The Hubbard-Stratonovich field (also called the mean field or the auxiliary field method) is a numerical method that uses an auxiliary variable in order to solve Gaussian integrations with an-harmonic terms on the exponential. Here, we modify the method for two cases. First we consider a (classical) zero dimensional model where it is introduced two and three auxiliary variables. The second...

In eletron-proton and proton-proton colliders, leading neutron production occurs when a proton (or both) splitts into a neutron and a pion. This process allows us to study pion-pion collisions at the LHC by selecitng events in which two neutrons are measured by the Zero Degree Calorimeters. In previous works we have shown that processes with leading neutrons are useful to the study of gluon...

We will describe two different strategies for the extraction

of the strong coupling, alpha_s, using data for e+e- to hadrons. In

the first one, we determine the strong coupling using finite-energy

sum rules and a new compilation of the hadronic R-ratio from available

data for e+e- ---> hadrons below the charm threshold. This

determination is done at relatively low-energies, with three...

Since centuries ago, Science seeks to understand nature. How did the Universe come about? What are we made of? These and other issues are still under discussion. However, an issue that has been the basis for the study in Quantum Chromodynamics (QCD) is the origin of the mass of subatomic particles. We know that 95% of the hadron mass comes from the strong interaction. QCD study has become very...

We have investigated anisotropic neutron stars in the framework of Rastall-Rainbow gravity. Our calculations were computed using the IU-FSU realistic equation of state (EoS), in which was considered two cases: standard nucleonic composition and the one with the eight lightest baryons. From the neutron star masses and radii obtained we conclude that when Rastall-Rainbow gravity and anisotropy...

We study the effects of heavy quarks on the equation of state for cold and dense quark matter obtained from perturbative QCD, yielding observables parametrized only by the renormalization scale. We investigate the behavior of charm quark matter under the constraints of β-equilibrium and electric charge neutrality in a region of densities where perturbative QCD is in principle much more...

We study the continuum limit of SU(2) Landau-gauge gluon and ghost propagators, obtained from numerical simulations performed on lattice volumes of up to 192⁴, in the scaling region.

We present an update of the Miettinen-Pumplim (MP) model for diffractive excitation for proton-proton ($pp$) and antiproton-proton ($\bar{p}p$) scattering considering recent LHC data. The energy dependence of cross sections is analyzed and compared to the available data. The implications of the diffractive excitation in proton-nucleus ($pA$) collisions are also discussed for different nuclei....

The bulk nuclear matter produced in heavy ion collisions carries a multitude of conserved quantum numbers: electric charge, baryon number and strangeness. Therefore, the diffusion processes associated to these conserved charges cannot occur independently and must be described in terms of a set of coupled diffusion equations. This physics is implemented by replacing the traditional diffusion...

The relative contributions of explicit and dynamical chiral symmetry breaking in QCD models of the quark-gap equation are studied in dependence of frequently employed Ansätze for the dressed interaction and quark-gluon vertex. In a naive quark picture, explicit symmetry breaking contributions are defined by a constituent-quark sigma term whereas the combined effects of explicit and dynamical...

We review some results in quark matter and few nucleon systems using effective models for QCD and the nuclear force.

In the present work the phase diagram of QCD is obtained by means of two effective models. For the description of the quarks matter we make use of the MIT bag model, and for the description of the hadronic matter we make use of the non-linear Walecka model (NLWM).

The Gibbs conditions are used to establish the crossing points of the pressures in function of the chemical potentials obtained...

The Efimov effect is a counterintuitive phenomenon concerning three non-relativistic particles with pairwise interactions supporting only one very shallow, two-particle bound state. In the so-called unitary limit, where the two-particle bound state energy goes to zero, the three-particle spectrum exhibits an infinite tower of bound states geometrically separated by a constant factor $\sim...

The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial

upgrade of the B factory facility at KEK in Tsukuba, Japan. The experiment began full operation in early 2019 and aims to record a factor of 50 times

more data than its predecessor. Belle II is uniquely capable of studying the so-called "XYZ"

particles: heavy exotic hadrons consisting of more than...

Quantum Chromodynamics is the accepted theory of the strong interaction. The gauge bosons transmitting the force are gluons. However, the non-perturbative part of QCD is far from being understood on a fundamental level. Non-perturbative aspects of QCD can be especially well studied when the gauge fields play a prominent role. A typical example are glueballs, massive particles composed solely...

In recent years, it is becoming more and more attractive the possibility of exploring the dynamics inside few-body systems directly in Minkowski space. A fully quantum-field treatment of the dynamics together with the adoption of the physical space open a new path for investigating the relativistic effects on the momentum distribution as well as the approach to critical regimes.

Three-body decays of heavy-flavoured hadrons into light particles are sequential processes, dominated by intermediate resonant states that requires a full amplitude analysis to be determined. These decays are a natural source of information about two-body scattering amplitudes, as an alternative to the early scattering data. However, the determination of the two-body amplitudes requires the...

Gauge symmetries are pervasive in particle physics, guiding the formulation of all interactions within the Standard Model. Usual methods for the calculation of processes, observables and properties of particles rely on perturbative expansions, which fail to converge for non-abelian gauge theories in the low-energy regime. The lattice formulation of a gauge theory, inherently non-perturbative,...

In this talk we present the recent results from LHCb experiment, related to hadronic final states from beaty and charm decays.

We present calculation of the hyperon elastic form factors

for the baryon octet for large four-momentum transfer squared,

$q^2$, in the timelike region ($q^2 > 0$).

Our calculations are based on a covariant quark model

developed in the spacelike region ($q^2 < 0$)

and on asymptotic relations between the

spacelike and the timelike regions.

Those asymptotic relations are derived based...

In the initial stage of a relativistic heavy ion collision a plasma of quarks and gluons (QGP) is created. The QGP expands, cools down and becomes a hadron gas made by, among other particles, the strange mesons K and K*. Previous statistical models were unable to explain the measured ratio, K*/K, of the strange meson abundances. In a previous work (by Cho and Lee, 2018) the observed...

The electromagnetic structure of the nucleon resonances $N^\ast$ are

usually parametrized by $\gamma^\ast N \to N^\ast$ helicity amplitudes,

at the resonance rest frame.

Those amplitudes are, however, constrained by kinematic conditions

in the limit where the photon three-momentum vanishes

(pseudothreshold limit).

Although the pseudothreshold limit is below the photon point...

In this note we study the conversion of nucleons into

deltas induced by a strong magnetic field in ultraperipheral relativistic heavy ion

collisions. The interaction

Hamiltonian couples the magnetic field to the spin operator,

which, acting on the spin part of the wave function, converts a spin 1/2

into a spin 3/2 state. We estimate this transition probability and calculate the...

To understand the strong interaction, we need to clarify how color confinement occurs in QCD. One of the most promising scenarios of confinement is the dual superconductor picture, in which magnetic monopoles play a crucial role. In non-Abelian gauge theories, however, the definition of magnetic monopoles is not trivial because the naive definition of magnetic charge is not gauge invariant. A...

This work is devoted to the discussion of the ground state and the orbitally and radially excited states of quark-antiquark mesons within the Tamm-Dancoff approximation of the Coulomb-gauge QCD model. The Regge trajectories for angular and radial excitations are constructed, and their properties are analyzed. The calculated meson masses and their quantum numbers are used as basis to attribute...

A flavor quark - level U(5) Nambu Jona Lasinio model is considered for the derivation of an effective model for heavy scalar and pseudoscalar mesons. Relations between scalar and pseudoscalar quark-antiquark mesons masses with at least one $b$ or $\bar{b}$ - quark. The mesons normalization constants are found by considering explicit chiral symmetry breakdown. For that, the auxiliary...

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 therefore accessible experimentally using...

We discuss properties of axial-vector mesons within an effective version of Quantum Chromodynamics in the Coulomb gauge. While recent studies have put emphasis in configuration mixing with open meson-meson channels, we here concentrate on the simpler closed-channel problem and follow the $1^+$ mixing through a wide range of quark masses. We also examine their radial excitations

and discuss...

We explore an update of the Lipari-Lusignoli model for multiple parton interaction in proton-pronton ($pp$) and antiproton-proton ($\bar{p}p$) collisions considering the recently released LHC precise measurements at $\sqrt(s)=13$ TeV. By means of a multi-channel eikonal model where the diffractive excitations are obtained using the Good-Walker approach, we give predictions to the total and...

Ultrahigh energy neutrinos are one of the components of the spectrum of particles that reach the Earth. In particular, astrophysical neutrinos have been observed with energies above 5 PeV, which allow us to study the neutrino absorption by the Earth's interior at ultrahigh energies. The opacity of the Earth to ultrahigh energy (UHE) neutrinos is strongly dependent on the behaviour of the...

For many years, the Standard Model has described neutrinos as massless particles. In 2015, Takaaki Kajita and Arthur B. McDonald received the Nobel Prize for the discovery of neutrino oscillations, which shows that they have mass. In this paper, we discuss the theory of this phenomenon, making a brief historical introduction to the neutrino's existence proposal and the solar neutrino problem,...

Neutron star observations, including those from Chandra, LIGO and anticipated results from the NICER mission, continue to provide unique insight into the role that neutron stars play in stellar evolution and the nature of the dense matter in the neutron star core. After being created in a core-collapse supernova explosion, the neutron star’s first minute (as a "proto-neutron star) is critical....

The physics of short-ranged correlations is reviewed from a pedagogical standpoint that is aimed to provide background sufficient for students to do research in the field. The lectures discuss:

1) how the earliest efforts allowed physicists to understand the qualitative features of nuclear binding and saturation.

2) the technical improvements, including relativistic effects

3)...

We review the computation of the two-point (propagators) and the quark-gluon vertex using non-perturbative first principle methods. Topics concerned with quark and gluon confinement together with chiral symmetry breaking and there relation with the propagators and vertex are also addressed.

Major progress in theoretical formalism of the interior structure of the Nucleon over the last 30 years has led to breakthroughs in our understanding of the theory of the fundamental substructure of the protons and neutrons. At the same time, the technical advances in particle accelerator and state of the art experimental detection technologies along with dramatic developments in computing...

We will present preliminary resuls of the axial and pseudoscalar form factors of the nucleon calculated using a Poincaré-covariant, symmetry-preserving treatment of a vector$\times$vector contact interaction.

In this work we study the effect of scalar spin coupling of constituent quarks on nucleon electroweak properties by introducing a two momentum scales wave function. By comparing the one scale wave function and the two scales wave function models, we found that the last case has shown a reasonable description of static observables and of the ratio µpGEp/GMp in which the value of the zero of...

Nucleon-nucleon correlations play an important role in the structure and binding energy of nuclei and nuclear matter. The attractive intermediate-range interaction tends to bind nucleons in pairs while the repulsive core of the interaction creates short-range correlations that keep the nucleons apart. Here, the standard $^{1}S_{0}$ and the quasideuteron $^{3}S_{1}-^{3}D_{1}$ pairing fields are...

The physics of Neutron Stars has been in a prominent position for the past few decades due to both its interdisciplinarity and its growing observational possibility. In this work we investigate the influence of the magnetic field on the Neutron Star crust and its consequences on its observational properties. The Baym-Pethick-Sutherland (BBP) equation of state was used as an initial model, the...

In this work we consider the possibility that strange quark matter may be manifested in the form of strange crystal planets. These planet-like objects are made up of nuggets of strange quark matter (SQM), organized in a crystalline structure. We consider the so--called strange matter hypothesis proposed by Bodmer, Witten and Terazawa, in that, strange quark matter may be the absolutely...

Parton Distribution Functions (PDFs) are the fundamental objects containing information on the flavour structure of hadrons, and on how the hadron spin and momentum are distributed among its constituents, quarks and gluons. Because they are non-perturbation quantities, we must rely on non-perturbative methods for their computation. Lattice QCD (LQCD) is the most successful method to access the...

Ultrarelativistic heavy ions are accompanied by a large flux of quasi-real Weizsäcker-Williams photons. This opens a broad range of research possibilities, as the Weizsäcker-Williams photons can be used to study photon-photon fusion reactions as well as photonuclear reactions in a wide range of energies, see for example the review [1].

Of special interest here are diffractive...

The light mesons, like pion, play special rules in try to understanting QCD, between another motivation, the pion is the Goldstone boson, and, is central to symmetry breaking and partial current conservation

(PCAC). The most general way to take informations about the hadronic substructure, i.e.; in terms of the degrees of freedom from QCD, quarks and gluons, are the study of the...

The Polyakov-Nambu-Jona-Lasinio (PNJL) is an effective quark model incorporating confinement effects in the original Nambu-Jona-Lasinio (NJL) one through the inclusion of the Polyakov loop ($\Phi$) at finite temperature regime. However, at zero temperature regime, the structure of the PNJL model completely loses information on the Polyakov loop. Its equations become the same as the NJL model....

In high energy hadron--hadron collisions, the process of Double Parton

Scattering (DPS) becomes important, in which two partons from one

hadron interact simultaneously with two from another one.

In this work, we will consider the production of a pair of leptons and

a pair of quark-antiquark from a ultra-peripheral ultra-relativistic

heavy ion collision.

Unlike the commonly explored...

White dwarfs have, at the beginning of their lives, temperature inside their structures. This temperature modifies the way interstellar matter behaves, since degeneration is no longer found throughout the entire star. An effective assumption for the structure of hot white dwarfs is to consider their cores as a degenerated Fermi gas, as in the case of T = 0K, and its surface as an ideal gas...

In the exclusive production of vector mesons in nuclear collisions

(\gamma A), we have to take into account two main nuclear effects in

order to make a precise calculation of the scattering amplitude: the

gluon shadowing and the finite coherence length. The first deals with

the main source of rescattering in the production of heavy quark

pairs, making the gluon density in a nuclei to be...

We use the Monte Carlo particle physics code FLUKA to calculate gamma-ray spectra expected from solar flare energetic ion distributions. The FLUKA code includes robust physics-based models for electromagnetic, hadronic and nuclear interactions, sufficiently detailed for it to be a useful tool for calculating nuclear de-excitation, positron annihilation and neutron capture line fluxes and...

In the present work, we investigate the effects of short-range correlations (SRC) on the dimensionless deformability of the binary neutron system related to the GW170817 event. We implemented phenomenological SRC in a relativistic mean-field model in which the bulk parameters, namely, incompressibility ($K_0$), effective nucleon mass ratio ($m^*$), symmetry energy ($J$) and

its slope...

In this work we study the quantization of Yang-Mills theories by taking into account the effects of Gribov copies in the Serreau-Tissier approach, therefore we finally establish a good explanation for the generation of the gauge field (gluon) mass added in the particular Curci-Ferrari by using the symmetry restoration phenomenon. To accomplish that, we also discuss the similarities between the...

Exotic shapes of nuclei exist which are known as pasta phase. These are possible to occur at high densities, such as the crust of neutron stars, and are due to the competition between the strong and electromagnetic forces, resulting in a frustrated system. Calculations of such shapes usually assume a crystalline structure described by repetitions of the same Wigner-Seitz cells for fixed...

We study the prompt photon production at the CERN LHC energies considering the color dipole approach. We estimate the rapidity and transverse momentum distributions of prompt photon production considering the more recent phenomenological models for the dipole-proton scattering amplitude, which are able to describe the inclusive and exclusive ep HERA data. A comparison between the predictions...

An extended flavor SU(3) linear sigma model for scalar and pseudoscalar mesons coupled to glueballs and tetraquarks is built based on one loop quark dynamics. For that, non linear functions of the chiral invariant scalar and pseudoscalar mesons compositions and covariant couplings to (scalar and pseudoscalar) glueballs fields and tetraquarks fields are envisaged. By considering the Dynamical...

Abstract: Heavy mesons play an important role to understand the properties of strongly interacting matter. Quarkonia that survived after the quark-gluon plasma phase are expected to collide with other particles that constitute hadronic matter. In this work, we present a study on the interactions of the $\Upsilon$ meson with a hadronic medium. The meson-meson interactions are described by an...

Different extensions of the Nambu-Jona-Lasinio model, known to satisfy expected QCD chiral symmetry aspects, are presented and used to investigate a possible hadron-quark phase transition at zero temperature. In special, one version of these NJL-type models, suitable to describe both nucleonic and hyperonic matter, is partially developed in this work. In an early exploratory study, it is shown...

In this work we revisit the thermal relaxation of neutron stars. We focus particularly on the cooling of neutron stars whose mass is slightly greater than the value above which the direct urca process sets in. Considering different mechanisms for neutrino production in each region of the star, and working with some equations of state whose saturation properties as well its predicted neutron...

Decades ago, particles that consist solely of gluons, so-called glueballs, have been predicted from theory. According to present knowledge, lattice-QCD calculations predict several glueball candidates in the mass range of 1.5 - 4 GeV/c^2 (depending on their quantum numbers). Studying the nature of light mesons in two-photon decays, offers indirect information on their gluonic content and acts...