Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12

(CLAS Collaboration)

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number022501
Number of pages7
JournalPhysical Review Letters
Issue number2
Publication statusPublished - 11 Jan 2023

Bibliographical note

© 2023 authors. Published by the American Physical Society.

Funding Information:
We acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at Jefferson Lab in making this experiment possible. This work was supported in part by the U.S. Department of Energy, the National Science Foundation (NSF), the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), the French Commissariat pour l’Energie Atomique, the U.K. Science and Technology Facilities Council, the National Research Foundation (NRF) of Korea, the Helmholtz-Forschungsakademie Hessen fr FAIR (HFHF), the Ministry of Science and Higher Education of the Russian Federation, the Chilean Agencia Nacional de Investigacion y Desarrollo (ANID) via Grant No. PIA/APOYO AFB180002 and the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement No. 824093 (STRONG2020). The Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy under Contract No. DE-AC05-06OR23177. The work is also supported in part by DOE Grant No. DE-FG02-04ER41309.

Cite this