Topological band theory has been studied for free fermions for decades,and one of the most profound physical results is the bulk-boundary correspondence.Recently a focus in topological physics is extending topological...Topological band theory has been studied for free fermions for decades,and one of the most profound physical results is the bulk-boundary correspondence.Recently a focus in topological physics is extending topological classification to mixed states.Here,we focus on Gaussian mixed states for which the modular Hamiltonians of the density matrix are quadratic free fermion models with U(1)symmetry and can be classified by topological invariants.The bulk-boundary correspondence is then manifested as stable gapless modes of the modular Hamiltonian and degenerate spectrum of the density matrix.In this article,we show that these gapless modes can be detected by the full counting statistics,mathematically described by a function introduced as F(θ).A divergent derivative atθ=πcan be used to probe the gapless modes in the modular Hamiltonian.Based on this,a topological indicator,whose quantization to unity senses topologically nontrivial mixed states,is introduced.We present the physical intuition of these results and also demonstrate these results with concrete models in both one-and two-dimensions.Our results pave the way for revealing the physical significance of topology in mixed states.展开更多
Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s co...Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. Here, a deeper investigation of the free fermion internal frequency is discussed, hinting to an exchange interaction between the two components of which a fermion is made of. An upper limit estimate is given to the strength of this interaction.展开更多
We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay betwe...We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay between non-Hermiticity and birefringence leads to distinct behaviors in two and three dimensions, where the system exhibits different fixed points and scaling properties due to dimension-dependent charge renormalization effects. In two dimensions, where the electronic charge remains unrenormalized, the system flows in the deep infrared limit from non-Hermitian birefringent spin-3/2fermions to two copies of non-Hermitian spin-1/2 Dirac fermions, demonstrating a crossover of relativistic liquid and nonrelativistic liquid. In three dimensions, dynamic screening of electromagnetic interactions modifies the logarithmic growth of Fermi velocity, leading to richer quantum corrections while maintaining similar suppression of birefringence in the infrared limit. Our findings provide theoretical insights into the emergence of Lorentz symmetry in non-Hermitian systems,laying theoretical foundations for studying low-energy behavior in other non-Hermitian models.展开更多
For understanding the hierarchies of fermion masses and mixing,we extend the Standard Model(SM)gauge group with U(1)_(X) and Z_(2) symmetry.The field content of the SM is augmented by three heavy right-handed neutrino...For understanding the hierarchies of fermion masses and mixing,we extend the Standard Model(SM)gauge group with U(1)_(X) and Z_(2) symmetry.The field content of the SM is augmented by three heavy right-handed neutrinos,two new scalar singlets,and a scalar doublet.U(1)_(X) charges of different fields are determined after satisfying anomaly cancellation conditions.In this scenario,the fermion masses are generated through higher-dimensional effective operators with O(1)Yukawa couplings.The small neutrino masses are obtained through type-1 seesaw mechanism using the heavy right-handed neutrino fields,whose masses are generated by the new scalar fields.We discuss the flavour-changing neutral current processes that arise due to the sequential nature of U(1)_(X) symmetry.We have written effective higher-dimensional operators in terms of renormalizable dimension-four operators by introducing vector-like fermions.展开更多
The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced qu...The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced quantum electrodynamics.We used the perturbative renormalization group method to study the low-energy behavior of the system and found that it flows to a fixed point of the non-Fermi liquid composed of relativistic pseudospin-1/2 Dirac fermions in the deep infrared limit.At the fixed point,the fermion Green function exhibits a finite anomalous dimension,and the residue of the quasiparticle pole vanishes in a power-law fashion.Our research provides new theoretical perspectives for understanding the origin of spin-1/2 fermions in the standard model.展开更多
Both, the dilemma to find a quantum field theory consistent with Einstein’s law of relativity and the problem to describe existing particles as bound states of matter has been solved by calculating bound state matrix...Both, the dilemma to find a quantum field theory consistent with Einstein’s law of relativity and the problem to describe existing particles as bound states of matter has been solved by calculating bound state matrix elements from a dual fermion-boson Lagrangian. In this formalism, the fermion binding energies are compensated by boson energies, indicating that particles can be generated out of the vacuum. This yields quantitative solutions for various mesons ω (0.78 GeV) - Υ (9.46 GeV) and all leptons e, μ and τ, with uncertainties in the extracted properties of less than 1‰. For transparency, a Web-page with the address htpps://h2909473.stratoserver.net has been constructed, where all calculations can be run on line and also the underlying fortran source code can be inspected.展开更多
We synthesize high-quality single crystal of CeGaSi by a Ga self-flux method and investigate its physical properties through magnetic susceptibility,specific heat and electrical resistivity measurements as well as hig...We synthesize high-quality single crystal of CeGaSi by a Ga self-flux method and investigate its physical properties through magnetic susceptibility,specific heat and electrical resistivity measurements as well as high pressure effect.Magnetic measurements reveal that an antiferromagnetic order develops below T_(m)~10.4 K with magnetic moments orientated in the ab plane.The enhanced electronic specific heat coefficient and the negative logarithmic slope in the resistivity of CeGaSi indicate that the title compound belongs to the family of Kondo system with heavy fermion ground states.The max magnetic entropy change-ΔS_(M)^(max)(μ_(0)H⊥c,μ_(0)H=7 T) around T_(m) is found to reach up to 11.85 J·kg^(-1)·K^(-1).Remarkably,both the antiferromagnetic transition temperature and-ln T behavior increase monotonically with pressure applied to 20 kbar(1 bar=10~5 Pa),indicating that much higher pressure will be needed to reach its quantum critical point.展开更多
Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism ...Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism which is proportional to Planck’s constant. This may be the result of two massless bosons (hypergluons) coupled by a preon (prequark) exchange. It also gives a physical explanation to the origin of the Planck constant, and origin of spin.展开更多
Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s co...Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. Quantum mechanics is described with real fields and real operators. Schrodinger and Dirac equations then are solved. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. For an incoming entangled pair of fermions, the combined solution is Ψin=c1ψ1+c4ψ4where c1and c4are some hidden variables. By applying a magnetic field in +Z and +x the theoretical results of a triple Stern-Gerlach experiment are predicted correctly. Then, by repeating Bell’s and Mermin Gedanken experiment with three magnetic filters σθ, at three different inclination angles θ, the violation of Bell’s inequality is proven. It is shown that all fermions are in a mixed state of spins and the ratio between spin-up to spin-down depends on the hidden variables.展开更多
In this work,we investigate the numerical evolution of massive Kaluza–Klein(KK)modes of a Dirac field on a thick brane.We deduce the Dirac equation in five-dimensional spacetime,and obtain the time-dependent evolutio...In this work,we investigate the numerical evolution of massive Kaluza–Klein(KK)modes of a Dirac field on a thick brane.We deduce the Dirac equation in five-dimensional spacetime,and obtain the time-dependent evolution equation and Schr?dinger-like equation of the extradimensional component.We use the Dirac KK resonances as the initial data and study the corresponding dynamics.By monitoring the decay law of the left-and right-chiral KK resonances,we compute the corresponding lifetimes and find that there could exist long-lived KK modes on the brane.Especially,for the lightest KK resonance with a large coupling parameter and a large three momentum,it will have an extremely long lifetime.展开更多
Quantum field theory creates fermions via abstract operators exciting abstract fields, with a specific field for each type of specific particle. This operator algebra lends itself well to quantum statistics, neverthel...Quantum field theory creates fermions via abstract operators exciting abstract fields, with a specific field for each type of specific particle. This operator algebra lends itself well to quantum statistics, nevertheless, our physical understanding of this process is nonintuitive at best. In this paper we analyze the creation of fermions from primordial gauge field quantum gravity loops in the context of Calabi-Yau manifold theory. I extend a prior mass-gap treatment based on Yang-Mills gauge theory of higher order self-interaction to include the half-integral spin of fermions.展开更多
Short Retraction NoticeThe paper does not meet the standards of "Journal of Applied Mathematics and Physics". This article has been retracted to straighten the academic record. In making this decision the Ed...Short Retraction NoticeThe paper does not meet the standards of "Journal of Applied Mathematics and Physics". This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused.Editor guiding this retraction: Prof. Wen-Xiu Ma (EiC of JAMP)The full retraction notice in PDF is preceding the original paper, which is marked "RETRACTED".展开更多
Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies...Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.展开更多
Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low ene...Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.展开更多
Due to the negligible non-perturbation effect in the low-energy region, quantum chromodynamics （QCD） is limited to be applied to hadron problems in particle physics. However, QED has mature non-perturbation models w...Due to the negligible non-perturbation effect in the low-energy region, quantum chromodynamics （QCD） is limited to be applied to hadron problems in particle physics. However, QED has mature non-perturbation models which can be applied to Fermi acting-energy between quark and gluon. This paper applies quantum electrodynamics in 2 ＋ 1 dimensions （QED3） to the Fermi condensation problems. First, the Dyson-Schwinger equation which the fermions satisfy is constructed, and then the Fermi energy gap is solved. Theoretical calculations show that within the chirality limit, there exist three solutions for the energy gap; beyond the chirality limit, there are two solutions; all these solutions correspond to different fermion condensates. It can be concluded that the fermion condensates within the chirality limit can be used to analyze the existence of antiferromagnetic, pseudogap, and superconducting phases, and two fermion condensates are discovered beyond the chirality limit.展开更多
Dynamical chiral symmetry breaking(DCSB) in thermal QED3 with fermion velocity is studied in the framework of Dyson–Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component...Dynamical chiral symmetry breaking(DCSB) in thermal QED3 with fermion velocity is studied in the framework of Dyson–Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component of gauge boson propagator at finite temperature, we numerically solve the fermion self-energy equation in the rainbow approximation. It is found that both DCSB and fermion chiral condensate are suppressed by fermion velocity.Moreover, the critical temperature decreases as fermion velocity increases.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406702)the Innovation Program for Quantum Science and Technology 2021ZD0302005+1 种基金the XPLORER Prizepartly supported by the Start-up Research Fund of Southeast University(RF1028624190)。
文摘Topological band theory has been studied for free fermions for decades,and one of the most profound physical results is the bulk-boundary correspondence.Recently a focus in topological physics is extending topological classification to mixed states.Here,we focus on Gaussian mixed states for which the modular Hamiltonians of the density matrix are quadratic free fermion models with U(1)symmetry and can be classified by topological invariants.The bulk-boundary correspondence is then manifested as stable gapless modes of the modular Hamiltonian and degenerate spectrum of the density matrix.In this article,we show that these gapless modes can be detected by the full counting statistics,mathematically described by a function introduced as F(θ).A divergent derivative atθ=πcan be used to probe the gapless modes in the modular Hamiltonian.Based on this,a topological indicator,whose quantization to unity senses topologically nontrivial mixed states,is introduced.We present the physical intuition of these results and also demonstrate these results with concrete models in both one-and two-dimensions.Our results pave the way for revealing the physical significance of topology in mixed states.
文摘Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. Here, a deeper investigation of the free fermion internal frequency is discussed, hinting to an exchange interaction between the two components of which a fermion is made of. An upper limit estimate is given to the strength of this interaction.
基金Project supported by the National Key Research and Development Program of China (Grants Nos. 2021YFA1400900,2021YFA0718300, and 2021YFA1400243)the National Natural Science Foundation of China (Grant Nos. 61835013,12174461, and 12234012)the Fund from the Space Application System of China Manned Space Program。
文摘We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay between non-Hermiticity and birefringence leads to distinct behaviors in two and three dimensions, where the system exhibits different fixed points and scaling properties due to dimension-dependent charge renormalization effects. In two dimensions, where the electronic charge remains unrenormalized, the system flows in the deep infrared limit from non-Hermitian birefringent spin-3/2fermions to two copies of non-Hermitian spin-1/2 Dirac fermions, demonstrating a crossover of relativistic liquid and nonrelativistic liquid. In three dimensions, dynamic screening of electromagnetic interactions modifies the logarithmic growth of Fermi velocity, leading to richer quantum corrections while maintaining similar suppression of birefringence in the infrared limit. Our findings provide theoretical insights into the emergence of Lorentz symmetry in non-Hermitian systems,laying theoretical foundations for studying low-energy behavior in other non-Hermitian models.
基金ARS thanks the Ministry of Minority Affairs,Government of India,for financial support through Maulana Azad National Fellowship under Grant No.F.82-27/2019(SA-Ⅲ).
文摘For understanding the hierarchies of fermion masses and mixing,we extend the Standard Model(SM)gauge group with U(1)_(X) and Z_(2) symmetry.The field content of the SM is augmented by three heavy right-handed neutrinos,two new scalar singlets,and a scalar doublet.U(1)_(X) charges of different fields are determined after satisfying anomaly cancellation conditions.In this scenario,the fermion masses are generated through higher-dimensional effective operators with O(1)Yukawa couplings.The small neutrino masses are obtained through type-1 seesaw mechanism using the heavy right-handed neutrino fields,whose masses are generated by the new scalar fields.We discuss the flavour-changing neutral current processes that arise due to the sequential nature of U(1)_(X) symmetry.We have written effective higher-dimensional operators in terms of renormalizable dimension-four operators by introducing vector-like fermions.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400900,2021YFA0718300,and 2021YFA1400243)the National Natural Science Foundation of China(Grant Nos.61835013,12174461,and 12234012)Space Application System of China Manned Space Program.
文摘The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced quantum electrodynamics.We used the perturbative renormalization group method to study the low-energy behavior of the system and found that it flows to a fixed point of the non-Fermi liquid composed of relativistic pseudospin-1/2 Dirac fermions in the deep infrared limit.At the fixed point,the fermion Green function exhibits a finite anomalous dimension,and the residue of the quasiparticle pole vanishes in a power-law fashion.Our research provides new theoretical perspectives for understanding the origin of spin-1/2 fermions in the standard model.
文摘Both, the dilemma to find a quantum field theory consistent with Einstein’s law of relativity and the problem to describe existing particles as bound states of matter has been solved by calculating bound state matrix elements from a dual fermion-boson Lagrangian. In this formalism, the fermion binding energies are compensated by boson energies, indicating that particles can be generated out of the vacuum. This yields quantitative solutions for various mesons ω (0.78 GeV) - Υ (9.46 GeV) and all leptons e, μ and τ, with uncertainties in the extracted properties of less than 1‰. For transparency, a Web-page with the address htpps://h2909473.stratoserver.net has been constructed, where all calculations can be run on line and also the underlying fortran source code can be inspected.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12274440)the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB33010100)+1 种基金the Fund from the Ministry of Science and Technology of China (Grant No. 2022YFA1403903)the Fund of the Synergetic Extreme Condition User Facility (SECUF)。
文摘We synthesize high-quality single crystal of CeGaSi by a Ga self-flux method and investigate its physical properties through magnetic susceptibility,specific heat and electrical resistivity measurements as well as high pressure effect.Magnetic measurements reveal that an antiferromagnetic order develops below T_(m)~10.4 K with magnetic moments orientated in the ab plane.The enhanced electronic specific heat coefficient and the negative logarithmic slope in the resistivity of CeGaSi indicate that the title compound belongs to the family of Kondo system with heavy fermion ground states.The max magnetic entropy change-ΔS_(M)^(max)(μ_(0)H⊥c,μ_(0)H=7 T) around T_(m) is found to reach up to 11.85 J·kg^(-1)·K^(-1).Remarkably,both the antiferromagnetic transition temperature and-ln T behavior increase monotonically with pressure applied to 20 kbar(1 bar=10~5 Pa),indicating that much higher pressure will be needed to reach its quantum critical point.
文摘Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism which is proportional to Planck’s constant. This may be the result of two massless bosons (hypergluons) coupled by a preon (prequark) exchange. It also gives a physical explanation to the origin of the Planck constant, and origin of spin.
文摘Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. Quantum mechanics is described with real fields and real operators. Schrodinger and Dirac equations then are solved. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. For an incoming entangled pair of fermions, the combined solution is Ψin=c1ψ1+c4ψ4where c1and c4are some hidden variables. By applying a magnetic field in +Z and +x the theoretical results of a triple Stern-Gerlach experiment are predicted correctly. Then, by repeating Bell’s and Mermin Gedanken experiment with three magnetic filters σθ, at three different inclination angles θ, the violation of Bell’s inequality is proven. It is shown that all fermions are in a mixed state of spins and the ratio between spin-up to spin-down depends on the hidden variables.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFC2201503)the National Natural Science Foundation of China(Grants No.12105126,No.11875151,and No.12247101)+3 种基金the 111Project under(Grant No.B20063)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky2021-pd08)the China Postdoctoral Science Foundation(Grant No.2021M701531)‘Lanzhou City’s scientific research funding subsidy to Lanzhou University’。
文摘In this work,we investigate the numerical evolution of massive Kaluza–Klein(KK)modes of a Dirac field on a thick brane.We deduce the Dirac equation in five-dimensional spacetime,and obtain the time-dependent evolution equation and Schr?dinger-like equation of the extradimensional component.We use the Dirac KK resonances as the initial data and study the corresponding dynamics.By monitoring the decay law of the left-and right-chiral KK resonances,we compute the corresponding lifetimes and find that there could exist long-lived KK modes on the brane.Especially,for the lightest KK resonance with a large coupling parameter and a large three momentum,it will have an extremely long lifetime.
文摘Quantum field theory creates fermions via abstract operators exciting abstract fields, with a specific field for each type of specific particle. This operator algebra lends itself well to quantum statistics, nevertheless, our physical understanding of this process is nonintuitive at best. In this paper we analyze the creation of fermions from primordial gauge field quantum gravity loops in the context of Calabi-Yau manifold theory. I extend a prior mass-gap treatment based on Yang-Mills gauge theory of higher order self-interaction to include the half-integral spin of fermions.
文摘Short Retraction NoticeThe paper does not meet the standards of "Journal of Applied Mathematics and Physics". This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused.Editor guiding this retraction: Prof. Wen-Xiu Ma (EiC of JAMP)The full retraction notice in PDF is preceding the original paper, which is marked "RETRACTED".
基金The Science Foundation of Southeast University,the National Natural Science Foundation of China (No. 11047005)
文摘Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1632275)the National Key R&D Program of China(Grant Nos.2017YFA0303100 and 2016YFA0300202)the Science Challenge Project of China(Grant No.TZ2016004)
文摘Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.
基金The National Natural Science Foundation of China(No.11047005)the Science Foundation of Southeast University
文摘Due to the negligible non-perturbation effect in the low-energy region, quantum chromodynamics （QCD） is limited to be applied to hadron problems in particle physics. However, QED has mature non-perturbation models which can be applied to Fermi acting-energy between quark and gluon. This paper applies quantum electrodynamics in 2 ＋ 1 dimensions （QED3） to the Fermi condensation problems. First, the Dyson-Schwinger equation which the fermions satisfy is constructed, and then the Fermi energy gap is solved. Theoretical calculations show that within the chirality limit, there exist three solutions for the energy gap; beyond the chirality limit, there are two solutions; all these solutions correspond to different fermion condensates. It can be concluded that the fermion condensates within the chirality limit can be used to analyze the existence of antiferromagnetic, pseudogap, and superconducting phases, and two fermion condensates are discovered beyond the chirality limit.
基金Supported in part by the National Natural Science Foundation of China under Grant No.11535005the Natural Science Foundation of Jiangsu Province under Grant No.BK20130387
文摘Dynamical chiral symmetry breaking(DCSB) in thermal QED3 with fermion velocity is studied in the framework of Dyson–Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component of gauge boson propagator at finite temperature, we numerically solve the fermion self-energy equation in the rainbow approximation. It is found that both DCSB and fermion chiral condensate are suppressed by fermion velocity.Moreover, the critical temperature decreases as fermion velocity increases.
