arXiv subjects

Eduardo Folco Capossoli

Publications and source records attributed to Eduardo Folco Capossoli.

At least 19 recordsLinked to original sources

arXiv2024

Joule-Thomson expansion for quantum corrected AdS-Reissner-Nordstrom black holes in Kiselev spacetime

In this work we study the inversion temperature associated with the Joule-Thomson expansion from the thermodynamics of AdS-Reissner-Nördstrom black holes. We include quantum corrections in a cosmological fluid that can describe phantom dark matter or quintessence, both in a Kiselev scenario. The description of such physical systems involves numerical solutions and the results are presented as temperature-pressure plots for various values of the parameters of our model. We find non-zero minimum inversion temperatures as well as non-zero minimum pressures depending on the values of those parameters. Completing our study, we also find isenthalpic curves associated with black hole fixed mass processes.

gr-qc↗

arXiv2022

A varying gravitational constant map in asymptotically AdS black hole thermodynamics

We propose a sequence of steps and a generic transformation for connecting common thermodynamic quantities considered in asymptotically anti-de Sitter black hole thermodynamics in the bulk and those that are appropriate for CFT thermodynamics in the boundary. We do this by constructing a "varying-$G$ map", where $G$ is the gravitational constant, and demonstrate its usefulness by considering various examples.

hep-th↗

arXiv2022

Fermionic DIS from a deformed string/gauge correspondence model

From a deformed AdS$_5$ space, we used the string/gauge duality to study the deep inelastic scattering for unpolarized fermions with spin 1/2, considering the large Bjorken $x$ parameter regime. Here, we also took into account an anomalous dimension of an operator which represents fermions at the boundary. From this analysis, we compute the corresponding structure functions, which are dependent on $x$ and on the photon virtuality $q$. The results achieved are in agreement with the experimental data.

hep-ph↗

arXiv2022

Pion form factor from an AdS deformed background

We consider a bottom-up AdS/QCD model with a conformal exponential deformation $e^{k\,z^2}$ on a Lorentz invariant AdS background. In this model, we assume the conformal dimension associated with the operator that creates pions at the boundary as $Δ=3$. Regarding the infrared scale related to photon field $k_γ$, we analyze two cases: constant and depending on the transferred momentum $q$. In these two cases, we computed the electromagnetic pion form factor as well as the pion radius. We compare our results with experimental data as well as other theoretical (holographic and non-holographic) models. In particular, for the momentum-dependent infrared scale, we find good agreement with the available experimental data as well as non-holographic models.

hep-ph↗

arXiv2022

AdS/QCD oddball masses and Odderon Regge trajectory from a twist-five operator approach

In this work, we consider a massive gauge boson field in AdS$_5$ dual to odd glueball states with twist-5 operator in 4D Minkowski spacetime. Introducing an IR cutoff we break the conformal symmetry of the boundary theory allowing us to calculate the glueball masses with odd spins using Dirichlet and Neumann boundary conditions. Then, from these masses we construct the corresponding Regge trajectories associated with the odderon. Our results are compatible with the ones in the literature.

hep-th↗

arXiv2022

Fermionic and bosonic fluctuation-dissipation theorem from a deformed AdS holographic model at finite temperature and chemical potential

In this work we study fluctuations and dissipation of a string in a deformed anti-de Sitter (AdS) space at finite temperature and density. The deformed AdS space is a charged black hole solution of the Einstein-Maxwell-Dilaton action. In this background we take into account the backreaction on the horizon function from an exponential deformation of the AdS space. From this model we compute the admittance and study the influence of the temperature and the chemical potential on it. We calculate the two-point correlations functions, and the mean square displacement for bosonic and fermionic cases, from which we obtain the short and large time approximations. For the long time, we obtain a sub-diffusive regime $\sim \log t$. Combining the results from the admittance and the correlations functions we check the fluctuation-dissipation theorem for bosonic and fermionic systems.

hep-th↗

arXiv2021

Joule-Thomson expansion for noncommutative uncharged black holes

In this work we study the Joule-Thomson expansion for uncharged black holes in a noncommutative scenario characterized by a parameter $θ$, which is present in the horizon function. We calculate the inversion temperature for some values of $θ$ and the isenthalpics for fixed masses. We find that the uncharged noncommutative black hole behaves as a charged commutative one.

hep-th↗

arXiv2021

AdS/BCFT correspondence and BTZ black hole thermodynamics within Horndeski gravity

In this work, we study gravity duals of conformal field theories with boundaries known as AdS/BCFT correspondence, put forward by Takayanagi [1], within a scalar-tensor theory, as proposed by Horndeski in 4D [2]. We consider the case of 3D gravity dual to 2D BCFT, take a Gibbons-Hawking surface term modified by Horndeski's theory and find the corresponding 3D (BTZ) black hole solutions. We analyze the effects of Horndeski's gravity on the profile of the extra boundary for the black hole by using an approximate analytic solution. Performing a holographic renormalization, we have calculated the free energy and obtained the total entropy and the corresponding area, as well as the boundary entropy for the black hole. In particular, the boundary entropy found here, can be seen as an extension of the one proposed by Takayanagi. From the free energy, we have done a systematic study of the 3D black hole thermodynamics and present, among our results, an indication of restoration of conformal symmetry for high temperatures. Finally, we present a study on the influence of the Horndeski's gravity on the Hawking-Page phase transition where we can see the stable and unstable phases throughout the plane of free energy {\sl versus} temperature.

hep-th↗

arXiv2021

Proton and neutron form factors from deformed gravity/gauge duality

In this work, we study the electric and magnetic Sachs form factors for proton and neutron by using a deformed gravity/gauge model. We describe holographically baryons as well as gauge bosons which are ruled by the parameters $k_{B}$ and $k_γ$, associated with confinement and kinematical energy scales, respectively. Then, we construct the interaction action and calculate the electric and magnetic form factors for the proton and the neutron, and their electromagnetic sizes. The obtained results are compatible with those found in the literature from experimental and theoretical data.

hep-ph↗

arXiv2021

Finite density effects on chiral symmetry breaking in a magnetic field in 2+1 dimensions from holography

In this work we study finite density effects in spontaneous chiral symmetry breaking as well as chiral phase transition under the influence of a background magnetic field in $ 2+1 $ dimensions. For this purpose, we use an improved holographic softwall model based on an interpolated dilaton profile. We find inverse magnetic catalysis at finite density. We observe that the chiral condensate decreases as the density increases, and the two effects (addition of magnetic field and chemical potential) sum up decreasing even more the chiral condensate.

hep-th↗

arXiv2021

Fluctuation and dissipation within a deformed holographic model with backreaction

In this work we study the fluctuation and dissipation of a string attached to a brane in a deformed and backreated AdS-Schwarzschild spacetime. This space is a solution of Einstein-dilaton equations and contains a conformal exponential factor $\exp(k/r^2)$ in the metric. We consider the backreaction contributions coming only from the exponential warp factor on the AdS-Schwarzschild black hole, where the string and brane are in the probe approximation. Within this Lorentz invariant holographic model we have computed the admittance, the diffusion coefficient, the two-point functions and the regularized mean square displacement $s^2_{reg}$. From this quantity we obtain the diffuse and ballistic regimes characteristic of the Brownian motion. From the two-point functions and the admittance, we also have checked the well know fluctuation-dissipation theorem in this set up.

hep-th↗

arXiv2021

Teaching Physics within STS Approach: Contributions Between Sciences and Act 10.639/2003

This paper is aimed to develop formative actions about Science Technology and Society (STS) relations in the teaching of Physics in order to integrate Act 10.639/2003, which includes African, and Afro-Brazilian history and culture in school syllabuses. Besides we also aim to overcome the challenges found in the educational system and to enable students to learn about the contributions made by African societies regarding to the Science and technology. The methodological procedure included a written questionnaire, pre- and post-test, both with the students. The results have been proven relevant for the teaching of racial relations in the classroom.

physics.ed-ph↗

arXiv2020

Criticality from Einstein-Maxwell-dilaton holography at finite temperature and density

We investigate consistent charged black hole solutions to the Einstein-Maxwell-Dilaton (EMD) equations that are asymptotically AdS. The solutions are gravity duals to phases of a non-conformal plasma at finite temperature and density. For the dilaton we take a quadratic ansatz leading to linear confinement at zero temperature and density. We consider a grand canonical ensemble, where the chemical potential is fixed, and find a rich phase diagram involving the competition of small and large black holes. The phase diagram contains a critical line and a critical point similar to the van der Waals-Maxwell liquid-gas transition. As the critical point is approached, we show that the trace anomaly in the plasma phases vanishes signifying the restoration of conformal symmetry in the fluid. We find that the heat capacity and charge susceptibility diverge as $C_V \propto (T-T^c)^{-α}$ and $χ\propto (T-T^c)^{-γ}$ at the critical point with universal critical exponents $α=γ=2/3$. Our results suggest a description of the thermodynamics near the critical point in terms of catastrophe theories. In the limit $μ\to 0$ we compare our results with lattice results for $SU(N_c)$ Yang-Mills theories.

hep-th↗

arXiv2020

Proton Structure Functions from an AdS/QCD model with a deformed background

In this work we study unpolarized spin $1/2$ baryonic deep inelastic scattering (DIS) in the regime of large Bjorken parameter $x$. We calculate the corresponding structure functions $F_{1,2}(x,q^2)$. Our approach is based on an AdS/QCD model with a deformed background, where we consider an exponential factor in the AdS$_5$ metric. Such a deformation implies the introduction of an anomalous dimension in the model. Our results for the structure functions are consistent with those found in the literature from experimental data.

hep-ph↗

arXiv2020

Fluctuation and Dissipation from a Deformed String/Gauge Duality Model

Using a Lorentz invariant deformed string/gauge duality model at finite temperature we calculate the thermal fluctuation and the corresponding linear response, verifying the fluctuation-dissipation theorem. The deformed AdS$_5$ is constructed by the insertion of an exponential factor $\exp(k/r^2)$ in the metric. We also compute the string energy and the mean square displacement in order to investigate the ballistic and diffusive regimes. Furthermore we have studied the dissipation and the linear response in the zero temperature scenario.

hep-th↗

arXiv2020

Hadronic Spectra from Deformed AdS Backgrounds

Because of the presence of modified warp factors in metric tensors, we use deformed AdS$_5$ spaces to apply the AdS/CFT correspondence to calculate the spectra for even and odd glueballs, scalar and vector mesons, and baryons with different spins. For the glueball cases, we derive their Regge trajectories and compare them with those related to the pomeron and the odderon. For the scalar and vector mesons as well as baryons the determined masses are compatible with the PDG. In particular for these hadrons we found Regge trajectories compatible with another holographic approach as well as with the hadronic spectroscopy, which present an universal Regge slope of approximately 1.1 GeV$^2$.

hep-ph↗

arXiv2020

Holographic Description of Chiral Symmetry Breaking in a Magnetic Field in 2+1 Dimensions with an Improved Dilaton

We consider a holographic description of the chiral symmetry breaking in an external magnetic field in $ (2+1) $-dimensional gauge theories from the softwall model using an improved dilaton field profile given by $Φ(z) = - kz^2 + (k+k_1)z^2\tanh (k_{2}z^2)$. We find inverse magnetic catalysis for $B B_c$, where $B_c$ is the pseudocritical magnetic field. The transition between these two regimes is a crossover and occurs at $B=B_c$, which depends on the fermion mass and temperature. We also find spontaneous chiral symmetry breaking (the chiral condensate $σ\not=0$) at $T=0$ in the chiral limit ($m_q\to 0$) and chiral symmetry restoration for finite temperatures. We observe that changing the $k$ parameter of the dilaton profile only affects the overall scales of the system such as $B_c$ and $σ$. For instance, by increasing $k$ one sees an increase of $B_c$ and $σ$. This suggests that increasing the parameters $k_1$ and $k_2$ will decrease the values of $B_c$ and $σ$.

hep-ph↗

arXiv2019

Deep inelastic scattering from string/gauge duality with soft IR cutoff and exponentially small Bjorken parameter

In this work we use the string/gauge duality within the Softwall Model (SW). In this model a dilaton field is introduced in the action for the fields playing the role of a soft infrared (IR) cutoff. The SW model is very useful as it provides linear Regge trajectories for mesons. Here, using a $10-$dimensional SW model, we calculate the corresponding structure functions for deep inelastic scattering (DIS) in which electrons are scattered off hadrons in a kinematical regime where the hadrons are broken apart, with high virtuality $q$, in the exponentially small $x$ (Bjorken parameter) regime. Our results for this regime are consistent with those achieved using other holographic and non-holographic approaches.

hep-ph↗