Výsledky vyhľadávania
Názov NICER data and a sigma-field-dependent stiffness of the hadronic equation of state Aut.údaje Evgeni Kolomeitsev, Dmitri Voskresensky Autor Kolomeitsev Evgeni E. 1970- ( 50%) UMBFP06 - Katedra fyziky
Spoluautori Voskresensky Dmitri (50%)
Zdroj.dok. Physical Review C. Vol. 110, no. 2 (2024), pp. 1-10. - Maryland : American Physical Society, 2024 Kľúč.slová neutrónové hviezdy nukleárna fyzika astrofyzika - astrophysics stavová rovnica Form.deskr. články - journal articles Jazyk dok. angličtina Krajina Spojené štáty Anotácia Analyses for the NICER data indicate that there is no significant variation of compact star radii within the mass range of 1.4 to 2.0 solar masses. Yamamoto et al. [Phys. Rev. C 108, 035811 (2023)] concluded recently that “this feature cannot be reproduced by the hadronic matter due to the softening of the equation of state (EoS) by hyperon mixing, suggesting the possible existence of quark phases in neutron-star interiors.” Using a collection of 162 purely nucleonic, hyperonic, and quarkish EoSs from the CompOSE database and some other works, we verify that hyperons indeed lead to a significant difference in radii of stars of 1.4 and 2.0 solar masses, which diminishes in the presence of quarks. We compare the shapes of the mass-radius curves and show that hyperons and quarks in the neutron star cores prefer a particular curve shape with backbending. It is argued that the shape is controlled by the density dependence of the nuclear symmetry energy. We draw attention to the existence of a class of purely hadronic relativistic mean-field EoSs with scalar-field dependent hadron masses and coupling constants that satisfy the known constraints on the EoSs including the analyses of the new NICER data and the above requirement of insignificant variation of the neutron star radii. URL Link na zdrojový dokument Kategória publikačnej činnosti ADC Číslo archívnej kópie 54690 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov Charge and isospin fluctuations in a non-ideal pion gas with dynamically fixed particle number Aut.údaje Evgeni E. Kolomeitsev ... [et al.] Autor Kolomeitsev Evgeni E. 1970- (34%) UMBFP06 - Katedra fyziky
Spoluautori Voskresensky Dmitri (33%)
Borisov Maxim E. (33%)
Zdroj.dok. The European Physical Journal A : Hadrons and Nuclei. Vol. 57, no. 4 (2021), pp. [1-29]. - Berlin : Springer, 2021 Kľúč.slová Bose-Einsteinova kondenzácia - Bose-Einstein condensation heavy ion collisions Form.deskr. články - journal articles Jazyk dok. angličtina Krajina Nemecko Kategória publikačnej činnosti ADC Číslo archívnej kópie 49947 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov On cooling of neutron stars with a stiff equation of state including hyperons Aut.údaje Hovik Grigorian, Evgeni E. Kolomeitsev ... [et al.] Autor Grigorian Hovik (25%)
Spoluautori Kolomeitsev Evgeni E. 1970- (25%) UMBFP06 - Katedra fyziky
Maslov Konstantin A. (25%)
Voskresensky Dmitri (25%)
Zdroj.dok. Universe. Vol. 4, no. 2 (2018), pp. 1-6. - Basel : Multidisciplinary Digital Publishing Institute, 2018 Kľúč.slová equation of state neutron stars neutrína - neutrinos Jazyk dok. angličtina Krajina Švajčiarsko Systematika 53 Anotácia Exploiting a stiff equation of state of the relativistic mean-field model MKVORHf with sigma-scaled hadron effective masses and couplings, including hyperons, we demonstrate that the existing neutron-star cooling data can be appropriately described within “the nuclear medium cooling scenario” under the assumption that different sources have different masses URL Link na zdrojový dokument Kategória publikačnej činnosti ADM Číslo archívnej kópie 43911 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov Charged rho meson condensate in neutron stars within RMF models Aut.údaje Konstantin A. Maslov, Evgeni E. Kolomeitsev, Dmitry N. Voskresensky Autor Maslov Konstantin A. (34%)
Spoluautori Kolomeitsev Evgeni E. 1970- (33%) UMBFP06 - Katedra fyziky
Voskresensky Dmitri (33%)
Zdroj.dok. Universe. Vol. 4, no. 1 (2018), pp. 1-8. - Basel : Multidisciplinary Digital Publishing Institute, 2018 ; Compact stars in the QCD Phase Diagram medzinárodná konferencia Kľúč.slová neutron stars equation of state rho meson condensation maximum mass Delta resonances Jazyk dok. angličtina Krajina Švajčiarsko Systematika 53 Anotácia Knowledge of the equation of state (EoS) of cold and dense baryonic matter is essential for the description of properties of neutron stars (NSs). With an increase of the density, new baryon species can appear in NS matter, as well as various meson condensates. In previous works, we developed relativistic mean-field (RMF) models with hyperons and Δ -isobars, which passed the majority of known experimental constraints, including the existence of a 2 M ⊙ neutron star. In this contribution, we present results of the inclusion of ρ − -meson condensation into these models. We have shown that, in one class of the models (so-called KVOR-based models, in which the additional stiffening procedure is introduced in the isoscalar sector), the condensation gives only a small contribution to the EoS. In another class of the models (MKVOR-based models with additional stiffening in isovector sector), the condensation can lead to a first-order phase transition and a substantial decrease of the NS mass. Nevertheless, in all resulting models, the condensation does not spoil the description of the experimental constraints URL https://www.mdpi.com/2218-1997/4/1/1 Kategória publikačnej činnosti AFC Číslo archívnej kópie 43907 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov Fluctuations in non-ideal pion gas with dynamically fixed particle number Aut.údaje E. E. Kolomeitsev, D. N. Voskresensky Autor Kolomeitsev Evgeni E. 1970- (50%) UMBFP06 - Katedra fyziky
Spoluautori Voskresensky Dmitri (50%)
Zdroj.dok. Nuclear Physics A. Vol. 973, (2018), pp. 89-103. - Amsterdam : Elsevier B.V., 2018 Kľúč.slová heavy ion collisions fluctuations Hartree approximation Bose-Einsteinova kondenzácia - Bose-Einstein condensation Jazyk dok. angličtina Krajina Holandsko Systematika 53 Anotácia We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the λφ4interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms responsible for the change of the total particle number. Reactions π+π−↔π0π0, which deter-mine the isospin balance of the medium, are permitted. Within the self-consistent Hartree approximation we compute the effective pion mass, thermodynamic characteristics of the system and the variance of the particle number at temperatures above the critical point of the induced Bose–Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. We analyze conditions for the con-densate formation in the process of thermalization of an initially non-equilibrium pion gas. The normalized variance of the particle number increases with a temperature decrease but remains finite in the critical point of the Bose–Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case. In the kinetic regime of the condensate formation the variance is shown to stay finite also URL Link na plný text Kategória publikačnej činnosti ADC Číslo archívnej kópie 43902 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov Charged rho-meson condensation in neutron stars Aut.údaje Evgeni E. Kolomeitsev, K. A. Maslov ... [et al.] Autor Kolomeitsev Evgeni E. 1970- (34%) UMBFP06 - Katedra fyziky
Spoluautori Maslov K. A. (33%)
Voskresensky Dmitri (33%)
Zdroj.dok. Nuclear Physics A. Vol. 970, (2018), pp. 291-315. - Amsterdam : Elsevier B.V., 2018 Kľúč.slová neutron stars equation of state condensation Jazyk dok. angličtina Krajina Holandsko Systematika 53 Anotácia We extend relativistic mean-field models with hadron masses and meson–baryon coupling constants dependent on the scalar field σ, including hyperons and (1232)baryons, to incorporate a possibility of the charged ρmeson condensation in neutron star matter. The influence of the ρ−condensation on the equation of state proves to be strongly model dependent. In our models of one type (KVORcut-based ones) the ρ−condensation arises by a second-order phase transition above a critical density and the maximum value of the neutron star mass diminishes only slightly. The matter composition changes more significantly. In our models of other type (MKVOR*-based ones), if the system is considered at fixed density, the ρ−condensation arises by a second-order phase transition at the baryon density n =n(II)c,ρand at a slightly higher density n =n(I)c,ρthere occurs a first-order phase transition. In a neutron star matter starting with a density n <n(II)c,ρthere appears a region of a mixed phase, or the system is described by Maxwell construction, that results in a substantial decrease of the value of the maximum neutron star mass. Nevertheless in the models under consideration the observational constraint on the maximum neutron star mass is fulfilled. Besides, in MKVOR*-based models the appearance of the ρ−condensate is accompanied by a strong rearrangement of the matter composition. Dependence of the results on a choice of the ρmeson scaling functions for the effective ρmeson mass and coupling constants is also investigated URL Link na plný text Kategória publikačnej činnosti ADC Číslo archívnej kópie 43905 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov Particle number fluctuations in a non-ideal pion gas Aut.údaje Evgeni E. Kolomeitsev, Maxim E. Borisov, Dmitry N. Voskresensky Autor Kolomeitsev Evgeni E. 1970- (98%) UMBFP06 - Katedra fyziky
Spoluautori Borisov Maxim E. (1%)
Voskresensky Dmitri (1%)
Zdroj.dok. 6th international conference on new frontiers in physics (ICNFP 2017). Pp. [1-7]. - Les Ulis : Édition Diffusion Presse Sciences, 2018 ; International conference on new frontiers in physics (ICNFP 2017) medzinárodná konferencia Poznámka Príspevok je evidovaný v databáze Scopus. Kľúč.slová particle number fluctuations pion gas particle physics Jazyk dok. angličtina Krajina Francúzsko Systematika 53 Anotácia We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the lambda-phi^4 interaction. The effective Lagrangian for the description of such a system is obtained by dropping the terms responsible for the change of the total particle number. Within the self-consistent Hartree approximation, we compute the effective pion mass, thermodynamic characteristics of the system and identify a critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. The normalized variance, skewness, and kurtosis of the particle number distributions are calculated. We demonstrate that all these characteristics remain finite at the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case URL Link na zdrojový dokument Kategória publikačnej činnosti AFC Číslo archívnej kópie 43933 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Názov Delta isobars in relativistic mean-field models with sigma-scaled hadron masses and couplings Aut.údaje E. E. Kolomeitsev, K. A. Maslov, D. N. Voskresensky Autor Kolomeitsev Evgeni E. 1970- (98%) UMBFP06 - Katedra fyziky
Spoluautori Maslov Konstantin A. (1%)
Voskresensky Dmitri (1%)
Zdroj.dok. Nuclear Physics A. Vol. 961 (2017), pp. 106-141. - Amsterdam : Elsevier B.V., 2017 Kľúč.slová neutron stars equation of state heavy ion collisions Jazyk dok. angličtina Krajina Holandsko Systematika 53 Anotácia We extend the relativistic mean-field models with hadron masses and meson-baryon coupling constants dependent on the scalar sigma field, studied previously to incorporate Delta(1232) baryons. Available empirical information is analyzed to put constraints on the couplings of Delta s with meson fields. Conditions for the appearance of Delta s are studied. We demonstrate that with inclusion of the Delta s our equations of state continue to fulfill majority of known empirical constraints including the pressure-density constraint from heavy-ion collisions, the constraint on the maximum mass of the neutron stars, the direct Urea and the gravitational baryon mass ratio constraints. (C) 2017 Elsevier B.V. All rights reserved. Kategória publikačnej činnosti ADC Číslo archívnej kópie 39909 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov Condensate of excitations in moving superfluids Aut.údaje E. E. Kolomeitsev, D. N. Voskresensky Autor Kolomeitsev Evgeni E. 1970- (99%) UMBFP06 - Katedra fyziky
Spoluautori Voskresensky Dmitri (1%)
Zdroj.dok. Progress of Theoretical and Experimental Physics. No. 2 (2017), pp. [1-14]. - [Oxford] : Oxford University Press, 2017 Kľúč.slová nuclear matter Fermi liquid Jazyk dok. angličtina Krajina Spojené štáty Systematika 53 Anotácia The possibility of the condensation of excitations with non-zero momentum in rectilinearly moving and rotating superfluid bosonic and fermionic (with Cooper pairing) media is considered in terms of a phenomenological order-parameter functional at zero and non-zero temperature. The results might be applicable to the description of bosonic systems like superfluid He-4, ultracold atomic Bose gases, charged pion and kaon condensates in rotating neutron stars, and various superconducting fermionic systems with pairing, like proton and color-superconducting components in compact stars, metallic superconductors, and neutral fermionic systems with pairing, like the neutron component in compact stars and ultracold atomic Fermi gases. The order parameters of the "mother" condensate in the superfluid and the new condensate of excitations, corresponding energy gains, critical temperatures, and critical velocities are found. Kategória publikačnej činnosti ADC Číslo archívnej kópie 39051 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika Názov The effect of inclusion of delta resonances in relativistic mean-field model with scaled hadron masses and coupling constants Aut.údaje K. A. Maslov, E. E. Kolomeitsev, D. N. Voskresensky Autor Maslov Konstantin A. (1%)
Spoluautori Kolomeitsev Evgeni E. 1970- (98%) UMBFP06 - Katedra fyziky
Voskresensky Dmitri (1%)
Zdroj.dok. Journal of Physics: Conference Series. Vol. 798 (2017), pp. 1-5. - Bristol : IOP Publishing, 2017 ; International conference on particle physics and astrophysics ICPPA 2017 medzinárodná konferencia Kľúč.slová astrofyzika - astrophysics neutron stars relativita - relativity Jazyk dok. angličtina Krajina Veľká Británia Systematika 53 Anotácia © Published under licence by IOP Publishing Ltd.Knowledge of the equation of state of the baryon matter plays a decisive role in the description of neutron stars. With an increase of the baryon density the filling of Fermi seas of hyperons and Δ isobars becomes possible. Their inclusion into standard relativistic mean-field models results in a strong softening of the equation of state and a lowering of the maximum neutron star mass below the measured values. We extend a relativistic mean-field model with scaled hadron masses and coupling constants developed in our previous works and take into account now not only hyperons but also the Δ isobars. We analyze available empirical information to put constraints on coupling constants of Δs to mesonic mean fields. We show that the resulting equation of state satisfies majority of presently known experimental constraints. Kategória publikačnej činnosti AFC Číslo archívnej kópie 39068 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika