The process of a resonant production of an ultrarelativistic electron–positron pair in the process of gamma-quantum scattering in the X-ray field of a pulsar is theoretically studied. This process has two reaction channels. Under resonant conditions, an intermediate electron (for a channel A) or a positron (for a channel B) enters the mass shell. As a result, the initial second-order process of the fine-structure constant in the X-ray field effectively splits into two first-order processes: the X-ray field-stimulated Breit–Wheeler process and the the X-ray field-stimulated Compton effect on an intermediate electron or a positron. The resonant kinematics of the process is studied in detail. It is shown that for the initial gamma quantum there is a threshold energy, which for the X-ray photon energy (1–${10}^2$) keV has the order of magnitude (${10}^3$–10) MeV. In this case, all the final particles (electron, positron, and final gamma quantum) fly in a narrow cone along the direction of the initial gamma quantum momentum. It is important to note that the energies of the electron–positron pair and the final gamma quantum depend significantly on their outgoing angles. The obtained resonant probability significantly exceeds the non-resonant one. The obtained results can be used to explain the spectrum of positrons near pulsars.

中文翻译：

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X射线脉冲星场在γ量子散射中产生的超相对论电子-正电子对的共振产生。

理论上研究了超相对论性电子-正电子对在脉冲星的X射线场中的伽马量子散射过程中的共振产生过程。该过程具有两个反应通道。在共振条件下，中间电子（对于通道A）或正电子（对于通道B）进入质量壳。结果，X射线场中的精细结构常数的初始二阶过程有效地分为两个一阶过程：X射线场激发的Breit-Wheeler过程和X射线场-对中间电子或正电子激发康普顿效应。详细研究了该过程的共振运动学。结果表明，对于初始伽马量子，有一个阈值能量，对于X射线光子能量（1–${10}^2$）keV具有数量级（${10}^3$–10）MeV。在这种情况下，所有最终粒子（电子，正电子和最终伽马量子）都沿着初始伽马量子动量的方向在一个狭窄的圆锥体中飞行。重要的是要注意，电子-正电子对和最终的伽马量子的能量在很大程度上取决于它们的出射角。所获得的谐振概率大大超过非谐振概率。所得结果可用于解释脉冲星附近正电子的光谱。