New framework for extracting GPDs from exclusive photon electroproduction

Recently, a new framework for studying generic <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mn>2</a:mn> <a:mo stretchy="false">→</a:mo> <a:mn>3</a:mn> </a:math> hard exclusive reactions, referred to as single-diffractive hard exclusive processes, has been introduced to provide a cleaner separation of the underlying physical mechanisms. In this work, we expand this formalism to the case of exclusive real-photon electroproduction off a nucleon, <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"> <d:mi>e</d:mi> <d:mo stretchy="false">(</d:mo> <d:mo>ℓ</d:mo> <d:mo stretchy="false">)</d:mo> <d:mo>+</d:mo> <d:mi>N</d:mi> <d:mo stretchy="false">(</d:mo> <d:mi>p</d:mi> <d:mo stretchy="false">)</d:mo> <d:mo stretchy="false">→</d:mo> <d:mi>e</d:mi> <d:mo stretchy="false">(</d:mo> <d:msup> <d:mo>ℓ</d:mo> <d:mo>′</d:mo> </d:msup> <d:mo stretchy="false">)</d:mo> <d:mo>+</d:mo> <d:mi>N</d:mi> <d:mo stretchy="false">(</d:mo> <d:msup> <d:mi>p</d:mi> <d:mo>′</d:mo> </d:msup> <d:mo stretchy="false">)</d:mo> <d:mo>+</d:mo> <d:mi>γ</d:mi> <d:mo stretchy="false">(</d:mo> <d:msup> <d:mi>q</d:mi> <d:mo>′</d:mo> </d:msup> <d:mo stretchy="false">)</d:mo> </d:math> , which represents the classical channel for accessing generalized parton distributions (GPDs) in nucleons and nuclei. This extension enables a more systematic and physically transparent formulation of the reaction dynamics, paving the way for improved extractions of GPDs from experimental data as compared to existing approaches.