标题： 近视界处的近极端黑洞周围的碰撞 显示英文标题

标题： Near-Horizon Collisions around Near-Extremal Black Holes

摘要： 黑洞有时被描述为天体物理粒子加速器，因为有限能量的粒子可以在视界附近碰撞，并具有发散的质心（CM）能量。 碰撞根据碰撞瞬间组成粒子的径向运动进行分类，每一类在接近视界时表现出不同的行为。 质心能量的发散来源于碰撞半径接近视界的速度与粒子角动量调整到由超辐射边界设定的关键值的速度之间的差异。 为了在近极端黑洞周围产生高能碰撞，至少有一个粒子必须比碰撞半径接近视界的速度更慢地接近临界状态。 当两个粒子都是向内或向外运动时，还要求粒子以不同的速度接近临界状态。 利用一种新颖的多尺度极限，我们计算了发散质心能量的显式形式。 显示英文摘要

摘要： Black holes have sometimes been described as astrophysical particle accelerators because finite energy particles can collide near the horizon with divergent center-of-mass (CM) energy. The collisions are classified by the radial motion of the constituent particles at the moment of collision, with each class exhibiting a distinct near-horizon behavior. Divergence in the CM energy is sourced by the difference in the rate at which the collision radius approaches the horizon and the rate at which a particle's angular momentum is tuned to a critical value set by the superradiant bound. To produce a high energy collision around a near-extremal BH, at least one particle must approach criticality slower than the collision radius approaches the horizon. When both particles are ingoing or outgoing, it is additionally required that the particles approach criticality at different rates. Using a novel multi-scaling limit, we calculate the explicit form for the divergent CM energy.