Search for charged massive long-lived particles

Area of Science:

• Particle Physics
• Beyond Standard Model Physics
• Collider Physics

Background:

• Charged Massive Long-Lived Particles (CMLLPs) are predicted by theories beyond the Standard Model.
• These particles may exhibit distinct signatures from Standard Model particles at particle colliders.

Purpose of the Study:

• To search for evidence of CMLLPs produced in proton-antiproton collisions.
• To constrain the masses of hypothetical beyond-Standard-Model particles, specifically charginos and scalar top quarks.

Main Methods:

• Analysis of 5.2 fb⁻¹ of integrated luminosity data collected by the D0 detector at the Fermilab Tevatron.
• Identification of candidate events with particles reconstructed as muons but with anomalous speed and ionization energy loss (dE/dx).
• Comparison of observed event rates with Standard Model background predictions.

Main Results:

• Exclusion of pair-produced long-lived gaugino-like charginos with masses below 267 GeV at 95% confidence level.
• Exclusion of pair-produced long-lived Higgsino-like charginos with masses below 217 GeV at 95% confidence level.
• Exclusion of long-lived scalar top quarks with masses below 285 GeV at 95% confidence level.

Conclusions:

• The search places stringent limits on the masses of certain CMLLPs, ruling out significant portions of parameter space for these hypothetical particles.
• This study contributes to the ongoing experimental effort to uncover new physics phenomena beyond the Standard Model.