Aleksas Mazeliauskas

Theoretical Physicist

Theoretical Physics Department, CERN

About me

[ˈaːlɛksɐs mɐzɛˈlʲæuˑskɐs]

[AH-lexas ma-zeh-LYOW-skas]

I am a theoretical physicist working on many-body phenomena emerging from fundamental interactions of elementary particles.

In my research I connect models of nuclear, hadronic and particle physics with methods of relativistic hydrodynamics, statistical physics and out-of-equilibrium dynamics to study the hot and dense nuclear matter created in high-energy hadron collisions. My work has contributed to a better understanding of fundamental states of matter, thermalisation of isolated quantum systems, and how a fluid-like behaviour emerges from a relatively small number of constituents interacting via the strong force.

I work at Theoretical Physics department at CERN, Switzerland. Previously I was a postdoctoral researcher at Heidelberg University, Germany. I had a joint postdoctoral research position in the groups of Prof. Dr. Jürgen Berges and Priv.-Doz. Dr. Stefan Flörchinger at the Institute for Theoretical Physics under the collaborative research project SFB 1225 ISOQUANT. Before that I was a PhD student at Nuclear Theory Group at Stony Brook University, US (PhD advisor Prof. Dr. Derek Teaney).


  • PhD in Physics, 2012 - 2017

    Stony Brook University, Department of Physics and Astronomy, United States

  • Master of Mathematics, 2011 - 2012

    Cambridge University, St. Catharine's college, United Kingdom

  • BA Mathematics, 2008 - 2011

    Cambridge University, St. Catharine's college, United Kingdom


Research and Teaching

Postdoctoral fellow
Oct 2019 – Present Geneva, Switzerland

I am a member of the heavy ion physics group at CERN Theoretical Physics Department. I have continued interest in

  • thermalization in QCD and the emergent macroscopic descriptions
  • jet quenching and other Standard Model processes in nuclear collisions
  • hadron and light nuclei production in heavy ion collisions
  • future LHC experiments with heavy and light ions

Other experience:

Postdoctoral researcher
Apr 2017 – Sep 2019 Heidelberg, Germany

I was a member of the collaborative research center “Isolated quantum systems and universality in extreme conditions”. isoquant sfb1225 logo

My work was centered on understanding the early times dynamics in heavy ion collisions and the universal aspects of information loss. I also maintained interest in other stages of the collision like hydrodynamic expansion and hadronization.

Other experience:

Teaching experience:

  • Head tutor, Advanced Quantum Field Theory, summer semester 2019
  • Head tutor, Quantum Field Theory I, winter semester 2018-2019
  • Master seminar leader, QCD Matter in heavy ion collisions, summer semester 2018
  • Head tutor, Quantum Field Theory I, winter semester 2017-2018
Research and teaching assistant
Stony Brook University
Aug 2012 – Mar 2017 Stony Brook, NY, USA

I did my PhD work on Fluctuations in ultra-relativistic heavy ion collisions with prof. Derek Teaney in Nuclear Theory Group. My main research topics were:

Other experience:

  • I organised graduate student seminars in our group and co-organised group dinners and BBQs.

Teaching experience:

  • Recitation instructor, undergraduate electromagnetism and mechanics, Spring/Fall semesters 2014.
  • Teaching assistant, undergraduate mechanics laboratory, Fall/Spring semesters 2012-2013. Received David Fox award for the outstanding Teaching Assistant.

Research Projects

I am fascinated by many-body physics emerging from interactions of elementary particles in a hot and dense nuclear matter created in high-energy hadron collisions at particle accelerators like LHC (CERN) and RHIC (BNL). I am trying to understand the properties of the new state of nuclear matter—the quark-gluon plasma (QGP), which is formed at extreme temperature and density. Outside hadron collisions, such conditions can be found only at the beginning of the Universe and in violent neutron start mergers.

Recently I have been particularly interested in the formation of the quark-gluon plasma at the earliest stages of the collision. I use a weakly coupled kinetic theory of quarks and gluons to perform state-of-the-art simulations elucidating the phenomena of equilibration and fluid-like behaviour of relatively small number of particles interacting via the strong force. I have also worked on the hydrodynamic descriptions of quark-gluon plasma expansion and I am actively working on improving the conversion from fluid fields to measurable hadrons at late stages of the collision.

High-pT partonic rescattering

Modifiications of energetic probes in nuclear environment

Effective Kinetic Theory

Simulating the non-equilibrium dynamics of QCD plasmas.

Chemical equilibration

Quark production in weakly coupled QCD plasma


Self-similar evolution in far from equilibrium systems


Stochastic fluctuations in out-of-equilibrium systems

Machine learning in heavy-ion collisions

Analysing harmonic flows using Principal Component Analysis

Hadron formation and resonance decays

Fluid to hadron conversion in heavy-ion models

Computer programs


Linear kinetic theory propagator for initial conditions of heavy ion collisions


Fast calculation of direct resonance decays


3D viscous relativistic hydrodynamics code.

Recent Publications

For up to date publication list see inSpire.
The medium-modified $g\to c\bar{c}$ splitting function in the BDMPS-Z formalism
Stability analysis of non-thermal fixed points in longitudinally expanding kinetic theory
Effect of thermal shear on longitudinal spin polarization in a thermal model
Ratios of jet and hadron spectra at LHC energies: measuring high-$p_T$ suppression without a $pp$ reference
An analysis of Bayesian estimates for missing higher orders in perturbative calculations


Dalelių fizikos tyrimai CERN: naujų fundamentalių reiškinių ir dalelių paieškos
Jet and hadron spectra modifications in oxygen-oxygen collisions at the LHC
Theoretical overview on space-time evolution of heavy-ion collisions and QGP temperature
Discovering Partonic Rescattering in Light Ion Collisions
High-Density QCD with Proton & Ion Beam (I and II)

Recent Posts

Second Lithuanian Particle Physics Meeting

On the 11th of April, 2022 around 30 Lithuanian scientists with interest in particle physics gathered virtually for the second time in …

Quark Matter conference in Krakow

From the 4th to 10th of April, 2022 the XXIX Quark Matter conference took place in Krakow, Poland. It was the first major conference …

First Lithuanian Particle Physics Meeting

On the 9th of March over 30 Lithuanian scientists with interest in particle physics gathered virtually for the first Lithuanian …


Just five months after it began, it is the wrap-up time for one of most exciting scientific adventures of my career so far—my …


During the three days on February 17-19, NMA students participated at virtual NMA winter session with subject lectures in the morning …


  • aleksas.mazeliauskas at cern.ch
  • +41-22-76-73204
  • CERN dep TH 4-2-065
    CH-1211 Geneva 23
  • aleksas.eu