arXiv subjects

João Barata

Publications and source records attributed to João Barata.

At least 19 recordsLinked to original sources

arXiv2026

From Nuclear Many-Body Correlations to Energy Detector Correlators

Relativistic nuclear collisions have opened an experimental arena for studying many-body correlations in nuclear ground states. However, the connection between initial-state correlations and final-state multi-particle observables measured at colliders is not yet formulated as a systematically improvable matching problem. We show that detector correlators built from asymptotic energy flows provide a natural framework for realizing such a construction. In particular, we express the asymptotic energy flow as a functional of the early-time stress tensor, and expand it in suitable modes to recover the familiar linear hydrodynamic relations at leading order. Then, motivated by small-$x$ QCD, we map angular projections of detector correlators to multipole-operator correlators computed in the colliding nuclei. We thus establish a systematic formalism for matching long-wavelength correlations between incoming and outgoing QCD states in high-energy hadronic collisions.

nucl-th↗

arXiv2026

Collider Detector Observables from Lattice Spin Systems

Detector observables pose a fundamental challenge for nonperturbative lattice methods due to their intrinsically real-time and asymptotic nature. We propose quantum simulation platforms as an ideal setting for studying these observables. Using quantum spin systems as a demonstration, we construct lattice detector operators and establish their connection to continuum energy-flow observables. We demonstrate this framework in the $1+1$-dimensional quantum Ising model, where finite lattice calculations show quantitative agreement with conformal field theory expectations at criticality. These results support the interpretation of the lattice flow operators as regulated counterparts of continuum detectors in the scaling and asymptotic limits, providing a concrete route toward realizing high-energy collider physics on table-top quantum platforms.

hep-ph↗

arXiv2026

Exact group invariant scar towers in two dimensional gauge theories

We construct exact many-body scar towers in two dimensional gauge theories with two flavors of massless fundamental fermions. For oppositely charged fermions, the scar subspace is generated by a gauge-neutral $η$-pairing operator, and admits a purely algebraic construction. Exact diagonalization methods reveal anomalously low entanglement and long-range pair correlations in the scar states. Charge conjugation maps the $η$-tower to a vector-flavor polarization sector of the equal charge model, yielding an interpretation as a coherent flavor mode with Josephson-like phase dynamics. Finite fermion masses mix the protected pair with an orthogonal channel and destroy the exact tower. The identified scar tower can be algebraically realized in a large family of lattice field theories, revealing a universal character of these states. Our results provide an analytical construction of invariant scar subspaces in a gauge theory with a nontrivial continuum interpretation.

hep-th↗

arXiv2026

Energy-Energy Correlators in $Z$-Tagged Jets in $pp$ Collisions

We present predictions for the collinear energy-energy correlator (EEC) measured inside $Z$-tagged jets in proton-proton collisions across the confinement transition. Our framework combines transverse-momentum-dependent factorization for back-to-back $Z+$jet production with an exclusive differential EEC jet function incorporating perturbative evolution and flavor-dependent non-perturbative fragmentation. The EEC jet function is evaluated at $\mathrm{NLL}^{\prime}$ accuracy, with separate quark and gluon non-perturbative scales constrained by existing $e^+e^-$ and inclusive-jet data. We provide predictions for forward $Z+$jet production at $\sqrt{s}=8~\mathrm{TeV}$ and $13~\mathrm{TeV}$ in the jet transverse-momentum intervals $(20, 30)$, $(30, 50)$ and $(50, 100) \, \mathrm{GeV}$. The EEC distributions as functions of $z_χ$ exhibit finite plateaus at small $z_χ$, while the corresponding angular distributions display the characteristic turnover associated with the confinement transition. A flavor decomposition shows that this transition becomes increasingly dominated by quark-initiated jets as the jet transverse momentum increases. Forward $Z$-tagged jets therefore provide a clean probe of non-perturbative quark fragmentation and offer a direct test of whether the characteristic confinement scale extracted from $e^+e^-$ collisions remains universal in a hadronic environment.

hep-ph↗

arXiv2026

Emergent hydrodynamic response and dynamical backreaction: Magnon bound-state propagation in a Bose-Hubbard fluid

We study the nonequilibrium response of a one-dimensional Bose-Hubbard medium to a two-magnon bound state propagating along an attractive XXZ chain. A Holstein-type displacement coupling makes the magnon density act both as a local chemical-potential perturbation and as a source of bosons. We derive a long-wavelength hydrodynamic description of the density and phase fluctuations and test it against matrix-product-state simulations of the full coupled dynamics. The theory predicts a comoving near-field deformation together with retarded density waves confined to a sound cone. In the Mott regime, the deformation remains localized around the moving pair. In the compressible regime, two counterpropagating fronts detach and approach the semiclassical sound velocity, recovered from the equilibrium density with no fitted parameters. The coupling also induces a dynamical backreaction that slows the bound state and broadens its magnon-density profile. The comparison delimits where hydrodynamics stays quantitative once the probe reacts back on the medium.

cond-mat.quant-gas↗

arXiv2026

Dressed magnon dynamics in a Bose-Hubbard bath: retardation, pairing, entanglement and two-magnon scattering

We study one- and two-magnon dynamics in a spin-$1/2$ XX chain coupled to a tunable Bose-Hubbard bath. The XX Hamiltonian transports the magnons, while the bath dresses their motion and mediates an effective attraction. A single magnon forms a mobile polaron whose retarded bosonic cloud reduces its velocity below the static Lang-Firsov prediction and generates magnon-boson entanglement. In the weak-dressing, off-resonant mobile regime, the residual velocity deficit and entanglement are governed by the excitation weight of the cloud, as captured by perturbation theory and tensor network-based real-time simulations. Transport therefore provides a model-calibrated proxy for entanglement without joint-state reconstruction. When two clouds overlap, the bath mediates a finite-range attraction, yielding finite-size evidence for a compact two-magnon bound state and a transient post-scattering signature. On-site bath interactions suppress local boson number fluctuations and stiffen the bath response, reducing entanglement and weakening ground-state binding. Bath deformability thus emerges as a common control parameter for magnon transport, entanglement, and bath-mediated pairing.

quant-ph↗

arXiv2026

Anomaly Realization in Charge-Flux Detector Correlators

Quantum anomalies provide a bridge between ultraviolet properties of a theory and its infrared sector. We study how this connection appears in axial-charge-flow observables. In the simplest example, an axial-charge detector probes the fermionic cut of the anomalous triangle and resolves its infrared content as an angular distribution. The massless limit does not commute with the angular integration: a contribution suppressed at fixed angle collapses onto the two beam-collinear directions while retaining the finite integrated sum rule fixed by the axial anomaly. We then replace the axial-charge detector by higher-spin helicity (zilch) detectors and study a family of axial-anomaly-controlled energy-weighted sum rules for the corresponding fluxes. We further show that the same singular localization mechanism and finite zilch-flux sum rules persist in the mixed axial-gravitational channel. We briefly comment on extensions to more general states and multipoint correlators.

hep-ph↗

arXiv2026

$Λ\bar Λ$ spin correlations in high-energy collisions from quantum channels: an open quantum system view of hadronization

We construct a quantum information-centered approach to describe the experimentally observed behavior of hyperon spin-pair correlations in high-energy collider experiments. The evolution of the spin density matrix of the hyperon pair is treated in the language of quantum channels, accounting both for the spin dynamics in $\mathbb{C}^2\otimes\mathbb{C}^2$ and for the pair's angular separation $ΔR$. We show that the experimental data are consistent with an evolution under a two-qubit depolarizing channel, from which a Lindblad master equation is derived. This provides an open quantum system picture of spin dynamics during the hadronization transition, which is not naturally captured by other quantum channels, and we discuss its microscopic origins. These results show that quantum information science can offer new insights into confinement dynamics beyond the classification of entanglement in the final particle states.

hep-ph↗

arXiv2026

Mapping jet substructure in heavy-ion collisions with track functions

We investigate the dynamics of high-energy QCD cascades in heavy-ion collisions, focusing on modifications to jets' substructure induced by the presence of a quark-gluon plasma (QGP). To this end, we study the properties and scale evolution of track functions, non-perturbative objects encoding the flow of energy from an initiating parton to all charged hadrons. In contrast to the more standard fragmentation functions, these objects have a non-linear renormalization group (RG) evolution, being sensitive to the entire jet fragmentation process. Using the JEWEL and HYBRID Monte-Carlo models of jet quenching, we find that in both frameworks the higher moments and cumulants of the track functions' distributions exhibit sizable deviations from their vacuum baselines, demonstrating that medium-induced energy loss imprints itself in the in-medium jet fragmentation pattern. We find that the quantitative magnitude of these modifications differs significantly between the two models. This identifies track functions as a class of observables capable of discriminating between competing microscopic pictures of jet-medium interactions. We further examined the (in-medium) RG flows for the leading moments, which remain in qualitative agreement with the in-vacuum evolution. This provides an avenue to directly test the RG flows inside a QGP, linking heavy-ion jet measurements to basic QFT understanding of partonic branching. Finally, we comment on the feasibility and challenges associated with extracting track functions from experimental data.

hep-ph↗

arXiv2026

Jet quenching in out-of-equilibrium QCD matter

We present the first study of jet substructure modifications during the bottom-up evolution that describes the early stages of heavy-ion collisions. To this end, we study the bremsstrahlung radiation rate of soft gluons from a hard parton propagating through out-of-equilibrium QCD matter. The gluon spectrum is computed within the Improved Opacity Expansion, which accounts for both multiple soft and single hard momentum exchanges between the hard probe and the medium. The background evolution is obtained from effective kinetic theory simulations that determine the jet quenching parameter, which in turn controls the radiation rate. We compute the radiation rate for initially under- and over-occupied systems, as well as for an expanding system undergoing hydrodynamization, which typically represents the initial stages of heavy-ion collisions. The results for these dynamical backgrounds are compared to static and thermally matched scenarios, allowing to gauge the importance of bulk expansion in the evolution of the jet cascade. Our findings show that the early stages of the bulk matter evolution in heavy-ion collisions leave a sizable imprint on the radiation pattern inside jets. These results establish a basis for incorporating pre-equilibrium dynamics into realistic descriptions of jet quenching and hard-probe evolution.

hep-ph↗

arXiv2026

Quantum simulating multi-particle processes in high energy nuclear physics: dijet production and color (de)coherence

Hard scattering events in high-energy collisions produce highly virtual partons that subsequently fragment into collimated hadronic cascades. When such partonic showers evolve in a QCD medium, as in deep-inelastic scattering or heavy-ion collisions, the resulting multi-particle distributions encode information about the surrounding matter. Decades of theoretical developments have led to a consistent and order-by-order improvable perturbative description of the shower. This description needs, however, the non-perturbative input that encodes the structure of the hadronic matter. The determination of such input remains challenging within conventional computational approaches, thereby limiting the applicability of the approach. In this work, we develop a framework that employs quantum simulation techniques to compute multi-particle processes in such environments by mapping partonic cross-sections to quantum circuits. As benchmarks, we analyze dipole formation and the QCD antenna radiation pattern at leading order in the strong coupling constant, comparing the results with analytic estimates in simplified limits. The quantum circuit formulation here introduced naturally extends to higher perturbative orders and enables amplitude-level computations in complex matter backgrounds. This provides a systematic foundation for applying quantum information science methods to study multi-particle dynamics in QCD media.

hep-ph↗

arXiv2026

Hadronic scattering in (1+1)D SU(2) lattice gauge theory from tensor networks

We present a first real-time study of hadronic scattering in a (1+1)-dimensional SU(2) lattice gauge theory with fundamental fermions using tensor-network techniques. Working in the gaugeless Hamiltonian formulation -- where the gauge field is exactly integrated out and no truncation of the electric flux is required -- we investigate scattering processes across sectors of fixed global baryon number $B = 0, 1, 2$. These correspond respectively to meson-meson, meson-baryon, and baryon-baryon collisions. At strong coupling, the $B = 0$ and $B = 2$ channels exhibit predominantly elastic dynamics closely resembling those of the U(1) Schwinger model. In contrast, the mixed $B = 1$ sector shows qualitatively new behavior: meson and baryon wave packets become entangled during the collision, and depending on their initial kinematics, the slower state becomes spatially delocalized while the faster one propagates ballistically. We characterize these processes through local observables, entanglement entropy, and the information-lattice, which together reveal how correlations build up and relax during the interaction. Our results establish a first benchmark for non-Abelian real-time scattering from first principles and open the path toward quantum-simulation studies of baryon-number dynamics and inelastic processes in gauge theories.

hep-lat↗

arXiv2026

Hydrodynamics and Energy Correlators

We study energy-energy correlators (EECs) in many-body quantum states, focusing on the matter produced in the aftermath of heavy-ion collisions. We analyze the angular structure of EECs in the collinear limit and identify a sequence of dynamical regimes. At the largest angular separations within the small-angle regime, the observable is dominated by disconnected contributions, leading to a classical scaling determined by the collective flow of the medium. We explicitly construct this contribution for hadrons produced from a hydrodynamic medium described by boost-invariant Gubser flow, obtaining the angular dependence of the EEC analytically. We further consider azimuthal perturbations to this flow, illustrating how EECs can be used to probe anisotropies in the initial state. At smaller angular separations, connected contributions become increasingly important. We argue that in this regime the EEC is controlled by collective hydrodynamic modes. The resulting angular behavior is similar to the one identified in the EECs of heavy and large-charge states of conformal field theories. At even smaller angles, this regime is expected to match onto the structure determined by the light-ray operator product expansion, before eventually crossing over to the smallest-angle behavior characteristic of dilute hadronic matter. Altogether, these results provide a unified picture of the angular structure of EECs in many-body QCD states and suggest new observables sensitive to the properties of matter in heavy-ion collisions.

hep-ph↗

arXiv2026

Quantum simulation of baryon scattering in SU(2) lattice gauge theory

We present a first real-time study of hadronic scattering in a $(1+1)$-dimensional SU(2) lattice gauge theory with fundamental fermions using tensor-network techniques. Working in the gaugeless Hamiltonian formulation, we investigate scattering processes across sectors of fixed global baryon number $B = 0, 1, 2$, corresponding respectively to meson--meson, meson--baryon, and baryon--baryon collisions. At strong coupling, the $B = 0$ and $B = 2$ channels exhibit predominantly elastic dynamics closely resembling the U(1) Schwinger model. The mixed $B = 1$ sector displays qualitatively new behavior: meson and baryon wavepackets become entangled during the collision, with the slower state becoming spatially delocalized while the faster one propagates ballistically. We characterize these processes through local observables, entanglement entropy, and the information lattice.

hep-lat↗

arXiv2026

Simulating Lattice Gauge Theories with Virtual Rishons

Classical tensor network and hybrid quantum-classical algorithms are promising candidates for the investigation of real-time properties of lattice gauge theories. We develop here a novel framework which enforces gauge symmetry via a quantum-link virtual rishon representation applied at intermediate steps. Crucially, the gauge and matter degrees of freedom are dynamical variables encoded in terms of qubits, enabling analysis of gauge theories in $d+1$ spacetime dimensions. We benchmark this framework in a U(1) gauge theory with and without matter fields. For $d = 1$, the multi-flavor Schwinger model with $1\leq N_f\leq3$ flavors is analyzed for arbitrary boundary conditions and nonzero topological angle, capturing signatures of the underlying Wess-Zumino-Witten conformal field theory. For $d = 2$, we extract the confining string tension in close agreement with continuum expectations. These results establish the virtual rishon framework as a scalable and robust approach for the simulation of lattice gauge theories using both classical tensor networks as well as near-term quantum hardware.

hep-th↗

arXiv2026

Scattering Processes from Quantum Simulation Algorithms for Scalar Field Theories

We provide practical simulation methods for scalar field theories on a quantum computer that yield improved asymptotics as well as concrete gate estimates for the simulation and physical qubit estimates using the surface code. We achieve these improvements through two optimizations. First, we consider a finite volume approach for estimating the elements of the S-matrix. This approach is appropriate in general for 1+1D and for certain low-energy elastic collisions in higher dimensions. Second, we implement our approach using a series of different fault-tolerant simulation algorithms for Hamiltonians formulated both in the field occupation basis and field amplitude basis. Our algorithms are based on either second-order Trotterization or qubitization. The cost of Trotterization in occupation basis scales as $O(λN^7 |Ω|^3/(M^{5/2} ε^{3/2}))$ where $λ$ is the coupling strength, $N$ is the occupation cutoff, $|Ω|$ is the volume of the spatial lattice, $M$ is the mass of the particles and $ε$ is the uncertainty in the energy calculation used for the $S$-matrix determination. Qubitization in the field basis scales as $O(|Ω|^2 (k^2 Λ+kM^2)/ε)$ where $k$ is the cutoff in the field and $Λ$ is a scaled coupling constant. We find in both cases that the bounds suggest physically meaningful simulations can be performed using on the order of $4\times 10^6$ physical qubits and $10^{12}$ $T$-gates which corresponds to roughly one day on a superconducting quantum computer with surface code and a cycle time of 100 ns. This places the simulation of scalar field theory within striking distance of the gate counts for the best available chemistry simulation results.

quant-ph↗

arXiv2025

Out-of-Equilibrium Dynamics in a U(1) Lattice Gauge Theory via Local Information Flows: Scattering and String Breaking

We introduce local information flows as a diagnostic tool for characterizing out-of-equilibrium quantum dynamics in lattice gauge theories. We employ the information lattice framework, a local decomposition of total information into spatial- and scale-resolved contributions, to characterize the propagation and buildup of quantum correlations in real-time processes. Focusing on the Schwinger model, a canonical $(1+1)$-dimensional U(1) lattice gauge theory, we apply this framework to two scenarios. First, in the near-threshold scattering of two vector mesons, we demonstrate that the emergence of correlations at a longer length scale in the information lattice marks the production of heavier scalar mesons. Second, in the dynamics of electric field strings, we clearly distinguish between the confining regime, which evolves towards a steady state with a static correlation profile, and the string-breaking sector. The latter is characterized by dynamic correlation patterns that reflect the sequential formation and annihilation of strings. This information-centric approach provides a direct, quantitative, and interpretable visualization of complex many-body phenomena, offering a promising tool for analyzing dynamics in higher-dimensional gauge theories and experiments on quantum hardware.

quant-ph↗

arXiv2025

Early-Time Dynamics of Heavy-Ion Collisions through Energy Correlators: celestial blocks and the spacetime structure of out-of-equilibrium QCD matter

Ultrarelativistic heavy-ion collisions provide a unique window into far-from-equilibrium states of QCD matter. The initial stages of these events are characterized by highly anisotropic, nonthermal dynamics that precede hydrodynamization, yet they remain largely inaccessible through conventional soft observables. In this work, we show that the substructure of mid-rapidity jets provides direct sensitivity to the spacetime structure of this early, anisotropic phase. Using classical Yang-Mills simulations and effective kinetic theory to model the early-time evolution of the jet quenching parameter, we compute the azimuthally differential energy-energy correlator within the BDMPS-Z framework. By decomposing the result into celestial blocks, we isolate the coefficients that encode the anisotropic geometry and dynamics of the underlying medium. We identify an observable that couples directly to spatial anisotropies in the out-of-equilibrium QCD matter and also discuss the impact of medium response on its behavior. We further extend our study to mid-rapidity jets generated with the JEWEL Monte-Carlo, adjusted to incorporate an anisotropic medium background, and find qualitative agreement with the analytical expectations. Finally, we discuss how higher-point energy correlators and generalized energy-flow operators can enhance the sensitivity to the microscopic structure of far-from-equilibrium QCD matter.

hep-ph↗