共查询到20条相似文献,搜索用时 31 毫秒
1.
W.K. Theumann 《Physica A》1975,83(1):85-120
The two-point correlation function ? (q, ξ) is calculated in the critical region of momentum space q in terms of a suitable correlation lenght ξ, by means of perturbation expansion to order 1/n, for an n-vector system with long-range interactions decaying as , for , where a is the spacing on a d-dimensional lattice, σ < d < 2σ and 0 < σ ? 2 ? ηSR. The calculations are done in zero field for T ? Tc. Explicit expansions for long-range propagators are developed for and for the neighborhood of σ ? 2 ? ηSR, in terms of which a universal, cut-off independent scaling function is obtained over the whole range of , and it is shown that the amplitude of the correlation-length dependence of the susceptibility becomes a universal parameter. Both the exponents and the coefficients of the expansion for fixed q as are calculated explicitly. The former are shown to require the validity of the operator-product expansion and explicit logarithmic correction terms are obtained for . For these and other dimensionalities, the coefficients are shown to be finite functions of d and σ. The correction to the Ornstein-Zernike form is given explicitly, with non-integer powers of x that have finite coefficients. 相似文献
2.
J.M. Blackledge 《Physics letters. A》1985,110(4):188-194
Exact inverse solutions to the integral equation , where g(r|rj, k); j = 0 or s is the free space Green function, are derived in plane and cylindrical coordinates for fixed ω. These solutions allow an inelastic scattering potential f(r, ω) which is of compact support r ? 3 to be recovered from scattering data collected over the surfaces of a plane and cylinder respectively. 相似文献
3.
W.G. Weitkamp I. Halpern T.A. Trainor S.K. Lamoreaux Z.Y. Liu 《Nuclear Physics A》1984,417(3):405-418
The energy-averaged depolarization parameter Kyy′ has been measured for the inelastic scattering of 18 MeV protons from 54Fe, 63Cu and 92Mo at 45°, 90° and 135°, and for 14.35 MeV protons from 63Cu at 45° and 135°. In all cases Kyy′ varies from approximately unity for scattering with low energy loss to approximately zero for inelastic scattering to high excitation energies. The change from one of these values to the other occurs over a region ≈ 6 MeV wide centered at about 5 MeV excitation. A simple two-component model fits both the Kyy′ and inelastic crosssection data. Kyy′ has also been measured for the 54Fe(, )Fe reaction with 16 MeV deuterons incident. Here Kyy′ changes from approximately the maximum possible value, , to about zero in a 6 MeV region centered at roughly 13 MeV excitation. The (,) data can be fitted by an extension of the model used for the proton scattering data. 相似文献
4.
Z. Berant C. Broude S. Dima G. Goldring M. Hass Z. Shkedi D.F.H. Start Y. Wolfson 《Nuclear Physics A》1974,235(2):410-416
The magnetic moment of the 4+, 3.55 MeV level of 18O has been determined to be |g| = 0.62 ± 0.10 in a perturbed angular correlation measurement on nuclei recoiling into gas and vacuum. Analysis of the recoil-into-gas data using the Abragam-Pound model agrees with analysis of the recoil-into-vacuum data using a model for the electronic ensemble described in a previous communication. The value of the g-factor shows the 4+ wave function to consist mainly of the configuration. 相似文献
5.
V. Sa-Yakanit 《Physics letters. A》1977,59(6):461-463
The mobility of an electron in a Gaussian random potential is evaluated. It is shown that the relaxation time of the electron is found to be proportional to for large and small correlation lengths L where |p| is the electron momentum. 相似文献
6.
M. Bogdanski T. Emura S.N. Ganguli A. Gurtu S. Hamada R. Hamatsu E. Jeannet I. Kita S. Kitamura J. Kishiro H. Kohno M. Komatsu P.K. Malhotra S. Matsumoto U. Mehtani L. Montanet R. Raghavan A. Subramanian T. Yamagata 《Physics letters. [Part B]》1976,62(1):117-120
Based on a sample of about 3500 events, we have measured the total and differential cross sections of in the 700–760 MeV/c incident momentum region. It is found that σCE = 10.7 ± 0.2 mb at the average momentum of 730 MeV/c. The differential angular distribution is characterised by a sharp peak and a dip in the forward direction followed by a secondary maximum. The position of the dip corresponds to |t| ≈ mπ2. These results are compared with the predictions of the model of Bryan-Phillips. On the other hand, this dip-bump structure can be well understood on a simple picture involving a π exchange and a constant background (for |t| ? 3 mπ2). 相似文献
7.
M. Ambrosio G. Anzivino G. Barbarino U. Becker G. Carboni V. Cavasinni T. Del Prete G. Kantardjian D. Lloyd Owen M. Morganti J. Paradiso G. Paternoster S. Patricelli M. Steuer M. Valdata-Nappi 《Physics letters. [Part B]》1982,113(4):347-352
We measured the elastic scattering of and of αp at . For αα, the differential cross section dσ/dt has a diffractive pattern minima at |t| = 0.10 and 0.38 GeV2. At small |t| = 0.05?0.07 GeV2, this cross section behaves like exp[(100 ± 10) t]. Extrapolating a fit to the data to the optical point, we obtained for the total cross section αtot(αα) = 250 ± 50 mb and an integrated elastic cross section σe1(αα) = 45 ± mb. Another method of estimating σtot(αα), based on measuring the interaction rate, yielded 295 ± 40 mb. For αp, dσ/dt has aminimum at |t| = 0.20 GeV2, and for 0.05 < |t| < 0.18 GeV2 behaves like exp[(41 ± 2) t]. Extrapolating this slope to |t| = 0, we found σtot(αp) = 130 ± 20 and σe1(αp) = 20 ± 4mb. Results on pp elastic scattering at agree with previous ISR experiments. 相似文献
8.
Seiichi Wakaizumi 《Physics letters. [Part B]》1982,113(3):275-278
The pronounced dip-bump structure with a sharp minimum at |t| = 1.5 (GeV/c)2, recently observed in elastic p scattering at PL = 50 GeV/c at the CERN SPS, is explained by the quark multiple scattering model with a realistic wavefunction for the proton and the antiproton. It is predicted that a second dip will appear around |t| = 7 (GeV/c)2 at PL = 50 GeV/ c and at higher energies. 相似文献
9.
G.P. Felcher 《Solid State Communications》1973,12(11):1167-1171
A beam of neutrons of wave vector K incident on a magnetic spiral structure with propagation vector q gives rise to two diffracted beams. These are peaked at , and their intensity varies with the direction of K with the same functional form as is derived in the dynamical theory of X-ray diffraction. In real cases the two lines are broad enough to overlap significantly, giving rise to intrinsic double diffraction effects in a multi-domain crystal. These have been observed experimentally in holmium. 相似文献
10.
To test further the prediction of collapse of the [110], q|| [11̄0] acoustic mode at the martensitic phase transition, pulse superposition measurements of ultrasonic wave velocities have been made in indium-thallium alloys containing 25 and 27 at. % thallium. These alloys are f.c.c. at room temperature and transform on cooling to the f.c.t. phase at 196 ± 2°K and 127 ± 2°K, respectively. Results show that (C11 ? C12) goes to zero within experimental error at the transition temperature. The room temperature elastic constants of the tetragonal 11.5 and 15 at. % thallium alloys are also reported. 相似文献
11.
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
12.
E.G. Auld R.R. Johnson G. Jones E.L. Mathie P. Walden D. Hutcheon P. Kitching W.C. Olsen C.F. Perdrisat B. Tatischeff 《Physics letters. [Part B]》1980,93(3):258-261
Cross sections and analyzing powers are presented for the reaction at 400, 425, 443 and 470 MeV, and laboratory pion angles of 120°, 130°, 140°, 150° and 160°. The cross sections have flat angular distributions, are in contradiction with an earlier experiment which indicated a backward peak at 470 MeV, but are in quantitative agreement with a calculation based on the two-nucleon model. 相似文献
13.
The microwave spectrum of MnO3F has been remeasured and several corrections and new results have been obtained: B0 = 4129.141 MHz, DJ = 1.12 kHz, DJK = 1.87 kHz; , , , |q5| = 16.005, and |q6| = 8.456 MHz. 相似文献
14.
J.J. Jarmer J.C. Martin G.G. Ohlsen G.C. Salzman J.E. Simmons 《Physics letters. [Part B]》1974,48(3):215-217
The longitudinal polarization of neutrons has been measured for the reaction with the incident proton beam longitudinally polarized. Measurements were performed at 0° for proton energies from 4 to 15 MeV and an angular distribution was measured at 10 MeV. The data determine the polarization transfer coefficient Kzz′, which is equivalent to the Wolfenstein A′ parameter for nucleon-nucleon scattering. The quantity Kzz′ at 0° increases from about 0.3 at 3 MeV incident energy to 0.9 at 9 MeV, and then decreases to 0.5 at 15 MeV. The data are computed with R-matrix calculations which reproduce the qualitative shape of the data at 0° and the angular distribution at 10 MeV. 相似文献
15.
K.R. Cordell S.T. Thornton L.C. Dennis P.G. Lookadoo T.C. Schweizer J.L.C. Ford J.Gomez Del Campo D. Shapira 《Nuclear Physics A》1979,323(1):147-160
Excitation functions were measured for states of 21Ne populated by the reaction over the bombarding energy range Elab = 18.2–32.0 MeV (18.4–27.0 MeV) at θlab = 7°(25°) in in 200 keV steps, and average coherence widths of states and the moment of inertia of the compound nucleus 25Mg were obtained from these excitation functions. A statistical analysis of these data was performed. Angular distributions for states in 21Ne to 10 MeV in excitation energy were measured at θlab = 7°, 18°, 28° and 43° at bombarding energies from 29.0 to 31.0 MeV in 400 keV steps. These data along with Hauser-Feshbach predictions allow us to suggest spins for some states as well as to suggest possible candidates for rotational bands in 21Ne. 相似文献
16.
H. Dobiasch R. Fischer B. Haesner H.O. Klages P. Schwarz B. Zetnitz R. Maschuw K. Sinram K. Wick 《Physics letters. [Part B]》1978,76(2):195-196
The polarisation asymmetry in elastic scattering has been measured at 30 MeV from 45° to 140° c.m. neutron angle with uncertainties less than 0.03. 相似文献
17.
S. Gjesdal G. Presser P. Steffen J. Steinberger F. Vannucci H. Wahl F. Eisele H. Filthuth V. Lüth G. Zech K. Kleinknecht 《Physics letters. [Part B]》1974,52(1):119-121
The phase φ+? is evaluated on the basis of measurements of the KS-KL interference in the π+π? decay mode and the mass difference Δm, both reported previously by this group. The result is: φ+? = 45.9° ± 1.6°. This, together with previous results on and the charge asymmetry δ in leptonic decay, is compared with the prediction of the superweak model, with good agreement.Finally the result is used to find, on the basis of unitarity, a new upper limit on CP violation in the decay K0 → 3π0. This limit is |η000|2? 0.21. 相似文献
18.
We calculate the spectrum of the four ground state hybrid nonets, JPC = (0, 1, 2)?+, 1??, using the MIT bag model to first order in cavity perturbation theory. Quark and gluon self-energies are included by a fit to the s-wave mesons and baryons and to the glueball candidate i(1440). We find a large gluon self-energy which substantially increases our predictions of the glueball and hybrid masses. We discuss the phenomenology of hybrids, including a suggestion that the A3 (1670) and a second peak at 1850 MeV in the fπ channel may be mixtures of the isovector d-wave state with the s-wave. 相似文献
19.
D. Bisello S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori J.E. Augustin G. Busetto G. Cosme F. Couchot B. Dudelzak P. Eschstruth F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne G. Capon 《Nuclear Physics B》1983,224(3):379-395
The cross section has been measured in the energy interval (1975 ? 2E ? 2250) MeV for |cosθ| < 0.7. The measurement is based on ~ 100 events, thus improving by a factor 3 on the previous existing statistics in this energy interval. The form factor |G|2 is given as a function of energy under the assumption |GE| = |GM|. We also give the first measurement of the differential cross section, averaged over the energy interval, and estimate the ratio GM|/|GE| from it. 相似文献
20.
We studied the energy width and the width in reciprocal space Δq of the central mode of SrTiO3 above Tc. At Tc+4° we observed an energy width of about 6×10?7 eV. If the measured Δq is interpreted by a correlation length we obtain . 相似文献