Coherent incoherent transition in the spin boson model with a super-ohmic bath

The temperature effect on tunnelling splitting in the spin boson model with a super-ohmic bath is studied by the small polaron theory. The coherent-incoherent transition temperature is calculated and its dependence on dissipation strength and bare tunnelling splitting is analysed. In additional to the traditional transition point described in textbooks, a new kind of transition is found in the low dissipation region, showing different temperature dependence in the transition. The relation to the corresponding transition in the polaron-phonon system is also discussed.

A note on localized transition in the spin-boson model by variational calculation

We present mathematical analyses of the evolution of solutions of the self-consistent equation derived from variational calculations based on the displaced-oscillator-state and the displaced-squeezed-state in spin-boson model at a zero temperature and a finite temperature. It is shown that, for a given spectral function defined as J（w） = π∑k Ck^2 = π/2αw^8w^1-s, there exists a universal sc for both kinds of variational schemes, the localized transition happens only for 2 s ≤ sc, moreover, the localized transition is discontinuous for s 〈 sc while a continuous transition always occurs when s = sc. At T = 0, we have sc = 1, while for T ≠ 0, sc = 2 which indicates that the localized transition in super-Ohmic case still exists, manifesting that the result is in discrepancy with the existing result.

Equilibrium dynamics of the sub-Ohmic spin-boson model under bias

Using the bosonic numerical renormalization group method, we studied the equilibrium dynamical correlation function C（ω） of the spin operator σz for the biased sub-Ohmic spin-boson model. The small-ω behavior C（ω） ∝ ω～s is found to be universal and independent of the bias ε and the coupling strength α（except at the quantum critical point α = αc and ε = 0）. Our NRG data also show C（ω） ∝ χ～2ω～s for a wide range of parameters, including the biased strong coupling regime（ε = 0 and α 〉 αc）, supporting the general validity of the Shiba relation. Close to the quantum critical point αc,the dependence of C（ω） on α and ε is understood in terms of the competition between ε and the crossover energy scale ω0^＊of the unbiased case. C（ω） is stable with respect to ε for ε《ε^＊. For ε 》ε^＊, it is suppressed by ε in the low frequency regime. We establish that ε^＊∝（ω0^＊）^1/θ holds for all sub-Ohmic regime 0≤s 〈 1, with θ = 2/（3s） for 0 〈 s≤1/2 and θ = 2/（1 ＋ s） for 1/2 〈 s 〈 1. The variation of C（ω） with α and ε is summarized into a crossover phase diagram on the α–ε plane.

Dynamical correlation functions of the quadratic coupling spin-Boson model

The spin-boson model with quadratic coupling is studied using the bosonic numerical renormalization group method.We focus on the dynamical auto-correlation functions CO（ω）, with the operator taken as σx, σz, and X, respectively. In the weak-coupling regime α 〈 αc, these functions show power law ω-dependence in the small frequency limit, with the powers 1 ＋ 2s, 1 ＋ 2s, and s, respectively. At the critical point α = αc of the boson-unstable quantum phase transition, the critical exponents yO of these correlation functions are obtained as yσx= yσz= 1-2s and yX=-s, respectively. Here s is the bath index and X is the boson displacement operator. Close to the spin flip point, the high frequency peak of Cσx（ω） is broadened significantly and the line shape changes qualitatively, showing enhanced dephasing at the spin flip point.

Microscopic Calculation of Parameters of the sdg Interacting Boson Model for ^(104-110)Pd Isotopes

The parameters of the sdg interacting boson model Hamiltonian are calculated for the 104-110Pdisotopes.The calculations utilize the microscopic procedure based on the Dyson boson mapping proposedby Yang-Liu-Qi and extended to include the g boson effects.The calculated parameters reproduce thosevalues from the phenomenological fits.The resulting spectra are compared with the experimental spectra.

RETRACTED: Nuclear Structure Study of Odd-Odd Yttrium Nuclei within Interacting-Boson Fermi-Fermion Model (IBFFM)

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".

Spectra and electromagnetic transitions of ^(98–104)Zr in the interacting boson model

The low-lying energy levels and electromagnetic transitions of even-even nuclei ^98Zr, ^100Zr, ^102Zr,^104Zr are studied within the framework of the interacting boson model. The Hamiltonian matrix elements and some of their states have been respectively analyzed and determined with respect to the current nuclear experimental data. The B（E2） of electromagnetic transitions have also been calculated and the wave function structures also analyzed. The results show good agreement with the available experimental data. The present study shows that these series of nuclei are in the transition from U（5） to SU（3）, namely from vibration to rotation.

Spectral fluctuations in the interacting boson model

The energy dependence of the spectral fluctuations in the interacting boson model(IBM)and its connections to the mean-field structures are analyzed by adopting two statistical measures:the nearest neighbor level spacing distribution P(S)measuring the chaoticity(regularity)in energy spectra and the Δ_(3)(L)statistics of Dyson and Metha measuring the spectral rigidity.Specifically,the statistical results as functions of the energy cutoff are determined for different dynamical scenarios,including the U(5)-SU(3)and SU(3)-O(6)transitions as well as those near the AW arc of regularity.We observe that most of the changes in spectral fluctuations are triggered near the stationary points of the classical potential,particularly for cases in the deformed region of the IBM phase diagram.Thus,the results justify the stationary point effects from the perspective of statistics.In addition,the approximate degeneracies in the 2^(+)spectrum on the AW arc is also revealed from the statistical calculations.

Spectra and electromagnetic transitions of ^(72-84)Kr in the interacting boson model-1

Within the framework of the interacting boson model- 1, the energy levels and electromagnetic transitions in 72-84Kr isotopes are calculated. The structures of the eigenstate and Hamiltonian matrix for some low-lying states are also calculated. The calculated results are compared with available experimental data, and the results are generally in good agreement. The present study shows that the 72,74,76,80,82,84Kr isotopes are in the transition from U（5）→ SU（3）, and 7SKr is in the transition from U（5）→ O（6）.

Simulation of the spin-boson model with superconducting phase qubit coupled to a transmission line

Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase transition.We design the spinboson model by using a superconducting phase qubit coupled to a semi-infinite transmission line,which is regarded as a bosonic reservoir with a continuum spectrum.By tuning the bias current or the coupling capacitance,the quantum KT transition can be directly detected through tomography measurement on the states of the phase qubit.We also estimate the experimental parameters using the numerical renormalization group method.

SU(3) limit of sdgpf interacting boson model

The \%SU\%(3) limit of the \%sdg\|pf\% interacting boson model is proposed. Applications to the collective states of 236,238 U are discussed. It is shown that the spectra can be well described by the model.

Littlest Higgs Model and Higgs Boson Associated Production with Top Quark Pair at High Energy Linear e^＋e^- Collider

在参数，空格由电镀物品允许弱精确测量数据，我们考虑最小的 Higgs 模型预言到 theHiggs 波色子的新粒子的贡献高在未来把生产与最高的夸克对联系了精力线性 e~+e~ 碰撞(ILC ) 。我们发现贡献主要来自新计量器波色子 Z_H 和免费参数的 B_H.For 合理价值，相对修正参数δσ/σ~( SM )的绝对值能 signiScanly 大，它可能与S~( 1/2 )=在未来 ILCexperiment 被观察 800 GeV 。

Probing the Lightest New Gauge Boson BH in the Littlest Higgs Model via Processes γγ→f■B_H at ILC

中立计量器波色子 B 有 GeV 是的百的团的 H 如果它确实存在，最小的 Higgs (LH ) 模型预言的最轻的粒子，和如此的粒子应该是在 planed ILC 的 LH 模型的第一个信号。在这篇论文，我们学习 B 在 ILC 与费米子对联系的 H 生产，即， γγ→ fB H 。研究证明最答应处理检测 B 在 γγ→ 之中的 H fB H 是 γγ→ l'+l'- B H l'= e， μ ) ，并且他们能在电镀物品比较喜欢的大多数参数空格生产足够的信号在 ILC 的弱精确数据。在另一方面，信号经由某些 B H 腐烂模式是典型的，如此的信号能容易从 SM 背景被识别。因此， B H , 在 LH 模型的最轻的计量器波色子，将在在 ILC 认识到的光子 collider 可检测。

No Spin-Localization Phase Transition in the Spin-Boson Model without Local Field

We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition(QPT) happening between the localized and delocalized phases, and the behavior of the model can be fully characterized by the even or odd parity as well as the parity breaking, instead of the QPT, owned by the ground state of the system. The parity breaking mentioned in our case is completely diferent from the spontaneously broken symmetry relevant to the conventionally defined QPT in previous studies. Our analytical treatment about the eigensolution of the ground state of the model presents for the first time a rigorous proof of nodegeneracy for the ground state of the model, which is independent of the bath type, the degrees of freedom of the bath and the calculation precision. We argue that the QPT mentioned previously appears due to incorrect employment of the ground state of the model and/or unreasonable treatment of the infrared divergence existing in the spectral functions for Ohmic and sub-Ohmic dissipations.

Energy Staggering in Ground Bands of ^(232)Th and ^(236,238)U Nuclei Using the Interacting Vector Boson Model

The△I = 2 and △I = 4 staggering parameters of transition energies Eγfor normally deformed positive parity ground bands in232 Th and236,238 U nuclei are studied in framework of the symplectic extension of the interacting vector boson model. The model parameters are obtained from the fitting procedure between the calculated excitation energies and the corresponding experimental ones. The staggering parameters represent the finite difference approximations to higher order derivatives dnEγ/d Inof the γ-ray transition energies in a△I = 2 and △I = 4 bands, which yielding multipoint formulae. The first order derivative(two-point formula) provides us with information about the dynamical moment of inertia. The staggering oscillation for the fourth order derivative(five-point formula) is about 0.5 Ke V and is even larger than that in superdeformed bands. The quite similarity in dynamical moments of inertia of the isotopes236,238 U up to high spin states indicate that the phenomenon of identical bands is not restricted to superdeformed bands.

SU(5) symmetry of spdfg interacting boson model

The extended interacting boson model with s-, p-, d-, f- and g-bosons included (spdfg IBM)is investigated. The algebraic structure including the generators, the Casimir operators of the groups at the SU(5) dynamical symmetry and the branching rules of the irreducible representation reductions along the group chain are obtained. The typical energy spectrum of the symmetry is given.

Nuclear Structure and Electromagnetic Transitions Investigation in Er Isotopes within Framework of Interacting Boson Model

Interacting Boson Model-2(IBM-2)is used to determine the Hamiltonian for Er nuclei.Fit values of parameters are used to construct the Hamiltonian,energy levels and electromagnetic transitions(B(E2),B(M1))multipole mixing ratios(δ(E2/M1))for some even-even Er nuclei and monopole transition probability are estimated.New ideas are used for counting bosons number at N=64 and results are compared with previous works.

Symmetries of the interacting boson model

This contribution reviews the symmetry properties of the interacting boson model of Arima and Iachello. While the concept of a dynamical symmetry is by now a familiar one, this is not necessarily so for the extended notions of partial dynamical symmetry and quasi dynamical symmetry, which can be beautifully illustrated in the context of the interacting boson model. The main conclusion of the analysis is that dynamical symmetries are scarce while their partial and quasi extensions are ubiquitous.