Search results for "mass [rho(770)]"
showing 10 items of 416 documents
The Influence of Absorption on the Extinction of Solar and Sky Radiation
1965
The purpose of this paper is to investigate the influence of absorption of the aerosol particles on the extinction of solar and sky radiation. The efficiency factors have been computed as well as the extinction, the scattering, the absorption, and the scattering function for the whole turbid atmosphere with help of the Mie theory for a complex index of refraction for a more or less absorbent medium. From these values the intensities of diffuse sky radiation have been obtained. The extinction and absorption coefficients increase for a more absorbent atmosphere, whereas the scattering coefficient decreases. The imaginary part of the complex index of refraction effects an increasing attenuatio…
Non-smooth modelling of billiard- and superbilliard-ball collisions
2008
Abstract A description of billiard-ball collisions using a ‘discontinuous’ model is presented considering a two-step situation corresponding to the ball–ball interaction followed by ball-supporting surface interaction. It is applied to the inelastic impact of a cue ball having arbitrary pivotment and ‘English’ spins against an object ball initially at rest. This formulation provides a simplified approximation to the ‘continuous’ models of impact and considers two different regimes of impact: gross slip, and slip–stick, described in terms of coefficients of friction and restitution. As a result, the angles of scattering of the balls just after the impact (post-collision angles) and when the …
Density Functional Theory of Multicomponent Quantum Dots
2004
Quantum dots with conduction electrons or holes originating from several bands are considered. We assume the particles are confined in a harmonic potential and assume the electrons (or holes) belonging to different bands to be different types of fermions with isotropic effective masses. The density functional method with the local density approximation is used. The increased number of internal (Kohn-Sham) states leads to a generalisation of Hund's first rule at high densities. At low densitites the formation of Wigner molecules is favored by the increased internal freedom.
Heavy fermion spin liquid in herbertsmithite
2015
We analyze recent heat capacity measurements in herbertsmithite $\rm ZnCu_3(OH)_6Cl_2$ single crystal samples subjected to strong magnetic fields. We show that the temperature dependence of specific heat $C_{mag}$ formed by quantum spin liquid at different magnetic fields $B$ resembles the electronic heat capacity $C_{el}$ of the HF metal $\rm YbRh_2Si_2$. We demonstrate that the spinon effective mass $M^*_{mag}\propto C_{mag}/T$ exhibits a scaling behavior like that of $C_{el}/T$. We also show that the recent measurements of $C_{mag}$ are compatible with those obtained on powder samples. These observations allow us to conclude that $\rm ZnCu_3(OH)_6Cl_2$ holds a stable strongly correlated …
Frequency-dependent relaxation rate in superconductingYBa2Cu3O6+δ
2000
The submillimeter-wave $3 {\mathrm{cm}}^{\ensuremath{-}1}l\ensuremath{\nu}l40 {\mathrm{cm}}^{\ensuremath{-}1}$ complex conductivity of the reduced ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6+\ensuremath{\delta}}$ film ${(T}_{C}=56.5 \mathrm{K})$ was investigated for temperatures $4 \mathrm{K}lTl300 \mathrm{K}$ and compared to the properties of the same film in the optimally doped state. The frequency dependence of the effective quasiparticle scattering rate $1/{\ensuremath{\tau}}^{*}(\ensuremath{\nu})$ was extracted from the spectra. $1/{\ensuremath{\tau}}^{*}$ is shown to be frequency independent at low frequencies and high temperatures. A gradual change to $1/{\ensuremath{\tau}}^{…
Correlation gap in the heavy-fermion antiferromagnetUPd2Al3
2002
The optical properties of the heavy-fermion compound ${\mathrm{UPd}}_{2}{\mathrm{Al}}_{3}$ have been measured in a frequency range from 0.04 to 5 meV $(0.3--40{\mathrm{cm}}^{\ensuremath{-}1})$ at temperatures $2\mathrm{K}lTl300\mathrm{K}.$ Below the coherence temperature ${T}^{*}\ensuremath{\approx}50\mathrm{K},$ a hybridization gap opens around 10 meV. As the temperature decreases further $(Tl~20\mathrm{K}),$ a well-pronounced pseudogap of approximately 0.2 meV develops in the optical response; we relate this to the antiferromagnetic ordering which occurs below ${T}_{N}\ensuremath{\approx}14\mathrm{K}.$ The frequency-dependent mass and scattering rate give evidence that the enhancement of …
Nature of Heavy Quasiparticles in Magnetically Ordered Heavy FermionsUPd2Al3andUPt3
2002
The optical conductivity of the heavy fermions $\mathrm{UPd}{}_{2}{\mathrm{Al}}_{3}$ and $\mathrm{UPt}{}_{3}$ has been measured in the energy range from 0.04 to 5 meV. In both compounds a well pronounced pseudogap of less than 1 meV develops in the optical response at low temperatures; we relate this to the antiferromagnetic ordering. From the energy dependence of the effective mass and scattering rate we conclude that the enhancement of the mass mainly occurs below the energy which is related to magnetic correlations between the local magnetic moments and the itinerant electrons. This implies that the magnetic order in these compounds is the prerequisite to the formation of the heavy quasi…
Breaking Symmetry Effects on Heavy Tetraquarks
2017
In this contribution we present symmetry arguments that can be applied to study the stability of four-quark systems with two different masses. The role played by different symmetry breaking effects and the non-Abelian algebra of color forces is discussed in detail. In the particular case of hidden-flavor all-heavy four-quark states, QQ (Q) over bar(Q) over bar, the system becomes unstable for standard color-additive models. Differences and similarities between Qq (Q) over bar(q) over bar and QQ (q) over bar(q) over bar configurations are presented. In the latter case, its stability when the mass ratio M/m increases was established almost forty years ago. In the former case, we find a kind o…
Density-near-zero using the acoustically induced transparency of a Fano acoustic resonator
2016
International audience; We report experimental results of near-zero mass density involving an acoustic metamaterial supporting Fano resonance. For this, we designed and fabricated an acoustic resonator with two closely coupled modes and measured its transmission properties. Our study reveals that the phenomenon of acoustically induced transparency is accompanied by an effect of near-zero density. Indeed, the dynamic effective parameters obtained from experimental data show the presence of a frequency band where the effective mass density is close to zero, with high transmission levels reaching 0.7. Furthermore, we demonstrate that such effective parameters lead to wave guiding in a 90-degre…
General Relativistic Dynamics of Irrotational Dust: Cosmological Implications
1994
The non--linear dynamics of cosmological perturbations of an irrotational collisionless fluid is analyzed within General Relativity. Relativistic and Newtonian solutions are compared, stressing the different role of boundary conditions in the two theories. Cosmological implications of relativistic effects, already present at second order in perturbation theory, are studied and the dynamical role of the magnetic part of the Weyl tensor is elucidated.