By means of critical behaviors of the dynamical fermion mass in fonr-fermion interaction models, we.show by explicit calculations that when T = 0 the particle density will have a discontinuous jumping across the criti...By means of critical behaviors of the dynamical fermion mass in fonr-fermion interaction models, we.show by explicit calculations that when T = 0 the particle density will have a discontinuous jumping across the critical chemical potential μc in 2D and 3D Gross Neveu (GN) model and these physically explain the first-order feature of the corresponding symmetry restoring phase transitions. For the second-order phase transitions in the 3D GN model when T→0 and in 4D Nambu Jona-Lasinio (N3L) model when T=0, it is proven that the particle density itself will be continuous across μc but its derivative over the chemical potential μ will have a discontinuous jumping. The results givea physical explanation of implications of the tricritical point (T,μ) z (0,μc) in the 3D GN model. The discussions alsoshow effectiveness of the critical analysis approach of phase transitions.展开更多
<正> A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemicalpotentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to ...<正> A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemicalpotentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe two-flavor normal quark matter.Depending on whether m_0/A,the ratio of dynamical quark mass in vacuum and the 3Dmomentum cutoff in the loop integrals,is less or greater than 0.413,the phase transition will be of the second or firstorder.A complete phase diagram of u quark chemical potential versus m_0 is given.With the electrical neutralityconstraint,the region where the second order phase transition happens will be wider than the one without electricalneutrality limitation.The results also show that,for the value of m_0/A from QCD phenomenology,the phase transitionmust be of the first order.展开更多
We present a theory of the multi-threshold second-order phase transition,and experimentally demonstrate the multi-threshold secondorder phase transition phenomenon.With carefully selected parameters,in an external cav...We present a theory of the multi-threshold second-order phase transition,and experimentally demonstrate the multi-threshold secondorder phase transition phenomenon.With carefully selected parameters,in an external cavity diode laser system,we observe secondorder phase transition with multiple(three or four) thresholds in the measured power-current-temperature three dimensional phase diagram.Such controlled death and revival of second-order phase transition sheds new insight into the nature of ubiquitous secondorder phase transition.Our theory and experiment show that the single threshold second-order phase transition is only a special case of the more general multi-threshold second-order phase transition,which is an even richer phenomenon.展开更多
在宇宙开始大爆炸的时候,电荷变号与镜象反射共轭（CP）是对称的.但现在我们的宇宙绝大部分是正物质核子和电子等组成的,所以我们的宇宙是不对称的.D和L-丙氨酸通常称为对映体（enantiomer）,实际上它们并不是由正、反粒子组成的真正的...在宇宙开始大爆炸的时候,电荷变号与镜象反射共轭（CP）是对称的.但现在我们的宇宙绝大部分是正物质核子和电子等组成的,所以我们的宇宙是不对称的.D和L-丙氨酸通常称为对映体（enantiomer）,实际上它们并不是由正、反粒子组成的真正的对映体,而是空间反演的,即x--x,y--y,z--z的非对映异构体（diastereoisomer）,所以D-和L-丙氨酸是不对称的,两者间有能量的差别.自然界的力只有弱力是宇称不守恒的.在分子物理中,电弱力宇称不守恒是导致D-和L-丙氨酸能差的根源.所有以前的研究都认为L型丙氨酸比D型稳定.但是,最近以Quack[9]和Schwerdtfeger[11]为首的理论物理学家计算了L-丙氨酸在气相和溶液两种状态下,宇称破缺能差与分子构象的关系,提出“D-和L-丙氨酸究竟哪一个稳定”的质疑.由于气相和液相中两面角较难测定,我们用X射线四圆单晶衍射法,测定了270K和250KD和L-丙氨酸的O（1）O（2）C（1）C（2）H（4）的原子坐标,算出了二面角,按照Quack[9]的MC-LR方法,D-和L-丙氨酸宇称破缺能差为1.2 x 10-19Hartree,相当于3.3 x 10-18eV/分子或3.2x10-16kJ·mol-1,从而得出D-丙氨酸能态高于L-丙氨酸的结论.展开更多
P2-Na_(0.67)N_(i0.33)Mn_(0.67)O_(2)is considered as a promising cathode material for sodium-ion battery (SIBs)because of its high capacity and discharge potential.However,its practical use is limited by Na^(+)/vacancy...P2-Na_(0.67)N_(i0.33)Mn_(0.67)O_(2)is considered as a promising cathode material for sodium-ion battery (SIBs)because of its high capacity and discharge potential.However,its practical use is limited by Na^(+)/vacancy ordering and P2-O2 phase transition.Herein,a Ti^(4+)/F^(-) co-doping strategy is developed to address these issues.The optimal P2-Na_(0.67)Ni_(0.33)Mn_(0.37)Ti_(0.3)O_(1.9)F_(0.1) exhibits much enhanced sodium storage performance in the high voltage range of 2.0–4.4 V,including a cycling stability of 77.2%over 300cycles at a rate of 2 C and a high-rate capability of 87.7 m Ah g^(-1) at 6 C.Moreover,the P2-Na_(0.67)Ni_(0.33)Mn_(0.37)Ti_(0.3)O_(1.9)F_(0.1) delivers reversible capacities of 82.7 and 128.1 m Ah g^(-1) at-10 and 50℃ at a rate of 2 C,respectively.The capacity retentions over 200 cycles at-10℃ is 94.2%,implying more opportunity for practical application.In-situ X-ray diffraction analysis reveals that both P2-O2 phase transitions and Na^(+)/vacancy ordering is suppressed by Ti^(4+)/F^(-) co-doping,which resulting in fast Na^(+) diffusion and stable phase structure.The hard carbon//P2-Na_(0.67)Ni_(0.33)Mn_(0.37)Ti_(0.3)O_(1.9)F_(0.1) full cell exhibits a high energy density of 310.2 Wh kg^(-1) and remarkable cyclability with 82.1%retention after 300 cycles at 1 C in the voltage range of 1.5–4.2 V.These results demonstrate that the co-doping Ti^(4+)/F^(-) is a promising strategy to improve the electrochemical properties of P2-Na_(0.67)Ni_(0.33)Mn_(0.67)O_(2),providing a facile tactic to develop high performance cathode materials for SIBs.展开更多
We have investigated the quasinormal modes (QNMs) of phantom scalar perturbation in a Reissner-Nordstrm (RN) background.We find that the dependence of QNMs on the mass of the field for the phantom perturbation is to...We have investigated the quasinormal modes (QNMs) of phantom scalar perturbation in a Reissner-Nordstrm (RN) background.We find that the dependence of QNMs on the mass of the field for the phantom perturbation is totally different from that of usual massive perturbation.However,we obtain the same critical value of the overtone number for an angular quantum number from which the mass will begin to have a reverse effect on the real part of QNM frequencies and the perturbation-independent relation between the QNMs and the second order thermodynamic phase transition.展开更多
第22届亚洲物理奥林匹克竞赛理论试题共三道,其中第二道题为相变的力学模型(A Mechanical Model for Phase Transitions)。该试题以朗道相变理论为背景,研究旋转的环上小球的运动,建立并分析相变的力学模型。本文介绍了该试题内容及解答...第22届亚洲物理奥林匹克竞赛理论试题共三道,其中第二道题为相变的力学模型(A Mechanical Model for Phase Transitions)。该试题以朗道相变理论为背景,研究旋转的环上小球的运动,建立并分析相变的力学模型。本文介绍了该试题内容及解答,并对试题和选手作答情况进行了简要分析。展开更多
基金The project supported by National Natural Science Foundation ot China
文摘By means of critical behaviors of the dynamical fermion mass in fonr-fermion interaction models, we.show by explicit calculations that when T = 0 the particle density will have a discontinuous jumping across the critical chemical potential μc in 2D and 3D Gross Neveu (GN) model and these physically explain the first-order feature of the corresponding symmetry restoring phase transitions. For the second-order phase transitions in the 3D GN model when T→0 and in 4D Nambu Jona-Lasinio (N3L) model when T=0, it is proven that the particle density itself will be continuous across μc but its derivative over the chemical potential μ will have a discontinuous jumping. The results givea physical explanation of implications of the tricritical point (T,μ) z (0,μc) in the 3D GN model. The discussions alsoshow effectiveness of the critical analysis approach of phase transitions.
基金The project supported by National Natural Science Foundation of China under Grant No. 10475113
文摘<正> A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemicalpotentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe two-flavor normal quark matter.Depending on whether m_0/A,the ratio of dynamical quark mass in vacuum and the 3Dmomentum cutoff in the loop integrals,is less or greater than 0.413,the phase transition will be of the second or firstorder.A complete phase diagram of u quark chemical potential versus m_0 is given.With the electrical neutralityconstraint,the region where the second order phase transition happens will be wider than the one without electricalneutrality limitation.The results also show that,for the value of m_0/A from QCD phenomenology,the phase transitionmust be of the first order.
基金supported by the National Natural Science Foundation of China(10874009 and 11074011)
文摘We present a theory of the multi-threshold second-order phase transition,and experimentally demonstrate the multi-threshold secondorder phase transition phenomenon.With carefully selected parameters,in an external cavity diode laser system,we observe secondorder phase transition with multiple(three or four) thresholds in the measured power-current-temperature three dimensional phase diagram.Such controlled death and revival of second-order phase transition sheds new insight into the nature of ubiquitous secondorder phase transition.Our theory and experiment show that the single threshold second-order phase transition is only a special case of the more general multi-threshold second-order phase transition,which is an even richer phenomenon.
文摘在宇宙开始大爆炸的时候,电荷变号与镜象反射共轭（CP）是对称的.但现在我们的宇宙绝大部分是正物质核子和电子等组成的,所以我们的宇宙是不对称的.D和L-丙氨酸通常称为对映体（enantiomer）,实际上它们并不是由正、反粒子组成的真正的对映体,而是空间反演的,即x--x,y--y,z--z的非对映异构体（diastereoisomer）,所以D-和L-丙氨酸是不对称的,两者间有能量的差别.自然界的力只有弱力是宇称不守恒的.在分子物理中,电弱力宇称不守恒是导致D-和L-丙氨酸能差的根源.所有以前的研究都认为L型丙氨酸比D型稳定.但是,最近以Quack[9]和Schwerdtfeger[11]为首的理论物理学家计算了L-丙氨酸在气相和溶液两种状态下,宇称破缺能差与分子构象的关系,提出“D-和L-丙氨酸究竟哪一个稳定”的质疑.由于气相和液相中两面角较难测定,我们用X射线四圆单晶衍射法,测定了270K和250KD和L-丙氨酸的O（1）O（2）C（1）C（2）H（4）的原子坐标,算出了二面角,按照Quack[9]的MC-LR方法,D-和L-丙氨酸宇称破缺能差为1.2 x 10-19Hartree,相当于3.3 x 10-18eV/分子或3.2x10-16kJ·mol-1,从而得出D-丙氨酸能态高于L-丙氨酸的结论.
基金supported by the National Natural Science Foundation of China(21901146,51907110,22078179)the Key Research and Development Program of Shandong Province(2019GGX103027)+2 种基金the Natural Science Foundation of Shandong Province(ZR2019MB034)the Taishan Scholar Foundation(tsqn201812063)the 111 Project(B12015)。
文摘P2-Na_(0.67)N_(i0.33)Mn_(0.67)O_(2)is considered as a promising cathode material for sodium-ion battery (SIBs)because of its high capacity and discharge potential.However,its practical use is limited by Na^(+)/vacancy ordering and P2-O2 phase transition.Herein,a Ti^(4+)/F^(-) co-doping strategy is developed to address these issues.The optimal P2-Na_(0.67)Ni_(0.33)Mn_(0.37)Ti_(0.3)O_(1.9)F_(0.1) exhibits much enhanced sodium storage performance in the high voltage range of 2.0–4.4 V,including a cycling stability of 77.2%over 300cycles at a rate of 2 C and a high-rate capability of 87.7 m Ah g^(-1) at 6 C.Moreover,the P2-Na_(0.67)Ni_(0.33)Mn_(0.37)Ti_(0.3)O_(1.9)F_(0.1) delivers reversible capacities of 82.7 and 128.1 m Ah g^(-1) at-10 and 50℃ at a rate of 2 C,respectively.The capacity retentions over 200 cycles at-10℃ is 94.2%,implying more opportunity for practical application.In-situ X-ray diffraction analysis reveals that both P2-O2 phase transitions and Na^(+)/vacancy ordering is suppressed by Ti^(4+)/F^(-) co-doping,which resulting in fast Na^(+) diffusion and stable phase structure.The hard carbon//P2-Na_(0.67)Ni_(0.33)Mn_(0.37)Ti_(0.3)O_(1.9)F_(0.1) full cell exhibits a high energy density of 310.2 Wh kg^(-1) and remarkable cyclability with 82.1%retention after 300 cycles at 1 C in the voltage range of 1.5–4.2 V.These results demonstrate that the co-doping Ti^(4+)/F^(-) is a promising strategy to improve the electrochemical properties of P2-Na_(0.67)Ni_(0.33)Mn_(0.67)O_(2),providing a facile tactic to develop high performance cathode materials for SIBs.
基金Supported by the National Natural Science Foundation of China under Grant No.10905020the China Postdoctoral Science Foundation under Grant Nos.201003245 and 20090460592
文摘We have investigated the quasinormal modes (QNMs) of phantom scalar perturbation in a Reissner-Nordstrm (RN) background.We find that the dependence of QNMs on the mass of the field for the phantom perturbation is totally different from that of usual massive perturbation.However,we obtain the same critical value of the overtone number for an angular quantum number from which the mass will begin to have a reverse effect on the real part of QNM frequencies and the perturbation-independent relation between the QNMs and the second order thermodynamic phase transition.
文摘第22届亚洲物理奥林匹克竞赛理论试题共三道,其中第二道题为相变的力学模型(A Mechanical Model for Phase Transitions)。该试题以朗道相变理论为背景,研究旋转的环上小球的运动,建立并分析相变的力学模型。本文介绍了该试题内容及解答,并对试题和选手作答情况进行了简要分析。
