Research

Broadly speaking, my interests lay in Standard Model Physics and Gravity. My main focus is the out-of-equilibrium dynamics of field theories . Primarily, I try to better understand the non-perturbative dynamics of gauge theories. My method of choice has been real-time classical statistical numerical simulations but I recently started to be interested in quantum information (see below) and quantum computation. Current projects on this topic include a study of the dynamics of the O(4) critical point using stochastic simulations and variational quantum simulations of some low dimensional field theory.

As a result of my interest in real-time dynamics, I have also heavily been involved in the development of CosmoLattice, a publicly available versatile parallelized modern C++ library to perform simulations of preheating scenarios. I am currently still involved in its further development (gravitational wave module for instance). I am also using it to study the gravitational wave signature of some preheating model and preheating scenarios with fields non-minimally coupled to gravity.

You can find below short descriptions of my published research (click on it!).

> Entanglement in High-Energy Theory

The notion of entanglement is familiar from quantum mechanics and its use has an organizational principle in condensed matter theory has revolutionized the study of low-dimensional systems, with methods such as the density-matrix renormalization group. The use of entanglement has a tool to better understand field theories is relatively recent and is actively investigated. In 2106.00838, I contributed to this endeavour by showing that the emergence of a statistical entropy in the phenomenon of pair creation in 1+1 electrodynamics can be traced back to the entanglement entropy with the particles created in pair and by presenting some practical way of extracting this entropy from the particle distribution.

> A Continuous Phase Transition in 5D Pure Yang-Mills?

The underlying structure between field theories is the renormalisation group. Any given field theory can be thought of as a point in the renormalization group manifold. In this language, fixed point of the renormalization group, “conformal field theories” are special. They can be thought off as signpost in this manifold; any field theory can be obtained by “flowing away” from such a fix point. These theories become rarer as the dimension increases. In particular, no non-trivial conformal field theory is known above 6 dimensions and the only one known above 4 dimensions are supersymmetric. Non-Abelian theories in 5 dimensions, have been suspected to describe such a fixed point. In 2103.15242, we revisited this conjecture using modern lattice Monte-Carlo techniques and found interesting evidences going in the direction of this conjecture.

> CosmoLattice
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I put a lot of effort into the development of CosmoLattice, a versatile, user-friendly  and performant parallelised C++ code to perform classical real-time simulations in the context of Preheating, with self-consistent expansion of the universe. From the perspective of these simulations, its main novelty is that it is the publicly available code capable of also evolving non-Abelian fields.

Atop of bringing a new tool to allow exploring new scenarios in this cosmological context, CosmoLattice has a far greater potential. More specifically, it has been developed around a core library, which we call TempLat, that has nothing to do with the specific problem to be solved. It is a library which implements field operations at an abstract level  using C++ expression templates to make it as user-friendly as possible. In this way, it achieves a complete decoupling between the abstract field expressions used to represent physics/equations from the technical details such as parallelisation. Moreover, it can be used in an arbitrary number of dimensions. Altogether, it makes it an ideal starting point to develop new libraries to tackle a large variety of physical problems, be them solving hydrodynamic equations or implementing versatile lattice Monte-Carlo simulators.

For more information, see the code webpage cosmolattice.net, our dissertation on lattice techniques for the early universe 2006.15122 and CosmoLattice user-manual 2102.01031 .

> Schwinger Effect from Truncated Weak-Field Expansion

It has been known for a while that non-perturbative information can be extracted from asymptotic expansions. In recent years, some works started investigating the extent to which this can be used in practice, knowing only a finite number of terms of an asymptotic series. They found that a surprisingly large amount of “non-perturbative” information could be extracted this way. In 1911.03489, I present what I find to be a neat example of these ideas. It turns out that the rate of particle productions from the vacuum due to the presence Schwinger rate) can be inferred by only the first few terms of the weak-field expansion, which is naively impervious to this effect.

> Chiral Charge Dynamics in U(1) Gauge Theory

Helical Magnetic Field generated through the decay of the chiral charge. The blue lines are field lines originating from a plane in the centre.

It is well-known that non-abelian fields have a non-trivial vacuum structure, which may have dynamical consequences, such as chirality non-conservation through anomalous processes. On the other hand, abelian fields do not have a degenerate vacuum. This does not prevent anomalous induced transitions to have an on the dynamics of the theory and be of relevance in different contexts, from cosmology to heavy ions collisions. This problem can be addressed by real-time classical simulations. A summary of the simulations is to be found here. Our latest results on the chiral chemical potential are presented in 1904.11892. The picture of the left is an illustration of the kind of fun phenomena that takes place in such systems. A net amount of chiral matter is unstable and creates long-ranges magnetic fields.

 

> Open-Boundary Conditions in Lattice QCD at non-zero Temperature

Lattice QCD simulations are plagued by what is often referred to as the problem of topological freezing. A potential way out consists in using open-boundary conditions. We investigated their use at finite temperature, close to the phase transition. The results can be found in 1903.02894.

> Poisson Solver for Beam Simulations

Previously, I had the opportunity to collaborate with CERN’s Accelerators and Beam Physics Group,  in the team of Dr. T. Pieloni, in charge of Head-On effects studies. In this context, I developed a numerical Poisson Solver to be used in their simulation software (COMBI).

This Poisson Solver is described in this CERN internal note (or here if you don’t have CERN credentials). More details about the simulations which it is used for can be found in this proceeding.

 

Past Talks

I also keep here a list of talk I have given.

2021

  •  Seminar BNL
  •  A Virtual Tribute to Confinement
  •  Strong and Electroweak Matter
  •  Asymptotic Safety Online Series
  •  Seminar, Saclay IHES
  •  Seminar, Chenai IMSc

2020

  •  Seminar, Bielefeld University

2019

  • Seminar, Basel University
  • Informal seminar, Imperial College London
  • Seminar, INT Seattle, slides
  • Lunch Seminar, Stony Brook
  • RIKKEN lunch seminar, BNL
  • Informal seminar, NYU
  • IFIC seminar, Valencia
  • Seminar, UChicago
  • Erice Summer School, Erice
  • Cosmo Coffee, CERN

2018

  • Lattice 2018, Michigan State University
  • Lattice seminars, CERN, slides
  • Lattice seminars, Zeuthen

2017

  • Helmholtz Summer School, Dubna
  • Lattice 2017, Granada

2016

  • Theory seminars, Bielefeld
  • Beam meeting, CERN