Pion production, pion absorption, and nucleon properties in dense nuclear matter: Relativistic Dirac-Brueckner approach at intermediate and high energies

1987 ◽  
Vol 36 (4) ◽  
pp. 1611-1620 ◽  
Author(s):  
Bernard ter Haar ◽  
Rudi Malfliet
2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Yong-Liang Ma ◽  
Mannque Rho

AbstractTopology effects have being extensively studied and confirmed in strongly correlated condensed matter physics. In the limit of large number of colors, baryons can be regarded as topological objects—skyrmions—and the baryonic matter can be regarded as a skyrmion matter. We review in this paper the generalized effective field theory for dense compact-star matter constructed with the robust inputs obtained from the skyrmion approach to dense nuclear matter, relying on possible “emergent” scale and local flavor symmetries at high density. All nuclear matter properties from the saturation density n0 up to several times n0 can be fairly well described. A uniquely novel—and unorthdox—feature of this theory is the precocious appearance of the pseudo-conformal sound velocity $v^{2}_{s}/c^{2} \approx 1/3$ v s 2 / c 2 ≈ 1 / 3 , with the non-vanishing trace of the energy momentum tensor of the system. The topology change encoded in the density scaling of low energy constants is interpreted as the quark-hadron continuity in the sense of Cheshire Cat Principle (CCP) at density $\gtrsim 2n_{0}$ ≳ 2 n 0 in accessing massive compact stars. We confront the approach with the data from GW170817 and GW190425.


2020 ◽  
Vol 1667 ◽  
pp. 012001
Author(s):  
Nicolas Baillot d’Étivaux ◽  
Jérôme Margueron ◽  
Sebastien Guillot ◽  
Natalie Webb ◽  
Màrcio Catelan ◽  
...  

2017 ◽  
Vol 26 (04) ◽  
pp. 1750015 ◽  
Author(s):  
Yeunhwan Lim ◽  
Chang Ho Hyun ◽  
Chang-Hwan Lee

In this paper, we investigate the cooling of neutron stars with relativistic and nonrelativistic models of dense nuclear matter. We focus on the effects of uncertainties originated from the nuclear models, the composition of elements in the envelope region, and the formation of superfluidity in the core and the crust of neutron stars. Discovery of [Formula: see text] neutron stars PSR J1614−2230 and PSR J0343[Formula: see text]0432 has triggered the revival of stiff nuclear equation of state at high densities. In the meantime, observation of a neutron star in Cassiopeia A for more than 10 years has provided us with very accurate data for the thermal evolution of neutron stars. Both mass and temperature of neutron stars depend critically on the equation of state of nuclear matter, so we first search for nuclear models that satisfy the constraints from mass and temperature simultaneously within a reasonable range. With selected models, we explore the effects of element composition in the envelope region, and the existence of superfluidity in the core and the crust of neutron stars. Due to uncertainty in the composition of particles in the envelope region, we obtain a range of cooling curves that can cover substantial region of observation data.


2019 ◽  
Vol 99 (2) ◽  
Author(s):  
Andrej Ilner ◽  
Justin Blair ◽  
Daniel Cabrera ◽  
Christina Markert ◽  
Elena Bratkovskaya

2018 ◽  
Vol 27 (11) ◽  
pp. 1850092 ◽  
Author(s):  
Akhtar Iqbal ◽  
Khusniddin K. Olimov ◽  
Kosim Olimov ◽  
Mushtaq Ahmad ◽  
Sh. Z. Kanokova ◽  
...  

The collision centrality dependencies of the average kinematical characteristics of the negative and positive pions, produced in [Formula: see text] collisions at [Formula: see text], were investigated. The ratio [Formula: see text] proved to be [Formula: see text], [Formula: see text] and [Formula: see text] in the peripheral, semicentral, and central [Formula: see text] collision events, respectively, decreasing noticeably with increasing collision centrality. The suppression (decrease) of the ratio [Formula: see text] was observed in the semicentral and central [Formula: see text] collisions as compared to the ratio [Formula: see text], estimated using the simple model for [Formula: see text] collision system. The ratio [Formula: see text] estimated using the simple model agreed well with the corresponding ratio [Formula: see text], estimated for [Formula: see text] collisions at [Formula: see text] based on the Wounded Nucleon Model (WNM). Comparison of the emission angle as well as momentum distributions of the charged pions in the peripheral and central [Formula: see text] collisions revealed the significant decrease of the fraction of the relatively fast charged pions (with smaller emission angles) and increase of the fraction of the relatively slow charged pions (with larger emission angles) with an increase in collision centrality. The results of the present analysis can be useful for analysis of the centrality dependence of the charged pion production in heavy ion collisions at high energies.


2009 ◽  
Vol 24 (02n03) ◽  
pp. 317-326 ◽  
Author(s):  
◽  
I. FRÖHLICH ◽  
G. AGAKISHIEV ◽  
C. AGODI ◽  
A. BALANDA ◽  
...  

The HADES experiment, installed at GSI, Darmstadt, measures di-electron production in A + A, p/π + N and p/π + A collisions. Here, the π0 and η Dalitz decays have been reconstruced in the exclusive p + p reaction at 2.2 GeV to form a reference cocktail for long-lived di-electron sources. In the C + C reaction at 1 and 2 GeV/u, these long-lived sources have been subtracted from the measured inclusive e+e- yield to exhibit the signal from the early phase of the collision. The results suggest that resonances play an important role in dense nuclear matter.


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