费米原子与玻色分子混合体系的相干态理论研究

以碱性费米金属原子气及其构成的玻色分子的混合体系为研究对象,利用量子方法研究此混合体系的相干态理论。研究结果表明,在绝对零度下,混合体系处在SU(2)SU(1,1)相干态,利用平均场近似以及李代数的方法计算体系的本征值,与玻戈留玻夫变换所得结果一致,它的优点在于不仅可以计算本征值而且可以给出态函数。

真正的冷分子

从量子角度看,任何粒子都可同时被看作波,它的动量对应着一个特定的波长.在超冷原子气体中,当绝对温度远低于百万分之一度时,原子的波长将大于原子的平均间距,由此将产生某些处于现代物理学研究前沿的量子力学性质.这种冷的量子气体的性质取决于原子是玻色子还是费米子.玻色原子具有整数的自旋量子数,可以形成玻色一爱因斯坦凝聚体,被捕陷在这种凝聚体中的原子占据在体系的单一基态上.

Functional Integrals and Collective Excitations in Boson-Fermion Model

In this paper, collective excitations in the boson-fermion model are investigated by means of functional integration method. The equations of energy gap and excitation spectrum are derived. Moreover, the Bose energy spectrum of zero wave vector Fermi fields is also calculated.

Fermion-Boson Vertex at Finite Chemical Potential

Based on the Ward-Takahashi identity at finite chemical potential and Lorentz structure analyms, we generalize the Ball-Chiu vertex to the case of nonzero chemical potential and obtain the general form of the frmionboson vertex in QED at finite chemical potential.

A Categorification of the Boson Oscillator

In this paper,we investigate the categorical description of the boson oscillator.Based on the categories constructed by Khovanov,we introduce a categorification of the Fock states and the corresponding inner product of these states.We find that there are two different categorical definitions of the inner product of the Fock states.These two definitions are consistent with each other,and the decategorification results also coincide with those in conventional quantum mechanics.We also find that there are some interesting properties of the 2-morphisms which relate to the inner product of the states.

Tunneling Dynamics Between Atomic and Molecular Bose-Einstein Condensates

Tunneling dynamics of multi-atomic molecules between atomic and multi-atomic molecular Bose-Einstein condensates with Feshbach resonance is investigated.It is indicated that the tunneling in the two Bose-Einstein condensates depends on not only the inter-atomic-molecular nonlinear interactions and the initial number of atoms in these condensates,but also the tunneling coupling between the atomic condensate and the multi-atomic molecular condensate.It is discovered that besides oscillating tunneling current between the atomic condensate and the multi-atomic molecular condensate,the nonlinear multi-atomic molecular tunneling dynamics sustains a self-locked population imbalance:a macroscopic quantum self-trapping effect.The influence of de-coherence caused by non-condensate atoms on the tunneling dynamics is studied.It is shown that de-coherence suppresses the multi-atomic molecular tunneling.Moreover,the conception of the molecular Bose-Einstein condensate,which is different from the conventional single-atomic Bose-Einstein condensate,is specially emphasized in this paper.

B→K^＊у/Decay in Top-Quark Two-Higgs-Doublet Model

By employing the QCD factorization approach for the exclusive B→Vу decays, we study the exclusive decay B→K^＊у in the top-quark two-Higgs-doublet mode/（T2HDM）. Within the considered parameter space, we find the following conclusions （a） A hght charged-Higgs boson with a mass about 200 GeV is clearly excluded by the date of B→K^＊у decay, and this lower limit is comparable with that from the inclusive B→X8＊у decay; （b） The theoretical predictions for CP asymmetry of B→K^＊у in the T2HDM is always less than 1% in size; and （c） The isospin symmetry breaking for B→K^＊у decay in the SM and T2HDM considered here is around 6% in size and well consistent with the data and the general expectations.

Tunneling Dynamics Between Any Two Multi-atomic-molecular Bose-Einstein Condensates

Tunneling dynamics of multi-atomic molecules between any two multi-atomicmolecular Bose-Einstein condensates with Feshbach resonance is investigated. It is indicated thatthe tunneiing in the two Bose-Einstein condensates depends not only on the inter-molecular nonlinearinteractions and the initial number of molecule in these condensates, but also on the tunnelingcoupling between them. It is discovered that besides oscillating tunneling current between themulti-atomic molecular condensates, the nonlinear multi-atomic molecular tunneling dynamics sustainsa self-locked population imbalance: a macroscopic quantum self-trapping effect. The influence ofde-coherence caused by non-condensate molecule on the tunneling dynamics is studied. It is shownthat de-coherence suppresses the multi-atomic molecular tunneling.

Novel Quantum Phases of Ultracold Bosonic Atoms in Honeycomb Optical Lattice

We study the quantum phase transition of ultracold atoms in the honeycomb optical lattice. The Hamiltonian of ultracold bosonic atoms in the honeycomb optical lattice is derived. We take the mean-field approximation and further solve the Hamiltonian with the numerical diagonalization method. We obtain the phase diagram and find that the Mort-insulator （MI）, density wave （DW） and modulated superfluid （MS） phases appear. Furthermore, the phase diagram is analyzed according to the order parameter and the average number of particles.

Tunneling Dynamics of Two-Species Bose-Einstein Condensates with Feshbach Resonances

We investigate tunneling dynamics of atomic group consisting of three atoms in Bose-Einstein condensates with Feshbach resonance. It is shown that the tunneling of the atom group depends not only on the inter-atomic nonlinear interactions and the initial number of atoms in these condensates, but also on the tunneling coupling between the atomic condensate and the three-atomic molecular condensate. It is found that besides oscillating tunneling current between the atomic condensate and the molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained population imbalance: a macroscopic quantum self-trapping effect. The influence of de-coherence caused by non-condensate atoms on the tunneling dynamics is studied. It is indicated that de-coherence suppresses the atomic group tunneling.

Lepton Flavor Violating Z→e_I■_J in SO(3) Gauge Extension of SM

The SO（3） gauge extension of SM, which is proposed to present a successful explanation for the observed small masses of neutrino and the nearly tri-bimaximal neutrino mixing, predicted the vector-like SO（3） triplet Majorana neutrinos and SUL（2） double Higgs bosons. In this work we calculate branching ratios of the charged lepton flavor violating decays lIlJV （V = γ, Z） induced by these Majorana neutrinos and Higgs bosons. We find that under the model parameters constrained by experimental bounds on the decays Z →lIlJ, the branching ratio of decays lI→lJγ can be up to 10^-10, which may be accessible at the future experiments.

Tunneling Dynamics of Two-Species Molecular Bose-Einstein Condensates

We study tunneling dynamics of atomic group in two-species molecular Bose-Einstein condensates. It is shown that the tunneling of the atom group depends on not only the tunneling coupling constant between the atomic pair molecular condensate and the three-atomic group molecular condensate, but also the inter-molecular nonlinear interactions and the initial number of atoms in these condensates. It is discovered that besides oscillating tunneling current between the atomic pair molecular condensate and the three-atomic group molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained population imbalance: a macroscopic quantum self-trapping effect.

Analytic Expression of Arbitrary Matrix Elements for Boson Exponential Quadratic Polynomial Operators

Making use of the transformation relation among usual, normal, and antinormal ordering for the multimode boson exponential quadratic polynomial operators （BEQPO＇s）I we present the analytic expression of arbitrary matrix elements for BEQPO＇s. As a preliminary application, we obtain the exact expressions of partition function about the boson quadratic polynomial system, matrix elements in particle-number, coordinate, and momentum representation, and P representation for the BEQPO＇s.

On a Singular Solution in Higgs Field （Ⅲ）： Condensates and Representation of Certain f0 Mesons＇ Masses

Recently the mass and the basic structure of SM Higgs boson （H^0） have been discussed by the author with obtaining asymptotic solution for the equation of motion of nonlinear Klein-Gordon type partial differential equation. In this paper, we will treat with above in mind： masses of glueball （GB） of ground state and of certain fo mesons, ur, Higgs boson （ur-H^0） which will consist of a number of GBs and/or fo above for respective fullerene structure, a representation of these fo mesons＇ masses by masses of n octet and GB, and transformation of ur-H^0 into H^0.

Pseudo-Classical Partition Function of Spin One-Half Derived by Coherent State Method

Using the bosonic coherent state representation and the Schwinger bosonic operator realization of angular momentum we find the formula for the quantum Hamiltonian H =iaiUijUjl a1 for SU（2） rotation U, in this way we further specify the angular velocity w, iUU = （1/2）σ·ω, where σ is the Pauli matrix. Though the spin as a quantum observable has no classical correspondence, we may still mimic it as a rigid body rotation characterized by 3 Euler angles, and calculate its Pseudo-classical rotational partition function of spin one-half.

s波散射作用下的原子-分子系统的量子动力学

研究自旋相反的两成份费米原子-分子耦合系统中,背景粒子s波散射对分子形成与分解的影响。这种粒子间的相互作用在以分子形式存在为主的演化阶段影响明显,其中排斥势散射有利于分子的形成。分子场在系统演化过程中会出现亚泊松(Sub-Poisson)统计分布。

Electron-plasmon interaction induced plasmonic-polaron band replication in epitaxial perovskite SrIrO_(3) films

Electron-boson interaction is fundamental to a thorough understanding of various exotic properties emerging in many-body physics. In photoemission spectroscopy, photoelectron emission due to photon absorption would trigger diverse collective excitations in solids, including the emergence of phonons,magnons, electron-hole pairs, and plasmons, which naturally provides a reliable pathway to study electron-boson couplings. While fingerprints of electron–phonon/-magnon interactions in this state-ofthe-art technique have been well investigated, much less is known about electron-plasmon coupling,and direct observation of the band renormalization solely due to electron-plasmon interactions is extremely challenging. Here by utilizing integrated oxide molecular-beam epitaxy and angle-resolved photoemission spectroscopy, we discover the long sought-after pure electron-plasmon couplinginduced low-lying plasmonic-polaron replica bands in epitaxial semimetallic SrIrO_(3) films, in which the characteristic low carrier concentration and narrow bandwidth combine to provide a unique platform where the electron-plasmon interaction can be investigated kinematically in photoemission spectroscopy. This finding enriches the forms of electron band normalization on collective modes in solids and demonstrates that, to obtain a complete understanding of the quasiparticle dynamics in 5 d electron systems, the electron-plasmon interaction should be considered on equal footing with the acknowledged electron–electron interaction and spin–orbit coupling.

The Lepton Flavor Violating Decays of AHin the Littlest Higgs Model with T-Parity Violation

The T-parity in the littlest Higgs model can be broken by the anomalous Wess-Zumin-Witten term, which leads that the lightest T-odd gauge boson AH decays into the SM particles. First, we examine some lepton flavor violating decays of AH, namely AH → τ±μ±, AH→ τ±e±, and AH→ τ±e±. We find that the branching ratios can reach 10-7 for AH → τ±μ±, 10-s for AH → τ±μ±, and 10-s for AH → τ±e± Then, we study the lepton flavor violating plus jets signatures of the heavy charged gauge boson and mirror quarks at the LHC, and find that it is possible to be detected for pp jets, and hardly to be detected for pp → τ±e± （μ±e±） ＋ 4 jets and p p → W H W H → τ±μ±（ τ±e±,μ±e±） ＋ 6 jets.

Note on Higgs Decay into Two Photons H → γγ

The Higgs decay H →γγ due to the virtual W-loop effect is revisited in the unitary gauge by using the symmetry-preserving and divergent-behavior-preserving loop regularization method, which is realized in the fourdimensional space-time without changing original theory. Though the one-loop amplitude of H →γγ is finite as the Higgs boson in the standard model has no direct interaction with the massless photons at tree level, it involves both tensor-type and scalar-type divergent integrals which can in general destroy the gauge invariance without imposing a proper regularization scheme to make them well-defined. As the loop regularization scheme can ensure the consistency conditions between the regularized tensor-type and scalar-type divergent irreducible loop integrals to preserve gauge invariance, we explicitly show the absence of decoupling in the limit Mw /MH → 0 and obtain a result agreeing exactly with the earlier one in the literature. We then clarify the discrepancy of the earlier result from the recent one obtained by R. Castmans, S.L. Wu and T.T. Wu. The advantage of calculation in the unitary gauge becomes manifest in that the non-decoupling arises from the longitudinal contribution of the W gauge boson.

A new explanation for statistical entropy of charged black hole

Using the Unruh-Verlinde temperature obtained by the idea of entropy force,we directly calculated the partition functions of Boson field in Reissner-Nordstro¨m spacetime with quantum statistical method.We obtain the expression of the black hole quantum statistical entropy.We find that the term is proportional to the area of black hole horizon and the logarithmic correction term appears.Our result is valid for flat spacetime.