Exotic Baryons in (Hot) Neutron Stars
Dr. Kauan Marquez
Departamento de Física, CFM, Universidade Federal de Santa Catarina Florianópolis, CP 476, Santa Catarina 88040-900, Brazil
20th June 2023
Time: 14:00 (Lisbon time)
Room F42
Department of Physics, University of Coimbra
This presentation will provide an overview of two research papers. The first paper focuses on the calculation of baryon-meson coupling constants for spin-1/2 baryonic octet and spin-3/2 decuplet using symmetry arguments based on SU(3) and SU(6) group transformations. The coupling constants are determined by reproducing known potential depths for hyperons and Δ resonances. These constants are then applied to study neutron star matter with hyperons and deltas. The findings reveal that the Δ− particle is crucial in the neutron star interior, consistently appearing and impacting the astrophysical properties, potentially increasing the maximum mass reached. The second paper investigates the nuclear isentropic equation of state for stellar matter composed of nucleons, hyperons, and Δ-resonances in different stages of a neutron star’s evolution. A relativistic model within the mean-field approximation is used, along with density-dependent couplings adjusted by the DDME2 parameterization. Baryon-meson couplings are determined based on SU(6) and SU(3) symmetry arguments. The dominant exotic particle in the star is found to be Λ at different entropies for both neutrino-free and neutrino-trapped stellar matter. The inclusion of new particles leads to a decrease in temperature, and increasing entropy per baryon results in larger stellar radii and lower mass due to neutrino diffusion. In neutrino transparent matter, radii decrease with entropy per baryon without significant changes in stellar mass.
PNJL Model at Zero Temperature: The Three-Flavor Case
Professor Odilon Lourenço
Physics Department of Instituto Tecnológico de Aeronáutica (ITA) São José dos Campos, Brazil
29th June 2023 (Thursday)
3:00 PM Lisbon Time (GMT+1)
Room F42
Department of Physics, University of Coimbra
In this talk, Prof. Lourenço will introduce a three-flavor version of the Polyakov-Nambu-Jona-Lasino (PNJL) model at zero temperature regime. This model incorporates a traced Polyakov loop (Φ) dependence in the scalar, vector, and ‘t Hooft channel strengths. The thermodynamics of the PNJL0 model will be thoroughly explored, with a specific focus on the first-order confinement/deconfinement phase transition, where Φ acts as the order parameter. Additionally, intriguing phenomena such as the reduction of the constituent strange quark mass (Ms) and the restoration of chiral symmetry, even for the strange quark, will be discussed. The investigation also encompasses a charge-neutral system of quarks and leptons in weak equilibrium.
Probing the Symmetry Energy with Neutron Stars Properties
Prof. B.K. Agrawal
Saha Institute of Nuclear Physics, India
3rd October 2023
2:00 PM Lisbon Time (GMT+1)
Room F42
Department of Physics, University of Coimbra
Probing the density dependence of nuclear symmetry energy through the neutron star observables has been quite challenging. The correlations of various neutron star properties with individual nuclear symmetry energy parameters remain inconclusive. This issue is addressed by performing a principal component analysis of tidal deformability and radius of neutron stars. It will be shown that multiple symmetry energy parameters are required to explain the variability of neutron star properties considered.
Meson mass properties in a magnetized medium using the Nambu-Jona-Lasinio model
Prof. Sidney dos Santos Avancini
Universidade Federal de Santa Catarina, Brazil
10th of October 2023 (Thursday)
2:00 PM Lisbon Time (GMT+1)
Room F42
Department of Physics, University of Coimbra
The light pseudo-scalar meson pole masses calculation under strong magnetic fields is discussed. The calculations are done within the framework of the Nambu-Jona-Lasinio model with two (su(2)-NJL) and three flavors (su(3)-NJL). Numerical results for neutral and charged mesons are considered in zero and finite temperatures. Some comparisons with lattice QCD simulations are presented. We use both constant coupling constants and magnetic field-dependent ones, where the latter, are fitted to reproduce the inverse magnetic catalysis behavior predicted by the lattice QCD results. We show that the chosen regularization scheme plays a crucial role in the correct calculation of the meson masses.
The low-density neutron star equation of state with light clusters
Prof. Helena Pais
Universidade de Coimbra
14th of May 2023
2:00 PM Lisbon Time (GMT+1)
Astrophysics and Cosmology Seminars
Department of Physics, University of Coimbra
Light Nuclei and Hypernuclei in hot stellar matter: calibrating their nuclear couplings using heavy-ion collisions data
Tiago Custódio
Universidade de Coimbra
16th of April 2023
2:00 PM Lisbon Time (GMT+1)
Astrophysics and Cosmology Seminars
Department of Physics, University of Coimbra
Trace anomaly and its relation to the existence of quark matter inside neutron stars
Prof. Milena Albino
Universidade de Coimbra
12th of December 2023
2:00 PM Lisbon Time (GMT+1)
Astrophysics and Cosmology Seminars
Department of Physics, University of Coimbra
Can Deep Learning Provide Reliable Predictions About the Composition of Neutron Stars
Prof. Valéria Carvalho
Universidade de Coimbra
2nd of April 2023
2:00 PM Lisbon Time (GMT+1)
Astrophysics and Cosmology Seminars
Department of Physics, University of Coimbra
MagStarMatter 