Biography
Michael Ratz, Ph.D., is Full Professor in the Department of Physics and Astronomy at the University of California, Irvine. His research focuses on theoretical particle physics, with particular emphasis on string phenomenology and flavor symmetry — areas in which he works to connect ultraviolet completions of the Standard Model, including string theory, to observable low-energy phenomena such as neutrino masses, CP violation, and the flavor structure of elementary particles.
Ratz received his Ph.D. from the Technical University of Munich, where he subsequently served as Associate Professor from 2006 to 2016 before joining UC Irvine. He held a fellowship at DESY Hamburg and an associateship at CERN. He has authored 82 peer-reviewed publications that have accumulated over 9,000 citations, with an h-index of 49. Among his former postdoctoral researchers and Ph.D. students, numerous have gone on to faculty and research positions at institutions worldwide.
Ratz has delivered plenary talks at major international conferences including SUSY, Planck, StringPheno, FLASY and the Rencontres de Moriond, and has lectured at summer and winter schools on several continents. He has organized or co-organized more than a dozen international workshops and conferences, including Strings 2012, PASCOS 2023, and Neutrino 2026. He referees for journals including Nature, Science, and Physical Review Letters, and reviews grant applications for the National Science Foundation and other funding agencies.
Return to topEducation
- Diploma, Technical University Munich, 1999
- PhD, Technical University Munich, 2002
Distinctions
- Distinguished Refereeing Award, 2016, 2022
- Outstanding Faculty Award for Graduate Teaching, 2021
- Best Teaching Award, TUM, 2011, 2013
Areas of Expertise
- String Phenomenology and Model Building
- Neutrino Mass Renormalization Group Evolution
- Heterotic Orbifold Compactifications
- Discrete Symmetries in Particle Physics
- Modular Flavor Symmetries
- CP Violation from Finite Groups
- Moduli Stabilization at Finite Temperature
Recent Publications
- Liu X.-G., Ratz M., “Modular Zeros” (opens in new tab), Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, vol. 875, 2026.
- Chen M.-C., Perez S., Ratz M., “Scale-Independent Relations Between Neutrino Mass Parameters” (opens in new tab), Universe, vol. 12, 2026.
- M.-C. Chen, X. Li, X.-G. Liu, M. Ratz, “Modular flavor symmetries and fermion mass hierarchies” (opens in new tab), Journal of High Energy Physics, vol. 10, pp. 033, 2025.
- X. Li, X.-G. Liu, H. P. Nilles, M. Ratz, A. Stewart, “Flavor symmetries and winding modes” (opens in new tab), Journal of High Energy Physics, vol. 09, pp. 026, 2025.
- C. Arriaga-Osante, M.-C. Chen, R. Diaz-Castro, X. Li, X.-G. Liu, S. Ramos-Sanchez, M. Ratz, “Multiple realizations of modular flavor symmetries and their phenomenology” (opens in new tab), Journal of High Energy Physics, vol. 06, pp. 096, 2025.
- M.-C. Chen, X. Li, X.-G. Liu, O. Medina, M. Ratz, “Modular invariant holomorphic observables” (opens in new tab), Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, vol. 852, pp. 138600, 2024.
- Ramos-Sanchez S., Ratz M., “Heterotic orbifold models” (opens in new tab), Handbook of Quantum Gravity, vol. 4-6, pp. 2669-2693, 2024.
- V. Knapp-Perez, X.-G. Liu, H. P. Nilles, S. Ramos-Sanchez, M. Ratz, “Matter matters in moduli fixing and modular flavor symmetries” (opens in new tab), Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, vol. 844, pp. 138106, 2023.
- S. Ramos-Sanchez, M. Ratz, Y. Shirman, S. Shukla, M. Waterbury, “Generation flow in field theory and strings” (opens in new tab), Journal of High Energy Physics, vol. 10, pp. 144, 2021.
- J. Hollingsworth, M. Ratz, P. Tanedo, D. Whiteson, “Efficient sampling of constrained high-dimensional theoretical spaces with machine learning” (opens in new tab), European Physical Journal C, vol. 81, no. 12, pp. 1138, 2021.
Most Cited Publications
- R. N. Mohapatra, et al., “Theory of Neutrinos: A White Paper” (opens in new tab), Reports on Progress in Physics, vol. 70, pp. 1757–1867, 2007.
- S. Antusch, J. Kersten, M. Lindner, M. Ratz, “Running neutrino masses, mixings and CP phases: Analytical results and phenomenological consequences” (opens in new tab), Nuclear Physics B, vol. 674, pp. 401–433, 2003.
- S. Antusch, J. Kersten, M. Lindner, M. Ratz, M. A. Schmidt, “Running neutrino mass parameters in see-saw scenarios” (opens in new tab), Journal of High Energy Physics, vol. 03, pp. 024, 2005.
- G. Weiglein, et al., “Physics interplay of the LHC and the ILC” (opens in new tab), Physics Reports, vol. 426, pp. 47–358, 2006.
- S. Antusch, M. Drees, J. Kersten, M. Lindner, M. Ratz, “Neutrino mass operator renormalization revisited” (opens in new tab), Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, vol. 519, pp. 238–242, 2001.
- T. Kobayashi, H. P. Nilles, F. Ploger, S. Raby, M. Ratz, “Stringy origin of non-Abelian discrete flavor symmetries” (opens in new tab), Nuclear Physics B, vol. 768, pp. 135–156, 2007.
- K. Dick, M. Lindner, M. Ratz, D. Wright, “Leptogenesis with Dirac neutrinos” (opens in new tab), Physical Review Letters, vol. 84, pp. 4039–4042, 2000.
- W. Buchmüller, K. Hamaguchi, O. Lebedev, M. Ratz, “Supersymmetric standard model from the heterotic string” (opens in new tab), Physical Review Letters, vol. 96, pp. 121602, 2006.
- O. Lebedev, H. P. Nilles, M. Ratz, “De Sitter vacua from matter superpotentials” (opens in new tab), Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, vol. 636, pp. 126–131, 2006.
- M.-C. Chen, M. Fallbacher, K. T. Mahanthappa, M. Ratz, A. Trautner, “CP Violation from Finite Groups” (opens in new tab), Nuclear Physics B, vol. 883, pp. 267–305, 2014.
Contact Information
Website: https://faculty.sites.uci.edu/mratz/
Email: mratz@uci.edu
Phone: (949) 824-6911
Address: 3123 Frederick Reines Hall
Return to topThis profile was created with the help of AI.
Last updated on 9/16/2026.