Hidden Valleys in the CMS muon endcap detector

Abstract: We demonstrate the sensitivity of the CMS search to displaced showers arising from the decays of long-lived particles in the muon system, in the context of Hidden Valley scenarios. To establish our simulation setup, we employ a theoretically consistent parameterization of Hidden Valley theory space. We also adopt a hybrid strategy where we treat lifetime as a free parameter to provide model-independent Hidden Valley quark production cross-section upper-limits. Our results demonstrate that the CMS search is sensitive to the underlying theory parameters and has the capacity to constrain the overall Hidden Valley scale as well as the relevant mass ratio. Additionally, we observe that the search exhibits comparatively weak sensitivity to the number of Hidden Valley colors or flavors. Finally, we establish model dependent limits on the maximum strength of the mediator coupling to the Hidden Valley quarks. Our setup and reinterpretation goes beyond the well-established simplified model strategies and demonstrates the use and effectiveness of following a first principles theory setup.