共查询到20条相似文献,搜索用时 609 毫秒
1.
Otto Nachtmann 《Nuclear Physics B》1981,187(1):141-148
We consider the contribution to 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 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.
M. Bishari 《Physics letters. [Part B]》1977,66(1):54-56
The origin for the smallness of is discussed within the framework of a factorizable dual bootstrap model with full t-dependence. 相似文献
3.
The infrared reflection of polycrystalline samples of perovskite 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
4.
New quarks and new flavor-changing neutral currents give multiple lepton plus hadron final states in e+e-, . 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 are not sensitive to the presence of flavor-changing neutral currents. Much more sensitive are the processes are +e-+βand (for charm changing neutral currents) . 相似文献
5.
Analysis of the attenuation of and values with distance over grassland from a line of moving traffic indicates that the noise sources effectively radiate energy in the horizontal plane with a distance term different from the commonly assumed inverse square law. This requires an adjustment to the angular corrections for partial screening which now become dependent on the noise index being measured. The attentuation of traffic noise by a wooden fence structure around a suburban house has also been investigated. Shielding effects caused by various components were isolated as the fence structure was sequentially demolished. The shape of the sound field behind the finite length of front fence was deduced, for the various values, by using the amended angular corrections. 相似文献
6.
The (0,0) band of the emission (Infrared Afterglow) system of molecular nitrogen has been recorded with a resolution of 0.046 cm?1 and a line position accuracy of 0.007 cm?1. Six hundred and seventy-two lines are tabulated into a line list for the 1.53 μm (low-resolution) emission feature. Of these, 482 are assigned as members of the 27 branches of the B′ → B transition, while 150 are identified with the 1PG (3,6) band. Molecular constants for the v = 0 levels of the and B3Πg states have been computed and tabulated. 相似文献
7.
A.R.W McKellar 《Journal of Molecular Spectroscopy》1981,86(1):43-54
Magnetic dipole transitions between the and components of the ground electronic state of BrO have been detected using the technique of laser magnetic resonance on three CO2 laser lines between 964 and 970 cm?1. This is the first direct observation of the state in BrO. The spin-orbit splitting parameter, A, is determined to be ?967.9831(2) cm?1 for 79Br16O and ?967.9981(2) cm?1 for 81Br16O. Accurate values for the rotational constant , the hyperfine parameters () and d, the Λ-doubling parameter p, and the Zeeman parameter g| are also determined from an analysis of the measured spectra. 相似文献
8.
D. Bertrand G. Bertrand-Coremans R. Blaes F.W. Bullock M. Dewit B. Escoubes E. Fett A. Haatuft A. Halsteinslid T.W. Jones J.G. Morfin K. Myklebost J.M. Olsen P. Petitjean M. Pohl F. Rahimi P.N. Ratoff J. Sacton L.C. Welch 《Physics letters. [Part B]》1979,84(3):354-356
Candidates for the purely leptonic process have been searched for in the bubble chamber Gargamelle exposed to the CERN-SPS antineutrino wide-band beam. No single e?, of energy greater than 1 GeV, was found in a total of 230 000 pictures, corresponding to 7400 charged current events. This leads to an upper limit for the observed cross section of cm2 (90% C.L.). Interpretation of this value in terms of the standard W Weinberg-Salam model yields an upper limit to the mixing parameter sin2θW < 0.39 at 90% C.L. 相似文献
9.
The question of fine structure in the variation of the average number of prompt neutrons, , 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 (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 for this nucleus. 相似文献
10.
11.
We have excited the and 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 and . The value of is in disagreement with the one reported by Schenk and Pillof. 相似文献
12.
The deviations from the exponential decay law of the states of the Dirac hydrogen atom with respect to the transition are numerically estimated. We find |a0(t) ? exp(?λt)|?2.5 × 10?4 for all t, where a0(t) is the “exact” decay amplitude and λ is a complex constant such that (2Re λ)?1 is the “natural lifetime” of the states with respect to the spontaneous transition to . 相似文献
13.
N.B. Manson J.T. Gourley E.R. Vance D. Sengupta G. Smith 《Journal of Physics and Chemistry of Solids》1976,37(12):1145-1148
At helium temperatures two sharp lines at 9350 and 9510 cm?1 have been observed for the first tune on the low-energy side of the broad double-peaked absorption corresponding to the transition in Fe2+ at the octahedral site in MgO. The lower energy line has a half width of 4 cm?1; Zeeman measurements show that it is of magnetic dipole origin. The Zeeman spectra are consistent with those expected for a pure electronic transition from the (5T2g)T2g ground state to the 5Eg excited state. The second line, with a halfwidth of ~ 35 cm?1, a vibrational sideband. 相似文献
14.
G. Carboni G. Gorini E. Iacopini L. Palffy F. Palmonari G. Torelli E. Zavattini 《Physics letters. [Part B]》1978,73(2):229-231
The measurement of the energy transition in muonic helium is presented. The energy difference S1 is found to be Sexp1 = 1381.3±0.5 meV. This result agrees with the expected value obtained assuming the previously measured value for the energy difference. 相似文献
15.
The dependence of the low-lying spectra of 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 spectrum. A relation between the Σ0-binding energies and has been established and on its basis a prediction is made about a possible binding energy of . 相似文献
16.
A. Eibofner 《Physics letters. A》1977,61(3):159-161
The double quantum r.f. transition in the n = 6 state of ionized helium has been observed using electron impact excitation in a helium atmosphere. The possibilities of the method are discussed. 相似文献
17.
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 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 state is estimated. It is found that the state at 5.123 MeV loses more than 80% of its strength to five collective states in 209Bi and the observed state at 3.64 MeV is actually an almost equal mixture of the single-proton state and the () collective state. 相似文献
18.
N.A. Narasimham K.V.S.R. Apparao T.K. Balasubramanian 《Journal of Molecular Spectroscopy》1976,59(2):244-254
Vibrational and rotational analyses of the near-infrared bands of S2 lying in the region 7440–8085 Å are reported. They form a new band system involving a transition and arise from the same initial 3Πgi state of the 3Πgi-3Δui band system reported earlier. The analyses of the bands of this system due to the isotopic molecules 32S34S and 34S2 are also reported. 相似文献
19.
The magnetic moments of the 12+ isomers in 192, 196, 198, 200, 206Pb and of the isomer in 205Pb have been measured using the PAD technique. The results for the g-factors are: g(192) = ?0.173(2), g(196) = ?0.1600(15), g(198) = ?0.1552(15), g(200) = ?0.1512(15), g(206) = ?0.1496(18), and g(205) = ?0.148(5). As all states have a rather pure configuration, the values reflect directly the orbital. They show a decrease towards the more neutron-deficient isotopes attributed to the reduced core polarisation as a result of decreasing occupation of the neutron shell. The measured systematics are discussed regarding core polarisation, mesonic corrections, and small admixtures of core-excited states to the wave function. 相似文献
20.
A magnetic dipole core polarization was studied by investigating a magnetic moment of the 1117 keV single-proton state in 141Pr. The 139La(α, 2nγ)141Pr reaction was used to populate the 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 state. The g-factor of the 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 . neutron states. It is . 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 state. 相似文献