Measurement of charged-pion production in deep-inelastic scattering off nuclei with the CLAS detector

CLAS Collaboration

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Energetic quarks in nuclear deep-inelastic scattering propagate through the nuclear medium. Processes that are believed to occur inside nuclei include quark energy loss through medium-stimulated gluon bremsstrahlung and intranuclear interactions of forming hadrons. More data are required to gain a more complete understanding of these effects. Purpose: To test the theoretical models of parton transport and hadron formation, we compared their predictions for the nuclear and kinematic dependence of pion production in nuclei. Methods: We have measured charged-pion production in semi-inclusive deep-inelastic scattering off D, C, Fe, and Pb using the CLAS detector and the CEBAF 5.014-GeV electron beam. We report results on the nuclear-to-deuterium multiplicity ratio for π+ and π− as a function of energy transfer, four-momentum transfer, and pion energy fraction or transverse momentum—the first three-dimensional study of its kind. Results: The π+ multiplicity ratio is found to depend strongly on the pion fractional energy z and reaches minimum values of 0.67±0.03, 0.43±0.02, and 0.27±0.01 for the C, Fe, and Pb targets, respectively. The z dependencies of the multiplicity ratios for π+ and π− are equal within uncertainties for C and Fe targets but show differences at the level of 10% for the Pb-target data. The results are qualitatively described by the GiBUU transport model, as well as with a model based on hadron absorption, but are in tension with calculations based on nuclear fragmentation functions. Conclusions: These precise results will strongly constrain the kinematic and flavor dependence of nuclear effects in hadron production, probing an unexplored kinematic region. They will help to reveal how the nucleus reacts to a fast quark, thereby shedding light on its color structure and transport properties and on the mechanisms of the hadronization process.

Original languageEnglish
Article number015201
Number of pages22
JournalPhysical Review C
Volume105
Issue number1
DOIs
Publication statusPublished - 12 Jan 2022

Bibliographical note

Funding Information:
The authors acknowledge the staff of the Accelerator and Physics Divisions at the Thomas Jefferson National Accelerator Facility who made this experiment possible. We thank Pia Zurita and Benjamin Guiot for providing calculations and Kai Gallmeister for help in setting up the GiBUU event generator. We also thank Sebastián Mancilla and Ricardo Oyarzun for their help on the evaluation of radiative corrections. This work was supported in part by the Chilean Agencia Nacional de Investigacion y Desarollo (ANID); by ANID PIA Grant No. ACT1413; by ANID PIA/APOYO AFB180002; by ANID FONDECYT No. 1161642, No. 1201964, and No. 11181215; ANID Millennium Program ICN2019_044; by the U.S. Department of Energy; by the Italian Instituto Nazionale di Fisica Nucleare; by the French Centre National de la Recherche Scientifique; by the French Commissariat à l'Energie Atomique; by the United Kingdom Science and Technology Facilities Council (STFC); by the Scottish Universities Physics Alliance (SUPA); by the National Research Foundation of Korea; by the National Science Foundation (NSF); by the HelmholtzForschungsakademie Hessen für FAIR (HFHF); by the Ministry of Science and Higher Education of the Russian Federation; and by the Office of Research and Economic Development at Mississippi State University. This work has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant No. 804480). The Southeastern Universities Research Association operates the Thomas Jefferson National Accelerator Facility for the United States Department of Energy under Contract No. DE-AC05-06OR23177.

Funding Information:
The authors acknowledge the staff of the Accelerator and Physics Divisions at the Thomas Jefferson National Accelerator Facility who made this experiment possible. We thank Pia Zurita and Benjamin Guiot for providing calculations and Kai Gallmeister for help in setting up the GiBUU event generator. We also thank Sebasti?n Mancilla and Ricardo Oyarzun for their help on the evaluation of radiative corrections. This work was supported in part by the Chilean Agencia Nacional de Investigacion y Desarollo (ANID); by ANID PIA Grant No. ACT1413; by ANID PIA/APOYO AFB180002; by ANID FONDECYT No. 1161642, No. 1201964, and No. 11181215; ANID Millennium Program ICN2019_044; by the U.S. Department of Energy; by the Italian Instituto Nazionale di Fisica Nucleare; by the French Centre National de la Recherche Scientifique; by the French Commissariat ? l'Energie Atomique; by the United Kingdom Science and Technology Facilities Council (STFC); by the Scottish Universities Physics Alliance (SUPA); by the National Research Foundation of Korea; by the National Science Foundation (NSF); by the HelmholtzForschungsakademie Hessen f?r FAIR (HFHF); by the Ministry of Science and Higher Education of the Russian Federation; and by the Office of Research and Economic Development at Mississippi State University. This work has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant No. 804480). The Southeastern Universities Research Association operates the Thomas Jefferson National Accelerator Facility for the United States Department of Energy under Contract No. DE-AC05-06OR23177.

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