论文标题
引力键盘和异常手性对称性破坏
Gravitational instantons and anomalous chiral symmetry breaking
论文作者
论文摘要
我们研究在功能重态化组方法中，在渐近安全的重力中，由重力和QCD-Instantons引起的两种流动QCD中的异常性手性对称性破裂。与QCD-Instantons类似，引力与K3表面相关，该k3表面是通过平坦的时空连接的K3表面相关的，它与与$ \ exp（-1/g_n）$成正比的't〜hooft耦合产生了贡献。因此，在渐近安全的重力方案中，$ g_n^*$均不呈固定点耦合，诱导的't Hooft耦合在Planck量表上是有限的，其大小取决于所选的紫外线完整。在这种情况下，对普朗克量表的异常$ u（1）_ $的重力影响可能在低能尺度下生存。反过来，不可能出现普朗克量表顺序的费米昂。这限制了重力QCD系统的允许渐近安全的紫外线完成。我们划出与低能策略中光费米相兼容的参数制度。
We study anomalous chiral symmetry breaking in two-flavour QCD induced by gravitational and QCD-instantons within asymptotically safe gravity within the functional renormalisation group approach. Similarly to QCD-instantons, gravitational ones, associated to a K3-surface connected by a wormhole-like throat in flat spacetime, generate contributions to the 't~Hooft coupling proportional to $\exp(-1/g_N)$ with the dimensionless Newton coupling $g_N$. Hence, in the asymptotically safe gravity scenario with a non-vanishing fixed point coupling $g_N^*$, the induced 't Hooft coupling is finite at the Planck scale, and its size depends on the chosen UV-completion. Within this scenario the gravitational effects on anomalous $U(1)_A$-breaking at the Planck scale may survive at low energy scales. In turn, fermion masses of the order of the Planck scale cannot be present. This constrains the allowed asymptotically safe UV-completion of the Gravity-QCD system. We map-out the parameter regime that is compatible with the existence of light fermions in the low-energy regime.
