Andrés Felipe Villacob Hernández (The Abdus Salam International Centre for Theoretical Physics): Study of a relativistic energy dependent equation, derived from the Dirac equation, for hadronic systems
In this work, a reduction procedure of the Dirac equation for two-body bound systems is introduced, correlating the components of the two-body Dirac wave function for an approximate solution. This method prevents the appearance of unphysical states, a problem known as the continuum dissolution problem. Finally, the terms of the resulting equation were separated by the order of the potential, showing its similarity at zero (non-interacting term) and first order with a previous reduction made in the literature, thus proposing corrections at first and higher orders. A numerical analysis is required.
Arthur Frazon (IFT/UNESP): Time Evolution of Chiral Quark Condensate Under a Strong Magnetic Field
Quantum chromodynamics (QCD) under the effect of strong magnetic fields is an environment present in many situations, for instance, from the early universe to magnetars and heavy-ion collisions; the latter allows us to reproduce conditions s of the early universe, in which the quark-gluon plasma (QGP) was the prominent matter. Another QCD quantity that is affected by strong magnetic fields is the chiral quark condensate, an approximate order parameter of the QCD transition between a high-temperature QGP phase and a low-temperature hadronic phase. We based our studies on a formalism in which the Linear-$\sigma$ Model addresses the quark condensate time evolution under a strong magnetic field and the closed time path formalism for out-of-equilibrium systems, which leads to a mean-field Langevin equation for the condensate. We numerically solved the mean-field Langevin equation for the condensate for long-time ranges for which, we adopted different initial conditions in the temperature quench and magnetic fields. We showed that the mean-field Langevin equation solution leads to thermalization after spinodal decomposition for strong magnetic damping. In contrast, for weak damping, the solution oscillates never reaching or taking longer times to thermalize. The temperature quench also impacts this dynamics: the explosive peak is stronger for stronger quenches affecting the condensate's maximum value. Even by lowering the magnetic field intensity, the explosive phenomenon occurs. The condensate's average spatial density allows us to note that for both magnetic field cases, the explosion occurs slightly before in the case of a strong quench than in the case of a weak quench. Finally, the 2-point connected correlation functions were also investigated.
Artur Soares Rodrigues (Universidade de São Paulo): Critical Phenomena in Spin Models
The interest in systems with many correlated degrees of freedom is a central aspect of Quantum Field Theory (QFT) and Statistical Mechanics. These conditions mean that the effective long-range interactions between the particles in the system become highly non-trivial, and we therefore use the Renormalization-Group method to analyze the behavior around the critical point. This process is arguably not so intuitive in QFT, since it relates to divergences that may not be directly observable. To create a better sense of understanding, we explore the theory for Spin Models, where renormalization-group ideas and critical phenomena show up as something more natural. Starting from symmetries and important scales that define a physical system, we highlight the principles behind the nonperturbative, multiscale study of such systems, noticing that, most of the times, analytical solutions are not possible. To deal with these problems, we also introduce the Monte Carlo method, which allows us to sample configurations of the system based on a probability measure. With these tools at hand, we explore the similarities of numerical simulation (via the Metropolis algorithm) for the Ising and XY spin models compared to lattice QCD, comparing the symmetries of these systems. The calculation of observables for each system is directly related to the symmetry group that defines the interaction, making each system unique, while the process itself is universal. In this work, developed during an undergraduate research project, we show the parallels between QFT and Statistical Mechanics, by highlighting the importance of critical phenomena to Lattice QFT and applying the methods to simpler systems.
Breno Agatão Garcia (University of Sao Paulo): Decay widths of an N* state with hidden strangeness
The study of exotic hadrons and their properties has recently experienced a colossal boom. The development in this area is so tremendous that studying exotic hadrons has become one of the main, and more prolific, research lines at experimental facilities like BES and LHC. There is an intrinsic challenge when studying these particles as they belong to the non-perturbative region of QCD. The use of effective Lagrangians to study hadron systems at such energies is a very powerful tool nowadays. By using these Lagrangians with the relevant symmetries for the system is possible to calculate the corresponding $T$-matrix in a coupled channel approach and obtain physical observables such as invariant mass distributions, cross sections and decay widths. In particular, through the vector meson and baryon dynamics was observed a N$^*$ resonance, thus isospin $1/2$, with spin-parity $J^P=\frac{3}{2}^-$, mass $M_{\text{N}^*}=2071$~MeV and decay width $\displaystyle \frac{\Gamma_{\text{N}^{*}}}{2}=70$~MeV. The properties of this state were in agreement with those of the N$^*(2080)$ listed by the PDG, however, nowadays, this entry among others nucleonic resonances have been compacted into the N$^*(2120)$ state. The interesting fact of the above mentioned state is that it can be the hidden-strange partner of some of the $P_c$ states recently discovered by the LHCb collaboration. In order to further investigate the properties of the N$^*$ resonance, or $P_s$ state, we calculate the decay widths to pseudoscalar meson and baryonic resonance as a consequence of the exotic nature of the state. In the same way, it is possible to obtain the decay widths to pseudoscalar meson and baryon channels. Once obtained, it is possible to determine which invariant mass of two hadrons could be the most promising to observe the properties of the $P_s$ state.
Fábio Köpp Nóbrega (Universidade Federal de Santa Catarina): Can hyperonic stars with anisotropy support the recent astronomical constraints?
In this work, we investigate the macroscopic effects in hyperonic stars of two anisotropy models along with the equation of state based on the quantum hadronic model, which simulates the interaction between nucleons and hyperons. The anisotropy here arises due to the appearance of hyperons within the star. Moreover, the effects of anisotropy depend on the model used, the equation of state, and the degree of anisotropy. Our results showed that with a low degree of anisotropy, the radii, masses, and dimensionless tidal deformability support the existence of anisotropy.
Felipe Fernandes Garcia (UERJ): Study of the renormalization of the Gribov-Zwanziger model in the maximal abelian gauge in SU(N)
The Gribov problem, identified by physicist Vladimir Gribov, refers to the insufficiency of the Faddeev-Popov gauge fixing method, known as the Gribov copies problem. Gribov demonstrated that a gauge orbit can have multiple configurations that satisfy the same gauge condition, leading to the overcounting of physical states in the functional measure of Feynman path integrals. Gribov's proposed solution was to restrict the gauge configuration space to the Gribov region, where only one configuration per gauge orbit is allowed, thus eliminating the copies in the functional measure. This solution was later extended by Daniel Zwanziger, who proposed a model to eliminate these Gribov copies by adding a new term to the action, called the horizon function. This model became known as the Gribov-Zwanziger model. This work aims to investigate the renormalizability of the Gribov-Zwanziger model in the context of the Maximal Abelian Gauge (MAG) with the internal symmetry group SU(N). Using the algebraic renormalization method, we explore the model's symmetries and general aspects of Quantum Field Theory and non-Abelian gauge theories. The Yang-Mills action, the starting point of this study, is quantized using the Faddeev-Popov method in the MAG. We highlight the importance of the horizon function, which restricts the model to the Gribov region. The MAG presents the particularity of having an explicit distinction between the Abelian and non-Abelian sectors of the theory, allowing us to investigate whether these sectors can exhibit different behaviors at certain energy scales. The choice of MAG is also justified by the fact that, like the Landau gauge, it has the property of hermiticity of the Faddeev-Popov operator, which is essential for defining the Gribov region in the gauge field configuration space. Initial studies in the MAG were conducted for SU(2) and later extended to SU(N), but renormalizability was not proven, a gap addressed in this work. In order to renormalize the model we introduce a local and invariant action by incorporating composite operators into the original model and analyze the functional symmetries present in the complete classical action. We address the derivation of the most general counterterm, respecting the symmetries up to the first perturbative order, and discuss the stability of the action.
João Octavio Kül (Instituto de Física de São Carlos - USP): Studying gauge-space geometry via lattice QCD
In quantum field theory, the quantization of non-Abelian gauge fields presents several issues. From the technical point of view, integrating the gauge field over all its possible configurations in the path integral has to be done very carefully, since it involves the inversion of operators in the Yang-Mills’ Lagrangian with null eigenvalues, leading to divergences. Using the Faddeev-Popov method, we impose a gauge condition for the gluon field, adding new integration variables in gauge space. The curves that connect physically equivalent fields through gauge transformations in this space are called gauge orbits and, in principle, the resulting formulation solves the divergences by factorization. Ideally, the gauge-fixing method just described causes a gauge orbit to intersect the region specified by the gauge condition only once. But this is not guaranteed for a general Yang-Mills theory, and hence there are still ambiguities coming from equivalent configurations in gauge space, called Gribov copies. For a gauge transformation, the existence of Gribov copies is directly related to the fact that there are non-trivial eigenstates of the Faddeev-Popov operator with null eigenvalues. Among the proposed confinement scenarios, the one due to Gribov and Zwanziger associates color confinement to infrared properties of propagators of (gauge-fixed) fields around null eigenvalues of the Faddeev-Popov operator in gauge space. Our main objective is to explore and test the Gribov-Zwanziger confinement scenario, comparing analytical predictions with numerical results from lattice QCD. In particular, we investigate how the static quark-antiquark potential relates to the gauge-fixing procedure.
João Paulo Sampaio Santos (Universidade do Estado do Rio de Janeiro (UERJ)): Superconductivity in a confining field-theory model
Many models of superconductivity are already present in high energy physics, since the end of last century, mainly in the study of color superconductivity in Quantum Chromodynamics and in other effective models of Strong Interactions at high densities. These models use in general a gluon propagator with specific electric and magnetic effects, resulting in an integral gap equation whose solutions are frequency dependent and could reach gaps of the order of 100 MeV. In this work, we will investigate a simple superconductivity model by changing the usual propagator of the mediator to a confining propagator, with a structure similar to that encountered in Gribov-Zwanziger and Refined Gribov-Zwanziger theories. In these theories, the gluon has an explicit mass parameter that is related with the phenomenon of confinement. Through this modification we try to explore the superconductivity of confined particles with a simple toy model with a Yukawa-type interaction. We present results for the full integral gap equations as well as for differential gap equations that arise under a series of approximations and investigate the effect of corrections originated from the new propagators. Two mass limits in the bosonic propagator must be reached: the high mass limit, reproducing the behavior of the "point like" approximation, making the gap function behave like a usual BCS superconductivity and the small mass, making the gap function behave similar to early results in color superconductivity. Solving numerically the integral gap equation, we can calculate the gap in function of the mass parameter. These calculations were performed too with improved gluon propagators, such as the ones appearing in the Gribov-Zwanziger, Refined Gribov-Zwanziger and anothers massive theories, like Curci-Ferrari model. These results allow us to understand how the introduction of the explicit mass parameter to the gluon can affect the phenomenon of superconductivity in high energies. This study could be a first step towards assessing how nonperturbative confinement effects might affect the phenomenon of color superconductivity at intermediate densities and understand how imaginary poles can generate non physical effects in the systems.
Jonatan Pantoja Paschoal (Instituto de Física Teórica e Computacional - LFTC): THE RELATIONSHIP BETWEEN SYMMETRIES, CONTINUITY EQUATION, AND CONSERVATION LAWS IN QED
This study examines in detail how symmetries and conservation laws are interconnected through the continuity equation, focusing our approach on local charge conservation, Noether's theorem in quantum field theory, and the Ward-Takahashi identities in Quantum Electrodynamics (QED). Initially, we define symmetry in the physical context, highlighting its importance in the formulation of fundamental theories. Next, we explore local charge conservation, introducing the continuity equation as a mathematical expression of this conservation. We apply Noether's theorem, which relates continuous symmetries to conservation laws, demonstrating its derivation and applicability in both classical and quantum field theories. Through specific examples, we illustrate how time and space translation symmetries lead to the conservation of energy and momentum, respectively. The study advances to the analysis of the Ward-Takahashi identities in QED, derived from gauge invariance. We mathematically demonstrate how these identities ensure the conservation of the electromagnetic current in processes involving the interaction between charged particles and the electromagnetic field. Practical applications of the Ward-Takahashi identities are discussed, highlighting their relevance in renormalization and the consistency of quantum field theories. We conclude by emphasizing the profound interconnection between symmetries and conservation laws, and how these form the basis for understanding and developing physical theories. This work not only reinforces the theoretical importance of symmetries in physics but also presents practical applications in QED, demonstrating the utility of Noether's theorem and the Ward-Takahashi identities in the formulation and verification of physical theories.
Lucas Falcao (CBPF): CP violation measurements in three-body charmless B decays
This study reports CP asymmetry measurements in charmless three-body decays of B mesons, both using the Run II data from proton-proton collisions at a center-of-mass energy of 13 TeV , collected by the LHCb detector from 2015 to 2018, with an integrated luminosity of 5.9 fb−1. Significant CP asymmetries are observed in B± → π±π+π− and B± → K±K+K− decays, while the previously observed asymmetry in B± → π±K+K− decays is confirmed, and the CP asymmetry of B± → K±π+π−decays is found to be compatible with zero. Additionally, a new method is used to measure the CP asymmetry in charmless B → PV decays, showing significant asymmetry in B± → K±π+π− decays dominated by ρ(770), representing the first observation of CP violation in this process. Other decay channels show CP asymmetries compatible with zero.
Lucas Morethes Mansur (IFSC | USP): Improved hadronic vector-isovector spectral function from tau -decay and electroproduction data
The determination of the Quantum Chromodynamics (QCD) coupling, alpha_s, from the theoretical description of inclusive tau into hadrons + nu_tau decays, dominated by perturbative QCD, is one of the most precise alpha_s extractions from experimental data. In these decays, the hadronic vector and axial vector spectral functions are experimentally accessible. Recently, this collaboration demonstrated that the vector spectral function can be improved, on the data side, through a combination of tau decay data for the dominant channels and the use of e+e- into hadrons cross sections, related by isospin symmetry, to describe the small contributions of higher-threshold subdominant modes. In this work, we will update and upgrade the vector-isovector spectral function by performing a data combination on a channel-by-channel basis, which will allow for the inclusion of the high-statistics Belle data set for tau into 2pi decays. Due to the presence of strong correlations and issues related with statistical bias, this method requires a new data-combination procedure, which can properly deal with this issue following state-of-the-art methods. With this improved vector-isovector spectral function, we will perform a new alpha_s determination at the tau-mass scale.
Marcelle Caram Patriota (Instituto de Física de São Carlos - USP): Renormalons of the QCD spectral function in the large-beta_0 limit and R(s)
Rernormalons of perturbation theory are the singularities of the series that appear once the Borel transform — which consists, in essence, in an inverse Laplace transform — is applied. These singularities can lead to badly behaved series, and are particularly important in QCD at relatively low energies, where the coupling is not so small (due to asymptotic freedom) but the perturbative QCD treatment can still be applied. In the present case, we are interested in studying renormalons of the QCD perturbative series and its implications to R(s), the celebrated observable defined as the ratio between the cross section for the electroproduction of hadrons and that of muons. Here, we focus on the renormalons of the QCD spectral function, which is the imaginary part of the correlator divided by pi, and is the ingredient for the perturbative prediction of R(s). We exploit results in the so-called large-beta_0 limit, where the series is known to all orders in the strong coupling. Our aim is to investigate the recently observed tension between perturbative QCD and BES-III experimental data, which could have implications for the data-driven approach to the hadronic vacuum polarization contribution to the muon anomalous magnetic moment, known and denoted simply as g-2.
Marcos Jhair Garzon guevara (Universidad de Investigación de Tecnología Experimental (Yachay Tech)): Fractal Geometry in General Relativity to explain quantum effects
“Gravity drags time towards an unknown end. It is a journey we all share, a destination none of us can avoid.” Stephen Hawking Agust 2, 2024 In 25 november at 1915, Albert Einstein publish the theory of the General Relativity which propose that gravity is the curvature of space time produce by matter and energy interaction. However, the quantum mechanics effects produce at small scales found in black holes suggest that there must be another theory that may joint this theories into one. The fractal geometry may provide a different point of view that could solve some of the questions asked about gravity. The notion that gravity at quantum scales may be fractal. Using a re normalization theory at scales provide a interesting solution to the problem, however there are some mathematical challenges that must be solve.
Maria Monalisa de Melo Paulino (Instituto de Física da USP): Study of the medium effects in jet observables in relativistic heavy-ion collisions
This work aims to study the influence of the medium formed in heavy ion collisions on the propagation of jets originating from parton fragmentation. The project uses Monte Carlo event generators JEWEL, \rm T$R$ENTo for initial medium conditions, and (2+1)D v-USPhydro for event-by-event evolution. By combining these models, the study explores observables such as di-jet ($x_J$), jet mass ($M{jet}$), and semi-inclusive hadron-jet in PbPb collisions at $2.76$~TeV and $5.02$~TeV, for anti-k$T$ jets with varying radius R from $0.2$ to $1.0$. The simulated $R{AA}$ and $M_{jet}$ match experimental results, while h-jet and $x_J$ show indifference to medium changes, suggesting further exploration of medium response using JEWEL with thermal subtraction.
Mateo Londoo (Stony Brook university): Rotational quenching of XF molecules in A ultracold gase of He.
We have studied the cross sections and reaction rates of rotational de-excitation of diatomic molecules immersed in an ultracold gas of helium, both numerically and analytically. Specifically, we have considered various XF-He collision processes using the quantum coupled channel formulation for inelastic collisions. Under the rigid rotor approximation, we have investigated different inelastic transitions in the rotational manifold of the molecule to identify the key parameters affecting rotational quenching in this medium.
Rafael Mendes Francisco (Instituto Tecnológico de Aeronáutica): Unatomic trimer states in trapped ultracold atoms
By means of Feshbach resonances, trapped ultracold atoms can be driven close to the unitarity limit , where a tower of three-body bound states displaying a geometric sequence is manifested. The fingerprint of this phenomenon, known as Efimov Effect, is the discrete scale symmetry in the energy spectrum of the resonantly interacting trimers. By using noninteger dimensions to mimic a progressive squeezing in the trap that confines ultracold atoms, a transition from the discrete scale symmetry regime to a continuous one, named Unatomic, can be reached. In the Unatomic regime, the wave functions of the trimers exhibit a power-law symmetry at short distances.
Rafael Pacheco Cardoso (Departamento de Física, Universidade Federal de Santa Catarina): The quark anomalous magnetic moment in the NJL model and how to avoid first-order phase transitions induced by regularization issues
Quark anomalous magnetic moment (AMM) has been studied in the context of the quantum chromodynamics (QCD) in the latest years. For massive quarks, this phenomena appears when we have a dynamical chiral symmetry breaking, the quark AMM values can be estimated from the nucleons magnetic moments. Using the Nambu--Jona-Lasinio (NJL) model, one of the most used to the strong matter, the QCD phase diagram can be explored with the strong magnetic fields effect, which is an important application to the peripheral relativistic heavy ion-collisions and magnetars phenomenology. Some studies with the NJL model with the quark AMM effect shown first-order phase transitions at the quark condensate, leading to a inverse magnetic catalysis (IMC) even in the zero-temperature case. Exploring the vacuum magnetic regularization scheme, we demonstrate that the transition is artificial and caused by mass-dependent terms in the thermodynamic potential which create massive minima at zero effective mass, unevening the potential. We also show, by constraining the magnetic field to be smaller than the vacuum effective quark mass squared, how this behavior can be avoided. In this way, it is possible to recover the one-loop Schwinger--Weisskopf effective quantum electrodynamics approach - already used to describe the quark AMM effect in the NJL literature. Our results agreed with the lattice QCD predictions to the IMC, and the quark AMM can be one of the possible explanations to the IMC also.
Rafael Tonhon (Instituto de Física de São Carlos/Universidade de São Paulo): Color Confinement and Topology on Lattice Gauge Theories
Color confinement is still an open and challenging problem in modern physics, being the non-perturbative regime of SU(N) Yang-Mills theory the primarily responsible for such difficulty. Among the various ideas proposed to understand the confinement mechanism, the center-vortex configurations seem to play a crucial role when reproducing the desired phenomenology. In this picture, the Yang-Mills vacuum consists of an ensemble of percolating magnetic flux lines, the center vortices (a ``spaghetti" like vacuum), in what is known as center dominance. These vortex carry charges proportional to the weights of the gauge group, and can be oriented or not. The random fluctuation in the vortices degrees of freedom is (believed to be) the origin of area law of the Wilson loops. Yet, the study of these degrees of freedom is a complicated analytical task. At the same time, Monte Carlo simulations on the lattice provide us a very useful way to study these degrees of freedom, and nowadays a great deal of numerical evidence to the center-vortex scenario is available in the literature. However, the detection of these vortices is not so simple on the lattice. In the continuum, they can be identified by their guiding center while, on the lattice, the same cannot be done and one can only see plaquettes pierced by projected vortices on a dual lattice. In this work, we aim to present the techniques utilized to study the center-vortex picture on the lattice, discussing some difficulties that appear, and show some results obtained by our research group at IFSC/USP.
Rita Natieli Oliveira (São Carlos Institute of Physics- University of São Paulo): Parametrization of perturbative QCD in tau hadronic decays
The determination of the strong coupling, alpha_s, from the theoretical description of inclusive hadronic tau decays in Quantum Chromodynamics (QCD), is one of the most precise extractions from experimental data. The theoretical description is dominated by perturbation theory but receives non-perturbative contributions from the Operator Product Expansion and duality violations, which cannot be neglected. The standard approach is to build sum rules where the QCD contribution is evaluated as closed-contour integrals in the complex plane. However, this method introduces complications related to the renormalization scale, notably in the perturbative series. Therefore, with its inherent complexity, the state-of-the-art five-loop QCD description is non-trivial. Although these complications are unavoidable in a realistic, high-precision analysis, it would be desirable to have a much simpler but reliable parametrization of the QCD result, including all correlations, to provide a simple interface with precision Electroweak Fits and Monte Carlo simulations for future accelerators, such as the FCC-ee. Furthermore, this parametrization could be applied in various fits where constraints from hadronic tau decays are of significant interest. In this work, we perform a parametrization for the perturbative QCD part, aiming to simplify the integration of theoretical predictions and check if this new version maintains the precision required.
Rodolfo Silva da Rocha (UERJ): Exploring pion condensation in an isospin medium using the Functional Renormalization Group
The full description of strongly interacting matter requires complete knowledge of the phase structure generated by a quantum field theory. In many cases, analyzing the fundamental theory that describes their interactions in a medium is quite complicated, so that it becomes interesting to use alternative theories that reproduce at least part of the physical characteristics of the fundamental theory. Effective theories provide us with a powerful mathematical and physical tool for the limit in which the application of the fundamental theory - Quantum Chromodynamics (QCD) in the case of Strong Interactions – becomes extremely complex. In the dense regime of matter, the main non-perturbative technique, lattice Monte Carlo simulations, presents an open problem called the Sign Problem due to the coupling of a specific chemical potential. However, in some situations, Monte Carlo simulations do not present such a problem, providing satisfactory results for various observable physical phenomena such as, for example, the dense isospin matter that could exist inside compact stars. Thus, the study of effective theories in environments with non-zero chemical potentials is even more relevant because it presents systems in which the Sign Problem is not present. In this work, we will investigate, using non-perturbative techniques, the phase transition of Bose-Einstein condensation in an effective theory for bosons at finite density and zero temperature. We will construct a toy model based on the Linear Sigma Model and implement the Functional Renormalization Group (FRG) to estimate the influence of non-perturbative effects on the critical parameters of the model.
Sandra Tacianny Karol de Araujo (UFPEL): Meson production by photon - photon interactions in fixed - target collisions at the LHC
The meson production cross-sections are estimated considering photon-photon interactions in fixed - target collisions at CERN LHC energies. We consider several mesons with photon-photon partial decay width well constrained by the experiment, and some mesons which are currently considered as hadronic molecule and glueball candidates. Our results demonstrate that the experimental analysis of these states is feasible at CERN - LHC.
Sofía Bortagaray (Universidad de la República): Influence of Gluon Mass on Non-Relativistic Tetraquark States
The matter we know is made up of subatomic particles called quarks, which group together to form hadrons. Hadrons are divided into mesons (formed by a quark and an antiquark) and baryons (formed by three quarks). The latter constitute protons and neutrons in atomic nuclei. This research focuses on the formation of exotic hadrons, specifically tetraquarks (states of four quarks). Tetraquarks are considered exotic due to the rarity of detected candidate particles. We use a low-energy model for the strong interaction that includes mass for gluons, the mediating particles of this interaction. The inclusion of gluon mass allows for analytical calculations to determine the interaction potential between quarks and, from this, calculate the possible masses of tetraquarks. The poster presents an advance of the results obtained so far. At the end of the research, using the gluon mass obtained from previous studies, we expect to predict the values of the tetraquark spectrum and also perform the reverse process, i.e., estimate the gluon mass from the already calculated values for the mass of the tetraquarks.
Úrsula Maria Martins da Silva Fonseca (UFRJ): Thermal evolution of quark stars from perturbative QCD
Since Witten’s proposal that symmetric deconfined u, d, and s quark matter might be the true absolute ground state, properties of quark stars have been extensively studied. By choosing an equation of state to describe the matter inside these stars, it is possible to solve the Tolman-Oppenheimer-Volkoff equations to obtain the mass and radius of the star. However, it has become clear that measuring solely the mass and radius will not be sufficient to distinguish between neutron stars, hybrid stars and quark stars. Therefore, it is necessary to take into account other observables that are closely related to microscopic physics. One possibility is the thermal evolution of these stars. The general relativistic equations of energy balance and energy transport that are solved in a numerical cooling simulation involve both microscopic (neutrino emissivity, heat capacity, thermal conductivity) and macroscopic (metric function, mass, radius) quantities. In this work, we study the structure and thermal evolution of quark stars employing equations of state from perturbative QCD. We build the framework for acquiring cooling solutions and discuss the consequences arising from the application of different equations of state to describe the properties of quark matter. Additionally, we examine the impact of a thin crust composed of nuclear matter on the cooling process of these stars
Vinícius Bruno Bet Ader (Instituto de Física - Universidade de São Paulo): Study of the first excited state of the 4He nucleus in coupled-channel Halo EFT
This work focuses on investigating the first excited state (Jπ = 0+) of the 4He nucleus, which consists of an alpha-particle. This excited state, probably associated with a four-body Efimov state, is found between the p-3H and n-3He thresholds, allowing for the use of a coupled channel formalism. It is thought to have a 3 + 1 halo structure, as per the thresholds structures, making it suitable for investigation using a Halo effective field theory framework. This resonance may influence the 3H(p,e+e−)3He reaction and shed light on the ATOMKI anomaly reported by Krasznahorkay et al., where an excess of produced lepton pairs suggests the existence of a new boson, with an approximate mass of 17 MeV, and that can be a strong candidate for dark matter.