Exclusive η Electro-Production Beam Spin Asymmetry Measurements using CLAS12 at Jefferson Lab*

The exploration of nucleon structure and electromagnetic transitions from ground state to excited state is a cornerstone of nuclear physics research. Meson electro-production experiments have opened new avenues for investigating these phenomena, particularly in the 12 GeV era at Jefferson Lab with the CLAS12 spectrometer. The ηN final states, accessible only via isospin I = 1/2 resonances, provide a complimentary tool to the more extensively studied πN system for the extraction of resonance properties. This work presents the first-ever measurement of the beam spin asymmetry (A_LU) in exclusive η electroproduction, covering a previously unexplored kinematic region with 1.6 ≤ W ≤ 2.2 GeV. A_LU is determined from the CLAS12 data using an analysis framework that considers the statistical limitations of the data set. Results are compared to theoretical models Jülich-Bonn-Washington and EtaMAID. A_LU exhibits discrepancies with model predictions, highlighting the potential for refining theoretical descriptions of nucleon resonances and their electromagnetic couplings. These new results in a previously unmeasured kinematic region provide valuable input for future theoretical developments.