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1.
It is proved that the quantum mechanical Hamiltonian for bosons (resp, fermions) is bounded from below if N ≤ cbκ?1 (resp. ). H is unbounded from below if N ≥ cblκ?1 (resp. ). The constants cb and cbl (resp. cf and cfl) differ by about a factor 2 (resp. 4). 相似文献
2.
H. Kleinert 《Physics letters. [Part B]》1976,62(1):77-80
In quark gluon theory with very small bare masses, -ψ, spontaneous breakdown of chiral symmetry generates sizable masses Mu, Md, Ms, … We find (. Scalar densities have well determined non-zero vaccum expectations at an SU(3) breaking of the vacuum c′ ≡ 〈0|u8|〉/〈0|uo|0〉 ≈ ? 16% 相似文献
3.
A.H.P. van der Burgh 《Journal of sound and vibration》1976,49(1):93-103
A procedure, closely related to the averaging method, is given for the construction of asymptotic approximations for the solutions of the Lagrangian system where ε > 0 and δ > 0 are small parameters, aij = aji and βij = βji are real constants. The solutions can be represented as follows: The asymptotic approximations (in a certain well-defined sense) of a, b, ξ and ψ are given. It is shown that a rapid variation of the phase, ψ(t), will take place if b → 0 for the case that δ ≈ ε or δ ? ε. In addition for the case δ ≈ ε the phenomenon of bifurcation will be discussed. 相似文献
4.
Elastoresistances of TCNQ high conducting salts have been measured at room temperature by an original strain gauge technique. The effects, on the longitudinal and transverse resistivities ?, of an elementary uniaxial strain ? applied along one of the three axes, a, b or c1 respectively, have been estimated.For TTF-TCNQ, they are: ; ; (5% risk).So, in an hydrostatic pressure experiment, the fraction of piezoresistivity attributable to transverse effects is 43± 10% of the total value χb (Kba and Kbc effects accumulated).Low values have been found for the anisotropy (?a/?b) variations due to strains. So one may write: ; ; .The TTF-, HMTTF-, TSF-, HMTSF-TCNQ elastoresistance values are coherent with the previously measured hydrostatic pressure piezoresistivity values.All these experimental results are in good agreement with a model where the longitudinal but also the transverse elastoresistivities are essentially due to variations with strains of the longitudinal scattering time τν defined by σb = ne2τν/m1. 相似文献
5.
The longitudinal conductivity of a quasi-one-dimensional metal is calculated for the case T?ωD (ωD being the limiting phonon frequency) and ωDl1/v?1 where l1 is the effective mean free path determined by impurity and phonon scattering: is the impurity mean free path. The conductivity is σ = (c1e2/πS)l3iv?2ωDλT for li?lph, σ = (c2e2/πS)vωD(λT)?2 for li?lph, λ being the dimensionless electron-phonon interaction constant, c1, c2 ~ 1, S = axay is the (xy) area per one chain. 相似文献
6.
H. Kleinert 《Physics letters. A》1983,96(6):302-306
We show that defect melting involving dislocations and disclinations is dually equivalent to an extension of an XY model with an energy of the type Σi, j{[cos(?iuj + ?jui) + ? cos ?iωj] }, where is the local rotation field. The. model clarifies the proper choice of defect core energies arising from nonlinear elasticity. These permit the pile-up of dislocations to disclinations which is essential for the first order of the melting transition. 相似文献
7.
Microwave spectrum of cis, trans-divinyl ether has been remeasured and doublet splittings were observed in most of the b and c type lines and also in a few of the a type transitions. The splittings were analyzed in terms of tunneling motion of the two vinyl groups through the planar configuration in which a steep potential barrier exists due to the repulsion between the α and β hydrogen atoms of trans and cis vinyl groups, respectively. An effective Hamiltonian the form was used for the analysis where terms in parenthesis apply only for the upper levels of the tunneling doublet. The values of Ga = 2.764, αv = ?0.391, βv = ?0.0067, and γv = +0.00065 (all in MHz) were derived in addition to the tunneling doubling Δv as 27.28 MHz and the refined rotational and centrifugal distortion constants. The potential barrier was approximated by a Gaussian function of the form and its height, A, was estimated to be 580 cm?1 (1.6 kcal/mole) by way of WKB approximation.The definitions of large-amplitude vibrations in non-planar and non-linear molecules were discussed and a criterion to distinguish internal rotation, pseudo-rotation, inversion, and puckering from each other was derived. The motion reported in this paper was classified as internal rotation by this criterion. 相似文献
8.
Yu.M. Antipov V.A. Bessubov N.P. Budanov Yu.P. Gorin S.P. Denisov S.V. Klimenko A.A. Lebedev Yu.V. Mikhailov A.I. Petrukhin S.A. Polovnikov V.N. Roinishvili D.A. Stoyanova F.A. Yotch 《Physics letters. [Part B]》1978,76(2):235-236
The differential cross sections and of inclusive J/ψ production by 43 GeV/c π? off Be, Cu and W nuclei have been measured. Fitting we observed the increase of α with pt2. 相似文献
9.
The Painlevé test for the parametrically driven sine-Gordon equation is performed. A new equation is derived which passes the Painlevé test. The connection with the integrability is discussed. 相似文献
10.
William H. Hamill 《Journal of Physics and Chemistry of Solids》1982,43(6):559-562
The time- and temperature-dependent drift mobility μd for dispersive transients in disordered solids is in terms of distance L, field E and transit time tT. Since current I ∝ tsu?(1?α) for t <Tand 0<α<1 by Scher-Montroll theory for hopping among localized states, it follows that where τ≈ 10?13s is estimated. Further and the activation energy Δ0 is time independent. On this basis Δ for the carbazole polymers is ca. zero, that for a-Se is ca. 0.05 eV, and that for a-As2Se3 is 0.35 eV rather than 0.5, 0.3 and 0.6 eV respectively on a phenomenological basis for μd(T,t). Trap-controlled hopping transport may be excluded. Time-resolved optical studies of excess carrier recombination supplement mobility measurements in a-Si:H and a-As2Se3 as well as other systems. Combined results suggest a dielectric response mechanism in which the time-dependent hopping frequency of localized carriers ν ∝ tα?1 arises from distortion of the medium at localization sites. This is satisfied by Δ(T,t) = Δ0+(1?α)KTT ln(t/τ) where τ is the mean initial localization time of the carrier, 10?13?10?12s, Δio is the height of the barrier at T, and 0<α<l. Consequently ν = ν0(t/τ)α?1 exp(frsol|?Δ0/KT) which applies also to bimolecular recombination. 相似文献
11.
For the prolate asymmetric (κ = ?0.58) top molecule dimethylketene the centrifugal constants have been determined in terms of the Δ constants by means of ΔK? ≠ 0 rotational transitions. Two earlier assigned torsional excited states (01, 10)1 and (01, 10)2 of symmetry B2 and A2 of C2v could be confirmed. A third fundamental vibration vr(b1), probably the inplane skeletal rock, has been found and analyzed in the vr = 1 and vr = 2 states. The variation of the centrifugal constants and of the inertial defects with the state of excitation could be explained by Coriolis coupling between the vr(b1) = 1 vibrational and vt(b2) = 1 torsional excited states. The Coriolis constant and the torsional frequency ωt(b2) have been estimated to be and ωr(b1) - ωt(b2) ≈ 5.8 cm?1, respectively. 相似文献
12.
The volt-ampere curves and their second derivatives were studied for niobium point contacts at low temperatures in the voltage range corresponding to the characteristic phonon energies. It was found that while for the dirty contacts in the normal state no PC spectra of phonons could be detected, in the superconducting state there were singularities in the I–V curves corresponding to maxima either in the first or in the second derivatives. The singularities observed were due to the energy dependence of the excess current. We suppose that the origin of these singularities is due to the inelastic transitions of electrons between chemical potentials of Cooper pairs at both sides of the contact, which differ in energy by eV. These transitions are possible if ξ(0) ? d ≈ Λ?, (ξ(0) being the coherence length; d, the contact diameter; , where li and l? being the elastic and inelastic electron mean free paths, respectively). 相似文献
13.
B. Ghidini F. Navach A. Palano V. Picciarelli G. Zito J. Bröring K. Müller E. Paul W. Renneberg W. Rühmer J. Eades B. French L. Mandelli J. Moebes M.E. Edwards I. Smith R.A. Donald C. Palazzi-Cerrina 《Nuclear Physics B》1978,132(5):429-438
The reaction , where ps is a slow proton, was measured at 12 GeV/c incident momentum with the CERN-OMEGA spectrometer. Both antiproton and proton were identified uniquely by electronics information. We obtained 1844 events with four-momentum Transfer squared in the range 0.13 ? |t| ? 0.33 GeV2 and with invariant masses up to 2.5 GeV. The corresponding cross section in this t range is determined to be σ = 4 ± 0.4 μb. Extrapolating the differential cross section over the whole t range assuming dσ/dt ≈ exp(5.3t) we estimate a cross section of σ = 9.3 ± 2.0 μb. Comparison with data on (where ns is a slow neutron) in the same t range shows that the cross sections have approximately the same magnitude. 相似文献
14.
The emission spectrum of the He2 molecule has been rephotographed in the ~4000–~5700 Å region and the , , and transitions analyzed. The 4dδj3Δu, 4dπj3Πu, and states have been characterized through v = 2 and the 4dδJ1Δu, 4dπJ1Πu, , and states for v = 0. The term levels for these perturbed and l-uncoupled states have been confirmed (a) by analyses of bands with common levels from Δv = 0, ±1 sequences and (b) by analyses of the transitions between the above states from 4d and 4s and the and states associated with 3pσ. Molecular constants are reported which have been partially corrected for the effects of l-uncoupling and the homogeneous perturbations between the state pairs J, H and j, h. 相似文献
15.
L.A.P. Balázs 《Physics letters. [Part B]》1974,48(3):232-234
By generalizing universality to Regge-particle “scattering” we obtain for pp → pX, where bf(t) and bP(t) are the f and P Regge residues for, say, pp → pp. This agrees with the recent NAL data. 相似文献
16.
Energy curves and transition moments of the excited valence states of Hg2 were obtained in a model calculation based on calculated Mg2 energy levels and the assumption that the asymptotic spin-orbit matrix elements for the Hg atom are applicable to the molecular states. The spin-orbit and orbital-rotational interaction of the excited states of Hg2 is analyzed in both a Hund's case (c) and (a) representation. The intermediate (a) → (c) transition moments are obtained as a function of the internuclear distance. The effect of the orbital-rotational interaction which introduces Hund's case (b) and (e) couplings is found to be small for transitions among excited states under the conditions normally encountered for populating excimer states.Using the energy level positions and transition moments, the observed spectra and predicted spectra are compared for both radiative transitions including the ground state and among the excited states. The lifetime of the excimer state is calculated to be 1.4 μsec with the 335 nm band assigned to the transition. The 485 nm bands cannot be assigned to any Hg2 transitions. Strong bound-continuum absorptions are predicted for the 485 nm bands. On the other hand, the 335 nm emission is predicted to be absorbed by bound-bound transitions only. 相似文献
17.
S.L. Verbeck J.C. Fong G. Igo C.A. Whitten D.L. Hendrie Y. Terrien V. Perez-Mendez G.W. Hoffmann 《Physics letters. [Part B]》1975,59(4):339-342
The energy spectra of α-particles recoiling from a 4He gas target bombarded by 0.58 and 0.72 GeV protons have been measured to obtain the differential cross sections for elastic scattering , in the region of four-momentum transfer squared, ?t=0.13 ? 0.55 (GeV/c)2. The experiment was designed especially to observe the region between the first and second diffraction maxima. 相似文献
18.
We study the potentials of the form U(r)=?r?1+λV(r), , and show that the energy levels satisfy the inequalities to first order in λ, where Nc denotes the coulombic principal quantum number and l the angular momentum. Similarly for potentials , we prove to first order in λ that , where NH denotes the harmonic oscillator quantum number. In the latter case, we give also quantitative restrictions on the relative positions at the lth and (l+1)th states. 相似文献
19.
John Miles 《Physica D: Nonlinear Phenomena》1984,11(3):309-323
The weakly nonlinear, resonant response of a damped, spherical pendulum (length l, damping ratio δ, natural frequency ω0) to the planar displacement εl cos ωt (ε ? 1) of its point of suspension is examined in a four-dimensional phase space in which the coordinates are slowly varying amplitudes of a sinusoidal motion. The loci of equilibrium points and the corresponding bifurcation points in this space are determined. The control parameters are and . If α < 0.441 there is a finite interval of v within which no stable equilibrium points exist. As v decreases through the upper bound (a Hopf-bifurcation point) of this interval the motion in the phase space becomes periodic and then, following a period-doubling cascade, chaotic. There may be alternating sub-intervals of chaotic and periodic motion. The chaotic trajectories in the phase space appear to lie on fractal attractors. 相似文献
20.
Taisuke Nakanaga Shigeo Kondo Shinnosuke Saëki 《Journal of Molecular Spectroscopy》1980,81(2):413-423
The Coriolis interactions between ν1 and ν3, and between ν2 and ν3 in SO2 have been analyzed to obtain the signs of the products and . It has been found that both of the signs of these products are positive. Then, relative signs of () have been determined using the calculated values of the Coriolis zeta constants for the present definition of the normal coordinates. The obtained sign combination of () is ±(+?+), which agrees with the one predicted by the molecular orbital calculations. Using the sign combination (+?+), the polar tensors of S and O atoms were also calculated. 相似文献