Hidden valley scenario sensitivity in the CMS muon endcap detector

TL;DR

This paper evaluates CMS detector sensitivity to displaced showers from long-lived particle decays in Hidden Valley models, providing model-independent limits and highlighting theoretical uncertainties in Hidden Valley phenomenology.

Contribution

It introduces a parameterized simulation framework for Hidden Valley scenarios and derives sensitivity and coupling limits, moving beyond simplified models.

Findings

CMS is sensitive to Hidden Valley parameters like scale and mass ratios.

Sensitivity shows weak dependence on Hidden Valley colors or flavors.

Results depend on the hadronization model used, indicating theoretical uncertainties.

Abstract

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 parameterization 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.