New Measurement of the π0 radiative decay width

Area of Science:

• Nuclear Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• The neutral pion (π0) is a fundamental particle in particle physics, crucial for understanding the strong nuclear force.
• Precise measurement of its decay width, specifically π0→γγ, provides a stringent test of theoretical models like Quantum Chromodynamics.
• Previous measurements have limited precision, necessitating new experimental efforts to refine this fundamental quantity.

Purpose of the Study:

• To perform high-precision measurements of differential cross sections for π0 photoproduction at forward angles.
• To extract the π0→γγ decay width with significantly improved accuracy compared to existing data.
• To test the validity of current theoretical predictions for π0 photoproduction and decay.

Main Methods:

• Experiment conducted at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter.
• Measurements focused on incident photon energies ranging from 4.9 to 5.5 GeV for 12C and 208Pb nuclei.
• Analysis involved fitting the measured differential cross sections using updated theoretical models to determine the π0→γγ decay width.

Main Results:

• The experiment successfully extracted the π0→γγ decay width with a total uncertainty of 2.8%.
• The measured decay width is Γ(π0→γγ) = 7.82 ± 0.14 (stat) ± 0.17 (syst) eV.
• This result is approximately 2.5 times more precise than the current Particle Data Group average.

Conclusions:

• The new high-precision measurement of the π0→γγ decay width is consistent with current theoretical predictions.
• This refined value offers a more stringent constraint for testing fundamental theories of particle and nuclear physics.
• The improved precision highlights the capability of modern experimental techniques in advancing our understanding of particle properties.