It is shown that production of low-mass \(e^+e^-\)-pairs in ultraperipheral nuclear collisions is enhanced due to the Sommerfeld–Gamow–Sakharov (SGS) factor. This effect is especially strong near the threshold of creation of unbound \(e^+e^-\)-pairs with low masses in the two-photon fusion. Coulomb attraction of the non-relativistic components of such pairs may lead to the increased intensity of 511 keV photons. It can be recorded at the NICA collider and has some astrophysical implications. The analogous effect can be observed at LHC in dilepton production.

中文翻译：

---

在超外围碰撞中增强低质量的双链体

结果表明，由于Sommerfeld–Gamow–Sakharov（SGS）因素，超外围核碰撞中低质量\（e ^ + e ^-\）-对的产生得以增强。在双光子融合中，低质量的未结合\（e ^ + e ^-\）对的生成阈值附近，这种效应尤其强烈。这些对的非相对论性成分的库仑吸引可能导致511 keV光子的强度增加。它可以在NICA对撞机上记录，并具有一些天体物理意义。可以在LHC的双链产生中观察到类似的作用。