scholarly journals Hyperons in Finite and Infinite Nuclear Systems

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 376
Author(s):  
Isaac Vidaña
Keyword(s):  
Neutron Stars ◽  
Weak Decay ◽  
Theoretical Description ◽  
Mode Instability ◽  
Decay Modes ◽  
Nuclear Systems ◽  
Γ Ray ◽  
Production Mechanisms

In this work, we shortly review the role and properties of hyperons in finite and infinite nuclear systems such as hypernuclei and neutron stars. Particularly, we describe different production mechanisms of hypernuclei, discuss some aspects of their γ-ray spectroscopy and their weak decay modes, and give a few strokes on their theoretical description. We reexamine also the role played by hyperons on the properties of neutron and proto-neutron stars with a special emphasis on the well-known “hyperon puzzle”, of which we discuss some of the solutions that have been proposed to tackle this problem. Finally, we review the role of hyperons on the cooling properties of newly born neutron stars and on the so-called r-mode instability.

scholarly journals Hyperons: the strange ingredients of the nuclear equation of state

2018 ◽  
Vol 474 (2217) ◽  
pp. 20180145 ◽  
Author(s):  
Isaac Vidaña
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Weak Decay ◽  
Effective Field ◽  
Meson Exchange ◽  
Decay Modes ◽  
Nuclear Equation Of State ◽  
Nuclear Systems ◽  
Consequent Reduction ◽  
Recent Developments

We review the role and properties of hyperons in finite and infinite nuclear systems. In particular, we present different production mechanisms of hypernuclei, as well as several aspects of hypernuclear γ -ray spectroscopy, and the weak decay modes of hypernuclei. Then we discuss the construction of hyperon–nucleon and hyperon–hyperon interactions on the basis of the meson-exchange and chiral effective field theories. Recent developments based on the so-called V low  k approach and lattice quantum chromodynamics will also be addressed. Finally, we go over some of the effects of hyperons on the properties of neutron and proto-neutron stars with an emphasis on the so-called ‘hyperon puzzle’, i.e. the problem of the strong softening of the equation of state, and the consequent reduction of the maximum mass, induced by the presence of hyperons, a problem which has become more intriguing and difficult to solve due the recent measurements of approximately 2 M ⊙ millisecond pulsars. We discuss some of the solutions proposed to tackle this problem. We also re-examine the role of hyperons on the cooling properties of newly born neutron stars and on the development of the so-called r-mode instability.

scholarly journals What will eROSITA reveal among X-ray faint isolated neutron stars?

2017 ◽  
Vol 13 (S337) ◽  
pp. 112-115
Author(s):  
Adriana M. Pires
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Radio Pulsar ◽  
X Rays ◽  
Evolutionary Models ◽  
X Ray ◽  
Sky Survey ◽  
Γ Ray ◽  
Unique Potential

AbstractSince the discovery of the first radio pulsar fifty years ago, the population of neutron stars in our Galaxy has grown to over 2,600. A handful of these sources, exclusively seen in X-rays, show properties that are not observed in normal pulsars. Despite their scarcity, they are key to understanding aspects of the neutron star phenomenology and evolution. The forthcoming all-sky survey of eROSITA will unveil the X-ray faint end of the neutron star population at unprecedented sensitivity; therefore, it has the unique potential to constrain evolutionary models and advance our understanding of the sources that are especially silent in the radio and γ-ray regimes. In this contribution I discuss the expected role of eROSITA, and the challenges it will face, at probing the galactic neutron star population.

A RELATIVISTIC EFFECTIVE MODEL WITH PARAMETERIZED COUPLINGS FOR NEUTRON STARS: THE ROLE OF ANTIKAON CONDENSATES

2011 ◽  
Vol 20 (supp02) ◽  
pp. 133-139
Author(s):  
ALEXANDRE MESQUITA ◽  
MOISÉS RAZEIRA ◽  
DIMITER HADJIMICHEF ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
ROSANA O. GOMES ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Coupling Constants ◽  
Effective Model ◽  
Extended Model ◽  
Many Body ◽  
Parametric Dependence ◽  
Interaction Terms ◽  
Coupling Terms ◽  
Effective Models

We study the effects of antikaon condensates in neutron stars in the framework of a relativistic effective model with derivative couplings which includes genuine many-body forces simulated by nonlinear interaction terms involving scalar-isoscalar (σ, σ*), vector-isoscalar (ω, ɸ), vector-isovector (ϱ), scalar-isovector (δ) mesons. The effective model presented in this work has a philosophy quite similar to the original version of the model with parameterized couplings. But unlike that, in which the parametrization is directly inserted in the coupling constants of the Glendenning model, we present here a method for the derivation of the parametric dependence of the coupling terms, in a way that allows in one side to consistently justify this parametrization and in the other to extend in a coherent way the range of possibilities of parameterizations in effective models with derivative couplings. The extended model is then applied to the description of the mass of neutron stars.

scholarly journals AGN surveys to study galaxy evolution along cosmic times

2013 ◽  
Vol 9 (S304) ◽  
pp. 180-186
Author(s):  
Luigi Spinoglio
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Energy Production ◽  
X Rays ◽  
Radio Frequencies ◽  
Ir Spectroscopic ◽  
Observational Techniques ◽  
Production Mechanisms

AbstractVarious observational techniques have been used to survey galaxies and AGN, from X-rays to radio frequencies, both photometric and spectroscopic. I will review these techniques aimed at the study of galaxy evolution and of the role of AGNs and star formation as the two main energy production mechanisms. I will then present as a new observational approach the far-IR spectroscopic surveys that could be done with planned astronomical facilities of the next future, such as SPICA from the space and CCAT from the ground.

Leading two-body weak-decay modes of λb

1981 ◽  
Vol 32 (7) ◽  
pp. 193-197 ◽  
Author(s):  
B. Guberina ◽  
D. Tadić ◽  
J. Trampetić
Keyword(s):  
Weak Decay ◽  
Decay Modes

Attention and Structural Choice in Sentence Production

2018 ◽  
pp. 526-546
Author(s):  
Andriy Myachykov ◽  
Mikhail Pokhoday ◽  
Russell Tomlin
Keyword(s):  
Experimental Evidence ◽  
Word Order ◽  
Syntactic Structure ◽  
Sentence Production ◽  
Regular Mapping ◽  
Structural Choice ◽  
Mapping Mechanism ◽  
Production Mechanisms

This chapter offers a review of experimental evidence about the role of the speaker’s attention in the choice of syntactic structure and the corresponding word order during sentence production. Here, we describe how the speaker’s syntactic choices reflect the regular mapping mechanism that reflects the features of the described event in the produced sentence. One of the most important event parameters that the speaker considers is the changing salience status of the event’s referents. This chapter summarizes current theoretical debate about the interplay between attention and sentence production mechanisms. Finally, it reviews the corresponding experimental evidence from languages with both restricted and flexible word orders.

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