讯作者：
Xilin Zhang;G. Miller
中科院分区：
文献类型：
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作者：
Xilin Zhang;G. Miller
2016年，ATOMKI合作项目宣布[物理学]在质子束入射到7li靶上引起的一个Be 8核跃迁中，e+-e−对产生信号的意外增强。许多超出标准模型的物理学解释随后被提出。一种流行的理论是，这种异常是由一个质量约为17兆电子伏特（例如物理学）的疏质子矢量玻色子(X)的产生引起的。核跃迁[j] .科学通报，2014(1):1 - 3。我们通过推导光子和X与核子的耦合之间的同位旋关系来研究这一假设。这使我们能够找到疏原生x产生截面与测量光子产生截面之间的简单关系。最终结果是，X的产生主要是由e1x和l1x（横向和纵向电偶极子）和c1x（电荷偶极子）引起的直接跃迁，而不经过任何核共振（即轫致辐射），所有质子束能量高于阈值时都发生平滑的能量依赖。这与实验观察相矛盾，并使疏质子矢量玻色子的解释无效。
In 2016, the ATOMKI collaboration announced [Phys. Rev. Lett. 116, 042501 (2016)] observing an unexpected enhancement of the e+-e− pair production signal in one of the Be 8 nuclear transitions induced by an incident proton beam on a 7 Li target. Many beyond-standard-model physics explanations have subsequently been proposed. One popular theory is that the anomaly is caused by the creation of a protophobic vector boson (X) with a mass around 17 MeV [eg Phys. Rev. Lett. 117, 071803 (2016)] in the nuclear transition. We study this hypothesis by deriving an isospin relation between photon and X couplings to nucleons. This allows us to find simple relations between protophobic X-production cross sections and those for measured photon production. The net result is that X production is dominated by direct transitions induced by E 1 X and L 1 X (transverse and longitudinal electric dipoles) and C 1 X (charge dipole) without going through any nuclear resonance (ie Bremsstrahlung radiation) with a smooth energy dependence that occurs for all proton beam energies above threshold. This contradicts the experimental observations and invalidates the protophobic vector boson explanation.