Fernando Gardim

• Ph.D.
• Professor (Associate) at Federal University of Alfenas

Hydrodynamic approaches to modeling relativistic high-energy heavy-ion collisions are based on the conservation of energy and momentum. However, the medium formed in these collisions also carries additional conserved quantities, including baryon number (B), strangeness (S), and electric charge (Q). In this Letter, we propose a new set of anisotropi...

In this work, the interior spacetime of stars is built in a Lorentz symmetry breaking model called bumblebee gravity. Firstly, we calculated the modified Tolman-Oppenheimer-Volkoff equation in this context of modified gravity. Then we show that the bumblebee field, responsible for the symmetry breaking, increases the star mass-radius relation when...

We propose a new observable derived from a centrality-dependent scaling of transverse particle spectra. By removing the global scales of total particle number and mean transverse momentum, we isolate the shape of the spectrum. In hydrodynamic simulations, while the multiplicity and mean transverse momentum fluctuate significantly, the scaled spectr...

Conservation laws play a crucial role in the modeling of heavy-ion collisions, including the those for charges such as baryon number (B), strangeness (S), and electric charge (Q). In this study, we present a new 2+1 relativistic viscous hydrodynamic code called CCAKE which uses the Smoothed Particle Hydrodynamics (SPH) formalism to locally conserve...

Heavy-ion collisions, such as Pb-Pb or p-Pb, produce extreme conditions in temperature and density that make the hadronic matter transition to a new state, called quark-gluon plasma (QGP). Simulations of heavy-ion collisions provide a way to improve our understanding of the QGP's properties. These simulations are composed of a hybrid description th...

The extreme temperature and density conditions that arise in ultrarelativistic collisions of heavy nuclei enable the formation of the most fundamental fluid in the universe, the deconfined phase of quantum chromodynamics known as quark-gluon plasma. Despite the extensive experimental evidence gathered over the last decade for the production of quar...

Ultrarelativistic isobar collisions can be used to determine nuclear structure. In systems of this nature, instantaneous achievement of local thermal equilibrium is not achievable, consequently requiring a prethermalization phase. In this phase, there is a possibility that some of the initial structure information may be lost and artifacts may be i...

The extreme conditions of temperature and density produced in ultrarelativistic collisions of heavy nuclei facilitate the formation of the most fundamental fluid in the universe, the deconfined phase of Quantum Chromodynamics called quark-gluon plasma. Despite the extensive experimental evidence collected over the past decade of its production in c...

In recent years, there has been a significant effort to extract the temperature-dependent shear ($\eta/s$) and bulk ($\zeta/s$) viscosity over entropy ratios of the quark-gluon plasma from a global comparison of heavy-ion data with results of hydrodynamic simulations. However, anisotropic flow, which is arguably the most sensitive probe of viscosit...

Data obtained at RHIC can be reproduced by relativistic viscous hydrodynamic simulations by adjusting the viscosity and initial conditions but it is difficult to disentangle these quantities. It is therefore important to find orthogonal observables to constrain the initial conditions separately from the viscosity. New observables have been measured...

We evaluate the viscous damping of anisotropic flow in heavy-ion collisions for arbitrary temperature-dependent shear and bulk viscosities. We show that the damping is solely determined by effective shear and bulk viscosities, which are weighted averages over the temperature. We determine the relevant weights for nucleus-nucleus collisions at sNN=5...

The correlation between the mean transverse momentum of outgoing particles, 〈pt〉, and the magnitude of anisotropic flow, vn, has recently been measured in Pb+Pb collisions at the CERN Large Hadron Collider, as a function of the collision centrality. We confirm the previous observation that event-by-event hydrodynamics predicts a correlation between...

We propose the skewness of mean transverse momentum 〈pt〉 fluctuations as a fine probe of hydrodynamic behavior in relativistic nuclear collisions. We describe how the skewness of the 〈pt〉 distribution can be analyzed experimentally, and we use hydrodynamic simulations to predict its value. We predict, in particular, that 〈pt〉 fluctuations have posi...

We show that in ideal hydrodynamic simulations of heavy-ion collisions, initial state fluctuations result in an increase of the mean transverse momentum of outgoing hadrons, 〈pt〉. Specifically, 〈pt〉 is larger by a few percent if realistic fluctuations are implemented than with smooth initial conditions, the multiplicity and impact parameter being k...

We present a Principal Component Analysis for a hydrodynamic simulation and compare with CMS experimental data. While the results are reasonable for anisotropic flow, for multiplicity fluctuations they are qualitatively different. We argue that this is due to too large transverse momentum (pT) fluctuations and N −pT covariance in the simulation tha...

We evaluate the viscous damping of anisotropic flow in heavy-ion collisions for arbitrary temperature-dependent shear and bulk viscosities. We show that the damping is solely determined by effective shear and bulk viscosities, which are weighted averages over the temperature. We determine the relevant weights for nucleus-nucleus collisions at $\sqr...

We predict that the mean transverse momentum of charged hadrons 〈pt〉 rises as a function of the charged-particle multiplicity in ultracentral nucleus-nucleus collisions. We explain that this phenomenon has a simple physical origin and represents an unambiguous prediction of the hydrodynamic framework of heavy-ion collisions. We argue that the relat...

Collisions between heavy atomic nuclei at ultrarelativistic energies are carried out at particle colliders to produce the quark–gluon plasma, a state of matter where quarks and gluons are not confined into hadrons, and colour degrees of freedom are liberated. This state is thought to be produced as a transient phenomenon before it fragments into th...

We propose the skewness of mean transverse momentum, $\langle p_t \rangle$, fluctuations as a fine probe of hydrodynamic behavior in relativistic nuclear collisions. We describe how the skewness of the $\langle p_t \rangle$ distribution can be analyzed experimentally, and we use hydrodynamic simulations to predict its value. We predict in particula...

The correlation between the mean transverse momentum of outgoing particles, $\langle p_t \rangle$, and the magnitude of anisotropic flow, $v_n$, has recently been measured in Pb+Pb collisions at the CERN Large Hadron Collider, as a function of the collision centrality. We confirm the previous observation that event-by-event hydrodynamics predicts a...

We show that in ideal hydrodynamic simulations of heavy-ion collisions, initial state fluctuations result in an increase of the mean transverse momentum of outgoing hadrons, $\langle p_t\rangle$. Specifically, $\langle p_t\rangle$ is larger by a few percent if realistic fluctuations are implemented than with smooth initial conditions, the multiplic...

We present a Principal Component Analysis for a hydrodynamic simulation and compare with CMS experimental data. While the results are reasonable for anisotropic flow, for multiplicity fluctuations they are qualitatively different. We argue that this is due to too large transverse momentum ($p_T$) fluctuations and $N-p_T$ covariance in the simulatio...

We carry out a principal component analysis of fluctuations in a hydrodynamic simulation of heavy-ion collisions, and compare with experimental data from the CMS Collaboration. The principal components of anisotropic flow reproduce the trends seen in data, but multiplicity fluctuations show a difference in transverse momentum dependence. We constru...

We show that, within the hydrodynamic framework of heavy-ion collisions, the mean transverse momentum of charged hadrons ($\langle p_t\rangle$) rises as a function of the multiplicity in ultra-central nucleus-nucleus collisions. The relative increase is proportional to the speed of sound squared ($c_s^2$) of the quark-gluon plasma, that is therefor...

We show that the mean transverse momentum of charged hadrons, $\langle p_t \rangle$, in ultrarelativistic heavy-ion collisions is proportional the temperature of the quark-gluon plasma from which particles are emitted. We introduce an effective hydrodynamic description of the system created in a relativistic heavy-ion collision to relate experiment...

We carry out a principal component analysis of fluctuations in a hydrodynamic simulation of heavy-ion collisions, and compare with experimental data from the CMS collaboration. The leading and subleading principal components of elliptic and triangular flow reproduce the trends seen in data. By contrast, the principal components of multiplicity fluc...

Disentangling the effect of initial conditions and medium properties is an open question in the field of relativistic heavy-ion collisions. We argue that, while one can study the impact of initial inhomogeneities by varying their size, it is important to maintain the global properties fixed. We present a method to do this. We show that many observa...

Disentangling the effect of initial conditions and medium properties is an open question in the field of relativistic heavy ion collisions. We argue that, while one can study the impact of initial inhomogeneities by varying their size, it is important to maintain the global properties fixed. We present a method to do this. We show that many observa...

An open question in the field of heavy-ion collisions is to what extent the size of initial inhomogeneities in the system affects measured observables. Here we present a method to smooth out these inhomogeneities with minimal effect on global properties, to quantify the effect of short-range features of the initial state. We show a comparison of hy...

An open question in the field of heavy-ion collisions is to what extent the size of initial inhomogeneities in the system affects measured observables. Here we present a method to smooth out these inhomogeneities with minimal effect on global properties, in order to quantify the effect of short-range features of the initial state. We show a compari...

Correlations of different azimuthal flow harmonics $v_n$ and symmetry planes $\Psi_n$ can add constraints to theoretical models, and probe aspects of the system that are independent of the traditional single-harmonic measurements. Using NeXSPheRIO, a hydrodynamical model which has accurately reproduced a large set of single-harmonic correlations at...

Correlations of different azimuthal flow harmonics $v_n$ and symmetry planes $\Psi_n$ can add constraints to theoretical models, and probe aspects of the system that are independent of the traditional single-harmonic measurements. Using NeXSPheRIO, a hydrodynamical model which has accurately reproduced a large set of single-harmonic correlations at...

Measurements of di-hadron azimuthal correlations at different centralities for Au+Au collisions at 200 A$\,$GeV were reported by the PHENIX Collaboration. The data were presented for different ranges of transverse momentum. In particular, it was observed that the away-side correlation evolves from double- to single-peak structure when the centralit...

Measurements of di-hadron azimuthal correlations at different centralities for Au+Au collisions at 200 AGeV were reported by the PHENIX Collaboration. The data were presented for different ranges of transverse momentum. In particular, it was observed that the away-side correlation evolves from double- to a single-peak structure when the centrality...

Recent measurements at the LHC involve the correlation of different azimuthal flow harmonics vn. These new observables add constraints to theoretical models and probe aspects of the system that are independent of the traditional single-harmonic measurements such as 2-and multi-particle cumulants vn{m}. Many of these new observables have not yet bee...

Recent measurements at the LHC involve the correlation of different azimuthal flow harmonics $v_n$. These new observables add constraints to theoretical models and probe aspects of the system that are independent of the traditional single-harmonic measurements such as 2- and multi-particle cumulants $v_n\{m\}$. Many of these new observables have no...

We study the relation between elliptic flow, $v_2$ and the initial eccentricity, $\varepsilon_2$, in heavy-ion collisions, using hydrodynamic simulations. Significant deviations from linear eccentricity scaling are seen in more peripheral collisions. We identify the mechanism responsible for these deviations as a cubic response, which we argue is a...

We investigate the correlation between various aspects of the initial geometry of heavy ion collisions at the Relativistic Heavy Ion Collider energies and the final anisotropic flow, using v-USPhydro, a 2+1 event-by-event viscous relativistic hydrodynamical model. We test the extent of which shear and bulk viscosity affect the prediction of the fin...

Collective flow observed in heavy-ion collisions is largely attributed to initial geometrical fluctuations, and it is the hydrodynamic evolution of the system that transforms those initial spatial irregularities into final state momentum anisotropies. Cumulant analysis provides a mathematical tool to decompose those initial fluctuations in terms of...

We calculate flow observables with the NeXSPheRIO ideal hydrodynamic model and make the first comparison to the complete set of mid-rapidity flow measurements made by the PHENIX collaboration in top energy Au+Au collisions. A simultaneous calculation of v_2, v_3, v_4, and the first event-by-event calculation of quadrangular flow defined with respec...

The system formed in ultrarelativistic heavy-ion collisions behaves as a nearly-perfect fluid. This collective behavior is probed experimentally by two-particle azimuthal correlations, which are typically averaged over the properties of one particle in each pair. In this Letter, we argue that much additional information is contained in the detailed...

The STAR Collaboration reported measurements of di-hadron azimuthal correlation in medium-central Au+Au collisions at 200 A$\,$GeV, where the data are presented as a function of the trigger particle's azimuthal angle relative to the event plane $\phi_s $. In particular, it is observed that the away-side correlation evolves from single- to double-pe...

We present in this work a generalization of the solution of Gorenstein and Yang to the inconsistency problem of thermodynamics for systems with a temperature dependent Hamiltonian. We show that there are, in principle, an infinite number of solutions.

We investigate how the initial geometry of a heavy-ion collision is transformed into final flow observables by solving event-by-event ideal hydrodynamics with realistic fluctuating initial conditions. We study quantitatively to what extent anisotropic flow (v_n) is determined by the initial eccentricity epsilon_n for a set of realistic simulations,...

In this work we study the connection between anisotropic flows and lumpy initial conditions for Au+Au collisions at 200GeV. We present comparisons between anisotropic flow coefficients and eccentricities up to sixth order, and between initial condition reference angles and azimuthal particle distribution angles. We also present a toy model to justi...

A unified description of the near-side and away-side structures observed in two-particle correlations as function of delta eta-delta phi is proposed for low to moderate transverse momentum. It is based on the combined effect of tubular initial conditions and hydrodynamical expansion.

Fluctuations in the initial geometry of a nucleus-nucleus collision have been recently shown to result in a new type of directed flow (v) that, unlike the usual directed flow, is also present at midrapidity. We compute this new v versus transverse momentum and centrality for Au-Au collisions at RHIC using the hydrodynamic code NeXSPheRIO. We find t...

We present in this work the thermodynamic consistent quasi-particle model at finite chemical potential, to describe the Quark Gluon Plasma composed of two light quarks and gluons. The quasi-particle general solution will be discussed, and comparison with perturbative QCD and lattice data will be shown.

We present in this work a generalization of the solution of Gorenstein and Yang to the inconsistency problem of thermodynamics for systems of quasi-particles whose masses depend on both the temperature and the chemical potential. We work out several solutions for an interacting system of quarks and gluons and show that there is only one type of sol...

We present in this work a generalization of the solution of Gorenstein and Yang for a consistent thermodynamics for systems with a temperature dependent Hamiltonian. We show that there is a large class of solutions, work out three particular ones, and discuss their physical relevance. We apply the particular solutions for an ideal gas of quasi-gluo...