Rosenbluth Separation of the π^{0} Electroproduction Cross Section Off the Neutron.

Area of Science:

• Nuclear Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• Deeply Virtual Exclusive Pion Electroproduction (DVPEP) probes the nucleon's internal structure.
• Understanding the nucleon's generalized parton distributions (GPDs) is crucial for mapping quark and gluon interactions.
• Previous studies focused on proton targets, necessitating neutron and deuteron data for a complete picture.

Purpose of the Study:

• To perform the first longitudinal-transverse separation of the DVPEP cross section off the neutron and coherent deuteron.
• To extract four structure functions (dσL/dt, dσT/dt, dσLT/dt, dσTT/dt) as a function of momentum transfer.
• To provide a flavor decomposition of u and d quark contributions by combining results with proton data.

Main Methods:

• Experimental measurement of electron-deuteron and electron-neutron scattering with pi0 production.
• Analysis of cross sections at specific kinematic conditions (Q^2=1.75 GeV^2, xB=0.36).
• Separation of structure functions and comparison with theoretical models based on GPDs.

Main Results:

• Cross sections for ed→edπ0 were found to be small, consistent with theoretical predictions.
• Cross sections for en→enπ0 exhibited dominance from transversely polarized photons.
• Results showed good agreement with calculations using transversity GPDs of the nucleon.

Conclusions:

• The study provides essential data on DVPEP off neutrons and deuterons, advancing the understanding of nucleon structure.
• The findings validate theoretical models employing transversity GPDs.
• A flavor decomposition of quark contributions to the cross section was achieved, offering insights into the nucleon's composition.