共查询到20条相似文献,搜索用时 46 毫秒
1.
M.A. Markov 《Physics letters. A》1983,94(9):427-429
A model of a perpetually oscillating universe is considered. In this model the universe, when contracting to Planck dimensions, transforms from the Friedmann to the De Sitter phase with one and the same , irrespective of the value of the total bare mass of the Friedmann universe. 相似文献
2.
D. Ziemińska 《Nuclear Physics A》1975,242(3):461-466
The branching ratios are calculated for 11ΛB decay to the 11C ground and excited states below 8 MeV for two possible spin values of 11ΛB. It is found that the decay rate to the 11C★ state at E★ = 6.48 MeV is comparable in magnitude to that leading to the 11C ground state if is assumed. This result, unlike the branching ratios calculated for the case, is in accord with experiment and lends support to the assumption that holds for 11ΛB. The necessity of the reinterpretation of some of the so-called 13ΛC events in terms of is indicated. 相似文献
3.
A simultaneous analysis of low-energy (W ? 2 GeV) data for the reactions π?p→ KOΛ and K?p → πOΛ has been made using the hypothesis of two-component duality combined with fixed-t dispersion relations. Results are presented for the and couplings. The low-energy amplitudes are used to evaluate FESR integrals and lead to large EXD breaking for the helicity flip amplitudes. 相似文献
4.
The probability distribution calculated for the decay sequence passing through the (JPN) = (2+, 1) intermediate state 12C1 (16.11 MeV) is cast in a symmetrical form and used to calculate the likelihood for on the basis of the 85 examples available for this decay process. This procedure has optimum sensitivity, is free from the uncertainties of the comparisons previously made using only projected angular distributions, and strongly indicates that JP = 1? holds for 12ΛB(g.s.). An appendix points out that all the data for the decay sequence passing through the (JPN, T) = (1+, 0) level of 12C1 is well fitted for J = 1 if the J = 1 → Jn = 1 transition amplitude as1 takes a value in the range as1/s = 0.08 to 0.09. 相似文献
5.
The characteristics of the decay sequences are discussed for the two sharp levels of 12C1 at excitation energies of 12.7 MeV (Jf = 1+, T = 0) and 16.11 MeV (Jf = 2+, T = 1), which are observed prominently in this decay process. The transition rates for these processes and the angular correlations in the final four-particle state αααπ? are discussed quantitatively, using the intermediate coupling model for both the 12ΛB and 12C1 systems, as a function of the 12ΛB spin J. Three distinct tests are proposed, which are sensitive to the spin J for ground-state 12ΛB, and which have been used by the European K? Collaboration to deduce that J = 1 for 12ΛB. The implications of this conclusion for the ΛN and ΛNN interactions are briefly discussed. 相似文献
6.
P. Benkheiri J. Boucrot B. Bouquet P. Briandet B. DAlmagne C.Dang Vu B. Eisenstein A. Ferrer P. Fleury B. Grossetête G. Irwin A. Jacholkowski A. Lahellec H. Nguyen P. Petroff F. Richard P. Rivet G. De Rosny H. Yoshida 《Physics letters. [Part B]》1977,68(5):483-486
From the study of the reaction using a fast proton (pF) trigger device in the CERN Omega spectrometer, we find evidence for two narrow states produced mainly in association with a Δ° (1232) and a N° (1520). The statistical significance of each peak is greater than 6 standard deviations. Masses and natural widths of these resonances are respectively M = 2020 ± 3 MeV, Λ1 = 24 ± 12 MeV and M2 = 2204 ± 5 MeV, Λ2 = 16?16+20 MeV. Our data are consistent with a small production of the narrow ~ 1935 MeV resonance already reported. Production cross sections for these new resonances are given. 相似文献
7.
The electroreflectance of Si under uniaxial stress has been measured in the 3.0–4.0 eV region at 77 K. The results indicate that the dominant structure in this energy region is attributed to Λv3 → Λc1 (or Lv3′ → Lc1 transition. The deformation potentials of these bands are determined to be . 相似文献
8.
G.W. Brandenburg W.B. Johnson D.W.G.S. Leith J.S. Loos J.A.J. Matthews F.C. Winkelmann R.J. Yamartino 《Physics letters. [Part B]》1973,44(3):305-309
Differential cross sections for center of mass scattering angles near 90° are presented for the reactions , and KL°p → KS°p in the momentum interval 1.0 to 7.5 GeV/c. The energy dependences of these cross sections are found to be equally well described by the parameterization: or . 相似文献
9.
G. Otter H. Remplewski G. Rudolph L. Becker R. Klein W. Lohmann H.J. Schreiber K. Böckmann U. Idschok J. Lowsky B. Schröder D.J. Kocher D.R.O. Morrison K.-L. Wernhard T. Coghen K.W.J. Barnham R. Eason H. Rohringer 《Nuclear Physics B》1979,155(2):295-306
Results are presented for p → (ΛK+) dissociation in the reactions K?p → ΛK+K? and and π±p → ΛK+π±at 10 and 16 GeV/c. The cross sections for the low-mass ΛK+ enhancement are compatible with the energy dependence σ ∝ plab?0.3. The t′ spectra or the (ΛK+) threshold enhancement are exponential in shape. Its decay angular distribution reveals neither s-channel nor t-channel helicity conservation. The relative probabilities of the processes dissociation are in the ratios 100 : 10 : 0.2, independent of the nature of the incident particle. 相似文献
10.
H. Roos 《Reports on Mathematical Physics》1978,14(2):161-170
A microcanonical system oΛ is considered together with a manometer Λ. The thermodynamic limit Λ → ∞ is taken for the system Λ composed of oΛ and Λ. This yields a definition of the pressure P(v, ε) of for given values ε and v of the energy and particle densities. P(v, ε) is shown to be equal to the thermodynamic function p(z, β) derived from the grand canonical ensemble for almost all values of ε and v provided the appropriate equilibrium values of the temperature β?1 and the chemical potential μ = β?1 log z are inserted. 相似文献
11.
The reactions pp → pp and pp → Δ++n with polarized beam and/or polarized target are currently under investigation at the Argonne ZGS. We discuss how to interpret various measured quantities in terms of amplitudes whose behavior is familiar (as functions of s, t). For pp total cross sections and elastic scattering, Argonne measurements will yield Im ?2 (s,t = 0) and the rather complicated combination , where ?i (i = 1, … 5) are conventional s-channel helicity amplitudes. The forward direction (t = 0) is of special interest. We find that for both pp → pp and pp → Δ++n, polarized beam — polarized target experiments plus the rather general (testable) assumption that amplitudes with the same s-channel helicity flip quantum numbers are proportional, are sufficient to fully determine all non-vanishing amplitudes at t = 0. Numerical estimates of some observables, based on calculations in a specific model, are also given. 相似文献
12.
H. Taureg G. Zech F. Dydak F.L. Navarria P. Steffen J. Steinberger H. Wahl E.G.H. Williams C. Geweniger K. Kleinknecht 《Physics letters. [Part B]》1976,65(1):92-96
The branching ratio has been determined to be (2.68±0.15)×10?3 for photon energies greater than 50 MeV in the KS0 rest frame. The decay KS0→π+π?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10?3 at 90% confidence level for . 相似文献
13.
M.B. Gavela A. Le Yaouanc L. Oliver O. Pène J.-C. RaynaL T.N. Pham 《Physics letters. [Part B]》1982,109(3):215-220
In the Kobayashi-Maskawa model, penguin diagrams can induce CP violating phases in matrix elements of the type n→Λ. This produce a neutron electric dipole moment through subsequent parity violating radiative weak decay Λ→nγ. We can expect , three to four orders of magnitude bigger than the mechanism based on the transition quark electric dipole moment. The reason is essentially that the GIM cancellation comes in the Penguin case from as for the transition quark electric dipole moment. 相似文献
14.
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
15.
Otto Nachtmann 《Nuclear Physics B》1974,74(3):422-428
Recent experimental results on electroproduction off protons show that the ratio σ(ep → eK+Σ0)/σ(ep → eK+Λ) decreases strongly with increasing Q2. A simple argument is given in the framework of the quark parton model which could provide a qualitative understanding of this fact. The decrease of the Σ0/Λ ratio is related to the decrease of the ratio as Q2 increases, where are the usual structure functions for deep inelastic electron-nucleon scattering. 相似文献
16.
H. Laven G. Otter G. Rudolph R. Klein H.J. Schreiber D.J. Kocher D.R.O. Morrison P. Schmid K.L. Wernhard R.M. Eason T.C. Bacon K.W.J. Barnham P.J. Dornan B. Pollock J. Macnaughton M. Markytan 《Nuclear Physics B》1977,127(1):43-56
The reactions (1) K?p → K+K?Λ and (2) have been studied on samples of 109 and 64 events, respectively, at 10 GeV/c and 125 and 69 events at 16 GeV/c, reasonably free from contaminations. The investigation of the first reaction uses also 84 events of the final state at 10 GeV/c. Analysis of the Van Hove plots indicates that the K+K?Λ and final states are produced by two main mechanisms: (i) a ΔQ = 0 process, with a strong diffractive component near threshold, involving the dissociations p → K+Λ in reaction (1) and in reaction (2) and (ii) a ΔQ = 1 process involving hypercharge exchange, and producing K+K? and systems in reactions (1) and (2), respectively, recoiling off the Λ. With increasing energy, this hypercharge exchange process decreases slowly when K+K? is produced, but fast where the production of , violating the Zweig rule, occurs. 相似文献
17.
The absorption and MCD spectra of the , , and spin-allowed transitions of Cr3+ in K2NaGaF6 are reported. It is shown that transitions to the . states are induced by T1u vibratio the other spin-allowed transition, , there are three competing intensity mechanisms: electric dipole induced by T1u vibrations, electric dipole induced by T2u vibrations and magnetic dipole, and an estimate is made of the relative importance of these. The magnetic dipole zero-phonon line is observed to be accompanied by a vibrational sideband for which the coupling is predominantly with T2u vibrations. Other weak transitions are observed in MCD spectra and their origin briefly discussed. 相似文献
18.
Moshe Moshe 《Physics letters. [Part B]》1981,98(4):297-300
Though high twist terms are becoming important as x→1, or equivalently, in large n moments, their detection in this regime in deep inelastic lepton scattering needs special caution. The high order terms in the twist two component are strongly dependent on n; one finds that at the perturbative expansion is invalid whereas higher twist terms are important at . Since grows very fast with n the necessary requirement for any deep inelastic phenomenological analysis, namely , cannot hold for too large moments. The scheme dependence of ak, αk and bk is also discussed. 相似文献
19.
20.
The two emission lines, Kα1α3h and Kα2α3h resulting from the two-electron transitions and were resolved for elemental nickel. Their measured energies agree well with calculations. Their relative intensity and their intensity relative to that of the Kα diagram lines is about 10?4. This is some 104 times larger than both theoretical results and the results of ion-atom collision experiments. 相似文献