Research — Charles-Joseph Naïm
Research

QCD, Cold Nuclear Matter & Detector Development

Experimental nuclear physicist working at the intersection of high-energy QCD, detector instrumentation, and nuclear non-proliferation — from COMPASS at CERN to RHIC and the future Electron–Ion Collider (EIC). My work spans the full spectrum of the field: phenomenology analysis, large-scale data processing, hardware development, and machine learning applied to particle identification and safeguards.

01 Research Focus

QCD and cold nuclear matter; jets, heavy quarkonium and Drell–Yan production; detector development for the Electron–Ion Collider (ePIC); high-energy nuclear collisions at RHIC; GEANT4 simulations; AI/ML for nuclear physics; nuclear non-proliferation; physics for societal impact.

Parton-to-Hadron Evolution in Cold Nuclear Matter
At COMPASS (CERN), led two pioneering analyses of pion-induced Drell–Yan and charmonium production — producing the first pion–nucleus results in three decades. These measurements revealed parton energy loss and a universal scaling of transverse-momentum broadening, enabling a quantitative extraction of the cold nuclear matter (CNM) transport coefficient. Co-led a white paper defining strategies and observables for hadron- and electron–nucleus collisions, shaping the EIC's cold QCD program. At RHIC, extended this work to jet hadronization, introducing a quantum-information framework using entanglement entropy to probe the emergence of hadrons from quarks and gluons.
Precision Particle Identification & Detector Development
Within the ePIC collaboration, led the mechanical design and construction of the proximity-focusing Ring Imaging Cherenkov (pfRICH) detector — including its carbon-fiber vessel and mirror components — while developing machine-learning algorithms to enhance Cherenkov ring reconstruction and π/K separation at high momentum.
Fixed-Target Program at the EIC — Cold QCD, Heavy-Ion & Space Radiation
Leading a fixed-target initiative at the EIC — explored within the ePIC collaboration and envisioned for a second detector — to obtain proton–nucleus and nucleus–nucleus fixed-target data while preserving collider running. This configuration closes a major energy gap in cold-QCD and heavy-ion collision data, extending the EIC's physics reach beyond its collider-only program. The same detector technologies and nuclear-data methods extend naturally to space radiation modeling and shielding studies — informing detection and protection strategies for human missions to the Moon and Mars.
Bridging High-Energy QCD and Nuclear Security
Established a collaboration with the National Security and Nonproliferation Department at Brookhaven National Laboratory, linking collider-based analysis techniques to low-energy nuclear data and safeguards monitoring — applying GEANT4 simulations to HALEU sources and detector response for nuclear safeguards.
02 Selected Publications

Publications with a leadership role in analysis, writing, or coordination.

C.-J. Naïm, A. Sorensen, D. Brown, D. Cebra, R. Corliss, J. M. Durham, R. Vogt, "Physics Opportunities with a Fixed-Target Program at the Electron-Ion Collider," Feb. 2026. arXiv:2603.00265 [nucl-ex]. Lead author — defined the physics case and coordinated the writing of the fixed-target program proposal.
arXiv:2603.00265
D. H. Dongwi, C.-J. Naïm, L. Rhode, A. Deshpande, "Hybrid Machine-Learning Particle Identification for the ePIC Proximity-Focusing RICH," Dec. 2025. arXiv:2512.14598 [physics.ins-det]. Co-lead — coordinated writing and publication.
arXiv:2512.14598
F. Arleo et al., "Nuclear Cold QCD: Review and Future Strategy," Phys. Rev. C 113, 040501 (2026). doi:10.1103/4jd1-tgh5. arXiv:2506.17454 [hep-ph]. Co-lead — coordinated the writing and publication of the White Paper on Cold Nuclear Matter.
arXiv:2506.17454
J. Datta, A. Deshpande, D. E. Kharzeev, C.-J. Naïm, Z. Tu, "Entanglement as a Probe of Hadronization," Phys. Rev. Lett. 134, 111902 (2025). doi:10.1103/PhysRevLett.134.111902. arXiv:2410.22331 [hep-ph]. Editor's Suggestion, PRL. Co-lead — developed the physics case on entanglement as a probe of hadronization.
arXiv:2410.22331
F. Arleo, C.-J. Naïm, "Nuclear p⊥-broadening of Drell-Yan and quarkonium production from SPS to LHC," JHEP 07, 220 (2020). doi:10.1007/JHEP07(2020)220. arXiv:2004.07188 [hep-ph]. Co-lead — analysis and interpretation of transverse-momentum broadening from SPS to LHC.
arXiv:2004.07188
F. Arleo, C.-J. Naïm, S. Platchkov, "Initial-state energy loss in cold QCD matter and the Drell-Yan process," JHEP 01, 129 (2019). doi:10.1007/JHEP01(2019)129. arXiv:1810.05120 [hep-ph]. Co-lead — analysis and interpretation of initial-state energy loss using global Drell–Yan data.
arXiv:1810.05120
03 Full Publication List

35 entries (peer-reviewed articles and dissertations), in reverse chronological order. arXiv links included.

C.-J. Naïm, A. Sorensen, D. Brown, D. Cebra, R. Corliss, J. M. Durham, R. Vogt, "Physics Opportunities with a Fixed-Target Program at the Electron-Ion Collider," Feb. 2026. arXiv:2603.00265 [nucl-ex].
arXiv
D. H. Dongwi, C.-J. Naïm, L. Rhode, A. Deshpande, "Hybrid Machine-Learning Particle Identification for the ePIC Proximity-Focusing RICH," Dec. 2025. arXiv:2512.14598 [physics.ins-det].
arXiv
M. Ddamulira et al., "Producing and studying rare isotopes in e+A collisions at the Electron–Ion Collider," J. Phys. G 53, 065101 (2026). doi:10.1088/1361-6471/ae71f4. arXiv:2602.17860 [nucl-th].
arXiv
G. Atoian et al. (EPIOS Scientific Consortium), "Realizing the scientific program with polarized ion beams at the future BNL Electron Ion Collider," Phys. Rev. C 113, 060501 (2026). doi:10.1103/261w-8f38. arXiv:2510.10794 [nucl-ex].
arXiv
F. Arleo et al., "Nuclear Cold QCD: Review and Future Strategy," Phys. Rev. C 113, 040501 (2026). doi:10.1103/4jd1-tgh5. arXiv:2506.17454 [hep-ph].
arXiv
M. I. Abdulhamid et al. (sPHENIX), "Measurement of charged hadron multiplicity in Au+Au collisions at √sNN=200 GeV with the sPHENIX detector," JHEP 08, 075 (2025). doi:10.1007/JHEP08(2025)075. arXiv:2504.02240 [nucl-ex].
arXiv
M. I. Abdulhamid et al. (sPHENIX), "Measurement of the transverse energy density in Au+Au collisions at √sNN=200 GeV with the sPHENIX detector," Phys. Rev. C 112, 024908 (2025). doi:10.1103/h8d5-swg6. arXiv:2504.02242 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC," Phys. Rev. Lett. 135, 072301 (2025). doi:10.1103/2qhx-cp79. arXiv:2504.02531 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Precision Measurement of Net-Proton-Number Fluctuations in Au+Au Collisions at RHIC," Phys. Rev. Lett. 135, 142301 (2025). doi:10.1103/9l69-2d7p. arXiv:2504.00817 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Measurement of Two-Point Energy Correlators within Jets in p+p Collisions at √s=200 GeV," Phys. Rev. Lett. 135, 111901 (2025). doi:10.1103/wv2t-dkgn. arXiv:2502.15925 [hep-ex].
arXiv
B. E. Aboona et al. (STAR), "Measurements of Υ states production in p+p collisions at √s=500 GeV with STAR: Cross sections, ratios, and multiplicity dependence," Phys. Rev. D 112, 032004 (2025). doi:10.1103/bsyx-qtjp. arXiv:2502.03769 [hep-ex].
arXiv
B. E. Aboona et al. (STAR), "Precision measurement of the longitudinal double-spin asymmetry for dijet production at intermediate pseudorapidity in polarized pp collisions at √s=200 GeV," Phys. Rev. D 112, 012003 (2025). doi:10.1103/r5jw-lwhg. arXiv:2411.18976 [hep-ex].
arXiv
J. Datta, A. Deshpande, D. E. Kharzeev, C.-J. Naïm, Z. Tu, "Entanglement as a Probe of Hadronization," Phys. Rev. Lett. 134, 111902 (2025). doi:10.1103/PhysRevLett.134.111902. arXiv:2410.22331 [hep-ph].
arXiv
B. E. Aboona et al. (STAR), "Light nuclei femtoscopy and baryon interactions in 3 GeV Au+Au collisions at RHIC," Phys. Lett. B 864, 139412 (2025). doi:10.1016/j.physletb.2025.139412. arXiv:2410.03436 [nucl-ex].
arXiv
M. I. Abdulhamid et al. (STAR), "Energy dependence of polarized γγ→e+e− in peripheral Au+Au collisions at √sNN=54.4 and 200 GeV with the STAR experiment at RHIC," Phys. Rev. C 111, 014909 (2025). doi:10.1103/PhysRevC.111.014909. arXiv:2407.14821 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Temperature measurement of Quark-Gluon plasma at different stages," Nature Commun. 16, 9098 (2025). doi:10.1038/s41467-025-63216-5. arXiv:2402.01998 [nucl-ex].
arXiv
M. I. Abdulhamid et al. (STAR), "Measurement of flow coefficients in high-multiplicity p+Au, d+Au, and He3+Au collisions at √sNN=200 GeV," Phys. Rev. C 110, 064902 (2024). doi:10.1103/PhysRevC.110.064902. arXiv:2312.07464 [nucl-ex].
arXiv
M. Abdulhamid et al. (STAR), "Production of protons and light nuclei in Au+Au collisions at √sNN=3 GeV with the STAR detector," Phys. Rev. C 110, 054911 (2024). doi:10.1103/PhysRevC.110.054911. arXiv:2311.11020 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Measurement of In-Medium Jet Modification Using Direct Photon+Jet and π0+Jet Correlations in p+p and Central Au+Au Collisions at √sNN=200 GeV," Phys. Rev. Lett. 134, 232301 (2025). doi:10.1103/PhysRevLett.134.232301. arXiv:2309.00156 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Semi-inclusive direct photon + jet and π0+jet correlations measured in p+p and central Au+Au collisions at √sNN=200 GeV," Phys. Rev. C 111, 064907 (2025). doi:10.1103/8b8y-98yh. arXiv:2309.00145 [nucl-ex].
arXiv
B. E. Aboona et al. (STAR), "Electric-charge-dependent directed flow splitting of produced quarks in Au+Au collisions," Phys. Lett. B 862, 139245 (2025). doi:10.1016/j.physletb.2025.139245. arXiv:2304.02831 [nucl-ex].
arXiv
G. D. Alexeev et al., "Collins and Sivers transverse-spin asymmetries in inclusive muoproduction of ρ0 mesons," Phys. Lett. B 843, 137950 (2023). doi:10.1016/j.physletb.2023.137950. arXiv:2211.00093 [hep-ex].
arXiv
G. D. Alexeev et al. (COMPASS), "Spin density matrix elements in exclusive ρ0 meson muoproduction," Eur. Phys. J. C 83, 924 (2023). doi:10.1140/epjc/s10052-023-11359-4. arXiv:2210.16932 [hep-ex].
arXiv
G. D. Alexeev et al. (COMPASS), "Double J/ψ production in pion-nucleon scattering at COMPASS," Phys. Lett. B 838, 137702 (2023). doi:10.1016/j.physletb.2023.137702. arXiv:2204.01817 [hep-ex].
arXiv
M. G. Alexeev et al. (COMPASS), "Exotic meson π1(1600) with JPC=1−+ and its decay into ρ(770)π," Phys. Rev. D 105, 012005 (2022). doi:10.1103/PhysRevD.105.012005. arXiv:2108.01744 [hep-ex].
arXiv
M. G. Alexeev et al. (COMPASS), "Probing transversity by measuring Λ polarisation in SIDIS," Phys. Lett. B 824, 136834 (2022). doi:10.1016/j.physletb.2021.136834. arXiv:2104.13585 [hep-ex].
arXiv
C.-J. Naïm, "Cold nuclear matter effects in Drell-Yan process and charmonium production," Ph.D. dissertation, Saclay, 2020. (tel-03121565)
M. G. Alexeev et al. (COMPASS), "Spin density matrix elements in exclusive ω meson muoproduction," Eur. Phys. J. C 81, 126 (2021). doi:10.1140/epjc/s10052-020-08740-y. arXiv:2009.03271 [hep-ex].
arXiv
G. D. Alexeev et al. (COMPASS), "Triangle Singularity as the Origin of the a1(1420)," Phys. Rev. Lett. 127, 082501 (2021). doi:10.1103/PhysRevLett.127.082501. arXiv:2006.05342 [hep-ph].
arXiv
F. Arleo, C.-J. Naïm, "Nuclear p⊥-broadening of Drell-Yan and quarkonium production from SPS to LHC," JHEP 07, 220 (2020). doi:10.1007/JHEP07(2020)220. arXiv:2004.07188 [hep-ph].
arXiv
G. D. Alexeev et al. (COMPASS), "Antiproton over proton and K− over K+ multiplicity ratios at high z in DIS," Phys. Lett. B 807, 135600 (2020). doi:10.1016/j.physletb.2020.135600. arXiv:2003.11791 [hep-ex].
arXiv
C.-J. Naïm, "Cold nuclear matter effects in Drell-Yan process and charmonium production," Ph.D. dissertation, U. Paris-Saclay, 2020.
J. Agarwala et al. (COMPASS), "Contribution of exclusive diffractive processes to the measured azimuthal asymmetries in SIDIS," Nucl. Phys. B 956, 115039 (2020). doi:10.1016/j.nuclphysb.2020.115039. arXiv:1912.10322 [hep-ex].
arXiv
M. G. Alexeev et al. (COMPASS), "Measurement of the cross section for hard exclusive π0 muoproduction on the proton," Phys. Lett. B 805, 135454 (2020). doi:10.1016/j.physletb.2020.135454. arXiv:1903.12030 [hep-ex].
arXiv
F. Arleo, C.-J. Naïm, S. Platchkov, "Initial-state energy loss in cold QCD matter and the Drell-Yan process," JHEP 01, 129 (2019). doi:10.1007/JHEP01(2019)129. arXiv:1810.05120 [hep-ph].
arXiv
04 Talks & Presentations
  • QCD Workshop (invited), St-Jacut-de-la-Mer, France (2018) — small focused meeting with A. H. MuellerInitial-state energy loss in cold QCD matter and the Drell–Yan process slides
  • JRJC — Young Researchers Day, Lège-Cap-Ferret, France (2018)
  • GDR-QCD Workshop, École Polytechnique, Palaiseau, France (2018)Initial-state energy loss in cold QCD matter and the Drell–Yan process slides
  • COMPASS Collaboration Meetings, CERN, Geneva, Switzerland (2018–2020)
  • QGP Workshop, Étretat, France (2019)Cold nuclear matter transport coefficient in Drell–Yan and quarkonium production slides
  • LHCb Heavy Ion Workshop (invited), Chia, Sardinia (2019)Probing cold QCD matter with COMPASS slides
  • GDR-QCD Workshop, LPT Orsay, France (2019)Probing cold QCD matter with COMPASS slides
  • Quarkonia as Tools (invited), Aussois, France (2020)Energy loss in pA collisions: new developments and ways forward slides
  • Imperial College Seminar, London, UK (2020)Probing nuclear parton densities and energy loss processes at COMPASS event page
  • Workshop on Pion and Kaon Structure Functions at the EIC (invited), Stony Brook University (2020)Pion/kaon gluon PDF studies with charmonia and prompt photon production slides
  • Moriond QCD, La Thuile, Italy (2020, cancelled — COVID-19)Cold nuclear matter transport coefficient from energy loss and pT broadening in DY and quarkonium program
  • QEIC II, New Delhi, India (2022)Nuclear matter studies at sPHENIX
  • Workshop on Non-Perturbative QCD via Energy Flow, CFNS, Stony Brook University (2023)Investigating non-perturbative QCD dynamics via internal jet structures indico
  • CFNS Seminar (invited), Stony Brook University (2024)Insights into the cold QCD medium seminars page
  • From Quarks and Gluons to Internal Dynamics of Hadrons, Stony Brook University (2024)Insights into the cold QCD medium slides
  • CPAD 2024, University of Tennessee, Knoxville (2024)pfRICH cylindrical vessel outer shell effort for ePIC indico
  • APS GHP (invited), Anaheim, USA (2025)Unresolved Questions in Cold Nuclear Matter indico
  • DIS 2025, Cape Town, South Africa (2025)Entanglement as a Probe of Hadronization indico
  • QCD Evolution, Jefferson Lab, USA (2025)Entanglement as a Probe of Hadronization indico
  • BOOST 2025, Brown University, USA (2025)Entanglement as a Probe of Hadronization slides
  • QCD@LHC 2025, Stony Brook University (2025)Cold Nuclear QCD: Review and Future Strategy slides
  • QCD@LHC 2025, Stony Brook University (2025)Entanglement as a Probe of Hadronization slides
  • CPAD 2025, University of Pennsylvania, USA (2025)Production of Vessel and Mirrors for the pfRICH Detector at the EIC indico
  • AI4EIC, Massachusetts Institute of Technology, USAMachine Learning for pfRICH PID: Pattern Recognition of Cherenkov Rings indico
  • APS Global Physics Summit 2026 (invited), Denver, USA — Mini-Symposium: Ideas for the Near and Not-so-Near Future Program at JLAB and EIC
  • Summer School for Light Ion Physics in the EIC Era (invited), Florida International University, Miami, USA (2026) indico
Posters
  • EIC Meeting, École de la Chimie, Paris, France (2019) indico
  • Quark Matter, Houston, TX, USA (2023)Drell–Yan process at sPHENIX: a golden probe to study Cold Nuclear Matter effects indico
Organizer
  • Pheniics Fest, Orsay, France (2019) indico
  • Journal Club, École Polytechnique, Palaiseau, France
  • Non-Perturbative QCD via Energy Flow (2nd Workshop), CFNS, Stony Brook University (2023) indico
  • From LHC to EIC: Cold QCD Matter (1st Workshop), CFNS, Stony Brook University (2025) indico
  • Exploring a Fixed-Target Program at the EIC, CFNS, Stony Brook University (2025) indico
05 Student Supervision & Mentoring
Emmett Gebb, Sannvi Madishetty, Mahomdol Mojumder (Undergraduates, Stony Brook University) — Assisted in the construction of the vessel for the pfRICH detector at ePIC (2023–2025).
Julian Driebeek (Graduate, Stony Brook University) — pfRICH detector construction; presented at APS Spring Meeting 2025, Los Angeles (2023–2025).
Ugo Laine (Graduate, Université de Nantes) — Nuclear broadening study on light and heavy mesons (2024).
Preet Mann, Mahomdol Mojumder (Undergraduates, Stony Brook University) — Mirror development for pfRICH; presented at APS DNP Fall Meeting 2025, Chicago.
Gabriel Rodriguez (Undergraduate, Stony Brook University) — AI/ML model for dilepton analysis; talk accepted at APS DNP Fall Meeting 2025, Chicago.
Lucas Rhode (Undergraduate, Stony Brook University) — AI/ML for pfRICH simulation and reconstruction (2025–present).
Aniruddha K P (Undergraduate, Stony Brook University) — J/ψ photoproduction as a probe of gluon density in nuclei (2023).
Anisa Khatun (Postdoc, CEA Saclay) — J/ψ production at COMPASS CERN (2020).
06 Peer Review & Activities

Referee for Physical Review C (since 2019) and Physics Letters B (since 2024).