# Emmy Noether Research Group

Many-body QCD phenomena in high-energy proton and nuclear collisions

In 2022, I was awarded Emmy Noether Group Funding by German Research Foundation (DFG) to conduct a six-year research programme on the Many-body QCD phenomena in high-energy proton and nuclear collisions at the Institute for Theoretical Physics at Heidelberg University. My group will develop the microscopic description of the emergent collective phenomena in systems of varying sizes and varying energy scales.

Emmy Noether was an outstanding mathematician with major contributions to mathematics and theoretical physics. In particular, she discovered that every continuous symmetry has a corresponding conserved charge. This principle is now known as Noether’s theorem. Emmy Noether was also a pioneering woman in science, who defied the norms of her time. I am honoured to receive the grant named after her.

#### Many-body QCD phenomena in high-energy proton and nuclear collisions

Studying the equilibration and collectivity in across size and energy scales

#### Emmy Noether Programme

Junior research group funding by German Research Foundation (DFG)

# People

## Aleksas Mazeliauskas

### Institute for Theoretical Physics, Heidelberg University

[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 Institute for Theoretical Physics at Heidelberg University. Previously, I was a senior research Fellow at Theoretical Physics department at CERN, Switzerland. My first postdoctoral position was at Heidelberg University, Germany. I worked 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).

### Education

• 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

# Experience

Research and Teaching

Emmy Noether junior research professor
Oct 2022 – Present Heidelberg, Germany

I am a junior research group leader at Heidelberg University. My main work directions are

• equilibration phenomena in nuclear collisions collisions and cold atomic gasses
• QCD kinetic theory simulations of Quark Gluon Plasma
• modification of Standard Model processes embedded in high density nuclear environment
• resonance decays in the final stages of heavy-ion collisions

I am also one of Principal Investigators at the Collaborative Research Centre ISOQUANT.

Other experience:

• leader of physics section at additional training school NMA for highschool students in Lithuania.
Postdoctoral fellow
Oct 2019 – Sep 2022 Geneva, Switzerland

I was 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:

Teaching experience:

• Two lectures at CERN-Fermilab summer school.
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”.

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.

# Other research interests

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.

#### Theory uncertainties of perturbative calculations

Estimating missing higher order terms with Bayesian inference

#### High-pT partonic rescattering

Modifications 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

#### Prescaling

Self-similar evolution in far from equilibrium systems

#### Hydro-kinetics

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 code

### MiHO

Theory uncertainties from MIssing Higher Orders

### KøMPøST

Linear kinetic theory propagator for initial conditions of heavy ion collisions

### FastReso

Fast calculation of direct resonance decays

### RNAVIER

3D viscous relativistic hydrodynamics code.

# Recent publications

For up to date publication list see inSpire.
Medium-enhanced $c\bar{c}$ radiation
The medium-modified $g\to c\bar{c}$ splitting function in the BDMPS-Z formalism
Ratios of jet and hadron spectra at LHC energies: Measuring high-pT suppression without a pp reference
Stability analysis of nonthermal fixed points in longitudinally expanding kinetic theory
Effect of thermal shear on longitudinal spin polarization in a thermal model

# Talks

The medium-modified g → cc̄ splitting function in the BDMPS-Z formalism
QCD thermalisation in kinetic theory
Jet and hadron nuclear modification factors
Energy loss in small systems (theory overview)
Dalelių fizikos tyrimai CERN: naujų fundamentalių reiškinių ir dalelių paieškos

# Recent Posts

### Settling in Heidelberg

It has been nearly four months since my start at Heidelberg as an Emmy Noether Group leader. The transition has been smooth, and I feel …

### There and back again

On May 5 2022, I received the official confirmation that my grant proposal for a junior research group within the Emmy Noether …

### End of the fellowship

After three exciting years, my tenure as a CERN fellow has come to the end. Since 2019 I had the privilege to work at CERN Theoretical …

### 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 …

# Contact

• me@aleksas.eu
• Philosophenweg 12
DE-69120 Heidelberg
Germany
• aleksas.eu