Exploiting the similarity between Bloch's theorem for electrons in crystalline solids and the problem of Landau gauge-fixing in Yang-Mills theory on a "replicated" lattice allows one to obtain essentially infinite-volume results from numerical simulations performed on regular-size lattices. We review our previous study of this subject, presenting some new preliminary results. A novel...
We revisit the mathematical formalism involved in the application of Bloch's theorem to non-Abelian gauge theory. In particular, we show how to map numerical simulations performed on the "replicated" lattice to the original (smaller) lattice, or "unit cell". Special emphasis is given to the rôle played by boundary conditions.
There is a flavor number range of $SU(3)$ gauge theory, $N_f^* < N_f < 16.5$, where spontaneous chiral symmetry breaking does not occur and the model is conformal. The upper end $16.5$ is determined by the 1-loop $\beta$-function but the lower end, $N_f^*$, may be determined by non-perturbative phenomena. In this contribution a new approach is presented to estimate or constrain $N_f^*$: high...
(Tentative abstract) We study the interplay between colour-confining and chiral symmetry-breaking dynamics in gauge-fermion theories. We target the challenging many-flavour limit of theory space using the non-perturbative functional Renormalisation Group approach. This work connects the QCD-like regime, in quantitative agreement with Lattice data, with the perturbative conformal limit of...
The study of entanglement in quantum field theories provides insight into universal properties which are typically challenging to extract by means of local observables. However, conventional numerical techniques to compute entanglement measures are limited to low-dimensional systems, and, for gauge theories, the definition itself of entanglement is ambiguous due to the non-factorizability of...
Quantum cellular automata (QCA) for quantum electrodynamics (QED) is a quantum algorithm that can be coded on a quantum computer to simulate QED. It is a unitary-based, strictly local discrete space-time formulation of QED. The space-time of the QCA is a square lattice and qubits in the lattice sites encode the information of occupation number of fermions. The dynamics of the QCA is done by...
Measuring temporal entanglement to identify integrable systems
The temporal entanglement has recently emerged as a new concept in the theory of many-body quantum systems. It is the entanglement computed from the overlap of the half-system right and half-system left influence functionals for a system evolving in time.
I will review the definition and show how such entanglement i)...
We propose a novel variational ansatz for the ground-state preparation of the ℤ2 lattice gauge theory (LGT) in quantum simulators. It combines dissipative and unitary operations in a completely deterministic scheme with a circuit depth that does not scale with the size of the considered lattice. We find that, with very few variational parameters, the ansatz can achieve >99% precision in energy...
A tensor network approach based on sign-problem free Monte-Carlo for studying lattice gauge theories beyond 1+1d"
Based on a suitable basis system for the quark-gluon vertex’ transverse tensor structures and on carefully chosen kinematical variables, the transverse part of the quark-gluon vertex in quenched QCD in the Landau gauge is obtained from a solution of systems of Dyson-Schwinger equations. We demonstrate by analysing this solution that the angular dependence of these transverse quark-gluon...
I will discuss the prospects of using quantum information concepts to study dynamical chiral symmetry breaking (DCSB) features in quantum chromodynamics (QCD). First, I will present a formalism based on the coherent state representation of Fock-space states, which we developed to compute density matrices and define entanglement measures over partitions of the Fock space. In the sequence, I...
In QCD, the Schwinger mechanism endows the gluons with a mass gap through the dynamical formation of longitudinally coupled poles at zero momentum in the interaction vertices. In this talk, we review the key aspects of the Schwinger mechanism in QCD, discuss recent evidence for its occurrence, and some of its implications on the infrared behavior of the QCD Green's functions. First, we show...
In the present work we determine the transversely-projected quark-gluon vertex in the context of unquenched QCD with two degenerate light dynamical quarks in the Landau gauge. This is accomplished by solving the Schwinger-Dyson equation within the 3PI effective action formalism, employing lattice data for the gluon and quark propagators, and the three-gluon vertex. Our findings reveal that the...
In this talk, I would like to discuss recent progress in the construction of functional renormalization group (fRG) approach to first-principles QCD within the four-quark scatterings, and its application to the calculation of quasi-parton distribution amplitudes (PDA) for pions. We investigate dynamical chiral symmetry breaking and the emergence of mesonic bound states from the infrared...
Several continuum and lattice investigations of the QCD three-gluon vertex have recently exposed its key properties, some intimately connected with the low-momentum behavior of the two-point gluon Green’s function and especially relevant for the emergence of a mass scale in this latter, via the Schwinger mechanism. We will report on a complete lattice determination of the Landau-gauge,...
We present our latest results on the quark spectral function in vacuum and at finite temperature, where we use the framework of spectral Dyson-Schwinger equations and a non-trivial but causal and gauge-consistent quark-gluon-vertex based on the respective Slavnov-Taylor identity. We show how the spectral functional approach can be used for the calculation of real-time observables such as the...
Two-dimensional QCD was first studied by G. 't Hooft as a model for mesons in the limit of an infinite number of colours where it admits an exact solution. We investigate the model with the FRG at finite number of colours in the vacuum and present the first stages of our study towards dynamical hadronization in this model. In particular, we derive how local four-fermion interactions emerge...
On this talk we report on the computation of the four gluon and of the ghost-gluon one-particle irreducible Green functions using lattice QCD simulations performed in the Landau gauge and for pure Yang-Mills SU(3) theory. For the four gluon vertex an update of our previous calculation combining 32^4 and 48^4 results is given for the three form factors published. For the ghost-gluon vertex we...
We report novel lattice QCD results for the general kinematics three-gluon vertex, focusing in the determination of the three gluon coupling in MOM scheme, $\alpha_{3g}$, for a wide variety of vertex kinematics. By employing the \textit{planar-degeneracy}, that states that the deep IR running of the vertex does not depend on the particularities of the kinematical configuration chosen to...
In this talk we present recent results on the transversely-projected four-gluon vertex in two families of kinematic configurations: i) ''collinear'' where all external momenta are parallel to each other and ii) ''soft'' with one vanishing and three arbitrary external momenta. The approach is based on the one-loop dressed Schwinger-Dyson equation obtained from the 4PI effective action. The key...
The last two decades have seen much progress in the calculation of quark and gluon correlation functions using functional methods and in their application to the calculation of hadronic observables. A tantalizing question is that of the systematic error inherent in such methods which is closely related to the stability of the employed truncations with respect to extensions. In this...
A more recent approach to light-front wave functions (LFWF) of hadrons consists, in the case of mesons, of projecting their Bethe-Salpeter wave functions on the light front. The latter is obtained within a functional approach to QCD, solving first the quark gap equation within a chiral-symmetry preserving truncation scheme and then the Bethe-Salpeter equation for pseudoscalar and vector...
Phenomenological evidence suggests that strong decays of low-excitation hadrons often involve the creation of a light quark-antiquark pair with zero angular momentum, known as the $^3P_0$ mechanism, derived from a scalar bilinear. Despite Quantum Chromodynamics being mediated perturbatively by spin-one gluons and exhibiting chiral symmetry in its Lagrangian, a scalar decay term appears...
Hadrons are strongly interacting particles composed of quarks and gluons and described by Quantum Chromodynamics (QCD). Their internal structure can be described in terms of structure functions that encode, for example, the momentum and spin distributions of their constituents. Parton distribution functions (PDFs) and Transverse Momentum Distributions (TMDs), for example, describe the quark...
We consider the interaction potential between a static quark and an antiquark forming a singlet in the quenched approximation. For this purpose we work in the Landau-De-Witt gauge and exploit some properties of the Yang-Mills theory in the Landau gauge observed in Monte-Carlo simulations and previously obtained by various semi-analytical methods. In particular, the gluon propagator exhibits...
We investigate the thermodynamic properties of color-superconducting two flavor quark matter at high densities and zero temperature, considering the next-to-leading order (NLO) correction in the strong coupling and the gap. Assuming that the ground state of dense quark matter is a color superconductor, we calculate the pressure and speed of sound for two massless quark flavors. Our results...
The dynamic criticality of chiral phase transition and QCD critical end point can be described by model G and model H from Hohenberg and Halperin's classification. In this talk, I will give an overview about our formulation of real-time functional renormalization group method to study systems of critical dynamics with reversible mode-coupling. Then I will apply such a formulation to study the...
We present a lattice implementation of the recently introduced center-symmetric Landau gauge and show that center symmetry imposes constraints on the gauge-link correlators in that gauge. In particular, we obtain constraints on the local one-link average and on the two-point link correlator which mirror those obtained in the continuum for the gauge-field one- and two-point functions. Then,...
We address the lattice computation of the gluon propagator in the center-symmetric Landau gauge. After discussing a proper lattice implementation of the center-symmetric Landau gauge, we show the first lattice results and study its behaviour with the temperature.
In this work, we study the Chiral Magnetic Effect (CME) from lattice QCD simulations considering two different scenarios, in particular focusing on the leading-order coefficient of the vector current in a chiral chemical potential expansion. In the first scenario, we consider continuum extrapolated QCD with 2+1 flavors of improved staggered fermions, a system in thermal equilibrium, with a...
The formalism of short-distance factorization connects light-cone correlators with spacelike ones. The later can be computed in Euclidean spacetime, common to many functional approaches to field theory. The former are central objects in the study of hadron structure, entering the definition of parton distributions. In this work we review the application of this formalism, conveyed through the...
Performing gauge theories’ calculations by realizing their Hamiltonians in controllable quantum systems to complement existing methods like perturbation theory and quantum Montecarlo is promising and challenging endeavor. After a brief and partial review of current successes and challenges, I will focus on the task of achieving continuum limit calculation with finite resources. I will present...
The dynamics of quantum many-body systems is one of the traditionally most challenging problems to study for classical simulators. Recently, however, the development of novel methodologies based on the concept of temporal entanglement has opened the way to a series of new results, allowing to access dynamical properties of quantum systems with efficient classical algorithms.
In this talk, I...
In this talk, I will describe how trapped-ion crystals can be used as platforms for the quantum simulation of gauge fields. Focusing on the crystal vibrations, I will show how Floquet engineering can be used to control an effective Peierls’ phase, and discuss a recent experiment demonstrating where this phase leas to Aharonov-Bohm interference of phonons. I will then discuss how to promote the...
It was shown in a certain approximation that dissociation of heavy quark
bound states in a quark-gluon plasma occurs due to the emergence of
an imaginary part of the potential. We check the robustness of this
prediction against corrections. We calculate higher order corrections to
the potential in a systematic and rigourous way, in the region where
bound states dissociate. This...
I report on technical advancements which are geared towards locating the conjectured critical endpoint of QCD using the functional renormalization group. Its use allows to access directly the high-density region, as this approach does not suffer from the sign problem of lattice QCD. In our first-principles setup, one can systematically identify and include all relevant physical degrees of...
Understanding the QCD phase diagram is a major challenge in high-energy physics.
To this end, two-color QCD offers an ideal theoretical laboratory since, unlike real-world QCD, its dynamics at finite density can be investigated via lattice simulations.
In this talk, I will use chiral perturbation theory to discuss the infrared dynamics of two-color QCD at finite density by focusing on the...
At nonzero temperature, the deconfining phase transition
and the change in non-trivial holonomy can be analyzed using an effective matrix model. The shear, and bulk viscosities are computed
in weak coupling but in non-zero holonomy. (shear viscosity/entropy density) decreases as we approach Td, it is still well above the conformal bound. In contrast, (bulk viscosity/entropy density) is...
Critical points are categorized based on the number of relevant variables. The standard critical point in systems like the Ising model involves two relevant variables, namely temperature and external magnetic field. In contrast, a tricritical point is characterized by four such variables. The protocritical point, widely known as the Yang-Lee edge singularity (YLE), is the simplest form of...
We study the realtime QCD dynamics underlying the moat behavior in QCD at finite chemical potential, present at baryon chemical potentials with µB /T & 4. It originates from the Landau damping of quarks scattering in the vicinity of Fermi surface. The moat appears as peaks in the spectral functions for the pion and sigma modes at space-like momenta.
Modern facilities, with their advanced capabilities, have enabled detailed investigations into the photo- and electro-excitation of nucleon resonances, shedding light on the evolution of their electromagnetic properties. These experimental breakthroughs have, in turn, driven significant progress in theoretical approaches.
In this seminar, I will present preliminary results on the transition...
This work conducts a systematic feasibility study of measuring backward
deeply virtual Compton scattering (bDVCS) on the pion in Sullivan processes, within the framework of collinear QCD factorization, where pion-to-photon transition distribution amplitudes (TDAs) describe the photon content of the pion. Using TDAs based on the overlap of light front wave functions, we employ a model for the...
Using the imaginary part of the self-energy function in the Landau-level representation, we derive the fermion damping rate in a hot magnetized plasma at the leading order of coupling. The results are used to investigate the longitudinal and transverse electrical conductivities by employing first-principles quantum field theoretical methods. In the relativistic regime, these conductivities...
