# Yen-Jie Lee
Yen-Jie Lee is an experimental particle physicist at the [Massachusetts Institute of Technology](https://www.edgepedia.org/massachusetts-institute-of-technology) who studies proton-proton and heavy-ion collisions at the [Large Hadron Collider](https://www.edgepedia.org/large-hadron-collider) (LHC), focusing on jets and heavy-flavor production in nucleus-nucleus collisions to probe the quark-gluon plasma.[1](https://physics.mit.edu/faculty/yen-jie-lee/) He is a recipient of the U.S. Department of Energy's Presidential Early Career Award for Scientists and Engineers (PECASE), and is known for heavy-flavor measurements with the CMS experiment and for founding the electron-positron alliance, a collaboration that tests high-density quantum chromodynamics (QCD) with archived electron-positron data.[1](https://physics.mit.edu/faculty/yen-jie-lee/)
| Key facts | |
|---|---|
| Field | Experimental particle physics; heavy-ion and proton-proton collisions at the LHC[1](https://physics.mit.edu/faculty/yen-jie-lee/) |
| Institution | Massachusetts Institute of Technology, Department of Physics (full professor since 2024)[1](https://physics.mit.edu/faculty/yen-jie-lee/) |
| Training | BSc and MSc, National Taiwan University; PhD, MIT, 2011, under Wit Busza[1](https://physics.mit.edu/faculty/yen-jie-lee/) • [2](https://www.ntu-ccms.ntu.edu.tw/en/seminar/412) |
| Awards | DOE Early Career Research Award (2015), Sloan Research Fellowship (2016), PECASE (MIT page: 2019; planning roster: 2017), NEC Corporation Fund Award[1](https://physics.mit.edu/faculty/yen-jie-lee/) |
| CMS leadership | Heavy Ion Physics Group co-convener (2014-2016); heavy-ion executive board representative (2016-2018)[1](https://physics.mit.edu/faculty/yen-jie-lee/) |
| Signature initiative | Founder and leader of the electron-positron alliance (ee-alliance.org)[1](https://physics.mit.edu/faculty/yen-jie-lee/) |
| Best-known paper | Two-particle correlations in e+e- collisions at 91 GeV with ALEPH archived data, Physical Review Letters (2019)[3](https://doi.org/10.1103/PhysRevLett.123.212002) |
## Early life and education
Lee completed his undergraduate degree and Master's in Physics at National Taiwan University under the supervision of Prof. Min-Zu Wang, working as part of the Belle collaboration.[2](https://www.ntu-ccms.ntu.edu.tw/en/seminar/412) After completing military service in Taiwan, he moved to MIT for doctoral work with Wit Busza, a professor of physics who leads heavy-ion physics research there.[1](https://physics.mit.edu/faculty/yen-jie-lee/) • [4](https://news.mit.edu/index%2Ephp/2022/yen-jie-lee-universe-origins-0311)
His timing was fortunate. The LHC was preparing its first heavy-ion collisions as he began his PhD, and near the end of his doctorate he analyzed some of the first such data, studying fast-moving quarks that streaked through the quark-gluon plasma in the form of jets.[4](https://news.mit.edu/index%2Ephp/2022/yen-jie-lee-universe-origins-0311) He completed his PhD at MIT in 2011.[1](https://physics.mit.edu/faculty/yen-jie-lee/)
## Career
Lee did postdoctoral work at MIT's Laboratory for Nuclear Science, then held a combined CERN and Marie Curie Fellowship from 2012 to 2013.[1](https://physics.mit.edu/faculty/yen-jie-lee/) In September 2013 he joined the MIT Physics faculty as the Class of 1958 Career Development Associate Professor of Physics, as a member of the Relativistic Heavy Ion Group.[1](https://physics.mit.edu/faculty/yen-jie-lee/) • [6](https://mithig.mit.edu/news/yen-jie-lee-awarded-tenure-mit/) • [4](https://news.mit.edu/index%2Ephp/2022/yen-jie-lee-universe-origins-0311) He was promoted to associate professor in 2018, awarded tenure, and promoted to full professor in 2024; he also serves as an Undergraduate Program Coordinator in the department.[1](https://physics.mit.edu/faculty/yen-jie-lee/)
## Research and contributions
**Heavy-ion physics at CMS.** Lee's research uses the LHC's highest-energy collisions to study the quark-gluon plasma, a state of matter in which quarks and gluons are deconfined, with the aim of moving beyond discovery-era qualitative measurements toward quantitative understanding of [QCD matter](https://www.edgepedia.org/qcd-matter) in extreme conditions such as the first microseconds of the universe and neutron-star cores.[1](https://physics.mit.edu/faculty/yen-jie-lee/) • [2](https://www.ntu-ccms.ntu.edu.tw/en/seminar/412) His cited CMS work includes measurements of prompt meson azimuthal anisotropy and nuclear modification factors in lead-lead and proton-lead collisions.[7](https://scholar.google.co.in/citations?hl=en&oi=sra&user=dqp6T_AAAAAJ)
From 2015 to 2020 he was principal investigator of DOE Early Career Award DE-SC0013905, "Study of Heavy Flavor Mesons and Flavor-Tagged Jets with the CMS Detector," under the DOE Office of Science Nuclear Physics program.[5](https://www.osti.gov/servlets/purl/1671784) The project built heavy-flavor meson and jet triggers for CMS that were deployed in pp, pPb, and PbPb data-taking between 2015 and 2018.[5](https://www.osti.gov/servlets/purl/1671784) The resulting measurements constrain the flavor dependence of parton energy loss (jet quenching), the in-medium charm quark diffusion coefficient, and the [hadronization](https://www.edgepedia.org/hadronization) mechanisms of charm and beauty quarks.[5](https://www.osti.gov/servlets/purl/1671784)
**The electron-positron alliance.** Lee pioneered investigations of high-density QCD using electron-positron annihilation data by founding and leading the electron-positron alliance collaboration (ee-alliance.org).[1](https://physics.mit.edu/faculty/yen-jie-lee/) The premise is that e+e- collisions provide a clean reference system with no dense medium, so that long-range particle correlations seen there can be compared directly with the correlations seen in proton-proton, proton-nucleus, and nucleus-nucleus collisions.[3](https://doi.org/10.1103/PhysRevLett.123.212002)
## Key publications
**Measurements of Two-Particle Correlations in e+e− Collisions at 91 GeV with ALEPH Archived Data** ([Physical Review Letters](https://www.edgepedia.org/physical-review-letters), 2019; DOI 10.1103/PhysRevLett.123.212002).[3](https://doi.org/10.1103/PhysRevLett.123.212002) This is his most cited paper, though citation counts diverge across databases: Crossref records 47 citations while NIH's iCite records 5.[8](https://orcid.org/0000-0003-2593-7767) The measurement used archived e+e- annihilation data collected with the ALEPH detector at LEP between 1992 and 1995, measuring two-particle angular correlations of charged particles from hadronic Z decays over a broad range of pseudorapidity and full azimuth, as a function of charged-particle multiplicity.[3](https://doi.org/10.1103/PhysRevLett.123.212002) No significant long-range correlation (a "ridge") was observed in either the lab coordinate analysis or the thrust coordinate analysis, the latter being sensitive to a medium expanding transverse to the color string between the outgoing quark-antiquark pair.[3](https://doi.org/10.1103/PhysRevLett.123.212002) The associated yield distributions agreed better with the PYTHIA 6.1 [event generator](https://www.edgepedia.org/event-generator) than with HERWIG 7.1.5, giving new input to showering and hadronization modeling and serving as an important reference for the long-range correlations observed in hadron and nucleus collisions.[3](https://doi.org/10.1103/PhysRevLett.123.212002)
**Measurement of Two-Particle Correlations of Hadrons in e+e− Collisions at Belle** (Physical Review Letters, 2022; DOI 10.1103/PhysRevLett.128.142005), a second e+e- correlation measurement, published 2022-04-08.[8](https://orcid.org/0000-0003-2593-7767)
**Studies of dijet pseudorapidity distributions and transverse momentum balance in pPb collisions at sqrt(sNN)=5.02 TeV** ([Annals of Physics](https://www.edgepedia.org/annals-of-physics), 2015; DOI 10.1016/j.aop.2014.07.043), part of his CMS work on proton-lead collisions.[8](https://orcid.org/0000-0003-2593-7767)
**Study of Heavy Flavor Mesons and Flavor-Tagged Jets with the CMS Detector** (2020; DOI 10.2172/1671784), the final technical report for DOE award DE-SC0013905.[5](https://www.osti.gov/servlets/purl/1671784)
## Honours and recognition
Lee received an Early Career Research Award from the U.S. Department of Energy in 2015 (DE-SC0013905), an NEC Corporation Fund Award, a Sloan Research Fellowship from the Alfred P. Sloan Foundation in 2016, and a Presidential Early Career Award for Scientists and Engineers.[1](https://physics.mit.edu/faculty/yen-jie-lee/) MIT's faculty page dates the PECASE to 2019.[1](https://physics.mit.edu/faculty/yen-jie-lee/) He also held the Class of 1958 Career Development Professorship at MIT from 2016.[2](https://www.ntu-ccms.ntu.edu.tw/en/seminar/412)
## Service and leadership
Within the CMS collaboration, Lee served as one of the Heavy Ion Physics Group co-conveners from 2014 to 2016 and as a heavy-ion physics executive board representative from 2016 to 2018.[1](https://physics.mit.edu/faculty/yen-jie-lee/) He started the heavy-flavor physics research program in heavy-ion physics at MIT and has trained many PhD students and postdocs in that group.[6](https://mithig.mit.edu/news/yen-jie-lee-awarded-tenure-mit/) He continues to lead the electron-positron alliance.[1](https://physics.mit.edu/faculty/yen-jie-lee/)
## References
Yen-Jie Lee has no standalone English Wikipedia article; this entry is built from institutional and primary records.
1. Yen-Jie Lee PhD '11 » MIT Physics — https://physics.mit.edu/faculty/yen-jie-lee/
2. Speaker biography, Center for Condensed Matter Sciences, National Taiwan University — https://www.ntu-ccms.ntu.edu.tw/en/seminar/412
3. Measurements of Two-Particle Correlations in e+e− Collisions at 91 GeV with ALEPH Archived Data, Phys. Rev. Lett. 123, 212002 (2019) — https://doi.org/10.1103/PhysRevLett.123.212002
4. Yen-Jie Lee probes particle collision data for clues to the universe's origins, MIT News — https://news.mit.edu/index%2Ephp/2022/yen-jie-lee-universe-origins-0311
5. DOE Final Technical Report, Early Career Award DE-SC0013905 (OSTI) — https://www.osti.gov/servlets/purl/1671784
6. Yen-Jie Lee awarded tenure from MIT, MIT Relativistic Heavy Ion Group — https://mithig.mit.edu/news/yen-jie-lee-awarded-tenure-mit/
7. Yen-Jie Lee, Google Scholar profile — https://scholar.google.co.in/citations?hl=en&oi=sra&user=dqp6T_AAAAAJ
8. Yen-Jie Lee (0000-0003-2593-7767), ORCID — https://orcid.org/0000-0003-2593-7767
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Physicists and astronomers › Experimental particle physicists*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026 · Edited: Sep 30, 2026; Oct 11, 2026; Oct 15, 2026 · Last review: Sep 30, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license