论文标题
量子重力的2D和4D理论中的婴儿宇宙
Baby universes in 2d and 4d theories of quantum gravity
论文作者
论文摘要
Coleman机制的有效性自动调整了基本常数，以二维和四维量子重力理论进行检查。首先，我们考虑在可定向的封闭歧管上与中央电荷的共形物质$ c \ leq1 $相连的二维欧几里得量子重力。该系统的适当时间哈密顿人被称为非批评字符串的田间理论，也可以将其视为二维中的第三个量化。通过直接计算各种拓扑的随机表面数量，我们发现婴儿宇宙的贡献太小，无法实现科尔曼机制。接下来，我们考虑四维洛伦兹重力。基于无所事事的母亲宇宙的创造与灭绝的灭绝之间的差异，我们为多元宇宙介绍了一个非热烈的有效的哈密顿式汉密尔顿人。我们表明，在这个模型中，科尔曼的想法得到了满足，并且宇宙学常数被调整为几乎为零。还讨论了对现象学的潜在影响。
The validity of the Coleman mechanism, which automatically tunes the fundamental constants, is examined in two-dimensional and four-dimensional quantum gravity theories. First, we consider two-dimensional Euclidean quantum gravity on orientable closed manifolds coupled to conformal matter of central charge $c \leq1$. The proper time Hamiltonian of this system is known to be written as a field theory of noncritical strings, which can also be viewed as a third quantization in two dimensions. By directly counting the number of random surfaces with various topologies, we find that the contribution of the baby universes is too small to realize the Coleman mechanism. Next, we consider four-dimensional Lorentzian gravity. Based on the difference between the creation of the mother universe from nothing and the annihilation of the mother universe into nothing, we introduce a non-Hermitian effective Hamiltonian for the multiverse. We show that Coleman's idea is satisfied in this model and that the cosmological constant is tuned to be nearly zero. Potential implications for phenomenology are also discussed.
