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1.
We consider the contribution to σLσt in deep inelastic lepton-hadron scattering from a certain class of 4-quark operators in the framework of QCD. We find for this case by explicit calculation that σLσT is of order g2(Q2), with g2(Q2) the running coupling strength of QCD, in agreement with a general result of Politzer.  相似文献   

2.
A technique applicable to situations with different noise sources is developed on the basis of a series of limited data (short-term Leq).This technique makes acoustic monitoring of a site possible, identifying and evaluating the respective contributions of the different components of the environment studied.  相似文献   

3.
The question of fine structure in the variation of the average number of prompt neutrons, νp, emitted per fission with energy in the neutron fission of 233U and 235U has been examined. Consistent structure has been found in measurements of both νpandEK (the average total fission fragment kinetic energy) for 233U. Channel analysis of the neutron fission cross section of 233U allows the structure to be calculated quantitatively provided the collective energy at the second hump in the fission barrier is weakly coupled to the nuclear degrees of freedom at scission. A similar calculation for neutron fission of 235U supports the case for the absence of fine structure in νpandEK for this nucleus.  相似文献   

4.
We have excited the 4D32 and 4D52 levels of sodium using Doppler-free two-photon excitation. By measuring the polarization rate in zero magnetic field of the fluorescence lines, we have deduced the following values for the hyperfine interaction |A(4D32) | = 0.23 ± 0.12 MHz and |A(4D52)| < 0.28 MHz. The value of A(4D32) is in disagreement with the one reported by Schenk and Pillof.  相似文献   

5.
Methods of obtaining nucleon occupancies from total energy-weighted sum rules for spectroscopic factors are described and applied to f72 neutron transfer data for Ca isotopes. The f72 neutron occupancies obtained are consistent with shell model expectations and, for 41Ca and 43Ca, with values previously obtained from an analysis using non-energy-weighted sum rules.  相似文献   

6.
The structure of negative-parity states in odd-mass N= 82 isotones (135 ≦ A ≦ 145) is investigated in the framework of a model which is based on coupling one 1h112 proton to π = + 1 states of the appropriate doubly-even isotonic core. It is shown that an effective model-space truncation can be achieved if only core states in the vicinity of the yrast line are taken into account. These have been selected from the several hundreds or even thousands of states obtained from shell-model calculations, where the 1g72, 2d52, 2d32 and 3s12 single- are assumed to be occupied. Spectroscopic data are calculated and predictions on the structure of low-lying π = ? 1 states are discussed and compared as far as possible to experimental findings. Thereby, the particle-core coupling approach is shown to be capable of describing essential properties of negative-parity levels in the N = 82 nuclei considered.  相似文献   

7.
The origin for the smallness of σelσT is discussed within the framework of a factorizable dual bootstrap model with full t-dependence.  相似文献   

8.
A magnetic dipole core polarization was studied by investigating a magnetic moment of the 1117 keV 1h112 single-proton state in 141Pr. The 139La(α, 2nγ)141Pr reaction was used to populate the 1h112 state with spin aligned in a plane perpendicular to the beam axis. The magnetic moment was obtained by measuring perturbed angular distributions of the 972 keV gamma rays from the 1h112 state. The g-factor of the 1h112 state in 141Pr was determined to be g = 1.30 ± 0.08. The isovector spin g-factor was deduced from the present result and the data for 1h112. neutron states. It is gs?effgs?free = 0.45 ± 0.1. The reduction is explaine spin-isospin (M1) core polarization.The isovector M1 core polarization factor (nuclear M1 susceptibility) is found to be one third of the M2 core polarization factor (nuclear M2 susceptibility) for the 1h112 state.  相似文献   

9.
An optimized Woods-Saxon potential, which gives excellent fits to the observed proton states in 209Bi and 207Tl, is used to calculate the excitation energy of the unbound 3p12 proton state in 209Bi. Using the wave functions given by the above potential, the strength of the core-particle interaction is calculated. The effect of the vibration of the core on the fragmentation of the 3p12 state is estimated. It is found that the 3p12 state at 5.123 MeV loses more than 80% of its strength to five 12? collective states in 209Bi and the observed 3p12 state at 3.64 MeV is actually an almost equal mixture of the 3p12 single-proton state and the (4+, 1h92) collective state.  相似文献   

10.
The dependence of the low-lying spectra of Λ, Σ9Be hypernuclei on hyperon-α interaction in the molecular α + α + Λ(Σ) scheme has been studied. A suggestion is made for obtaining the strengths of both p-wave and spin-orbit Λ-α interactions from the experimental Λ9Be spectrum. A relation between the Σ0-binding energies BΣ(Σ9Be) and BΣ(Σ9He) has been established and on its basis a prediction is made about a possible binding energy of Σ5He.  相似文献   

11.
We determine bounds on quark mixing angles in the standard six-quark model from an analysis of the decay KL → μμ. When combined with previous bounds from a Cabibbo fit and study of the K0 ? K0 transition amplitude, these can yield an improved upper limit on one of the angles.  相似文献   

12.
We report a systematic increase of the linewidth of luminescence, absorption and excitation spectra of undoped GaAs-Ga1-xAlxAs Multi-Quantum structures with decreasing layer thickness. This broadening is interpreted as due to the island-like structure of the interfaces. A very simple model assuming islands with a one monolayer height and a lateral size ? 300 Å gives very good agreement with the reported linewidths.  相似文献   

13.
The electrical resistivity of the system (La, Ce)B6 has been measured in the temperature range 0.04–300 K. The alloys show a Kondo minimum at about 20 K and a strong increase of the resistivity with decreasing temperature. The low temperature increase of the resistivity due to the Kondo effect of a sample containing 1, 2 at.% is about half as large as the room temperature resistivity of LaB6. The Kondo temperature TK of (La, Ce)B6 was found to be 1.1 ± 0.2 K by comparison of the experimental results with theoretical predictions of the resistance anomaly associated with the formation of the spin-compensated state.  相似文献   

14.
The total cross-sections for ve (ve)-nucleon scattering have been measured. A test has been made of the muon number conservation law. A limit of 2.4 GeV is found the mass of the “Georgi-Glashow type” heavy lepton  相似文献   

15.
New quarks and new flavor-changing neutral currents give multiple lepton plus hadron final states in e+e-, vμN, vμN. We observe that (i) e+e- is a favored place to search for their effects through inclusive ratios σ(e+e-+x:σ (μ+μ- +x): σ(e±μ±+x) and same sign leptons e±e±+x, μ±μ±+x,e±μ±+x. Above a new flavor threshold four charged lrpton final states may become important. (ii) Trilepton final states in vμN, vμN are not sensitive to the presence of flavor-changing neutral currents. Much more sensitive are the processes vμN are +e-+βand (for charm changing neutral currents) vμN→e+β.  相似文献   

16.
If KS1,Lis a K1 resonance decaying into KS,L (the short- and long-lived kaon) and a neutral system So of pions, one can isolate the C-even and C-odd, crossed-channel contributions to KN → K1N by using the reactions KLN → KS1, LN whether So is a C-eigenstate, or a mixture of C-even and C-odd states. Applications to the production of K1(890) and the Q-meson are discussed, and simple numerical predictions made for QS,L production. Q-production data indicate approximate t-channel helicity conservation for the ω and P' exchanges at vertices involving a spin change, in similarity to the belief for the pomeron. QS,L production data can give information also on Q-decays.  相似文献   

17.
The 2p32 alignment of silver following 0.1–5.1 MeV proton impact ionization has been determined from the polarization of the L3M1 X-ray transition, as measured by a Johansson-type crystal spectrometer. The results were corrected for thick target effects and are in agreement with the results of thin target measurements as well as theoretical predictions.  相似文献   

18.
19.
The infrared reflection of polycrystalline samples of perovskite Sr(Sr13Nb23)O3 are reported and analysed with Kramers-Kronig inversion. Results give information on the structures of the high-temperature and low-temperature forms of the atomic arrangements.  相似文献   

20.
An investigation of the γ-decay of the 1g92 analogue state in 59Cu has been performed using the 58Ni(p, γ)59Cu reaction. The (p, γ) excitation function has been taken in the range Ep = 3450–3650 keV. The decay schemes of the (p, γ) resonances at Ep = 3483, 3532 and 3547 keV, measured with Ge(Li) detectors, lead to eight new levels in 59Cu with excitation energies between 1.8 and 4.7 MeV and to spin assignments of several states. The spins of the first two resonances are found to be (12, 32) and (52). The spin of the Ep = 3547 keV resonan is, from angular distributions, uniquely determined to be Jπ = 92+ and this state is found to be the unfragmented analogue state of the E1 = 3.062 MeV, Jπ = 92+ parent state in 59Ni. The measured complete decay scheme of this resonance shows that its isovector M1 decay is in disagreement with all existing theoretical predictions.  相似文献   

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