Hidden valley scenario sensitivity in the CMS muon end cap detector

We study the sensitivity of the CMS search to displaced showers arising from the decays of long-lived particles in the muon system, within the framework of hidden valley scenarios. To establish our simulation setup, we employ a parametrization of hidden valley theory space and adopt a hybrid strategy where the lifetime is treated as a free parameter to provide model-independent hidden valley quark production cross-section upper limits. Our results indicate that the CMS search is broadly sensitive to variations in hidden valley parameters such as the overall scale and relevant mass ratios, while showing comparatively weak dependence on the number of hidden valley colors or flavors. The exact quantitative results we derive depend on the underlying hadronization model employed and thus, we urge caution in interpreting the results. Within these limitations, we also establish model-dependent limits on the maximum strength of the mediator coupling to hidden valley quarks. Our approach illustrates how one can move beyond simplified model strategies by employing a first-principles-inspired theory setup, while highlighting the theoretical uncertainties inherent in modeling hidden valley phenomenology.