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Probing new physics with dedicated data streams at CMS

Ali Eren Simsek

TL;DR

The paper addresses the challenge of detecting new physics signatures that may be missed by standard triggers due to low thresholds or long lifetimes. It presents CMS strategies—data scouting, data parking, and forthcoming Level-1 scouting—to record large samples with reduced or full detector content for deferred processing. Across Run-II and Run-III, the work demonstrates improved constraints on low-mass dijet/multijet resonances, long-lived heavy neutrinos, low-mass tau resonances, and light LLP decays to displaced jets, illustrating the practical impact of dedicated data streams on expanding CMS reach. These approaches are poised to play a crucial role during the HL-LHC era and Phase-2 upgrades, enabling broader and more sensitive searches in challenging regions of parameter space.

Abstract

Signatures of new physics at the LHC are varied and, by nature, often very different from those of Standard Model processes. Novel experimental techniques, including dedicated data streams, are exploited to enhance the sensitivity of the CMS Experiment to search for such signatures. This report highlights the CMS results obtained using data collected at the LHC during Run-II and Run-III through the so-called "Data Scouting" and "Data Parking" strategies. These approaches have allowed us to set some of the strongest constraints to date for low-mass resonances in prompt and long-lived signatures.

Probing new physics with dedicated data streams at CMS

TL;DR

The paper addresses the challenge of detecting new physics signatures that may be missed by standard triggers due to low thresholds or long lifetimes. It presents CMS strategies—data scouting, data parking, and forthcoming Level-1 scouting—to record large samples with reduced or full detector content for deferred processing. Across Run-II and Run-III, the work demonstrates improved constraints on low-mass dijet/multijet resonances, long-lived heavy neutrinos, low-mass tau resonances, and light LLP decays to displaced jets, illustrating the practical impact of dedicated data streams on expanding CMS reach. These approaches are poised to play a crucial role during the HL-LHC era and Phase-2 upgrades, enabling broader and more sensitive searches in challenging regions of parameter space.

Abstract

Signatures of new physics at the LHC are varied and, by nature, often very different from those of Standard Model processes. Novel experimental techniques, including dedicated data streams, are exploited to enhance the sensitivity of the CMS Experiment to search for such signatures. This report highlights the CMS results obtained using data collected at the LHC during Run-II and Run-III through the so-called "Data Scouting" and "Data Parking" strategies. These approaches have allowed us to set some of the strongest constraints to date for low-mass resonances in prompt and long-lived signatures.
Paper Structure (8 sections, 5 figures)

This paper contains 8 sections, 5 figures.

Table of Contents

  1. Introduction
  2. Physics results with dedicated data streams
  3. Search for pair-produced multijet resonances
  4. Search for dijet resonances with Calo-scouting
  5. Search for long-lived heavy neutrinos with the B-parking data set
  6. Search for a low-mass resonance decaying to two tau leptons
  7. Search for light long-lived particles decaying to displaced jets
  8. Summary

Figures (5)

  • Figure 1: Schematic illustration of the CMS data flow, showing the L1 trigger, the high-level trigger, and the three main data streams: normal, parking, and scouting.
  • Figure 2: Observed and expected 95% confidence level upper limits on the product of the cross-section ($\sigma$), branching ratio ($B$), and acceptance ($A$) for pair-produced multijet resonances in the merged trijet (left), merged dijet (center), and resolved trijet (right) final states.
  • Figure 3: Observed and expected 95% confidence level upper limits on the universal quark coupling $g_q'$ as a function of the mass of a leptophobic $Z'$ boson that only couples to quarks.
  • Figure 4: Observed 95% confidence level lower limits on $c\tau_\mathrm{N}$ as a function of the mixing ratios $(r_{e}, r_{\mu}, r_{\tau})$ for fixed N masses of 1GeV. The left (right) panel corresponds to the Majorana (Dirac-like) hypothesis.
  • Figure 5: Observed 95% confidence level upper limits on the branching fraction $B(H\to SS)$ as a function of the LLP proper decay length $c\tau_{0}$ for representative signal points. The three panels show the cases $S\to bb$ with $m_{S}=40$ GeV (left), $S\to bb$ with $m_{S}=15$ GeV (center), and $S\to dd$ with $m_{S}=15$ GeV (right).