arXiv subjects

Víctor López-Pardo

Publications and source records attributed to Víctor López-Pardo.

5 recordsLinked to original sources

arXiv2026

Optimal observables for (non-)equilibrium quantum metrology from the master equation

We demonstrate how observables with optimal sensitivity to environmental properties can be constructed explicitly from the master equation of an open quantum system. Our approach does not rely on the explicit solution of the master equation and instead expresses the symmetric logarithmic derivative (SLD), the operator of optimal sensitivity and key quantity in quantum metrology, solely in terms of expectation values. This makes the SLD available to a large class of systems of interest, both in and out of equilibrium. We validate our approach by reproducing the SLD for temperature in quantum Brownian motion and demonstrate its versatility by constructing the optimal observable for the non-equilibrium relaxation rate.

quant-ph↗

arXiv2026

Lindblad-driven quarkonium production in heavy-ion collisions

We study the production of the conventional quarkonium states in ultrarelativistic heavy-ion collisions using an open quantum system framework based on the Lindblad equation. Starting from the complex-valued in-medium potential, we derive the dissociation temperature and thermal decay width for each state, and compute their survival probabilities for a system undergoing Bjorken expansion. We then extend the framework to include recombination from thermalized charm and bottom quarks in the quark-gluon plasma, deriving a coalescence model for quarkonia from the Lindblad equation under the adiabatic approximation. The methodology provides a unified, first-principles-inspired description of suppression and recombination for both charmonium and bottomonium.

hep-ph↗

arXiv2026

Lindblad-driven recombination of the X(3872) tetraquark

The internal structure of the exotic meson X(3872) remains an open question. We investigate its production in heavy-ion collisions under the hypothesis that it is a compact tetraquark. To this end, we derive a coalescence model from the Lindblad equation, assuming that unbound heavy quarks are thermalized within the quark-gluon plasma and that the adiabatic approximation holds. Using this model, we predict the nuclear modification factor of the X(3872) at LHC energies, with proton-proton baseline cross sections estimated from available experimental data. We also consider the effect of simplifying assumptions on the model, and a complementary approach based on chemical equilibration. Our results indicate that recombination is the dominant production mechanism for a tetraquark X(3872). It leads to a significant yield enhancement in heavy-ion collisions, suggesting that the nuclear modification factor is a powerful observable for probing the exotic nature of this state

hep-ph↗

arXiv2025

Exploring the DGLAP resummation in the JIMWLK Hamiltonian

We explore the recently derived equation that resums DGLAP corrections to the JIMWLK Hamiltonian in the simplified setting of the SU(2) gauge theory. We solve the equation numerically for the scattering matrix of a dressed gluon for a particular initial condition, that corresponds to a dipole initial state. As expected, the $S$-matrix of a single dressed gluon state ceases to be unitary if evolved to significant $\ln Q^2/Q_s^2$. Our numerical results indicate an interesting universal (independent of the coupling constant) pattern for this deviation from unitarity.

hep-ph↗

arXiv2025

A potential approach to the $X(3872)$ thermal behavior

We study the potential of $X(3872)$ at finite temperature in the Born-Oppenheimer approximation under the assumption that it is a tetraquark. We argue that, at large number of colors, it is a good approximation to assume that the potential consists in a real part plus a constant imaginary term. The real part is then computed adapting an approach by Rothkopf and Lafferty and using as input lattice QCD determinations of the potential for hybrids. This model allows us to qualitatively estimate at which temperature range the formation of a heavy tetraquark is possible, and to propose a qualitative picture for the dissociation of the state in a medium. Our approach can be applied to other suggested internal structures for the $X(3872)$ and to other exotic states.

hep-ph↗