Novel ideas for CMS L1 trigger in HL-LHC using RPC ultimate timing performance

Document Type

Article

Publication Date

8-2025

Abstract

The CMS RPC system has been upgraded for Phase-2 with two major projects. First is the comprehensive redesign of the Link System connecting the Front-End Boards (FEBs) of existing CMS RPC chambers to the trigger processors, which leads to the full exploitation of the intrinsic time resolution of 1.6 ns. Second is the extension of the pseudorapidity coverage by adding new chambers from |η|" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; font-size-adjust: none; word-spacing: normal; overflow-wrap: normal; text-wrap: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">|𝜂| = 1.9 to 2.4. The newly assembled chambers utilize improved Resistive Plate Chambers (iRPC) technology, enabling signal readout from both ends of the strip for 2-dimensional hit reconstruction. Equipped with advanced electronics, iRPCs deliver hit timing with a 500 ps resolution, facilitating the development of precise Time of Flight triggers. We will discuss algorithms in which RPCs can be used as a starting point for new physics searches, given the vital role of RPC in the CMS experiment, specifically upgraded to cope with high luminosity and high number of simultaneous proton–proton collisions per bunch crossing (also called pileup) expected in the upcoming High-Luminosity Large Hadron Collider (HL-LHC) phase. We aim at improving the detection efficiency of Long-lived particles (LLPs), offering a tantalizing glimpse into new physics, potentially providing clues about beyond-the-Standard-Model theories. The focus will be on one type of LLPs, the heavy stable charged particles (HSCPs) that leave traces in the muon chambers as if they were muons but with a time delay. The ultimate time resolution performance of existing RPCs and iRPCs will enhance the discovery potential of our searches in CMS for new physics.

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