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This work presents the results of developing a set of electronic and chemical reactions for a plasma discharge in octafluoropropane (C3F8). Electronic reactions were obtained using the most relevant set of cross sections at the moment, taking into account experimentally known dissociation and ionization channels. Based on the dissociation products obtained during electronic reactions, a set of chemical reactions was adapted by analogy with the C4F8 reaction scheme from the literature. Next, the resulting complete set of reactions was tested against published experimental data on the concentration of electrons, negative ions, and electronegativity in a capacitive plasma discharge at different gas pressures and discharge input powers. For this purpose, a one-dimensional hydrodynamic drift-diffusion model was used. Reasonable agreement was obtained between the model and experimental data on electronegativity. Eventually, the resulting set of reactions was adapted for a two-dimensional hydrodynamic drift-diffusion model of an ICP discharge. The results of the calculations are two-dimensional distributions of radicals and ions, radical and ion composition of fluxes onto the substrate under conditions typical for industrial reactors. [ABSTRACT FROM AUTHOR]

Analytical expressions for the effective mass of heavy, light, and spin split-off electrons are obtained by diagonalizing the k ⋅ p Hamiltonian for cubic perovskite crystal structures and used to calculate these in nine perovskite materials. An expression for the effective hole g-factor is also derived and calculated in these perovskites. The calculated effective mass of heavy electrons ranges from 1.619 m0 to 0.201 m0, of light electrons from 0.357 m0 to 0.146 m0, and of spin split-off electrons from 0.584 m0 to 0.169 m0. It is found that Cl- and Pb-based perovskite materials have larger heavy, light, and spin split-off electron effective masses. It is also found that the effective g-factor increases with the atomic size, from Cl to I, for the series CsSn X 3 (X = Cl , Br , I). [ABSTRACT FROM AUTHOR]

InAsSb-based strained layer superlattices (SLS) have strong fundamental absorption, which can be easily modified in a controlled manner by injecting excess carriers. This makes them attractive for intensity modulation of infrared lasers as well as beam steering and spatial beam shaping with a nanosecond-scale time response. This paper reports the modulation of the fundamental absorption and the refractive index by carrier injection in a 3.45-nm-period InAsSb0.65/InAsSb0.35 SLS with a low temperature energy gap of 85 meV grown by molecular beam epitaxy on a GaSb substrate with a GaInSb metamorphic buffer. The SLS absorber was sandwiched by n- and p-type wider energy gap layers for electrical injection and confinement of excess carriers. The population of conduction band states was obtained by measuring the intensity modulation of a 10.6 μm CO2 laser for temperatures ranging from T = 77 to 200 K. An increase of the electron quasi-Fermi level with electrical injection up to 20 meV was observed. The experimental data imply a decrease in the Auger coefficient with temperature, from 3 × 1024 cm6/s at 77 K to 1 × 1024 cm6/s at T = 200 K attributed to recombination involving two electrons and a heavy hole. The refractive index changes obtained by electrical injection of excess carriers can reach 0.05 at T = 77 K and 0.035 at T = 200 K, which are at least three orders of magnitude greater than those obtained with electro-optical materials. [ABSTRACT FROM AUTHOR]

The characteristics of atmospheric pressure Ar-plasma such as the spatial distributions of number densities, fluxes, and temperatures of electrons and heavy plasma particles, as well as the spatial distribution of electric potential around an individual spherical particle, were studied numerically on the basis of the hydrodynamic (diffusion) equations for plasma components. The governing equations were formulated for plasma that is not in thermal and ionization equilibrium. The boundary conditions near the particle were set on the edge of the space charge layer (sheath) adjacent to the particle surface. The nonlinear problem was solved taking into account the temperature dependencies of transport and kinetic coefficients. The heat flux introduced by the plasma into the particle was calculated and compared with the results of the simple heat conduction model. The range 10 − 5 – 10 − 4 m of particle radius and the range 6–18 kK of unperturbed plasma temperature were considered. [ABSTRACT FROM AUTHOR]

We investigate the transition probabilities for the "flavor" eigenstates in the two-level quantum system, which is described by a non-Hermitian Hamiltonian with the parity and time-reversal (PT) symmetry. Particularly, we concentrate on the so-called PT-broken phase, where two eigenvalues of the non-Hermitian Hamiltonian turn out to be a complex-conjugate pair. In this case, we find that the transition probabilities will be unbounded in the limit of infinite time t → +∞. However, after performing a connection between a non-Hermitian system, which exhibits passive PT symmetry and global decay, and the neutral-meson system in particle physics, we observe that the diverging behavior of the transition probabilities is actually applicable to the gauge-transformed neutral-meson states, whereas the transition probabilities for physical states are exponentially suppressed by the global decay. We also present a brief review on the situation at the so-called exceptional point, where both the eigenvalues and eigenvectors of the Hamiltonian coalesce. [ABSTRACT FROM AUTHOR]

To predict the nonequilibrium flows around a hypersonic vehicle entering the Martian atmosphere, the two-temperature collisional-radiative model "CoRaM-MARS" has been developed. The species CO2, CO, C2, CN, N2, NO, O2, C, N, O, Ar, CO+, C 2 + , CN+, N 2 + , NO+, O 2 + , C+, N+, O+, Ar+, and free electrons are taken into account. The model can therefore be used for conditions belonging to wide ranges of temperatures and pressures. The model is vibrationally specific on the ground electronic state of CO2, CO, C2, CN, N2, NO, and O2 and electronically specific for all species, with a total of almost 445 vibrational states and 1139 electronic states, respectively. Due to the high temperatures involved (∼40 000 K), a wide set of elementary processes is considered under electron and heavy particle impact reaching ∼106 forward and backward elementary processes. The model is implemented in a 1D Eulerian code simulating the shock crossing of the hypersonic flow in the conditions of the entry of the EXOMARS Schiaparelli module into the Martian atmosphere. [ABSTRACT FROM AUTHOR]

We report on the electronic properties of β-(InxGa1-x)2O3 alloys with different In-content up to 18.75% using density functional theory (DFT) calculations. The effect of In-content on the band structures as well as the crystal structures of β-(InxGa1-x)2O3 alloys is presented and discussed. Our analysis shows that β-(InxGa1-x)2O3 alloys exhibits indirect gap property, with the band gap reducing from 4.817 eV to 4.422 eV when the In-content increases up to 18.75%. The bandgap energy corresponds to the wavelength region extending from 255 to 280 nm, which implies the possibility for β-(InxGa1-x)2O3 alloys to be applied in the deep UV photodetectors. The electron and heavy hole effective masses are also obtained for the first time based on the band edge dispersions of the β-(InxGa1-x)2O3 materials. Additionally, the effect of band parameters on the impact ionization processes using β-(InxGa1-x)2O3 materials are analyzed. Our new insight regarding the electronic properties indicate the potential of β-(InxGa1-x)2O3 alloys in deep ultraviolet photodetector applications. [ABSTRACT FROM AUTHOR]

We provide explicit lower bounds for the ground-state energy of the renormalized Nelson model in terms of the coupling constant α and the number of particles N, uniform in the meson mass and valid even in the massless case. In particular, for any number of particles N and large enough α, we provide a bound of the form −Cα2N3 log2(αN), where C is an explicit positive numerical constant; and if α is sufficiently small, we give one of the form −Cα2N3 log2N for N ≥ 2 and −Cα2 for N = 1. Whereas it is known that the renormalized Hamiltonian of the Nelson model is bounded below (as realized by Nelson) and implicit lower bounds have been given elsewhere (as in a recent work by Gubinelli, Hiroshima, and Lörinczi), ours seem to be the first fully explicit lower bounds with a reasonable dependence on α and N. We emphasize that the logarithmic term in the bounds above is probably an artifact in our calculations since one would expect that the ground-state energy should behave as −Cα2N3 for large N or α, as in the polaron model of Fröhlich. [ABSTRACT FROM AUTHOR]

In this paper, we propose a simple quantum model of the kaons decay providing an estimate of the CP symmetry violation parameter. We use the two-level Friedrich’s Hamiltonian model to obtain a good quantitative agreement with the experimental estimate of the violation parameter for neutral kaons. A temporal wave-function approach, based on an analogy with spatial wave-functions, plays a crucial role in our model. [ABSTRACT FROM AUTHOR]

Reports on the magnetoresistance measurements of the heavy electron compound Ube[sub13] above the superconducting transition temperature. Preparation of the polycrystalline UBe[sub13]; Data on the normalized magnetoresistivity.

Tables of scalar factors are presented for 63x63 and 120x63 in SU(8)⊃SU(4)xSU(2), and for 35x35 and 56x35 in SU(6)⊃SU(3)xSU(2). Related tables for SU(4)⊃SU(3)xU(1) and SU(3)⊃SU(2)xU(1) are also provided so that the Clebsch-Gordan coefficients can be completely reconstructed. These are suitable to study meson-meson and baryon-meson interactions within a spin-flavor symmetric scheme. [ABSTRACT FROM AUTHOR]

The article describes an activity program for physics students regarding the physical principles of the bound states of quarks which are the baryons and mesons.

The influence of uniaxial deformation on the transport properties of bismuth wires is studied in a wide range of temperatures. Measurements of the resistance of bismuth nanowires with several diameters and different quality reveal oscillations in the strain dependence of the resistance for uniaxial strain at T=4.2 K. The amplitude of oscillations is significant (38%) at helium temperature and becomes smeared at T=77 K. The oscillations observed are due to the quantum size effect. By evaluating the period of oscillations we are able to identify the groups of carriers involved in transport. The computed periods of 42.2 and 25.9 nm are approximatively in the ratio 2:1 for two experimentally observed sets of oscillations from light and heavy electrons. [ABSTRACT FROM AUTHOR]

We obtain from first principles, i.e., from the quark-gluon dynamics, the Gell’Mann-Ne’eman baryonic eightfold way energy momentum spectrum exactly in an imaginary-time functional integral formulation of strongly coupled lattice quantum chromodynamics in 3+1 dimensions, with local SU(3)c gauge and global SU(3)f flavor symmetries. We take the hopping parameter κ and the pure gauge coupling β satisfying the strong coupling regime condition 0<β«κ«1. The form of the 56 baryon fields emerges naturally from the dynamics and is unveiled using the hyperplane decoupling method. There is no a priori guesswork. In the associated physical quantum mechanical Hilbert space H, spectral representations are derived for the two-baryon functions, which are used to rigorously detect the particles in the energy-momentum spectrum. Using the SU(3)f symmetry, the 56 baryon states admit a decomposition into 8×2 states associated with a spin 1/2 octet and 10×4 states associated with a spin 3/2 decuplet. The states are labeled by the quantum numbers of total hypercharge Y, total isospin I, its third component I3, and the value of the quadratic Casimir of SU(3)f; they also carry a label of total spin J and its z component Jz. The total spin operators are defined using π/2 rotations about the spatial coordinate axes and for improper zero momentum baryon states agree with the infinitesimal generators of the continuum. We show there is a partial restoration of continuous rotational symmetry which implies that all the octet (decuplet) masses are the same. For β=0, the masses of the 56 baryon states have the form M=-3 ln κ-3κ3/4+κ6r(κ), with r(κ) analytic. There is no mass splitting within the octet (decuplet). However, we find an octet-decuplet mass splitting given by 3κ6/4+O(κ7). For β=0, [M(κ,β)-(-3 lnκ)], the non-singular part of the masses, is analytic in κ and β and the mass splitting persists for β≠0. For spatial momentum p≠0, p≠(p1,p2,p3)∈(−π,π]3, the 56 baryon dispersion curves have the form w(κ,p)=−3 ln κ-3κ3/4+κ3∑j=1,2,3(1-cos pj)/4+r(κ,p), where r(κ,p) is of O(κ6). For the octet, r(κ,p) is jointly analytic in κ and in each pj for small |Im pj|. For each baryon, there is an antibaryon related to it by charge conjugation and with identical spectral properties. It is shown that the spectrum associated with baryons and antibaryons is the only spectrum in the subspace of H with an odd number of quarks, up to near the meson-baryon energy threshold of ≈-5 ln κ. A new time reflection is found which is used to define a local spin flip symmetry. The spin flip symmetry, together with the usual parity, time reversal, and spatial π/2 rotation symmetries and analytic implicit function arguments, are used to obtain these results. Our method extends to the SU(N)f case to uncover (2N+2)!/[3!(2N-1)!] baryon states and also to treat mesons. Coupling our baryon results with our similar results for the eightfold mesons (of asymptotic mass -2 lnκ) shows that the model exhibits confinement up to near the two-meson threshold. [ABSTRACT FROM AUTHOR]

We consider one flavor lattice quantum chromodynamics in theimaginary time functional integral formulation for space dimensions d=2, 3 with 4×4 Dirac spin matrices, small hopping parameter κ, 0<κ<1, and zero plaquette coupling. We determine the energy-momentum spectrum associated with four-component gauge invariant local meson fields which are composites of a quark and an antiquark field. For the associated correlation functions, we establish a Feynman–Kac formula and a spectral representation. Using this representation, we show that the mass spectrum consists of two distinct masses m[sub a] and m[sub b], given by m[sub c]=-2 ln κ+r[sub c](κ), c=a,b, where r[sub c] is real analytic. For d=2, m[sub a] and m[sub b] have multiplicity two and the mass splitting is κ[sup 4]+O(κ[sup 6]); for d=3, one mass has multiplicity one and the other three, with mass splitting 2κ[sup 4]+O(κ[sup 6]). In the subspace of the Hilbert space generated by an even number of fermion fields the dispersion curves are isolated (upper gap property) up to near the two-meson threshold of asymptotic mass -4 ln κ. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Focuses on the color wave functions of the quark model for colorless multiquark configurations. Construction without group theory; Nonexistence of normalizable color singlet wave functions for free quarks; Derivation of color wave functions for mesons and baryons.

Investigates a variational approach to the study of two-particle bound states in quantum field theory. Use of the scalar Yukawa model in which scalar nucleons interact via meson exchange; Use of a variational trial state that contains one or two scalar nucleons with any number of mediating scalar mesons; Integral equations for the one- and two-nucleon systems.

Non-Abelian vector gauge theories, with gauge groups of the type U(1)×SU(n)×SU(n’)×···, have been formulated in terms of scalar singleton fields. Massless vector mesons appear as two-singleton states. The theory is a gauge theory already at the singleton level, and singleton brst transformations induce BRST transformations of the ordinary kind. [ABSTRACT FROM AUTHOR]