We propose a new type of search for a pseudoscalar particle $\eta$ pair produced via an off-shell Higgs, $pp\to h^*\to \eta\eta$. The search is motivated by a composite Higgs model in which the $\eta$ is extremely narrow and decays almost exclusively into $Z\gamma$ in the mass range $65$ GeV$\lesssim m_\eta \lesssim 160$ GeV. We devise an analysis strategy to observe the novel $Z\gamma Z\gamma$ channel and estimate potential bounds on the Higgs-$\eta$ coupling. The experimental sensitivity to the signatures depends on the power to identify fake photons and on the ability to predict large photon multiplicities. This search allows us to exclude large values of the compositeness scale $f$, being thus complementary to other typical processes.

中文翻译：

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在复合希格斯模型中通过壳外希格斯产生伪标量对

我们提出了一种新的搜索类型，用于通过壳外希格斯产生的伪标量粒子$ \ eta $对，$ pp \ to h ^ * \ to \ eta \ eta $。该搜索是由复合希格斯模型激发的，其中$ \ eta $非常狭窄，并且几乎完全衰减为质量范围$ 65 $ GeV $ \ lesssim m_ \ eta \ lesssim 160 $ GeV的$ Z \ gamma $。我们设计了一种分析策略，以观察新颖的$ Z \ gamma Z \ gamma $通道并估计Higgs-$ \ eta $耦合的潜在边界。对签名的实验敏感性取决于识别假光子的能力以及预测大光子多重性的能力。该搜索使我们能够排除合成度标度$ f $的较大值，从而与其他典型过程互补。