Decays of charmonium into hyperon and antihyperon pairs provide a pristine laboratory for exploring hyperon properties,such as their polarization and decay parameters,and for conducting tests of fundamental symmetries...Decays of charmonium into hyperon and antihyperon pairs provide a pristine laboratory for exploring hyperon properties,such as their polarization and decay parameters,and for conducting tests of fundamental symmetries.This brief review highlights the significant progress made in precise tests of CP symmetry at BESIII using entangled hyperon-antihyperon pairs。展开更多
The study of the charge conjugation and parity(CP)violation of hyperon is the precision frontier for probing possible new CP violation sources beyond the standard model(SM).With the large number of quantum entangled h...The study of the charge conjugation and parity(CP)violation of hyperon is the precision frontier for probing possible new CP violation sources beyond the standard model(SM).With the large number of quantum entangled hyperonantihyperon pairs to be produced at Super Tau-Charm Facility(STCF),the CP asymmetry of hyperon is expected to be tested with a statistical sensitivity of 10^(−4) or even better.To cope with the statistical precision,the systematic effects from various aspects are critical and need to be studied in detail.In this paper,the sensitivity effects on the CP violation parameters associated with the detector resolution,including those of the position and momentum,are studied and discussed in detail.The results provide valuable guidance for the design of STCF detector.展开更多
The numerical results of the populations for the baryon octet in neutron star matter have been presented by solving a set transcendental equations in the framework of the relativistic mean field approximation. The inf...The numerical results of the populations for the baryon octet in neutron star matter have been presented by solving a set transcendental equations in the framework of the relativistic mean field approximation. The influence of the hyperon interactions on hyperon populations in neutron star matter is discussed. The results manifest that when the ratio of the hyperon-to-nucleon couplings increases, all hyperons appear towards low baryon density direction.展开更多
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 structure and properties of a Keplerian rotating hyperon star with an equation of state （EOS） investigated using the relativistic σ-ω-p model are examined by employing an accurate numerical scheme. It is shown...The structure and properties of a Keplerian rotating hyperon star with an equation of state （EOS） investigated using the relativistic σ-ω-p model are examined by employing an accurate numerical scheme. It is shown that there is a clear rotating effect on the structure and properties, and that hyperon star matter cannot support a star with a mass larger than 1.9 M~, even a star rotating at the fastest allowed frequency. The constraints of the two known fastest rotating frequencies （716 Hz and 1122 Hz） on the mass and radius of a hyperon star are also explored. ~rthermore, our results indicate that the imprint of the rapid rotation of a hyperon star on the moment of inertia is clear; the backward equatorial redshift, the forward equatorial redshift and the polar redshift can be distinguished clearly, the forward equatorial redshift is always negative; and its figuration is far from a spherical symmetric shape.展开更多
In the context of the relativistic mean field theory,we propose two new hyperon coupling models,namely the limitation model and the potential well depth model,in the light of the observed data for the massive neutron ...In the context of the relativistic mean field theory,we propose two new hyperon coupling models,namely the limitation model and the potential well depth model,in the light of the observed data for the massive neutron PSR J0348+0432.The radius of PSR J0348+0432 given by the limitation model is found to be 12.52 km^12.97 km,while the radius given by the potential well depth model is found to be 12.19 km^12.89 km.We also calculate the gravitational redshift of PSR J0348+0432 within these two models,for which the limitation model gives 0.346~0.391 and the potential well depth model gives 0.350~0.409.Further exploration of these two models shows that,these two models are almost degenerate for neutron stars lighter than 1.85 M⊙,and start to give different results for massive neutron stars heavier than 1.85 M⊙.Therefore,the studies of massive neutron stars could be crucial for discriminating these two models and help deepen our understanding of hyper-nuclear interactions.展开更多
By using the new experimental data of AA potential, this paper has performed a full calculation for strange hadronic matter with different strangeness contents as well as its consequences on the global properties of n...By using the new experimental data of AA potential, this paper has performed a full calculation for strange hadronic matter with different strangeness contents as well as its consequences on the global properties of neutron star matter in relativistic mean field model. It finds that the new weak hyperon-hyperon interaction makes the equations of state much stiffer than the result of the previous strong hyperon hyperon interaction, and even stiffer than the result without consideration of hyperon-hyperon interaction. This new hyperon-hyperon interaction results in a maximum mass of 1.75M⊙ （where M⊙ stands for the mass of the Sun）, about 0.2-0.5M⊙ larger than the previous prediction with the presence of hyperons. After examining carefully the onset densities of kaon condensation it finds that this new weak version of hyperon-hyperon interaction favours the occurrence of kaons in comparison with the strong one.展开更多
With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic...With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic mean field theory （RMFT） including σ＊ and φ mesons, in comparison with the results calculated with the strong YY interaction and with no （σ＊ ,φ ） mesons included. In neutron star matter, the weak YY interaction supplies the additional repulsive interaction between hyperons while the strong YY interaction supplies the attractive one. With the weak YY interaction, the effective masses of hyperons are larger than those with the strong YY interaction while smaller than those with no （σ＊ ,φ） mesons included. The threshold star masses for the DURCA processes involving nucleons and A are not sensitive to the strength of the YY interaction. The weak YY interaction leads to larger threshold masses for the DURCA process involving [1]1 and [1]0 than the other two cases. The process involving [1]0 can take place in the neutron star only when the weak YY interaction is used. The weak YY interaction is able to bring in the agreement with the observation of the neutron star with larger mass and faster cooling than the strong YY interaction.展开更多
The properties of hadronic matter at β equilibrium in a wide range of densities are described by appropriate equations of state in the framework of the relativistic mean field model. Strange meson fields, namely the ...The properties of hadronic matter at β equilibrium in a wide range of densities are described by appropriate equations of state in the framework of the relativistic mean field model. Strange meson fields, namely the scalar meson field σ＊（975） and the vector meson field φ（1020）, are included in the present work. We discuss and compare the results of the equation of state, nucleon effective mass, and strangeness fraction obtained by adopting the TM1, TMA, and GL parameter sets for nuclear sector and three different choices for the hypcron couplings. We find that the parameter set TM1 favours the onset of hyperons most, while at high densities the GL parameter set leads to the most hyperon-rich matter. For a certain parameter set （e.g. TM1）, the most hyperon-rich matter is obtained for the hyperon potential model. The influence of the hyperon couplings on the effective mass of nucleon, is much weaker than that on the nucleon parameter set. The nonstrange mesons dominate essentially the global properties of dense hyperon matter. The hyperon potential model predicts the lowest value of the neutron star maximum mass of about 1.45 Msun to be 0.4--0.5 Msun lower than the prediction by using the other choices for hyperon couplings.展开更多
The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined. It is shown that as the appearance of hyperons softens the equation of state of the super-density matter, the frequency of gravitat...The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined. It is shown that as the appearance of hyperons softens the equation of state of the super-density matter, the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass. Moreover, the eigenfrequencies of hyperon stars also have scaling universality. It is shown that the EURO third-generation gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star.展开更多
Using an extended version of quantum hadrodynamics,I propose a new microscopic equation of state(EoS)that is able to correctly reproduce the main properties of symmetric nuclear matter at the saturation density,as wel...Using an extended version of quantum hadrodynamics,I propose a new microscopic equation of state(EoS)that is able to correctly reproduce the main properties of symmetric nuclear matter at the saturation density,as well as produce massive neutron stars and satisfactory results for the radius and the tidal parameter.I show that this EoS can reproduce at least a 2.00 solar mass neutron star,even when hyperons are present.The constraints about the radius of a 2.00 M_(⊙) and the minimum mass that enables a direct Urea effect are also checked.展开更多
The influences of hyperon-hyperon interaction on the overall properties of hadronic star are investigated in the framework of relativistic mean field （RMF） theory. For certain hyperon coupling, the weaker hyperon-hy...The influences of hyperon-hyperon interaction on the overall properties of hadronic star are investigated in the framework of relativistic mean field （RMF） theory. For certain hyperon coupling, the weaker hyperon-hyperon interaction can lead to the heavier hadronic star, which accords with the observation of heavy neutron star in X-ray binaries. We find that the threshold densities of the hyperons with larger masses are brought to a lower values with the increase of the hyperon-hyperon interaction. The possibility of the existence of hyperon star is checked with the consideration of hyperon-hyperon interaction.展开更多
The helicity amplitudes for the processes of e^＋e^- →J/ψ→γηc→γYY（Y： hyperon） are presented, together with the joint angular distributions for ηc decays into ∧∧,∑^0 ∑^0, and [1]-[1]＋. The sensitivities...The helicity amplitudes for the processes of e^＋e^- →J/ψ→γηc→γYY（Y： hyperon） are presented, together with the joint angular distributions for ηc decays into ∧∧,∑^0 ∑^0, and [1]-[1]＋. The sensitivities to measure the hyperon decay parameters in these decays are evaluated based on the helicity amplitudes. The prospects to test the Bell inequality in experiment using the decay of ηc→∧∧ are discussed.展开更多
Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/（GM2） of uniformly rotat- ing ...Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/（GM2） of uniformly rotat- ing neutron stars. It is shown that the maximum value of the spin parameter jmax of a neutron star rotating at the Keplerian frequency fK is .jmax - 0.7 when the star mass M 〉 0.SM⊙, which is sustained for various versions of equations of state without and with hyperons. The relationship between j and the scaled rotation frequency f /fK is found to be insensitive to the star mass or the adopted equation of state in the models without hyperons. However, the emergence of byperons in neutron stars will lead to an uncertainty of the spin parameter j, which in turn could generate a complexity in the theoretical study of the quasi-periodic oscillations observed in disk-accreting compact-star systems.展开更多
Hypernuclei,nuclei containing one or more hyperons,serve as unique laboratories for probing the non-perturbative quantum chromodynamics(QCD).Recent progress in hypernuclear physics,driven by advanced experimental tech...Hypernuclei,nuclei containing one or more hyperons,serve as unique laboratories for probing the non-perturbative quantum chromodynamics(QCD).Recent progress in hypernuclear physics,driven by advanced experimental techniques and theoretical innovations,is briefly reviewed with a focus on key findings and unresolved challenges,such as the precise determination of the hypertriton binding energy,investigations of charge symmetry breaking in mirror hypernuclei,and the search for exotic systems,including the neutral nnΛstate.Experimental breakthroughs,including invariant-mass analyses and femtoscopy studies in heavy-ion collisions,as well as high-resolutionγ-spectroscopy,have enabled precise studies of light hypernuclei and offered critical insights into the hyperon–nucleon interaction.Theoretical progress,including ab initio calculations based on chiral effective field theory and lattice QCD,has further enhanced our understanding of hyperon–nucleon and hyperon–hyperon interactions.展开更多
Neutron star physics has wrestled with the longstanding challenge of the hyperon puzzle,attempting to reconcile lowered theoretical predictions of maximum masses due to hyperons with astrophysical observations based o...Neutron star physics has wrestled with the longstanding challenge of the hyperon puzzle,attempting to reconcile lowered theoretical predictions of maximum masses due to hyperons with astrophysical observations based on the measured masses of the heaviest pulsars.In this study,we conduct a comprehensive statistical analysis of equations of state(EoS)for neutron stars with hyperons,including both laboratory data and astrophysical observations.Results from the statistical analysis reveal the important role of the correlations between the scalar and vector channels of hyperon-nucleon interactions deduced from availableΛ-separation-energy data of singleΛhypernuclei.The analysis preliminarily quantifies uncertainties in hyperon star properties due to the uncertain hyperon-nucleon interaction in dense matter,and the maximum mass of hyperon star is found to reach-2.2M_(⊙),challenging the existence of the hyperon puzzle.As part of a broader initiative connecting nuclear physics and astronomy to quantitatively determine neutron star EoS,the study provides valuable insights into the hyperon puzzle and its implications for our understanding of neutron star interiors.Moreover,the investigation addresses the lack of precise knowledge regarding hyperonic interactions,emphasizing the need for additional hypernuclear data through a combined effort involving theory,experiments,and observations.展开更多
Neutron star tidal deformability extracted from gravitational wave data provides a novel probe to the neutron star structures that encode the information of the nuclear equation of state(EOS).In this contribution to Q...Neutron star tidal deformability extracted from gravitational wave data provides a novel probe to the neutron star structures that encode the information of the nuclear equation of state(EOS).In this contribution to QCS2023 special issue,attention is paid to the role of the hyperon compositions and core-crust transition in the tidal deformability in a relativistic mean-field approach with the density-dependent parametrizations.Since both the corecrust transition density and the hyperon compositions involve large uncertainties in neutron stars,it is demonstrated that various core-crust transition density and hyperon compositions allowed by the parametrization can both have significant effects on the tidal deformability of neutron stars.These results are instructive for further experimental and theoretical works.展开更多
We evaluate the three-body baryon effect in the quark model to solve the hyperon puzzle.As candidates for the extra repulsive effect required to solve the puzzle,we focus on the structural repulsive core caused by the...We evaluate the three-body baryon effect in the quark model to solve the hyperon puzzle.As candidates for the extra repulsive effect required to solve the puzzle,we focus on the structural repulsive core caused by the quark-Pauli effect and the color-magnetic term.The result is that in the lowest thresholdΛNN system,no significant structural repulsive core is obtained,but a strong repulsive three-body effect is obtained from the color-magnetic term.展开更多
The difference between the transition density of a larger mass hyperon star （for example, the neutron star PSR J1614-2230） and that of a smaller mass hyperon star is investigated in the framework of the relativistic...The difference between the transition density of a larger mass hyperon star （for example, the neutron star PSR J1614-2230） and that of a smaller mass hyperon star is investigated in the framework of the relativistic mean field theory. We see that the transition density p0H increases with the increase of xw （i.e. the mass of the neutron star）. For the nucleons parts, the neutrons make the main contribution to the transition density as the baryon density P=p0H. With the increase of the xw （i.e. the mass of the neutron star）, the relative particle number density of neutrons decreases while that of protons increases. For the parts of hyperons, the ∧ and ≡. make the main contributions to the transition density as the baryon density p=p0H. The relative particle number density of A decreases while that of ≡ increases with the increase of the xw （i.e. the mass of the neutron star）. For the hyperons ∑-, ∑0 and E-, the total contributions are less than 16 per cent.展开更多
Weak radiative hyperon decays,important to test the strong interaction and relevant in searches for beyond the standard model physics,have remained puzzling both experimentally and theoretically for a long time.The re...Weak radiative hyperon decays,important to test the strong interaction and relevant in searches for beyond the standard model physics,have remained puzzling both experimentally and theoretically for a long time.The recently updated branching fraction and first measurement of the asymmetry parameter of Λ→nγ by the BESIII Collaboration further exacerbate the issue,as none of the existing predictions can describe the data.We show in this work that the covariant baryon chiral perturbation theory,with constraints from the latest measurements of hyperon non-leptonic decays,can well describe the BESIII data.The predicted branching fraction and asymmetry parameter for Ξ→Σγ are also in agreement with the experimental data.We note that a more precise measurement of the asymmetry parameter,which is strongly constrained by chiral symmetry and related with that of Σ→pγ,is crucial to test Hara’s theorem.We further predict the branching fraction and asymmetry parameter of Σ~0→nγ,whose future measurement can serve as a highly nontrivial check on our understanding of weak radiative hyperon decays and on the covariant baryon chiral perturbation theory.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12225509),the National Natural Science Foundation of China(Grant No.12247101)the Polish National Science Centre(Grant No.2024/53/B/ST2/00975)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2024-jdzx06)the Natural Science Foundation of Gansu Province(Grant No.22JR5RA389)the‘111 Center’under Grant No.B20063。
文摘Decays of charmonium into hyperon and antihyperon pairs provide a pristine laboratory for exploring hyperon properties,such as their polarization and decay parameters,and for conducting tests of fundamental symmetries.This brief review highlights the significant progress made in precise tests of CP symmetry at BESIII using entangled hyperon-antihyperon pairs。
基金supported by the National Key R&D Program of China(2022YFA1602200)the International Partnership Program of the Chinese Academy of Sciences(211134KYSB20200057).
文摘The study of the charge conjugation and parity(CP)violation of hyperon is the precision frontier for probing possible new CP violation sources beyond the standard model(SM).With the large number of quantum entangled hyperonantihyperon pairs to be produced at Super Tau-Charm Facility(STCF),the CP asymmetry of hyperon is expected to be tested with a statistical sensitivity of 10^(−4) or even better.To cope with the statistical precision,the systematic effects from various aspects are critical and need to be studied in detail.In this paper,the sensitivity effects on the CP violation parameters associated with the detector resolution,including those of the position and momentum,are studied and discussed in detail.The results provide valuable guidance for the design of STCF detector.
基金The project supported by National Natural Science Foundation of China under Grant Nos.10047001 and 10275029+2 种基金the State Key Basic Research Development Program under Grant No.G2000-0774-07the CAS Knowledge Innovation Project under Contract No.KJCX2-SW-N02
文摘The numerical results of the populations for the baryon octet in neutron star matter have been presented by solving a set transcendental equations in the framework of the relativistic mean field approximation. The influence of the hyperon interactions on hyperon populations in neutron star matter is discussed. The results manifest that when the ratio of the hyperon-to-nucleon couplings increases, all hyperons appear towards low baryon density direction.
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 (Grant No. 10947023)the Fundamental Research Funds for the Central University,China (Grant No. 2009ZM0193)
文摘The structure and properties of a Keplerian rotating hyperon star with an equation of state （EOS） investigated using the relativistic σ-ω-p model are examined by employing an accurate numerical scheme. It is shown that there is a clear rotating effect on the structure and properties, and that hyperon star matter cannot support a star with a mass larger than 1.9 M~, even a star rotating at the fastest allowed frequency. The constraints of the two known fastest rotating frequencies （716 Hz and 1122 Hz） on the mass and radius of a hyperon star are also explored. ~rthermore, our results indicate that the imprint of the rapid rotation of a hyperon star on the moment of inertia is clear; the backward equatorial redshift, the forward equatorial redshift and the polar redshift can be distinguished clearly, the forward equatorial redshift is always negative; and its figuration is far from a spherical symmetric shape.
基金Supported by the National Key R&D Program of China under Grant Nos.2018YFA0404403,2016YFE0129300the National Natural Science Foundation of China under Grant Nos.11535004,11761161001,11375086,11120101005,11175085,11235001,11565010,and 11881240623+1 种基金the Science and Technology Development Fund of Macao under Grant No.008/2017/AFJsupported by a Project funded by China Postdoctoral Science Foundation under Grant No.2018M640470
文摘In the context of the relativistic mean field theory,we propose two new hyperon coupling models,namely the limitation model and the potential well depth model,in the light of the observed data for the massive neutron PSR J0348+0432.The radius of PSR J0348+0432 given by the limitation model is found to be 12.52 km^12.97 km,while the radius given by the potential well depth model is found to be 12.19 km^12.89 km.We also calculate the gravitational redshift of PSR J0348+0432 within these two models,for which the limitation model gives 0.346~0.391 and the potential well depth model gives 0.350~0.409.Further exploration of these two models shows that,these two models are almost degenerate for neutron stars lighter than 1.85 M⊙,and start to give different results for massive neutron stars heavier than 1.85 M⊙.Therefore,the studies of massive neutron stars could be crucial for discriminating these two models and help deepen our understanding of hyper-nuclear interactions.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10575119 and 10235030）, the Knowledge Innovation Project （Grant No KJCX2-SW-N02） of Chinese Academy of Sciences, the Major State Basic Research Development Program of China （Grant No G2000077400）, the Major Prophase Research Project of Fundamental Research of the Ministry of Science and Technology of China （Grant No 2002CCB00200）, and the Asia Europe Link project （Grant No CN/ASIA-LINK/008（94791）） of the European Commission.
文摘By using the new experimental data of AA potential, this paper has performed a full calculation for strange hadronic matter with different strangeness contents as well as its consequences on the global properties of neutron star matter in relativistic mean field model. It finds that the new weak hyperon-hyperon interaction makes the equations of state much stiffer than the result of the previous strong hyperon hyperon interaction, and even stiffer than the result without consideration of hyperon-hyperon interaction. This new hyperon-hyperon interaction results in a maximum mass of 1.75M⊙ （where M⊙ stands for the mass of the Sun）, about 0.2-0.5M⊙ larger than the previous prediction with the presence of hyperons. After examining carefully the onset densities of kaon condensation it finds that this new weak version of hyperon-hyperon interaction favours the occurrence of kaons in comparison with the strong one.
基金Supported by the Natural Science Fundamental Research Project of Jiangsu Colleges and Universities under Grant No.10KJB140002
文摘With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic mean field theory （RMFT） including σ＊ and φ mesons, in comparison with the results calculated with the strong YY interaction and with no （σ＊ ,φ ） mesons included. In neutron star matter, the weak YY interaction supplies the additional repulsive interaction between hyperons while the strong YY interaction supplies the attractive one. With the weak YY interaction, the effective masses of hyperons are larger than those with the strong YY interaction while smaller than those with no （σ＊ ,φ） mesons included. The threshold star masses for the DURCA processes involving nucleons and A are not sensitive to the strength of the YY interaction. The weak YY interaction leads to larger threshold masses for the DURCA process involving [1]1 and [1]0 than the other two cases. The process involving [1]0 can take place in the neutron star only when the weak YY interaction is used. The weak YY interaction is able to bring in the agreement with the observation of the neutron star with larger mass and faster cooling than the strong YY interaction.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10575119 and 10235030）, the Knowledge Innovation Program of Chinese Academy of Sciences （Grant No KJCX2-SW-N02）, the State Key Development Program for Basic Research of China （Grant No G2000077400）, the Key Preresearch Program of the Ministry of Science and Technology of China （Grant No 2002CCB00200）, and the Asia Europe Link project of the European Commission （Grant No CN/ASIA-LINK/008（94791））.
文摘The properties of hadronic matter at β equilibrium in a wide range of densities are described by appropriate equations of state in the framework of the relativistic mean field model. Strange meson fields, namely the scalar meson field σ＊（975） and the vector meson field φ（1020）, are included in the present work. We discuss and compare the results of the equation of state, nucleon effective mass, and strangeness fraction obtained by adopting the TM1, TMA, and GL parameter sets for nuclear sector and three different choices for the hypcron couplings. We find that the parameter set TM1 favours the onset of hyperons most, while at high densities the GL parameter set leads to the most hyperon-rich matter. For a certain parameter set （e.g. TM1）, the most hyperon-rich matter is obtained for the hyperon potential model. The influence of the hyperon couplings on the effective mass of nucleon, is much weaker than that on the nucleon parameter set. The nonstrange mesons dominate essentially the global properties of dense hyperon matter. The hyperon potential model predicts the lowest value of the neutron star maximum mass of about 1.45 Msun to be 0.4--0.5 Msun lower than the prediction by using the other choices for hyperon couplings.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10947023)the Fundamental Research Funds for the Central Universities (Grant No. 2012ZZ0079)
文摘The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined. It is shown that as the appearance of hyperons softens the equation of state of the super-density matter, the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass. Moreover, the eigenfrequencies of hyperon stars also have scaling universality. It is shown that the EURO third-generation gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star.
文摘Using an extended version of quantum hadrodynamics,I propose a new microscopic equation of state(EoS)that is able to correctly reproduce the main properties of symmetric nuclear matter at the saturation density,as well as produce massive neutron stars and satisfactory results for the radius and the tidal parameter.I show that this EoS can reproduce at least a 2.00 solar mass neutron star,even when hyperons are present.The constraints about the radius of a 2.00 M_(⊙) and the minimum mass that enables a direct Urea effect are also checked.
文摘The influences of hyperon-hyperon interaction on the overall properties of hadronic star are investigated in the framework of relativistic mean field （RMF） theory. For certain hyperon coupling, the weaker hyperon-hyperon interaction can lead to the heavier hadronic star, which accords with the observation of heavy neutron star in X-ray binaries. We find that the threshold densities of the hyperons with larger masses are brought to a lower values with the increase of the hyperon-hyperon interaction. The possibility of the existence of hyperon star is checked with the consideration of hyperon-hyperon interaction.
基金Supported by the National Natural Science Foundation of ChinaYouth Innovation Project of IHEPthe Innovation Projcct of Guangxi Graduate Eduction under Grant No. 2007106020702M54
文摘The helicity amplitudes for the processes of e^＋e^- →J/ψ→γηc→γYY（Y： hyperon） are presented, together with the joint angular distributions for ηc decays into ∧∧,∑^0 ∑^0, and [1]-[1]＋. The sensitivities to measure the hyperon decay parameters in these decays are evaluated based on the helicity amplitudes. The prospects to test the Bell inequality in experiment using the decay of ηc→∧∧ are discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175108,U1432119,1146114100,11205075,11375076 and 11475104the Shandong Natural Science Foundation under Grant No ZR2014AQ012the Foundation of Shandong University under Grant No 2015WHWLJH01
文摘Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/（GM2） of uniformly rotat- ing neutron stars. It is shown that the maximum value of the spin parameter jmax of a neutron star rotating at the Keplerian frequency fK is .jmax - 0.7 when the star mass M 〉 0.SM⊙, which is sustained for various versions of equations of state without and with hyperons. The relationship between j and the scaled rotation frequency f /fK is found to be insensitive to the star mass or the adopted equation of state in the models without hyperons. However, the emergence of byperons in neutron stars will lead to an uncertainty of the spin parameter j, which in turn could generate a complexity in the theoretical study of the quasi-periodic oscillations observed in disk-accreting compact-star systems.
基金supported by the the National Key R&D Program of China(Grant Nos.2022YFA1604900 and 2023YFA1606703)the National Natural Science Foundation of China(Grant Nos.12025501,12435007,12405133,and 12347180)+1 种基金China Postdoctoral Science Foundation(Grant No.2023M740189)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233381).
文摘Hypernuclei,nuclei containing one or more hyperons,serve as unique laboratories for probing the non-perturbative quantum chromodynamics(QCD).Recent progress in hypernuclear physics,driven by advanced experimental techniques and theoretical innovations,is briefly reviewed with a focus on key findings and unresolved challenges,such as the precise determination of the hypertriton binding energy,investigations of charge symmetry breaking in mirror hypernuclei,and the search for exotic systems,including the neutral nnΛstate.Experimental breakthroughs,including invariant-mass analyses and femtoscopy studies in heavy-ion collisions,as well as high-resolutionγ-spectroscopy,have enabled precise studies of light hypernuclei and offered critical insights into the hyperon–nucleon interaction.Theoretical progress,including ab initio calculations based on chiral effective field theory and lattice QCD,has further enhanced our understanding of hyperon–nucleon and hyperon–hyperon interactions.
文摘Neutron star physics has wrestled with the longstanding challenge of the hyperon puzzle,attempting to reconcile lowered theoretical predictions of maximum masses due to hyperons with astrophysical observations based on the measured masses of the heaviest pulsars.In this study,we conduct a comprehensive statistical analysis of equations of state(EoS)for neutron stars with hyperons,including both laboratory data and astrophysical observations.Results from the statistical analysis reveal the important role of the correlations between the scalar and vector channels of hyperon-nucleon interactions deduced from availableΛ-separation-energy data of singleΛhypernuclei.The analysis preliminarily quantifies uncertainties in hyperon star properties due to the uncertain hyperon-nucleon interaction in dense matter,and the maximum mass of hyperon star is found to reach-2.2M_(⊙),challenging the existence of the hyperon puzzle.As part of a broader initiative connecting nuclear physics and astronomy to quantitatively determine neutron star EoS,the study provides valuable insights into the hyperon puzzle and its implications for our understanding of neutron star interiors.Moreover,the investigation addresses the lack of precise knowledge regarding hyperonic interactions,emphasizing the need for additional hypernuclear data through a combined effort involving theory,experiments,and observations.
文摘Neutron star tidal deformability extracted from gravitational wave data provides a novel probe to the neutron star structures that encode the information of the nuclear equation of state(EOS).In this contribution to QCS2023 special issue,attention is paid to the role of the hyperon compositions and core-crust transition in the tidal deformability in a relativistic mean-field approach with the density-dependent parametrizations.Since both the corecrust transition density and the hyperon compositions involve large uncertainties in neutron stars,it is demonstrated that various core-crust transition density and hyperon compositions allowed by the parametrization can both have significant effects on the tidal deformability of neutron stars.These results are instructive for further experimental and theoretical works.
文摘We evaluate the three-body baryon effect in the quark model to solve the hyperon puzzle.As candidates for the extra repulsive effect required to solve the puzzle,we focus on the structural repulsive core caused by the quark-Pauli effect and the color-magnetic term.The result is that in the lowest thresholdΛNN system,no significant structural repulsive core is obtained,but a strong repulsive three-body effect is obtained from the color-magnetic term.
基金Supported by Anhui Provincial Natural Science Foundation(1208085MA09)Scientific Research Program Foundation of the Higher Education Institutions of Anhui Province"Study on the Massive Neutron Star PSR J0348+0432 in the Framework of Relativistic Mean Field Theory"and Fundamental Research Funds for the Central Universities(SWJTU12ZT11)
文摘The difference between the transition density of a larger mass hyperon star （for example, the neutron star PSR J1614-2230） and that of a smaller mass hyperon star is investigated in the framework of the relativistic mean field theory. We see that the transition density p0H increases with the increase of xw （i.e. the mass of the neutron star）. For the nucleons parts, the neutrons make the main contribution to the transition density as the baryon density P=p0H. With the increase of the xw （i.e. the mass of the neutron star）, the relative particle number density of neutrons decreases while that of protons increases. For the parts of hyperons, the ∧ and ≡. make the main contributions to the transition density as the baryon density p=p0H. The relative particle number density of A decreases while that of ≡ increases with the increase of the xw （i.e. the mass of the neutron star）. For the hyperons ∑-, ∑0 and E-, the total contributions are less than 16 per cent.
基金supported in part by the National Natural Science Foundation of China (11735003, 11975041, and11961141004)support from the National Natural Science Foundation of China (12147145)+2 种基金support from the National Natural Science Foundation of China (12105006)Project funded by China Postdoctoral Science Foundation (2021M700343)China Postdoctoral Science Foundation (2021M690008)
文摘Weak radiative hyperon decays,important to test the strong interaction and relevant in searches for beyond the standard model physics,have remained puzzling both experimentally and theoretically for a long time.The recently updated branching fraction and first measurement of the asymmetry parameter of Λ→nγ by the BESIII Collaboration further exacerbate the issue,as none of the existing predictions can describe the data.We show in this work that the covariant baryon chiral perturbation theory,with constraints from the latest measurements of hyperon non-leptonic decays,can well describe the BESIII data.The predicted branching fraction and asymmetry parameter for Ξ→Σγ are also in agreement with the experimental data.We note that a more precise measurement of the asymmetry parameter,which is strongly constrained by chiral symmetry and related with that of Σ→pγ,is crucial to test Hara’s theorem.We further predict the branching fraction and asymmetry parameter of Σ~0→nγ,whose future measurement can serve as a highly nontrivial check on our understanding of weak radiative hyperon decays and on the covariant baryon chiral perturbation theory.
