arXiv subjects

João Barata

Publications and source records attributed to João Barata.

At least 37 records · Page 2Linked to original sources

arXiv2025

Directional dead-cone effect in QCD matter

We consider the propagation of heavy quarks through a dense, hydrodynamically flowing QCD medium, representative of the quark-gluon plasma formed in ultrarelativistic heavy-ion collisions. Working in the high-energy limit, we identify two novel mass-dependent effects arising from the heavy quark coupling to the local medium flow. The first is the emergence of a tensorial jet transport coefficient, $\hat{q}_{ij}$, which encodes the directional structure of transverse-momentum broadening. The second, named the directional dead-cone effect, corresponds to an anisotropic suppression of medium-induced radiation aligned with the hydrodynamic flow. We discuss how these effects manifest in jet observables and identify distinctive signature of heavy quark dynamics in an evolving medium.

hep-ph↗

arXiv2025

Thermal modifications of mesons and energy-energy correlators from real-time simulations of a $U(1)$ lattice gauge theory

We investigate thermal properties of a $U(1)$ lattice gauge theory in $1+1$-dimensions through real-time simulations. We extract the spectral functions directly coupling to the pseudoscalar and scalar mesons, demonstrating the thermal modifications of these states with increasing temperatures. Introducing the notion of energy-flow operators, we quantify the temporal build-up of correlations in the energy flows across the lattice. We demonstrate that energy-energy correlators fail to factorize to products of energy flows, both in the vacuum and at nonzero-temperature, indicating the presence of non-trivial correlations in the quantum states. Our results constitute a first real-time \textit{ab-initio} study of bound state thermal broadening and finite temperature energy-flow correlations in a gauge theory, providing a benchmark for future studies of hadronic matter under extreme conditions.

hep-ph↗

arXiv2025

Quantum computing for heavy-ion physics: near-term status and future prospects

We discuss recent advances in applying Quantum Information Science to problems in high-energy nuclear physics. After outlining key developments, open challenges, and emerging connections between these disciplines, we highlight recent results on the study of matter states, hard probes, and spin correlations using novel quantum technologies. This work summarizes the corresponding presentation delivered at the Quark Matter 2025 conference in Frankfurt, Germany.

quant-ph↗

arXiv2025

Heavy Quark Pair Energy Correlators: From Profiling Partonic Splittings to Probing Heavy-Flavor Fragmentation

We introduce heavy-flavor energy correlators, $\langle Ψ|\mathcal{E}_{\mathcal{H}}(\vec{n}_1) \mathcal{E}_{\mathcal{H}}(\vec{n}_2)|Ψ\rangle$, as a powerful observable for profiling partonic splittings and characterizing heavy-flavor fragmentation. We present its collinear factorization, perform resummation, and demonstrate the angular distribution's sensitivity to both the heavy-quark pair splitting and their subsequent fragmentation. We then apply the heavy-flavor EEC to probe medium-induced effects, revealing its sensitivity to medium modifications to heavy-quark pair splitting functions and to the medium's spatial structure.

hep-ph↗

arXiv2025

Giving wake to energy-energy correlators: Hydrodynamic response on the celestial sphere

The observation of the medium response generated by the propagation of high energy partons in the quark gluon plasma produced in heavy-ion collisions would provide a clear and unmistakable evidence for the hydrodynamic behavior of the bulk. Recently, it has been argued that the features of the medium's back-reaction to the jet could be cleanly imprinted in the correlations of asymptotic energy flows, in principle allowing to isolate this signal from other uncorrelated physical processes. Nonetheless, the current limited theoretical understanding of these jet observables in heavy-ion collisions constrains their applicability as probes of the medium (hydro)dynamics. In this work, we provide an analytic picture for the medium back-reaction's effect on the energy flux and two point energy correlator. We show that the medium response leads to the emergence of an universal classical scaling law, competing with the perturbative QCD contribution at large angles. Comparing the associated correlator to recent experimental measurements, we find that the observed large angle features can be qualitatively described by a purely hydrodynamically driven response and its interplay with the hard jet component.

hep-ph↗

arXiv2025

Energy-Energy Correlator for jet production in $pp$ and $pA$ collisions

In this Letter, we study the collinear limit of the Energy-Energy Correlator (EEC) in single-inclusive jet production in proton-proton ($pp$) and proton-nucleus ($pA$) collisions. We introduce a non-perturbative model that allows us to describe the EEC in the entire angular region of the current experiments. Our results for $pp$ collisions show excellent agreement with CMS and ALICE data over a wide range of jet transverse momenta. For $pA$ collisions, we include modifications from the nuclear medium, and our predictions align well with the trends observed in recent ALICE measurements.

hep-ph↗

arXiv2025

A Systematic Literature Review of Unmanned Aerial Vehicles for Healthcare and Emergency Services

Unmanned aerial vehicles (UAVs), initially developed for military applications, are now used in various fields. As UAVs become more common across multiple industries, it is crucial to understand how to adopt them effectively, efficiently, and safely. The utilization of UAVs in healthcare and emergency services has evolved significantly in recent years, with these aerial vehicles potentially contributing to increased survival rates and enhanced healthcare services. This paper presents a two-stage systematic literature review, including a tertiary study of 15 review papers and an in-depth assessment of 136 primary publications focused on using UAVs in healthcare and emergency services. The research demonstrates how civilian UAVs have been used in numerous applications, such as healthcare emergencies, medical supply delivery, and disaster management, for diverse use cases such as Automated External Defibrillator (AED) delivery, blood delivery, and search and rescue. The studies indicate that UAVs significantly improve response times in emergency situations, enhance survival rates by ensuring the timely delivery of critical medical supplies such as AEDs, and prove to be cost-effective alternatives to traditional delivery methods, especially in remote or inaccessible areas. The studies also highlight the need for ongoing research and development to address existing challenges, such as regulatory frameworks, security, privacy and safety concerns, infrastructure development, and ethical and social issues. Effectively understanding and tackling these challenges is essential for maximizing the benefits of UAV technology in healthcare and emergency services, ultimately leading to safer, more resilient, and responsive systems that can better serve public health needs.

cs.CY↗

arXiv2025

Dissecting Jet Modification in the QGP with Multi-Point Energy Correlators

Energy correlators have recently attracted significant attention in the study of heavy ion collisions due to their potential to robustly connect experimental measurements with an underlying quantum field theoretic description. While theoretical studies have so far primarily focused on the simplest two-point correlator, mapping out the dynamics of the quark-gluon plasma (QGP) will require developing a theoretical understanding of multi-point energy correlators. In this paper we present a systematic theoretical study of multi-point energy correlators for jets fragmenting in a dense quark-gluon plasma, accounting for both the medium's perturbative modification to the jet, and its hydrodynamical back-reaction. We consider both the scaling behavior of projected correlators, as well as the shape dependent three-point correlator, highlighting how both provide insight into interactions with the QGP. We discuss the parametric dependence of modifications on the medium scales, opening new opportunities to experimentally separate jet modifications from the medium response. Our results open the door to a systematic exploration of multi-point energy correlators in heavy ion collisions.

hep-ph↗

arXiv2025

Real-time simulation of jet energy loss and entropy production in high-energy scattering with matter

In analogy to high-energy nuclear scattering experiments, we study a real-time scattering process between a propagating state and a dense target in $1+1$-d massive QED. In our setup, we identify three distinct regimes that qualitatively characterize the evolution: for a dilute medium, the incoming probe state evolves nearly ballistically; in an intermediate setting, it traverses the matter, locally exciting it; and for dense targets, one approaches a black-disk limit, where the matter acts as a strong wall potential. We find evidence that the probe's energy loss rate scales linearly with the path length in the medium, and we study how the entanglement entropy reveals the mixing between the probe and medium states. With the goal of one day replicating high-energy nuclear experiments in quantum devices, we briefly discuss how the current tensor network-based simulations can be translated to a quantum simulator.

hep-ph↗

arXiv2025

Towards a Real-Time Computation of Timelike Hadronic Vacuum Polarization and Light-by-Light Scattering: Schwinger Model Tests

Hadronic vacuum polarization (HVP) and light-by-light scattering (HLBL) are crucial for evaluating the Standard Model predictions concerning the muon's anomalous magnetic moment. However, direct first-principle lattice gauge theory-based calculations of these observables in the timelike region remain challenging. Discrepancies persist between lattice quantum chromodynamics (QCD) calculations in the spacelike region and dispersive approaches relying on experimental data parametrization from the timelike region. Here, we introduce a methodology employing 1+1-dimensional quantum electrodynamics (QED), i.e. the Schwinger Model, to investigate the HVP and HLBL. To that end, we use both tensor network techniques, specifically matrix product states, and classical emulators of digital quantum computers. Demonstrating feasibility in a simplified model, our approach sets the stage for future endeavors leveraging digital quantum computers.

hep-ph↗

arXiv2025

Non-local high-$p_t$ transport in anisotropic QCD matter

We perform a numerical study of non-local partonic transport in anisotropic QCD matter, relevant to the evolution of hard probes in the aftermath of high-energy nuclear scattering events. The recently derived master equation, obtained from QFT considerations, differs from Boltzmann transport by incorporating a non-local elastic scattering kernel arising from density gradients. After rewriting the master equation in a form suitable for numerical implementation and assuming a static density profile, we compare the non-local evolution to Boltzmann transport, demonstrating that the new interaction kernel is essential for accurately describing the azimuthal structure of the final-state momentum distribution. We further study the non-local partonic transport in the case of a matter profile governed by two-dimensional hydrodynamics, accounting for its flow and generalizing the evolution equation. Our results demonstrate the necessity of going beyond classical transport at high-$p_t$ to accurately capture the structure of jets propagating through structured QCD matter. The master equation used in the numerical simulations can be seamlessly integrated into state-of-the-art transport codes.

nucl-th↗

arXiv2025

Probing Celestial Energy and Charge Correlations through Real-Time Quantum Simulations: Insights from the Schwinger Model

Motivated by recent developments in the application of light-ray operators (LROs) in high energy physics, we propose a new strategy to study correlation functions of LROs through real-time quantum simulations. We argue that quantum simulators provide an ideal laboratory to explore the properties LROs in lower-dimensional quantum field theories (QFTs). This is exemplified in the 1+1-d Schwinger model, employing tensor network methods, focusing on the calculation of energy and charge correlators. Despite some challenges in extracting the necessary correlation functions from the lattice the methodology used can be extended to real quantum devices.

hep-ph↗

arXiv2024

Tracking Energy Loss in Heavy Ion Collisions

The main modification to high $p_t$ jets evolving in the quark gluon plasma is the depletion of their energy to the thermal background. Despite the prominent role played by energy loss effects in jet quenching, their theoretical description is still limited, being, to a large extent, driven by phenomenological considerations. As the field moves towards the measurement of multi-scale jet substructure observables, it is necessary to develop new field theoretic techniques to describe energy loss. In this letter, we highlight a formal similarity between energy loss, and the renormalization group based track function formalism for computing jet substructure observables on charged particles. We introduce an energy loss function, $L_i(x)$, tracking the energy fraction $x$ flowing from an initial hard parton $i$ down to the measured hadrons, and show that its renormalization group evolution can be studied in perturbative QCD, and is related to that of the track functions. The features of this new approach are illustrated in the computation of projected energy correlators, opening the window to a better theoretical treatment of these observables in heavy ion collisions.

hep-ph↗

arXiv2024

Gluon to $q\bar q$ antenna in anisotropic QCD matter: spin-polarized and azimuthal jet observables

We study the production of a quark-antiquark antenna in the presence of a dense and anisotropic QCD medium. We assume the antenna to originate from an unpolarized gluon state, and consider both massless and massive final states. The medium anisotropy is captured by allowing the jet quenching coefficient to take different magnitudes in orthogonal directions with respect to the jet axis. We find that the final particle distribution is sensitive to the medium anisotropy, and more importantly, that this effect couples directly to the helicity/spin of the final states. We propose to look into these effects by performing a Fourier decomposition of the particle distribution inside the jet. In our medium model, we find that the spin independent terms contribute to the even harmonics of the cosine series. The helicity/spin dependence enters only through the sine Fourier series. We further explore the spin dependence by examining the degree of polarization of the final states in different directions. Our results indicate that the anisotropies present in the QCD matter produced in heavy ion collisions can be probed by studying azimuthal and spin observables inside jets.

hep-ph↗

arXiv2024

Jet quenching in the glasma phase: medium-induced radiation

Inspired by the recent considerations of parton momentum broadening in the glasma phase, we study the medium-induced soft gluon radiation of jet partons at early times in heavy-ion collisions. The glasma state is assumed to be comprised of independent color domains with homogenous longitudinal fields that vary event by event, and we further complete this model with an event-averaging procedure accounting for the finite correlation length. Using this description, we evaluate the rate of medium-induced radiation from an energetic parton at midrapidity in the glasma phase. We mainly focus on SU(2) color fields for simplicity, also referring to the U(1) case and comparing with the BDMPS-Z rate to gain further insight. Our results show that there is an intricate interplay of the synchrotron-like radiation in a single color domain with the destructive interference between different color domains, after the medium averaging is performed. Thus, we find that the emission rate is sensitive to the matter structure, decreasing for a glasma state populated by smaller color domains, i.e. for a glasma with a larger characteristic saturation scale. Our approach can be applied to more realistic backgrounds, and sets the stage for the modelling of jet evolution in the early stages of heavy-ion collisions.

hep-ph↗

arXiv2024

Realtime dynamics of hyperon spin correlations from string fragmentation in a deformed four-flavor Schwinger model

Self-polarizing weak decays of $Λ$-hyperons provide unique insight into the role of entanglement in the fragmentation of QCD strings through measurements of the spin correlations of $Λ{\bar Λ}$-pairs produced in collider experiments. The simplest quantum field theory representing the underlying parton dynamics is the four-flavor massive Schwinger model plus an effective spin-flip term, where the flavors are mapped to light (up/down) and heavy (strange) quarks and their spins. This construction provides a novel way to explore hyperon spin-correlations in 1+1-dimensions. We investigate the evolution of these correlations for different string configurations that are sensitive to the rich structure of the model Hamiltonian.

hep-ph↗

arXiv2024

Medium induced gluon spectrum in dense inhomogeneous matter

We calculate the spectrum of gluons sourced by the branching of an energetic quark in the presence of an inhomogeneous QCD medium, focusing on the soft radiation limit. We take into account multiple soft interactions between the partons and matter, treating the transverse variations of its parameters within a gradient expansion. Thus, we derive the general form of the medium induced spectrum up to the first order in gradients, and consider its simplifying limits. In particular, we show that to the leading order in matter gradients and using the harmonic approximation for the scattering potential, the full gluon spectrum can be written in a compact closed form suitable for numerical evaluation. The final gluon transverse momentum tends to align along the anisotropy direction, resulting in a non-trivial azimuthal pattern in the jet substructure.

hep-ph↗

arXiv2024

Leading order track functions in a hot and dense QGP

We study the modifications to the fragmentation pattern of partons into charged particles in the presence of a hot and dense Quark Gluon Plasma. To this end, we analyze the perturbative renormalization group equations of the track functions, which describe the energy fraction carried by charged hadrons. Focusing on pure Yang-Mills theory, we compute the lowest order moments of the medium-modified track functions, which are found to be sensitive to the reduced phase space for emissions in the medium and to energy loss. We use the extracted moments to calculate the Energy Energy Correlator (EEC) on tracks in the collinear limit. The EEC on medium-evolved tracks does not differ qualitatively from the EEC on vacuum tracks despite being sensitive to the color decoherence transition and suppressing the distribution due to quenching, as seen in other jet observables.

hep-ph↗