Connection between the elastic GEp/GMp and P-->Delta form factors

Area of Science:

• Nuclear Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• The magnetic form factor G*M for the proton to Delta (P-->Delta) transition exhibits a decrease at higher squared momentum transfer (Q2).
• Recent experiments show a similar decrease in the elastic electric form factor G(Ep)/G(Mp).

Purpose of the Study:

• To investigate the relationship between the Q2 falloff of the P-->Delta magnetic form factor G*M and the elastic electric form factor G(Ep)/G(Mp).
• To model the P-->Delta transition using a generalized parton distribution (GPD) approach.

Main Methods:

• Utilized a generalized parton distribution model.
• Determined model parameters by fitting elastic proton form factors F(1p) and F(2p).
• Incorporated isospin symmetry in the model calculations.

Main Results:

• The GPD model, when applied to the P-->Delta transition, successfully reproduces the observed Q2 falloff of G*M.
• No additional parameters were required for the P-->Delta transition calculation, validating the model's predictive power.

Conclusions:

• The observed falloff in the P-->Delta magnetic form factor G*M is consistent with a description based on generalized parton distributions.
• The GPD model provides a unified framework for understanding both elastic and transition form factors.