INFLUENCE ON SPACETIME STRUCTURE OF QUANTUM BACK REACTION

首先，在提取了黑洞几何最本质特征的模型中，研究了由于霍金辐射引起的黑洞蒸发；事件视界的存在。通过采用二维膨胀引力或模拟霍金辐射本质的运动镜模型，结果表明，黑洞可以在没有进一步辐射的情况下完全消失，但会留下稳定的残留物。在第二个项目中，我们研究了伴随粒子产生的相干场振荡问题。用泛函薛定谔图像分析了由玻色量子场与经典振子场耦合所描述的量子系统的行为。在几个振荡周期内的短时间平均值表明，粒子产生发生在粒子波数和振荡幅度的参数空间中的无限多个频带区域，称为参数共振频带。因此，对于初始的大幅度振荡，由于摄动的波生率而导致的导航估计是严重错误的。这对膨胀后的再热问题和超重力模型中的Polonyi问题具有重要的影响；膨胀可能会随着温度更高的中间时期而结束，这一中间时期很容易实现肠道重力发生，同时抑制成功的核合成所需的引力的产生。

Firstly, evaporation of the black hole due to Hawking radiation has been investigated in models that extract most essential features of the black hole geometry ; existence of the event horizon. By taking either a two dimensional dilaton gravity or the moving mirror model that mimics essence of the Hawking radiation, it was shown that the black hole can completely disappear without furthere radiation, but leaving behind stable remnants. In the second project the problem of coherent field oscillation accompanying particle production has been studied. The behavior of the quantum system described by bose quantum fields coupling to the classical oscillator field was shown to be analyzed vigorously by using a functional Schrodinger picture. The short time average over a few oscillation periods exhibits particle production taking place in infinitely many band regions in the parameter space of the particle wave number and the oscillation amplitude, known as the band of parametric resonance. Accordingly the navive estimate due to the perturbative Born rate is grossly wrong for an initial large amplitude oscillation. This has important effects hitherto ignored on the reheating problem after inflation and the Polonyi problem in supergravity models ; inflation may end with intermediate epoch of much higher temperatures that realizes readily the GUT baryogenesis at the same time suppressing production of gravitino required by successful nucleosynthesis.