Precise Measurement of the D_{s}^{+} Lifetime at Belle II

Area of Science:

• Particle Physics
• High-Energy Physics
• Hadron Spectroscopy

Background:

• The D_{s}^{+} meson is a key particle in understanding the Standard Model.
• Precise measurements of its properties, like lifetime, are crucial for testing theoretical predictions.
• Previous measurements had limited precision, necessitating further investigation.

Purpose of the Study:

• To measure the lifetime of the D_{s}^{+} meson with unprecedented precision.
• To provide a more accurate value for theoretical comparisons in particle physics.
• To contribute to the ongoing research program at the Belle II experiment.

Main Methods:

• Utilized a large dataset of 207 fb^{-1} collected at the SuperKEKB collider.
• Analyzed 116×10^{3} D_{s}^{+}→ϕπ^{+} decays.
• Employed a fit to the decay-time distribution to determine the lifetime.

Main Results:

• The measured lifetime of the D_{s}^{+} meson is τ_{D_{s}^{+}}=(499.5±1.7±0.9) fs.
• The result incorporates both statistical and systematic uncertainties.
• This measurement represents a significant improvement in precision over previous results.

Conclusions:

• The obtained lifetime value offers a stringent test for theoretical models of heavy quark decays.
• The high precision achieved by Belle II enhances our understanding of D_{s}^{+} meson physics.
• This result underscores the capabilities of the Belle II experiment in precision measurements.