We discuss the Casimir force of Maxwell-Chern-Simons A belian gauge tield in different limits between twoparallel ideal conducting wires by using the Feynman path integral method.
In the framework of the relativistic mean field theory （RMFT）, the relativistic energy losses of the direct Urea processes with hyperons （Y-DURCA ） for reactions A → p ＋ e ＋ υe and ≡^-→ A＋e＋υe are studied...In the framework of the relativistic mean field theory （RMFT）, the relativistic energy losses of the direct Urea processes with hyperons （Y-DURCA ） for reactions A → p ＋ e ＋ υe and ≡^-→ A＋e＋υe are studied in neutron stars. We calculate the energy gap of A hyperons and investigate the effects of the ^1S0 superfluidity （SF） of A hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data △ BAA ～ 1.01 ±0.20-0.11^＋0.18 MeV. The results indicate that the ^1S0 SF of A hyperons exists in most density ranges of happening the two reactions. The theoretical cooling curves are in agreement with observation data.展开更多
The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor...The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.展开更多
The quark potential model is used to investigate the low-energy elastic scattering of πN system. The model potential consists of the t-channel and s-channel one-gluon exchange potentials and the harmonic oscillator c...The quark potential model is used to investigate the low-energy elastic scattering of πN system. The model potential consists of the t-channel and s-channel one-gluon exchange potentials and the harmonic oscillator confining potential. By means of the resonating group method, a nonlocal effective potential for the πN system is derived from the interquark potentials and used to calculate the πN elastic scattering phase shifts. By considering the effect of QCD renormalization, the suppression of the spin-orbital coupling and the contribution of the color octet of the clusters （qq） and （qqq）, the numerical results are in fairly good agreement with the experimental data. The same model and method are employed to investigate the possible πN resonances. For this purpose, the resonating group equation is transformed into a standard Schrodinger equation in which the nonlocal effective πN interaction potential is included. Solving the Schrodinger equation by the variational method, we are able to reproduce the masses of some currently concerned πN resonances.展开更多
In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The ca...In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.展开更多
In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can oc...In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly.展开更多
In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We inves...In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the Y-DURCA processes on the N-DURCA processes,and the total neutrino emissivity of neutron star matter.The results show that the existence of hyperons decreases the abundance of protons and leptons,and can sharply suppress the neutrino emissivity of the N-DURCA processes.展开更多
In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degre...In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.展开更多
Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calc...Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a (∧∧) pair. The parameter set we use is in line with the recent experimental data △B_(∧∧) ~ 1.01 ± 0.20_+0.18-0.11 MeV.It is found that with σ^(*) and φ mesons the pairing energy gap △F of ∧ hyperons and the corresponding SF critical temperature T_(C∧) are suppressed.In addition the NS mass range of ∧ hyperon SF is enlarged obviously.展开更多
We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interact...We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.展开更多
The necessary and sufficient condition of the existence of the Fock-like space for quons with a fixed number q is proven, and the uniqueness theorem of the Fock-like space is given. The general-q operators, which sati...The necessary and sufficient condition of the existence of the Fock-like space for quons with a fixed number q is proven, and the uniqueness theorem of the Fock-like space is given. The general-q operators, which satisfy the q-mutation relation a_ja_k - qa_ka_j =δ_jk, areconstructed by using the q = 0 operators as standard building blocks. The Fock-like spaces for quons with q∈(-1,1) prove to be the same as the one with q = 0, which manifestly is the direct sum of all the tensor product powers of the single particle state subspace, hence allow only the Boltzmann statistics .展开更多
Working in the physics of Wilson factor and Aharonov-Bohm effect, we find in the fluxtubequark system the topology of a baryon consisting of three heavy flavor quarks resembles that of the fractional quantum Hall effe...Working in the physics of Wilson factor and Aharonov-Bohm effect, we find in the fluxtubequark system the topology of a baryon consisting of three heavy flavor quarks resembles that of the fractional quantum Hall effect （FQHE） in condensed matter. This similarity yields the result that the constituent quarks of baryon have the ＂filling factor＂ 1/3, thus the previous conjecture that quark confinement is a correlation effect is confirmed. Moreover, by deriving a Hamiltonian of the system analogous to that of FQHE, we predict an energy gap for the ground state of a heavy three-quark system.展开更多
Based on a general variational principle, Einstein–Hilbert action and sound facts from geometry, it is shown that the long existing pseudotensor, non-localizability problem of gravitational energy-momentum is a resul...Based on a general variational principle, Einstein–Hilbert action and sound facts from geometry, it is shown that the long existing pseudotensor, non-localizability problem of gravitational energy-momentum is a result of mistaking different geometrical, physical ob jects as one and the same. It is also pointed out that in a curved spacetime, the sum vector of matter energy-momentum over a finite hyper-surface can not be defined. In curvilinear coordinate systems conservation of matter energy-momentum is not the continuity equations for its components. Conservation of matter energy-momentum is the vanishing of the covariant divergence of its density-flux tensor field. Introducing gravitational energy-momentum to save the law of conservation of energy-momentum is unnecessary and improper. After reasonably defining "change of a particle's energy-momentum", we show that gravitational field does not exchange energy-momentum with particles. And it does not exchange energy-momentum with matter fields either. Therefore, the gravitational field does not carry energy-momentum, it is not a force field and gravity is not a natural force.展开更多
The presence of the isovector scalar interaction in neutron star matter is considered by exchangingδmeson;we study the effects ofδmesons on the direct Urca processes involving hyperons.The calculation is based on th...The presence of the isovector scalar interaction in neutron star matter is considered by exchangingδmeson;we study the effects ofδmesons on the direct Urca processes involving hyperons.The calculation is based on the framework of the relativistic mean field theory.By our analysis,the hyperon direct Urca processes under beta equilibrium are open at lower densities due toδmesons,which create a larger energy gap between two baryons in the reactions.Theδmeson leads to an obvious enhancement of the neutrino emissivity for the hyperon direct Urca processes.In particular,the relativistic neutrino emissivity is found to be substantially larger than predicted in the nonrelativistic approach whetherδmesons appear in an neutron star or not.In our results,δmesons not only change the baryons properties,but also result in more rapid cooling rate of neutron stars by hyperon direct Urca processes.展开更多
This study investigates the relativistic neutrino emissivity of the nucleonic and hyperonic direct Urca processes in the degenerate baryon matter of neutron stars, within the framework of relativistic mean field theor...This study investigates the relativistic neutrino emissivity of the nucleonic and hyperonic direct Urca processes in the degenerate baryon matter of neutron stars, within the framework of relativistic mean field theory. In particular, we study the influence of the isovector scalar interaction on the nucleonic and hyperonic direct Urca processes by exchanging δ mesons. The results indicate that δ mesons lead to obvious enhancement of the total neutrino emissivity, which must result in a more rapid cooling rate of neutron star matter.展开更多
In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that...In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that relativistic effect makes the neutrino emissivity,neutrino luminosity and cooling rate lower,compared with the nonrelativistic case.And the influence of relativistic effect grows with the mass of the neutron star.GPS300 set leads to the biggest fall in neutrino emissivity,whereas GM1 set leads to the largest disparity in cooling rate caused by relativistic effect.展开更多
Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn...Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle interactions.The dependence on the different nuclear matrix elements is observed,and the results are explained.We also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation energies.Finally,we present our results for the half-lives of this decay mode for different nuclei.展开更多
A detailed description of the baryon direct Urca processes A: n → p + e + ν_e, B: Λ→ p + e + ν_e and C: Ξ^-→Λ + e + ν_e related to the neutron star cooling is given in the relativistic mean field approximatio...A detailed description of the baryon direct Urca processes A: n → p + e + ν_e, B: Λ→ p + e + ν_e and C: Ξ^-→Λ + e + ν_e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range(1.603–2.067) M_⊙((1.515–1.840) M_⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton ~1S_0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton ~1S_0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling.展开更多
Effects of gravitational correction through the introduction of U bosons on neutron stars with antikaon condensation are studied in the relativistic mean field theory. How the global properties of neutron stars, redsh...Effects of gravitational correction through the introduction of U bosons on neutron stars with antikaon condensation are studied in the relativistic mean field theory. How the global properties of neutron stars, redshift and the momentum of inertia are modified by gravitational correction and antikaon condensation are discussed here. Results show that antikaon condensation can occur at the core of pulsar PSR J1614-2230. Gravitational correction and antikaon condensation influence each other, and when coupling constant of U bosons and baryons becomes very high, effects of antikaon condensation almost vanish. Moreover, both the redshift and the momentum of inertia of neutron stars are sensitive to the constant of U bosons. Combining with observation data, we can provide a further constraint on coupling constant of U bosons.展开更多
文摘We discuss the Casimir force of Maxwell-Chern-Simons A belian gauge tield in different limits between twoparallel ideal conducting wires by using the Feynman path integral method.
基金Supported by National Natural Science Foundation of China under Grant Nos. 10675024, 11075063the National Fundamental Fund project Subsidy Funds of Personnel Training J0730311
文摘In the framework of the relativistic mean field theory （RMFT）, the relativistic energy losses of the direct Urea processes with hyperons （Y-DURCA ） for reactions A → p ＋ e ＋ υe and ≡^-→ A＋e＋υe are studied in neutron stars. We calculate the energy gap of A hyperons and investigate the effects of the ^1S0 superfluidity （SF） of A hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data △ BAA ～ 1.01 ±0.20-0.11^＋0.18 MeV. The results indicate that the ^1S0 SF of A hyperons exists in most density ranges of happening the two reactions. The theoretical cooling curves are in agreement with observation data.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11447165,11373047 and 11265009the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2016056
文摘The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.
基金The project supported by National Natural Science Foundation of China under Grant No.10675054
文摘The quark potential model is used to investigate the low-energy elastic scattering of πN system. The model potential consists of the t-channel and s-channel one-gluon exchange potentials and the harmonic oscillator confining potential. By means of the resonating group method, a nonlocal effective potential for the πN system is derived from the interquark potentials and used to calculate the πN elastic scattering phase shifts. By considering the effect of QCD renormalization, the suppression of the spin-orbital coupling and the contribution of the color octet of the clusters （qq） and （qqq）, the numerical results are in fairly good agreement with the experimental data. The same model and method are employed to investigate the possible πN resonances. For this purpose, the resonating group equation is transformed into a standard Schrodinger equation in which the nonlocal effective πN interaction potential is included. Solving the Schrodinger equation by the variational method, we are able to reproduce the masses of some currently concerned πN resonances.
基金supported by National Natural Science Foundation of China (Nos.10675024,11075063)National Fundamental Fund Project of Subsidy Funds of Personnel Training of China (J0730311)
文摘In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.
基金Supported in part by National Natural Science Foundation of China under Grant Nos.10275029 and 10675054
文摘In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly.
基金by the National Natural Science Foundation of China under Grant Nos 10675024 and 11075063the National Fundamental Project for Subsidy Funds of Personnel Training J0730311.
文摘In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the Y-DURCA processes on the N-DURCA processes,and the total neutrino emissivity of neutron star matter.The results show that the existence of hyperons decreases the abundance of protons and leptons,and can sharply suppress the neutrino emissivity of the N-DURCA processes.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11075063,11073033,11247312 and 11103047.
文摘In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10675024 and 11075063the National Fundamental Fund Project in Subsidy Funds of Personnel Training J0730311.
文摘Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a (∧∧) pair. The parameter set we use is in line with the recent experimental data △B_(∧∧) ~ 1.01 ± 0.20_+0.18-0.11 MeV.It is found that with σ^(*) and φ mesons the pairing energy gap △F of ∧ hyperons and the corresponding SF critical temperature T_(C∧) are suppressed.In addition the NS mass range of ∧ hyperon SF is enlarged obviously.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11075063,11073033,11247312 and 11103047.
文摘We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.
基金Project supported in part by the National Natural Science Foundation of China.
文摘The necessary and sufficient condition of the existence of the Fock-like space for quons with a fixed number q is proven, and the uniqueness theorem of the Fock-like space is given. The general-q operators, which satisfy the q-mutation relation a_ja_k - qa_ka_j =δ_jk, areconstructed by using the q = 0 operators as standard building blocks. The Fock-like spaces for quons with q∈(-1,1) prove to be the same as the one with q = 0, which manifestly is the direct sum of all the tensor product powers of the single particle state subspace, hence allow only the Boltzmann statistics .
文摘Working in the physics of Wilson factor and Aharonov-Bohm effect, we find in the fluxtubequark system the topology of a baryon consisting of three heavy flavor quarks resembles that of the fractional quantum Hall effect （FQHE） in condensed matter. This similarity yields the result that the constituent quarks of baryon have the ＂filling factor＂ 1/3, thus the previous conjecture that quark confinement is a correlation effect is confirmed. Moreover, by deriving a Hamiltonian of the system analogous to that of FQHE, we predict an energy gap for the ground state of a heavy three-quark system.
文摘Based on a general variational principle, Einstein–Hilbert action and sound facts from geometry, it is shown that the long existing pseudotensor, non-localizability problem of gravitational energy-momentum is a result of mistaking different geometrical, physical ob jects as one and the same. It is also pointed out that in a curved spacetime, the sum vector of matter energy-momentum over a finite hyper-surface can not be defined. In curvilinear coordinate systems conservation of matter energy-momentum is not the continuity equations for its components. Conservation of matter energy-momentum is the vanishing of the covariant divergence of its density-flux tensor field. Introducing gravitational energy-momentum to save the law of conservation of energy-momentum is unnecessary and improper. After reasonably defining "change of a particle's energy-momentum", we show that gravitational field does not exchange energy-momentum with particles. And it does not exchange energy-momentum with matter fields either. Therefore, the gravitational field does not carry energy-momentum, it is not a force field and gravity is not a natural force.
基金partially supported by the National Natural Science Foundation of China(11075063,11073033,11247312,and 11103047)
文摘The presence of the isovector scalar interaction in neutron star matter is considered by exchangingδmeson;we study the effects ofδmesons on the direct Urca processes involving hyperons.The calculation is based on the framework of the relativistic mean field theory.By our analysis,the hyperon direct Urca processes under beta equilibrium are open at lower densities due toδmesons,which create a larger energy gap between two baryons in the reactions.Theδmeson leads to an obvious enhancement of the neutrino emissivity for the hyperon direct Urca processes.In particular,the relativistic neutrino emissivity is found to be substantially larger than predicted in the nonrelativistic approach whetherδmesons appear in an neutron star or not.In our results,δmesons not only change the baryons properties,but also result in more rapid cooling rate of neutron stars by hyperon direct Urca processes.
基金Supported by Natural Science Foundation of China(11447165,11373047,11303063)
文摘This study investigates the relativistic neutrino emissivity of the nucleonic and hyperonic direct Urca processes in the degenerate baryon matter of neutron stars, within the framework of relativistic mean field theory. In particular, we study the influence of the isovector scalar interaction on the nucleonic and hyperonic direct Urca processes by exchanging δ mesons. The results indicate that δ mesons lead to obvious enhancement of the total neutrino emissivity, which must result in a more rapid cooling rate of neutron star matter.
基金Supported in part by National Natural Science Foundation of China under Grant Nos.11265009,11175077,11271055General Project of Liaoning Provincial Department of Education under Grant No.L2015005
文摘In the relativistic mean field theory and cooling theories,relativistic correction on neutrino emission from neutron stars in four typical nuclear parameter sets,GM1,GL85,GPS250 and GPS300 is studied.Results show that relativistic effect makes the neutrino emissivity,neutrino luminosity and cooling rate lower,compared with the nonrelativistic case.And the influence of relativistic effect grows with the mass of the neutron star.GPS300 set leads to the biggest fall in neutrino emissivity,whereas GM1 set leads to the largest disparity in cooling rate caused by relativistic effect.
基金Supported by National Natural Science Foundation of China(11505078,1164730)“Light of West China”Program and key research program(XDPB09-2)from Chinese Academy of Sciences。
文摘Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle interactions.The dependence on the different nuclear matrix elements is observed,and the results are explained.We also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation energies.Finally,we present our results for the half-lives of this decay mode for different nuclei.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11447165,11373047,11404336 and U1731240Youth Innovation Promotion Association,CAS under Grant No.2016056the Development Project of Science and Technology of Jilin Province under Grant No.20180520077JH
文摘A detailed description of the baryon direct Urca processes A: n → p + e + ν_e, B: Λ→ p + e + ν_e and C: Ξ^-→Λ + e + ν_e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range(1.603–2.067) M_⊙((1.515–1.840) M_⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton ~1S_0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton ~1S_0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling.
基金Supported by National Natural Science Foundation of China under Grant Nos.11265009,11271055,and 11175077General Project of Liaoning Provincial Department of Education under Grant No.L2015005
文摘Effects of gravitational correction through the introduction of U bosons on neutron stars with antikaon condensation are studied in the relativistic mean field theory. How the global properties of neutron stars, redshift and the momentum of inertia are modified by gravitational correction and antikaon condensation are discussed here. Results show that antikaon condensation can occur at the core of pulsar PSR J1614-2230. Gravitational correction and antikaon condensation influence each other, and when coupling constant of U bosons and baryons becomes very high, effects of antikaon condensation almost vanish. Moreover, both the redshift and the momentum of inertia of neutron stars are sensitive to the constant of U bosons. Combining with observation data, we can provide a further constraint on coupling constant of U bosons.
