The Tomonaga–Luttinger liquid with quantum impurity revisited: Critical line and phase diagram

We revisit the $(1+1)$ dimensional field theoretical model, which describes the Tomonaga–Luttinger liquid (TLL), interacting with a static impurity at the origin of the half line. Applying the Fermi–Bose equivalence and finite conformal transformations only, we map the model onto the Schmid model. Some details of the bosonization procedure have been given. The critical line and the phase diagram of the model follow from the renormalization group analysis of the Schmid model. The obtained critical line of the model is a hyperbola in the parameter space of the two couplings of the TLL.     

用代数哈米顿量研究CH_3Cl分子的振动谱(英文)

我们提出一种描述XH3分子的伸缩和弯曲振动的U(2)代数哈米顿量,其中包括了伸缩和弯曲振动的费米共振耦合,用它来拟合CH3Cl分子的实验数据,结果表明有较少参数的代数模型算得的偏差比其它模型算得的偏差要小.     

用代数哈米顿量研究CH3C1分子的振动谱

我们提出一种描述XH3分子的伸缩和弯曲振动的U(2)代数哈米顿量,其中包括了伸缩和弯曲振动的费米共振耦合;用它来拟合CH3Cl分子的实验数据,结果表明有较少参数的代数模型算得的偏差比其它模型算得的偏差要小.     

Thermopower of a ballistic nanowire subjected to an in-plane magnetic field in the presence of Rashba and Dresselhaus interactions

Using the single-particle formalism, we calculate the thermopower of conduction electrons in a nanowire considering dispersion relations containing local maxima. At low temperatures, the thermopower exhibits positive and negative peaks that are consistent with Mott's approximation. The peaks are degenerate at a certain direction of the magnetic field defined by the strengths of the Rashba and Dresselhaus interactions. The sign and the height of the peak depend on the number of channels available for conduction.     

Exponential law for the equipartition times among translational and vibrational degrees of freedom

Boltzmann and Jeans discussed the possibility of explaining classically the “freezing” of the high frequency degrees of freedom, in spite of its apparent conflict with the equipartition principle. Their proposal is based on the possible existence of extremely long time scales for the energy sharing with such degrees of freedom. This possibility is here supported by numerical simulation on a simple model of diatomic gas. In particular, some evidence is produced that a conjecture by Jeans, on the exponential dependence of the time scales on the frequency, is correct.     

Light scattering from a system with vibrational degrees of freedom: Approximate calculation of dispersion relations

It is shown that a scheme for the approximate calculation of the dispersion relations suggested by Gershon and Oppenheim seems to account for the sound speed dispersion reasonably well but poorly describes the wave vector dependence of the damping.     

Thermopower evidence for Wigner crystallization in the insulating phase of two-dimensional GaAs bilayer hole systems

We report on low-temperature thermopower measurements of interacting GaAs bilayer hole systems in the limit of no interlayer tunneling. These systems exhibit a reentrant insulating phase near the many-body quantum Hall state (QHS) at total filling factor ν=1, when both layers have the same density. The diffusion thermopower is expected to diverge as T^-1 in the presence of an energy gap (Wigner crystal) or to vanish in the case of a disordered induced mobility gap. Our results show that, as the temperature is decreased, the diffusion thermopower exhibits a T^-1 dependence in the insulating phase around ν=1. This behavior clearly indicates the opening of an energy gap at low temperature, in agreement with the formation of a pinned Wigner solid. Finally, we report on the T-dependence of the thermopower at ν=1.     

Superstrings with tensor degrees of freedom

We add antisymmetric tensor degrees of freedom to the usual superstring coordinates. We show that super and kappa symmetries are only achieved for the spacetime dimensionD=4. We also address problems related to the quantization of the model and discuss the influences of this extended spacetime in the usual quantum field theory.     

Breakdown of Landau Fermi liquid theory: Restrictions on the degrees of freedom of quantum electrons

One challenge in contemporary condensed matter physics is to understand unconventional electronic physics beyond the paradigm of Landau Fermi-liquid theory. Here, we present a perspective that posits that most such examples of unconventional electronic physics stem from restrictions on the degrees of freedom of quantum electrons in Landau Fermi liquids. Since the degrees of freedom are deeply connected to the system’s symmetries and topology, these restrictions can thus be realized by external constraints or by interaction-driven processes via the following mechanisms: (i) symmetry breaking, (ii) new emergent symmetries, and (iii) nontrivial topology. Various examples of unconventional electronic physics beyond the reach of traditional Landau Fermi liquid theory are extensively investigated from this point of view. Our perspective yields basic pathways to study the breakdown of Landau Fermi liquids and also provides a guiding principle in the search for novel electronic systems and devices.     

Chiral dynamics with quark degrees of freedom

The possibility to detect DCC fluctuations is discussed. It is shown that interactions with quark background and dissipative effects due to interactions in the chiral field may result in damping of fluctuations. Since the magnitude of fluctuations depends strongly on the initial state and speed of chiral phase transition an accurate evaluation of all modifying processes is required to predict the observability of DCCs.     

Intrinsic stochasticity with many degrees of freedom

We study a simple model equation describing a system with an infinity of degrees of freedom which displays an intrinsically chaotic behavior. Some concepts of fully developed turbulence are discussed in relation to this model. We also develop an approach based on Lyapunov exponent measurements. Numerical results on the distribution of Lyapunov numbers and the power spectrum of the associated Lyapunov vectors are presented and briefly discussed.     

Nucleon-nucleon correlations with quark degrees of freedom

A dynamical equation of two nucleons in a nucleus is formulated in the nonrelativistic quark model including Pauli blocking due to the other nucleons. This equation is solved with a model wave function containing the possiblity of six-quark bags with different radii. It is shown that the Pauli blocking effect is emphasized by the non-nucleonic degrees of freedom represented by six-quark bags. The modification of the quark momentum distribution for correlated nucleons is calculated and probabilities of non-NN components in nuclei are estimated.     

Dynamics of nematics with conformational degrees of freedom

On the basis of Hamilton approach the dynamics of the biaxial nematics is considered. All hydrodynamic parameters, connected with broken symmetry, are introduced in terms of the distortion tensor. The equations of ideal hydrodynamics are obtained and the three spectra of collective excitations of biaxial nematics are considered, taking into account the rod-shape of molecules.     

Microscopic nuclear structure with subnucleonic degrees of freedom

Czechoslovak Journal of Physics - The long-standing picture of the nucleus as a system of nucleons is considered to be basically correct and therefore forms the starting point for corrections. The...