Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12
Physical Review Letters
We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back dihadron electroproduction in the deep inelastic scattering process. In this reaction, two hadrons are produced in opposite hemispheres along the z axis in the virtual photon-target nucleon center-of-mass frame, with the first hadron produced in the current-fragmentation region and the second in the target-fragmentation region. The data were taken with longitudinally polarized electron beams of 10.2 and 10.6 GeV incident on an unpolarized liquid-hydrogen target using the CLAS12 spectrometer at Jefferson Lab. Observed nonzero sinΔφ modulations in ep→e′pπ+X events, where Δφ is the difference of the azimuthal angles of the proton and pion in the virtual photon and target nucleon center-of-mass frame, indicate that correlations between the spin and transverse momenta of hadrons produced in the target- and current-fragmentation regions may be significant. The measured beam-spin asymmetries provide a first access in dihadron production to a previously unexplored leading-twist spin- and transverse-momentum-dependent fracture function. The fracture functions describe the hadronization of the target remnant after the hard scattering of a virtual photon off a quark in the target particle and provide a new avenue for studying nucleonic structure and hadronization.
Avakian, H., Hayward, T., Kotzinian, A., Armstrong, W., Atac, H., Ayerbe Gayoso, C., Baashen, L., Baltzell, N., Barion, L., Bashkanov, M., Battaglieri, M., Bedlinskiy, I., Benkel, B., Benmokhtar, F., Bianconi, A., Biondo, L., Biselli, A., Bondi, M., & Boiarinov, S. (2023). Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12. Physical Review Letters, 130 (2). https://doi.org/10.1103/PhysRevLett.130.022501