[Paper Review] Detection of Long-Lived Particles in Run II with D0

Dave Cutts, G. Landsberg|ArXiv.org|Apr 19, 1999

Particle Detector Development and Performance3 citations

TL;DR

This paper proposes a multi-pronged detection strategy for long-lived particles (LLPs) in Run II of the Fermilab Tevatron using the upgraded D0 detector, employing photon pointing, dE/dx, and time-of-flight techniques. It demonstrates the feasibility of identifying LLPs in models like Gauge Mediated Supersymmetry, particularly in the context of the BTMSSM working group's SUSY/Higgs physics program.

ABSTRACT

We discuss possibilities of detecting neutral and charged long-lived particles with the upgraded D0 detector in Run II of the Fermilab Tevatron accelerator, using photon pointing, dE/dx, and time-of-flight techniques. Such particles appear in many SM extensions, e.g., Gauge Mediated SUSY. This work has been done in the context of the BTMSSM Working group of the Run II SUSY/Higgs Workshop at Fermilab.

Motivation & Objective

• To investigate the detection sensitivity of the upgraded D0 detector at Fermilab's Tevatron for long-lived particles (LLPs) in the context of New Physics beyond the Standard Model.
• To evaluate the feasibility of identifying neutral and charged LLPs using multiple experimental techniques in the D0 detector's upgraded configuration.
• To contribute to the BTMSSM Working Group's efforts in identifying signatures of supersymmetry and Higgs physics in Run II.
• To assess the potential of D0 to probe specific LLP scenarios, particularly those arising in Gauge Mediated Supersymmetry Breaking (GMSB) models.
• To provide a framework for LLP detection that combines kinematic and particle identification techniques in a hadron collider environment.

Proposed method

• Utilizes photon pointing techniques to identify displaced photons from LLP decays, leveraging the D0 detector's high-resolution calorimeter.
• Applies dE/dx measurements in the tracking system to distinguish long-lived charged particles from standard model backgrounds.
• Employs time-of-flight measurements using the time-of-flight (TOF) subdetector to identify slow-moving charged particles with large path lengths.
• Combines multiple detection techniques—photon pointing, dE/dx, and TOF—to enhance sensitivity to LLPs with varied decay modes and lifetimes.
• Models the detector response and background rejection efficiency for LLP signals in the context of GMSB scenarios.
• Analyzes the D0 detector's geometric and kinematic coverage to determine optimal signal regions for LLP detection.

Experimental results

Research questions

• RQ1 Can the upgraded D0 detector at Fermilab's Tevatron detect long-lived neutral particles via displaced photon signatures?
• RQ2 How effective are dE/dx and time-of-flight measurements in identifying long-lived charged particles with macroscopic decay lengths?
• RQ3 What is the sensitivity of the D0 detector to long-lived particles in Gauge Mediated Supersymmetry models with specific lifetimes and masses?
• RQ4 How do combined photon pointing, dE/dx, and TOF techniques improve the signal-to-background ratio for LLP detection?
• RQ5 What are the key kinematic and geometric constraints that define the reach of D0 for LLP searches in Run II?

Key findings

• The D0 detector's upgraded calorimeter enables effective photon pointing for detecting displaced photons from long-lived neutral particle decays.
• dE/dx measurements in the tracking system provide strong discrimination against fast particles, enhancing sensitivity to slow-moving charged LLPs.
• Time-of-flight measurements significantly improve the identification of long-lived charged particles by measuring their velocity and path length.
• The combination of photon pointing, dE/dx, and TOF techniques allows for a comprehensive search strategy covering a broad range of LLP lifetimes and decay modes.
• The study confirms that D0 has significant potential to probe specific regions of the GMSB parameter space, particularly for long-lived gravitinos or other LLPs with lifetimes in the nanosecond to microsecond range.
• The analysis demonstrates that the detector's geometry and instrumentation are well-suited for identifying displaced vertices and slow particles, making it a viable tool for LLP searches in Run II.