标题： 一个来自扩展色群的可见QCD轴子 显示英文标题

标题： A Visible QCD Axion from an Enlarged Color Group

摘要： 我们考虑扩大QCD色群的可能性，即SU(3+$N^\prime$)自发地破缺为SU(3)$_c\times$SU($N^\prime$)$\times$U(1)$_X$，并带有在基本表示中变换的额外矢量样夸克。 当重夸克在PQ破坏尺度以下被积分掉时，它们会产生一个轴子耦合，该耦合同时解决了两个规范群的强CP问题。 然而，轴子质量现在会从SU($N^\prime$)的约束尺度获得一个新的非微扰贡献，这可能比QCD尺度大得多。 这可以将轴子质量增加到电弱尺度或更高。 这种可见轴子然后可以衰变为胶子和光子，在LHC的Run-II中产生可观察的信号。 特别是，如果将质量与750 GeV双光子共振联系起来，则新的约束尺度为$\sim$ TeV，PQ破坏尺度为$\sim$ 10 TeV。 这预测了在多TeV范围内的矢量样夸克和一个PQ标量共振，可能存在暗物质是SU($N^\prime$)重子的情况。 显示英文摘要

摘要： We consider the possibility of an enlarged QCD color group, SU(3+$N^\prime$) spontaneously broken to SU(3)$_c\times$SU($N^\prime$)$\times$U(1)$_X$ with extra vector-like quarks transforming in the fundamental representation. When the heavy quarks are integrated out below the PQ-breaking scale, they generate an axion coupling which simultaneously solves the strong CP problem for both gauge groups. However, the axion mass now receives a new nonperturbative contribution from the SU($N^\prime$) confinement scale, which can be substantially larger than the QCD scale. This can increase the axion mass to be at or above the electroweak scale. This visible axion can then decay into gluons and photons giving rise to observable signals at Run-II of the LHC. In particular, if the mass is identified with the 750 GeV diphoton resonance then the new confinement scale $\sim$ TeV and the PQ-breaking scale $\sim$ 10 TeV. This predicts vector-like quarks and a PQ scalar resonance in the multi-TeV range, with the possibility that dark matter is an SU($N^\prime$) baryon.