Quantum corrections to the classical reflection factor in a2(1) Toda field theory

The O(β²) quantum correction to the classical reflection factor is calculated for one of the integrable boundary conditions of a₂⁽¹⁾ affine Toda field theory. This is found to agree with the conjectured exact reflection factor of the quantum theory. We consider the existence of other exact reflection factors consistent with our perturbative answer and examine the question of how duality transformations might relate theories with different boundary conditions.     

Supersymmetric enhancement factor for the 1-jet cross-section inp - \bar p reactions

We compare the 1-jet inclusive cross-section at highp _⊥ in proton-antiproton reaction atSPS collider predicted by standard QCD and by its simplest supersymmetric extension (SQCD). We first compute the total enhancement factorK between QCD and SQCD jets as a function ofp _⊥. Then we compute the observable enhancement factor which is smaller thanK since the transverse momentum of supersymmetric particles is not fully observable. We have analyzed two cases (i)p _⊥ is small compared to the masses of squarks and only light gluinos (2 GeV) are considered (ii)p _⊥ is large compared to the masses of squarks (17 GeV in our analysis) and both gluinos and squarks are taken into account. The observable enhancement factor between QCD and SQCD is found to be small (of order 1.3 to 1.5 forp _⊥=100 GeV). Missingp _⊥ events with one ordinary jet and one jet due to the production of a supersymmetric particle are found to be non negligible with respect to those with two supersymmetric jets. We also display some interesting supersymmetric relations among parton cross-sections.     

Nonlinear optical properties in a quantum well with the hyperbolic confinement potential

We have performed theoretical calculation of the nonlinear optical properties in a quantum well (QW) with the hyperbolic confinement potential. Calculation results reveal that the transition energy, oscillator strength, second-order nonlinear optical rectification (OR), geometric factor and nonlinear optical absorption (OA) are strongly affected by the parameters (α,σ) of the hyperbolic confinement potential. And an increment of the parameter α reduces all these physical quantities, while an increment of the parameter σ enhances them, but not for geometric factor. In addition, it is found that one can control the optical properties of QW by tuning these parameters.     

Isoscalar amplitude dominance in e + e − annihilation to N N̄ pair close to the threshold

We use the Paris nucleon-antinucleon optical potential for explanation of experimental data in the process e ⁺ e ^? → p p? near threshold. It turns out that final-state interaction due to Paris optical potential allows us to reproduce available experimental data. It follows from our consideration that the isoscalar form factor is much larger than the isovector one.     

Bound state poles of the form factors in eikonal approximation and infinite component wave equations

We investigate the form factor in eikonal approximation for the whole region of momentum transfer t in electrodynamics and in φ³ theory, and determine the poles in the time-like region below the threshold. A covariant mass formula is obtained similar to the one derived from four point functions in eikonal approximation. The mass formula does not become imaginary for large values of the coupling constant. The relation to positronium Regge trajectory and infinite component wave equations is discussed.     

Superconducting proximity effect in interacting quantum dots revealed by shot noise

We study the full counting statistics of charge transport through a quantum dot tunnel coupled to one normal and one superconducting lead with a large superconducting gap. As a function of the level detuning, there is a crossover from a regime with strong superconducting correlations in the quantum dot to a regime in which the proximity effect on the quantum dot is suppressed. We analyze the current fluctuations of this crossover in the shot-noise regime. In particular, we predict that the full counting statistics changes from Poissonian with charge 2e, typical for Cooper pairs, to Poissonian with charge e, when the superconducting proximity effect is present. Thus, the onset of the superconducting proximity effect is revealed by the reduction of the Fano factor from 2 to 1.     

Compactification and signature transition in Kaluza-Klein spinor cosmology

We study the classical and quantum cosmology of a 4 + 1-dimensional space-time with a non-zero cosmological constant coupled to a self-interacting massive spinor field. We consider a spatially flat Robertson-Walker universe with the usual scale factor R (t) and an internal scale factor a (t) associated with the extra dimension. For a free spinor field the resulting equations admit exact solutions, whereas for a self-interacting spinor field one should resort to a numerical method for exhibiting their behavior. These solutions give rise to a degenerate metric and exhibit signature transition from a Euclidean to a Lorentzian domain. Such transitions suggest a compactification mechanism for the internal and external scale factors such that a ∼ R⁻¹ in the Lorentzian region. The corresponding quantum cosmology and the ensuing Wheeler-DeWitt equation have exact solutions in the mini-superspace when the spinor field is free, leading to wavepackets undergoing signature change. The question of stabilization of the extra dimension is also discussed.     

The Bose Molecule in One Dimension

We give the Green function, momentum distribution, two-particle correlation function, and structure factor for the bound state of N indistinguishable bosons with an attractive delta-function interaction in one dimension, and an argument showing that this boson “molecule” has no excited states other than dissociation into separated pieces.     

Nonlocal potentials and their exact and approximate local and velocity-dependent equivalents

We show that good approximations to the exact equivalent local potential (ELP) and damping factor of a nonlocal Perey-Buck potential can be calculated in the partial wave WKB approximation of Horiuchi. The exact ELP and damping factor are obtained by means of a method previously given by one of us. We also confirm that an approximate ELP proposed by Bauhoff et al. is of comparable accuracy as the Horiuchi approximation. Thesel-dependent ELP's exhibit reduced attraction in the interior and provide a test for higher order WKB approximations. We subsequently obtain an equivalent velocity dependent potential (EVDP) which is even exactly wave function equivalent to the original nonlocal potential. This almost local potential, unlike the trivial equivalent local potential, is smooth and well-behaved and is therefore particularly useful in nuclear reactions where the off-shell behaviour of the potential is important.     

Numerical evidence of Luttinger liquid to Fermi liquid transformation in lithium doped trans-polyacetylene chain

We report on the first direct numerical evidence of doping-induced transformation of Tomonaga-Luttinger liquid to Fermi liquid in quasi-one-dimensional lithium doped trans-polyacetylene chain. Using density functional theoretical calculation, an analysis of density of states near the Fermi energy reveals a power-law scaling factor of Tomonaga-Luttinger liquid at low dopant concentration in the metallic regime. As soon as the doping level reaches 0.0763e/C, normal power-law scaling factor of Fermi liquid has been realized as a special case of Luttinger liquid in one dimension. The variation of density-density correlation is consistent with the present theoretical prediction.     

Vergleich zweier Methoden zur Berechnung des dynamischen Strukturfaktors für klassische Systeme

Starting from the equation of motion of the one-particle distribution function as given in the BBGKY-hierarchy Nelkin and Ranganathan and Singwiet al., respectivly, have developped two different methods of calculating the dynamic structure factor. We show, that both methods are equivalent, if one uses the same approximation for the two-particle distribution function.     

Momentum distributions in the nucleus

The nuclear form factor F(q) and one particle momentum distribution p(q) can be shown to have a power law decrease for large momenta. For the form factor F(q) we show that it is q/A that must be large for this asymptotic behavior to be important. For only q large the form factor, in a simple model, is shown to decrease exponentially in q. A similar behavior for p(q) is proposed.     

Complete Classification of Conformal Killing Symmetries of Plane-Symmetric Static Spacetimes in Teleparallel Theory

We have studied the conformal, homothetic and Killing vectors in the context of teleparallel theory of gravitation for plane-symmetric static spacetimes. We have solved completely the non-linear coupled teleparallel conformal Killing equations. This yields the general form of teleparallel conformal vectors along with the conformal factor for all possible cases of metric functions. We have found four solutions which are divided into one Killing symmetries and three conformal Killing symmetries. One of these teleparalel conformal vectors depends on x only and other is a function of all spacetime coordinates. The three conformal Killing symmetries contain three proper homothetic symmetries where the conformal factor is an arbitrary non-zero constant.     

Spin bath interaction effects on the geometric phase

We calculate the geometric phase of a spin-1/2 particle coupled to an external environment comprising N spin-1/2 particle in the framework of open quantum systems. We analyze the decoherence factor and the deviation of the geometric phase under a nonunitary evolution from the one gained under an unitary one. We show the dependence upon the system's and bath's parameter and analyze the range of validity of the perturbative approximation. Finally, we discuss the implications of our results.     

Broadening processes in GaAsδ-doped quantum wire superlattices

We use both Quantum Hall and Shubnikov de Haas experiments at high magnetic field and low temperature to analyse broadening processes of Landau levels in a δ -doped 2D quantum well superlattice and a 1D quantum wire superlattice generated from the first one by controlled dislocation slips. We deduce first the origin of the broadening from the damping factor in the Shubnikov de Haas curves in various configurations of the magnetic field and the measured current for both kinds of superlattice. Then, we write a general formula for the resistivity in the Quantum Hall effect introducing a dephasing factor we link to the process of localization.     

Laser beam brightness of apertured optical resonators

We model the fundamental mode of a circularly symmetric plano-concave resonator where one mirror is apertured by a super-Gaussian aperture, while the other is apertured by a π/2 phase aperture. The aim of the paper is to find the best values of the apertured cavity parameters allowing the highest output beam brightness. For that we take into account loss level, fundamental mode volume and beam quality factor M². We demonstrate that for a given loss level, the phase aperture is able to increase the laser beam brightness, with a rate of about 60% when its diameter is properly chosen.     

Pion-nucleon vertex form factor in a chiral soliton model with vector mesons

We investigate the pion-nucleon vertex from factor in an extended Skyrme soliton model with explicit inclusion of ϱ and ω mesons. We find a pion-nucleon coupling constant quite close to the empirical value and a cutoff mass ⋮ ⋍ 0.9 MeV in a monopole approximation to the πNN form factor at low q². This value of ⋮ is considerably larger than the prediction of the original Skyrme model (⋮⋍0.6 GeV). We also investigate the ϱ-meson-nucleon form factor and present results for the NN isovector tensor potential in comparison with empirical data.     

Reliable measurement of the FRET sensitized-quenching transition factor for FRET quantification in living cells

3-cube-based Förster resonance energy transfer (FRET) microscopy, a sensitized acceptor FRET quantification method, has been widely used to visualize dynamic protein–protein interaction in living cells. Determining the FRET sensitized-quenching transition factor (G factor) of a particular donor-acceptor pair and optical system is crucial for 3-cube FRET quantification. We here improved the acceptor photobleaching-based G factor determination method (termed as mPb-G) and the two-plasmid-based G factor determination method (termed as mTP-G) for rapid and reliable measurement of the G factor. mTP-G method determines G factor by simultaneously detecting three images of cells exclusively expressing each of two tandem constructs with multiple donors and multiple acceptors. This method circumvents switchover of the cells exclusively expressing each of the two constructs. mPb-G method images G factor by detecting three images of cells expressing a donor-acceptor tandem FRET construct before and after partially photobleaching acceptor. We performed the two methods on our dual-channel wide-field FRET microscope to obtain reliable G factor, and also measured the FRET efficiency and acceptor-to-donor concentration ratio of tandem constructs with different acceptor-donor stoichiometries in living HepG2 cells. mTP-G and mPb-G methods provide two simple and reliable tools for determining the G factor, in turn, quantitatively measuring FRET signal and monitoring dynamic biochemical processes in living cells.     

Efficiency of heteronuclear broadband decoupling and homonuclear J cross polarization analyzed on two time scales

Decoupling sequences can be evaluated, as shown in Waugh's theory, with a J scaling factor on a long time scale. The efficiency of low-power decoupling, however, must be determined by cycling sidebands, as well as by the J scaling factor, when the sampling is not synchronized with the decoupling cycle. We introduced, therefore, another scaling factor which characterizes the decoupling on a short time scale. It is also shown that these scaling factors are useful for evaluating the efficiency of homonuclear J cross polarization. We clarified criteria of the factors suitable for various J coupling constants and chemical-shift ranges. Typical decoupling sequences were analyzed using the two scaling factors.