First Measurement of Hard Exclusive <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi mathvariant="normal">Δ</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math> Electroproduction Beam-Spin Asymmetries off the Proton

The polarized cross-section ratio σLT′/σ0 from hard exclusive π−Δ++ electroproduction off an unpolarized hydrogen target has been extracted based on beam-spin asymmetry measurements using a 10.2 GeV/10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. study, which provides first observation of this channel in deep-inelastic regime, focuses very forward-pion kinematics valence photon virtualities ranging 1.5 GeV2 up to 7 GeV2. reaction novel access d-quark content nucleon p→Δ++ transition generalized parton distributions. A comparison existing results for π+n π0p is provided, shows clear impact excitation mechanism, encoded distributions, asymmetry.Received 21 March 2023Revised 22 May 2023Accepted 20 June 2023DOI:https://doi.org/10.1103/PhysRevLett.131.021901Published by American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution work must maintain attribution author(s) published article’s title, journal citation, DOI. Funded SCOAP3.Published SocietyPhysics Subject Headings (PhySH)Research AreasElectron & positron scatteringPhysical SystemsBaryonsMesonsPionsNuclear Physics