Classical and Quantum Many-Body Description of Bremsstrahlung in Dense Matter

Knoll, J.; Voskresensky, D. N.

doi:10.1006/aphy.1996.0082

Cited by 68 publications

(88 citation statements)

References 43 publications

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“…As a result, the emissivity of the MNB process proves to be several times suppressed for n < n c1 as compared to the values computed within the FOPE model because correlation effects are incorporated in the particleparticle channel, in the same manner as they have been taken into account in [30,31]. The MMU emissivity is less affected by these correlation effects for n < n c1 , see [32]. Sometimes these important points are overlooked by authors who continue to exploit emissivities for all two-nucleon processes which are at n < n c 1 ∼ 0.5 − 0.8 n 0 several times suppressed compared to those computed in the FOPE based model [37] also for n > n 0 , where the pion softening effect should be dominant and leads to an enhancement compared to the FOPE case.…”

Section: Hadronic Starsmentioning

confidence: 92%

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Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

2016

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Abstract. Measurements of the low masses for the pulsar PSR J0737-3039B, for the companion of PSR J1756-2251 and for the companion of PSR J0453+1559 on the one hand and of the high masses for the pulsars PSR J1614-2230 and PSR J0348-0432 on the other demonstrate the existence of compact stars with masses in a broad range from 1.2 to 2 M . The most massive of these objects might be hybrid stars. To fulfill the constraint Mmax > 2 M with a reserve we exploit the stiff DD2 hadronic equation of state (EoS) without and with excluded volume (DD2vex) correction, which produce maximum neutron star masses of Mmax = 2.43 M and 2.70 M , respectively. We show that the stiffness of the EoS does not preclude an explanation of the whole set of cooling data within "nuclear medium cooling" scenario for compact stars by a variation of the star masses. We select appropriate proton gap profiles from those exploited in the literature and allow for a variation of the effective pion gap controlling the efficiency of the medium modified Urca process. However, we suppress the possibility of pion condensation. In general, the stiffer the EoS the steeper a decrease with density of the effective pion gap is required. Results are compared with previously obtained ones for the HDD EoS for which Mmax = 2.06 M . The cooling of the compact star in the supernova remnant Cassiopeia A (Cas A) is explained mainly by an efficient medium modified Urca process. To explain a > ∼ 2.5% decline of the cooling curve for Cas A, as motivated by an analysis of the ACIS-S instrument data, together with other cooling data exploiting the DD2 EoS a large proton gap at densities n < ∼ 2n0 is required vanishing for n > ∼ 2.5 n0, where n0 is the saturation nuclear density. A smaller decline, as it follows from an analysis of the HRC-S instrument data, is explained with many choices of parameters. With the DD2vex EoS and using an effective pion gap steeper decreasing with the density and/or a proton gap shifted to smaller densities we are also able to reproduce both a strong decline compatible with ACIS-S data and HRC-S instrument data. The mass of Cas A is estimated as 1.6 − 1.9 M , above the value 1.5 M , which we have evaluated with the softer HDD equation of state. Different mass choices for the hottest object XMMU J173203.3-344518 are discussed. We make general remarks also on hybrid star cooling and on its dependence on the stiffness of the hadronic EoS.PACS. 97.60.Jd Neutron stars -95.30.Cq Elementary particle processes -26.60-c Nuclear matter aspects of neutron stars

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Section: Hadronic Starsmentioning

confidence: 92%

“…On the contrary, the correlation effects for n < n 0 result in a suppression of the MMU and MNB emissivities compared to MU and NB ones, cf. [30,31,32].…”

Section: Introductionmentioning

confidence: 99%

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

2016

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“…Further details are given in ref. 13 . The above example shows that we have to deal with particle transport that explicitly takes account of the particle mass-width in order to properly describe soft radiation from the system.…”

Section: Radiation On the Quantum Levelmentioning

confidence: 99%

Soft Modes, Quantum Transport and Kinetic Entropy

Ivanov¹,

Knoll²,

Hees³

et al. 2000

Progress in Nonequilibrium Green's Functions

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The effects of the propagation of particles which have a finite life-time and an according width in their mass spectrum are discussed in the context of transport descriptions. In the first part the coupling of soft photon modes to a source of charged particles is studied in a classical model which can be solved completely in analytical terms. The solution corresponds to a re-summation of certain field theory diagrams. The general properties of broad resonances in dense finite temperature systems are discussed at the example of the ρ-meson in hadronic matter. The second part addresses the problem of transport descriptions which also account for the damping width of the particles. The Kadanoff-Baym equation after gradient approximation together with the Φ-derivable method of Baym provides a self-consistent and conserving scheme. Memory effects appearing in collision term diagrams of higher order are discussed. We derive a generalized expression for the nonequilibrium kinetic entropy flow, which includes corrections from fluctuations and mass-width effects. In special cases an H-theorem is proved. Memory effects in collision terms provide contributions to the kinetic entropy flow that in the Fermi-liquid case recover the famous bosonic type T 3 ln T correction to the specific heat of liquid Helium-3.With the aim to describe the collision of two nuclei at intermediate or even high energies one is confronted with the fact that the dynamics has to include particles like the delta or rho-meson resonances with life-times of less than 2 fm/c or equivalently with damping widths above 100 MeV. Also the collisional damping rates deduced from presently used transport codes are of the same order, whereas typical mean temperatures range between 50 to 150 MeV depending on beam energy. Thus, the damping width of most of the constituents in the system can by no means be treated as a perturbation. As a consequence the mass spectrum of the particles in the dense matter is no longer a sharp delta function but rather acquires a width due to collisions and decays. One thus comes to a picture which unifies resonances which have § Combined contribution summarizing the talks of J. Knoll on the subject "Soft Modes and Resonances in Dense Matter" and Y.B. Ivanov on the subject "Quantum Transport and Kinetic Entropy". † Permanent address: Kurchatov Institute,

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“…Its analytical structure therefore is not easily understood, and especially when combining several of such propagators in a perturbative scheme one has to implement more or less complicated cutting rules to understand pieces of diagrams physically [16,17].…”

Section: Spectral Functionsmentioning

confidence: 99%

Damping Rate of a Massive Fermion in a Hot Medium

Henning¹

2000

Condens. Matter Phys.

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In a hot system every excitation acquires a finite lifetime, manifesting itself in a non-zero spectral width. Ordinary damping as well as quantum memory effects arise from this nontrivial spectral function. This report presents a new method for the self-consistent calculation of the spectral width of a fermion coupled to massless bosons of scalar, vector and pseudoscalar type. In accordance with the known procedures of Quantum Electrodynamics, the self-consistent summation of the corresponding Fock diagram eliminates all infrared divergences although the bosons are not screened at all. The solutions for the fermion damping rate are analytical in the coupling constant g , but not analytical in the temperature parameter, i.e., γ ∝ g 2 T + O(g 4 T log(T /M )) .

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Classical and Quantum Many-Body Description of Bremsstrahlung in Dense Matter

Cited by 68 publications

References 43 publications

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

Soft Modes, Quantum Transport and Kinetic Entropy

Damping Rate of a Massive Fermion in a Hot Medium

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