标题： 二维和一阶相变在CDT中 显示英文标题

标题： Second- and First-Order Phase Transitions in CDT

摘要： 因果动力学三角剖分（CDT）是量子引力的一个理论方案，它将引力的路径积分量子化作为分段平坦时空几何求和的连续极限。 我们使用蒙特卡洛模拟来分析四维CDT模型中物理上有趣的德西特相的相变边界线。 通过一系列数值标准，我们提供了强有力的证据，表明所谓的A-C相变是一阶的，而B-C相变是二阶的。 二阶相变的存在可能与量子引力的紫外固定点有关，从而为探测普朗克尺度及可能超出该尺度的物理提供关键。 显示英文摘要

摘要： Causal Dynamical Triangulations (CDT) is a proposal for a theory of quantum gravity, which implements a path-integral quantization of gravity as the continuum limit of a sum over piecewise flat spacetime geometries. We use Monte Carlo simulations to analyse the phase transition lines bordering the physically interesting de Sitter phase of the four-dimensional CDT model. Using a range of numerical criteria, we present strong evidence that the so-called A-C transition is first order, while the B-C transition is second order. The presence of a second-order transition may be related to an ultraviolet fixed point of quantum gravity and thus provide the key to probing physics at and possibly beyond the Planck scale.