共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
The exact vanishing of all β functions of the Callan-Symanzik equation is proved in a two-dimensional model with Thirring and gradient couplings: , and , where ψ, π and σ are fermion, pseudoscalar and scalar massive fields, respectively. The anomalous dimensions of scalar and pseudoscalar fields are also shown to be zero. Then we demonstrate that in two-dimensional models including at most one fermion field, only these three couplings can give asymptotic scale invariance. 相似文献
3.
The rate for the decay of a Z-boson into a Higgs boson and monochromatic photon is computed to leading order in the standard SU(2) × U(1) gauge theory. The coupling has contributions from fermion and W-boson loops. The W-boson loop dominates unless the number of heavy fermion generations exceeds six. The branching ratio computed from the W-boson loop contribution, B(Z→Hγ), is approximately 2 × 10?6. 相似文献
4.
Planar channelling of 1, 1.5 and 2 MeV 4He+ ions along (100), (110) and (111) MgO have been studied experimentally using Rutherford backscattering. Values of the half angle , shoulder half angle and surface minimum yield xPmin have been determined for channelling with respect to the two sublattices. Agreements and discrepancies with existing theories are discussed. 相似文献
5.
N. Kimura 《Nuclear Physics B》1984,246(1):143-156
Masses of all the glueballs which are created by 6- or 7-link operators are calculated to order g?8 in pure SU(3) hamiltonian lattice gauge theory. Several low-lying states are found with masses (1 and 7 stand for radial excitations and ms is the mass of the lowest 0++ state), . These values are obtained at the point g?2 ? 0.8, which lies near the scaling region. 相似文献
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7.
The cyclotron resonance of inversion-layer electrons on (100)p-type Si is found to depend sensitively on an externally applied compressive stress. At low temperatures (T ? 10 K) we observe a considerable increase of the cyclotron mass m1c with stress S along the [001] direction. The effect is most strongly observed at low electron densities ns. For and ns~2 × 1011cm-2 we obtain instead of the expected 0.2m0. Along with this change of a strong narrowing of the resonance is noted. Raising the temperature gives an additional ns- dependent increase of . 相似文献
8.
C.A. Piketty 《Nuclear Physics B》1974,68(1):44-65
We have evaluated the parity-violation contribution in atoms in the framework of SO(3) gauge theory. Various hadronic models have been used: first, for simplicity, the unrealistic five-quark one, next, others involving three ordinary SU(3) triplets for which all unwanted strangeness-changing processes are suppressed, up to order . In the free quark approximation, we obtain quite similar parity-violation effects which are proportional to (ΔM2 is the difference of squared masses of leptons (MX02 ? Mν2 = MX02), or of quarks (ΔMq2)). Namely, in large atoms (Z ? 1) the electronic contribution which is proportional to gives the largest effect (are the spin, momentum operators and mass of the lepton). Parity-violating effects in SO(3) gauge models are ?10?4 smaller than those evaluated in the Weinberg theory with a neutral parity-violating current and will remain undetectable in the near future. 相似文献
9.
J. Leotin R. Barbaste S. Askenazy M.S. Skolnick R.A. Stradling J. Tuchendler 《Solid State Communications》1974,15(4):693-697
The first observation of cyclotron resonance in p-type InP is reported. The holes were thermally excited at 110 K and the resonance was observed at 337μm wavelength (HCN laser) using a pulsed magnetic field of 0–350 kG. The effective masses of the light and heavy holes in the 〈111〉 direction were found to be , and in the 〈100〉 direction , . We obtain an estimate of the Dresselhaus parameters A = ?5.04, |B| = 3.12, C2 = 6.57. We also report the effective masses for p-type GaP in the 〈111〉 direction as , . 相似文献
10.
We show, in the euclidean path-integral formulation of strong-coupling lattice gauge theory, that continuous chiral symmetry is dynamically broken, and obtain the standard current algebra result that . We also remark that the center of the gauge group does not seem very relevant for this result; chiral symmetry breaking is a property of strong-coupling lattice theories both in the case where quark color is confined, and also in the case where it is screened by gauge field fluctuations. 相似文献
11.
H. Braun M. Cornelssen H.-U. Martyn O. Erriquez S. Natali F. Romano D. Bertrand M. Csejthey-Barth J. Lemonne P. Renton P. Vilain D.C. Cundy T.I. Pedersen D. Waldren 《Physics letters. [Part B]》1973,47(2):185-188
The q2 variation of the factor in the decay K+→π0e+ν has been studied using a sample of even detected in the CERN 1.1 m3 heavy-liquid bubble chamber. The data are consistent with a linear development with λ+=0.027±0.008. 相似文献
12.
Zhao Zhiyong 《Nuclear Physics B》1983,212(2):224-236
The phenomenological predictions of the SO(10) supersymmetric grand unified model (SO(10) SGUM) for the mass scales M1, M2, weak angle ifsin2θw, quark-leptons mass ratios , , and proton lifetime τp are estimated by using renormalization group analysis at one-loop level. In contrast with SU(5) SGUM, we find that the SO(10) SGUM still has problems with τp but not with sin2θw and , which may suggest that supersymmetry would be bro at a mass scale . 相似文献
13.
The stability of soliton solutions to the nonlinear Schrödinger equation iψt + ψxx + β|ψ|νψ = 0 is investigated for arbitrary positive ν. 相似文献
14.
Rediative masses are generated for the first and the second fermion families by exploiting the idea that their chirality is a symmetry of the “low-energy” SU(3) × SU(2) × U(1) approximation of SU(5), broken only by including the effects of superheavy particles. With only 5's of Higgs coupled to fermions and getting a non-zero vacuum expectation value, we unavoidably get (i) at the grand unification scale; (ii) the charm quark needing a direct mass as the third family; (iii) neutrino masses of size . 相似文献
15.
In this note we determine the oscillator strengths for the dipole absorption of neutral bound excitons in direct gap semiconductors, using our previously obtained 35-term Page and Fraser type wave function, and taking into account the detailed electronic structure as well as the electron-hole exchange interaction.The envelope part of the oscillator strengths varies considerably with the electron-hole mass ratio , and is maximum for the (D0, X)- complex when σ = 0.4. For typical σ-values (σ? 0.1–0.2), . But when σ approaches zero, the overlapping of the electron and the hole envelope wave functions of the (A0,X)-complex decreases progressively so that the oscillator strength also decreases and tends to zero.In the case of zinc-blende materials (Td) and positive spin-orbit coupling at , we confirm that the line strength for transitions to or from or level of the (A0, X)-complex is equal to one quarter of the line strength to or from the level.In the case of CdS, where our computed values are only in qualitative agreement with the experimental values, we discuss the use of the phenomenological result of Rashba. 相似文献
16.
The present article is a review of phenomena connected with neutrino oscillations. Mixing of two neutrinos (Majorana as well as Dirac) with masses m1 and m2 is considered in detail. It is shown that the hypothesis of lepton mixing is not in contradiction with the existing data if |m12?m22| ? 1 (eV)2. Possible experiments designed to reveal neutrino oscillations at reactor, meson factory and high energy accelerator facilities are considered. In such experiments oscillation might be found if . The possibilities of searching for oscillations by experiments on cosmic ray neutrinos and especially on solar neutrinos are discussed in detail. The last experiments have an incredible high sensitivity from the point of view of testing the lepton mixing hypothesis (oscillation effects might be observable if ). The “solar neutrino puzzle” is also discussed from the point of view of lepton mixing. Neutrino oscillations are considered then in the case where in nature there exist N ? 2 neutrino types.In conclusion the case of heavy lepton mixing is considered. It is shown that in a concrete scheme with right-handed currents, the probabilities of such processes as μ → eγ, μ → 3e etc. can be close to existing experimental upper limits, provided the heavy lepton masses are of an order of a few GeV, whereas the probabilities of the above processes are entirely negligible if only neutrinos are mixed. 相似文献
17.
Given a mapping , whose bifurcation points accumulate at λ = Λ∞, it is shown that the iterates converge to a function ψ(μ,y)asp→∞, where X∞ maximizes . The function ψ is universal up to scaling in μ and y, and satisfies ψ(μ/δ,ψ(μ/δ,?y/α)) = ?α?1ψ(μ,y). This result generalizes the well-known Feigenbaum universal function g(y) with g(g(?y/α)) = ?g(y/α, which is the special case for μ = 0. 相似文献
18.
F.E. Close 《Physics letters. [Part B]》1973,43(5):422-426
The small ω′ behaviour of F2en/F2ep and the apparent difference in the q2 dependences of the magnetic form factor of the proton and of the transition to Δ+(1236) are quantitatively correlated in a model where nucleon consistes of a quarks and a scalar or vector core. The proton and Δ transition form factors suggest that only the scalar core contributes at large q2 and small ω′. As a result the ω′ dependence of is obtained for ω′ < 3 and predictions for the weak structure functions and polarisation asymmetries at smallω′ are presented. We predict asymmetries and also expect that as q2→∞. 相似文献
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20.
The relativistic generalization of the Thomas-Fermi model of the atom is derived. It approaches the usual nonrelativistic equation in the limit Z ? Zcrit, where Z is the total number of electrons of the atom and and α is the fine structure constant. The new equation leads to the breakdown of scaling laws and to the appearance of a critical charge, purely as a consequence of relativistic effects. These results are compared and contrasted with those corresponding to N self-gravitating degenerate relativistic fermions, which for give rise to the concept of a critical mass against gravitational collapse. Here m is the mass of the fermion and is the Planck mass. 相似文献