arXiv subjects

Letícia F. Palhares

Publications and source records attributed to Letícia F. Palhares.

10 recordsLinked to original sources

arXiv2026

Susceptibilities and Taylor coefficients of magnetic QCD from perturbation theory

We compute the coefficients $c_2(T,B)$ and $c_4(T,B)$ of the Taylor expansion for the pressure in powers of $μ_B/T$ in the presence of a large magnetic field within perturbative QCD at finite temperature and baryon density up to two-loops for $N_f=3$ flavors with physical quark masses. We also present results for the excess of pressure, baryon density and baryon number susceptibility as functions of $μ_B$, as well as susceptibilities as functions of the temperature in the $\{ μ_B,μ_Q,μ_S \}$ basis. Our results can be directly compared to recent lattice QCD data. Even though current lattice results do not overlap with its region of validity, perturbative results seem to be compatible with those obtained on the lattice for large temperatures.

hep-ph↗

arXiv2025

Hot and dense pQCD in a very strong magnetic background

We compute the pressure, chiral condensate and strange quark number susceptibility from perturbative QCD up to two-loop order at finite temperature and very high magnetic fields with physical quark masses. We also discuss the case of cold and dense quark matter in the presence of a very strong magnetic field and constraints for quark magnetars.

hep-ph↗

arXiv2024

Strongly interacting matter in extreme magnetic fields

Magnetic fields are ubiquitous across different physical systems of current interest; from the early Universe, compact astrophysical objects and heavy-ion collisions to condensed matter systems. A proper treatment of the effects produced by magnetic fields during the dynamical evolution of these systems, can help to understand observables that otherwise show a puzzling behavior. Furthermore, when these fields are comparable to or stronger than Λ_QCD, they serve as excellent probes to help elucidate the physics of strongly interacting matter under extreme conditions of temperature and density. In this work we provide a comprehensive review of recent developments on the description of QED and QCD systems where magnetic field driven effects are important. These include the modification of meson static properties such as masses and form factors, the chiral magnetic effect, the description of anomalous transport coefficients, superconductivity in extreme magnetic fields, the properties of neutron stars, the evolution of heavy-ion collisions, as well as effects on the QCD phase diagram. We describe recent theory and phenomenological developments using effective models as well as LQCD methods. The work represents a state-of-the-art review of the field, motivated by presentations and discussions during the "Workshop on Strongly Interacting Matter in Strong Electromagnetic Fields" that took place in the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) in the city of Trento, Italy, September 25-29, 2023.

nucl-th↗

arXiv2024

Ghost-gluon vertex in the presence of the Gribov horizon: General kinematics

Correlation functions are important probes for the behavior of quantum field theories. Already at tree-level, the Refined Gribov Zwanziger (RGZ) effective action for Yang-Mills theories provides a good approximation for the gluon propagator, as compared to that calculated by nonperturbative methods such as Lattice Field Theory and Dyson-Schwinger Equations. However, the study of higher correlation functions of the RGZ theory is still at its beginning. In this work we evaluate the ghost-antighost-gluon vertex function in Landau gauge at one-loop level, in $d=4$ space-time dimensions for the gauge groups SU(2) and SU(3). More precisely, we extend the analysis conducted in [1] for the soft-gluon limit to an arbitrary kinematic configuration. We introduce renormalization group effects by means of a toy model for the running coupling and investigate the impact of such a model in the ultraviolet tails of our results. We find that RGZ results match fairly closely those from lattice simulations, Schwinger-Dyson equations and the Curci-Ferrari model for three different kinematic configurations. This is compatible with RGZ being a feasible theory for the strong interaction in the infrared regime.

hep-ph↗

arXiv2024

Cold and dense perturbative QCD in a very strong magnetic background

We compute the pressure from first principles within perturbative QCD at finite baryon density and very high magnetic fields up to two-loops and with physical quark masses. The region of validity for our framework is given by $m_s \ll μ_q \ll \sqrt{eB}$, where $m_s$ is the strange quark mass, $μ_q$ is the quark chemical potential, $e$ is the fundamental electric charge, and $B$ is the magnetic field strength. We include the effects of the renormalization scale in the running coupling, $α_s (μ_q,\sqrt{eB})$, and running strange quark mass. We also discuss the simplifications that come about in the chiral limit. The effectively negligible contribution of the exchange diagram allows for building a simple analytic model for the equation of state for pure quark magnetars and computing their mass and radius at very large values of $B$. These results provide constraints on the behavior of the maximum mass and associated radius from perturbative QCD. We also discuss the magnetic bag model for extreme magnetic fields.

hep-ph↗

arXiv2023

Hot perturbative QCD in a very strong magnetic background

We compute the pressure, chiral condensate and strange quark number susceptibility from first principles within perturbative QCD at finite temperature and very high magnetic fields up to next-to-leading order and physical quark masses. The region of validity for our framework is given by $m_s \ll T \ll \sqrt{eB}$, where $m_s$ is the strange quark mass, $e$ is the fundamental electric charge, $T$ is the temperature, and $B$ is the magnetic field strength. We study the convergence of the perturbative series for the pressure for different choices of renormalization scale in the running coupling, $α_s (T,B)$. Our results for the chiral condensate and strange quark number susceptibility can be directly compared to recent lattice QCD data away from the chiral transition. Even though current lattice results do not overlap with the region of validity above, perturbative results seem to be in the same ballpark.

hep-ph↗

arXiv2011

Finite-size effects and the search for the critical endpoint of QCD

Taking into account the finiteness of the system created in heavy ion collisions, we show sizable results for the modifications of the chiral phase diagram at volume scales typically encountered in current experiments and demonstrate the applicability of finite-size scaling as a tool in the experimental search for the critical endpoint. Using data from RHIC and SPS and assuming finite-size scaling, we find that RHIC data from 200 GeV down to 19.6 GeV is only consistent with a critical point at μ\gtrsim 510 MeV. We also present predictions for the fluctuations at lower energies currently being investigated in the Beam Energy Scan program.

hep-ph↗

arXiv2008

Perturbative Yukawa theory at finite density: the role of masses and renormalization group flow at two loops

Yukawa theory at vanishing temperature provides (one of the ingredients for) an effective description of the thermodynamics of a variety of cold and dense fermionic systems. We study the role of masses and the renormalization group flow in the calculation of the equation of state up to two loops within the MSbar scheme. Two-loop integrals are computed analytically for arbitrary fermion and scalar masses, and expressed in terms of well-known special functions. The dependence of the renormalization group flow on the number of fermion flavors is also discussed.

hep-ph↗

arXiv2007

Fermion mass and the pressure of dense matter

We consider a simple toy model to study the effects of finite fermion masses on the pressure of cold and dense matter, with possible applications in the physics of condensates in the core of neutron stars and color superconductivity.

hep-ph↗

arXiv2006

Non-local effects at the onset of the chiral transition

Inspired by analytic results obtained for a systematic expansion of the memory kernel in dissipative quantum mechanics, we propose a phenomenological procedure to incorporate non-markovian corrections to the Langevin dynamics of an order parameter in field theory systematically. In this note, we restrict our analysis to the onset of the evolution. As an example, we consider the process of phase conversion in the chiral transition.

hep-ph↗