Search for Dark Photons Produced in 13 TeV pp Collisions.

Area of Science:

• Particle Physics
• High-Energy Physics
• Dark Matter Searches

Background:

• Dark photons (A^{‘}) are hypothetical particles that could mediate interactions between the Standard Model and a hidden sector.
• Searches for dark photons are crucial for understanding dark matter and extending the Standard Model.
• Previous searches have constrained dark photon properties, but gaps remain, particularly for long-lived scenarios.

Purpose of the Study:

• To search for both promptlike and long-lived dark photons (A^{‘}) produced in proton-proton collisions.
• To constrain the kinetic-mixing strength between the photon and the dark photon.
• To establish new limits on dark photon properties and explore novel search strategies.

Main Methods:

• Utilized a data sample of 1.6 fb^{-1} from proton-proton collisions at 13 TeV center-of-mass energy.
• Searched for A^{‘} → μ^{+}μ^{-} decays using the LHCb detector.
• Investigated promptlike A^{‘} in the mass range up to 70 GeV and long-lived A^{‘} in the 214–350 MeV range using displaced vertices.

Main Results:

• No evidence for a signal of either promptlike or long-lived dark photons was found.
• Exclusion limits at 90% confidence level were placed on the γ-A^{‘} kinetic-mixing strength.
• Achieved the most stringent constraints to date for promptlike dark photons in the 10.6–70 GeV mass range.

Conclusions:

• The search sets new benchmarks for promptlike dark photon constraints and is the first to probe long-lived dark photons with displaced vertices.
• The results contribute to narrowing the parameter space for dark photon models.
• Future searches with enhanced sensitivity could further explore the dark photon parameter space.