Search for long-lived massive charged particles in 1.96 TeV pp collisions.

Area of Science:

• High Energy Physics
• Particle Physics
• Collider Physics

Background:

• Searches for new physics phenomena at the Large Hadron Collider (LHC) are crucial for understanding fundamental particles and forces.
• Long-lived massive particles are predicted by various extensions to the Standard Model, such as supersymmetry.
• Previous searches have constrained the properties of such hypothetical particles.

Purpose of the Study:

• To search for evidence of long-lived charged massive particles produced in proton-antiproton collisions.
• To set limits on the production cross-section and mass of these hypothetical particles.
• To interpret the results within the framework of a stable scalar top-quark model.

Main Methods:

• Utilized a signature-based search targeting high transverse-momentum (pT) muons from 1.0 fb^-1 of proton-antiproton collision data at sqrt(s)=1.96 TeV.
• Employed time-of-flight measurements to identify slowly moving, high-pT particles.
• Applied selection criteria to isolate candidate events and estimated the expected background.

Main Results:

• Observed one event that passed all selection criteria.
• The expected background for this event was calculated to be 1.9 +/- 0.2 events.
• An upper bound was placed on the production cross-section for these particles.

Conclusions:

• The absence of a significant excess of events is consistent with the Standard Model background.
• A lower limit on the mass of a stable scalar top-quark particle was established at 249 GeV/c2 at 95% confidence level.
• This result contributes to the ongoing search for physics beyond the Standard Model.