共查询到20条相似文献,搜索用时 15 毫秒
1.
Benjamin Grinstein 《Nuclear Physics B》1992,380(3):369-376
The decay constants for D and Ds mesons, denoted fD and fDS respectively, are equal in the SU(3)V limit, as are the hadronic amplitudes for
and
mixing. The leading SU(3)V violating contribution to (FDS/FD) and to the ration of hadronic matrix elements relevant for
and
mixing amplitudes are calculated in chiral perturbatiion theory. We discuss the formalism needed to include both meson and anti-meson fields in the heavy quark effective theory. 相似文献
2.
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
3.
Most studies on Co-doped TiO2 system were focused on thin films grown by MBE-based methods. In this work we report the ferromagnetism of nanometer-thick-layered TiO2/Co/TiO2/TiN film grown on Si substrate by conventional magnetron sputtering. For the growth of TiO2 on silicon, a non-oxide thermally stable material, TiN, was introduced to prevent Ti penetration into the Si substrate. Structural, magnetic, and transport measurements respectively by Raman, SQUID and Hall effect show that our samples are n-type semiconductors and exchange bias effect due to exchange coupling between Co and interfacial CoO. For the rapid vacuum annealed specimen, we found an enhanced loss and a Perminvar-type constricted hysteresis loop, which attributed to pinning of domain walls due to an induced anisotropy by the pair ordering in the metallic alloy of Co-Ti-Si. 相似文献
4.
The branching ratio is calculated for Λ8Li decay to the (2+) 8Be1 states near 17 MeV, using intermediate coupling wave functions for Λ8Li and for the relevant 8Be1 states. It is pointed out that this ratio is sensitive primarily to a mixing angle ? in the Λ8Li wave function. Within one standard deviation, the data allow two ranges (+0.05 to +0.25 rad and +1.10 to +1.25 rad) for the value of ?. The further requirement that there also be acceptable agreement between the angular distribution expected for the subsequent decay and the data, shifts these allowed ranges for ?, to (+0.13 to 0.40) rad and (+0.9 to +1.2) rad. It is predicted that the dominant transition should be to 8Be1 (16.6 MeV), as is observed to be the case, rather than to 8Be1 (16.9 MeV). The interpretation of these values for ? is discussed in some detail and their implications for intermediate coupling shell-model calculations of Λ-hypernuclear wave functions are considered. 相似文献
5.
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
6.
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
7.
The effects of HfOxNy on the electrical property of HfOxNy-HfO2-HfOxNy sandwich-stack (signed as SS) films were investigated. Excellent electrical performances were achieved in SS films, with a high dielectric constant of 16 and a low leakage current of ∼2 × 10−8 A/cm2 at 1 MV/cm. Schottky (SK) emission and Frenkel-Poole (PF) emission are found to be the dominant mechanisms for the current conduction behavior. After a long time stress, the flat-band voltage shift in the SS film is much smaller than that in a pure HfOxNy film indicating fewer charge traps existed in the SS film. Based on the experiments, the new SS structure is more favorable for the improvement of electrical performances than a pure HfOxNy or HfO2 structure. 相似文献
8.
We present techniques which enable one to calculate quickly the amplitudes for many scattering processes in the high-energy limit. As an illustration of the method, these are applied to the diagrams for , where V = W± or Z0. The form of the results lends itself to immediate numerical evaluation. 相似文献
9.
J.L. Soubeyroux J.M. Reau S. Matar G. Villeneuve P. Hagenmuller 《Solid State Ionics》1982,6(1):103-111
Bragg neutron diffraction studies have been carried out on the fluorite type solid solutions K1?xBixF1+2x (0.50 ? × ? 0.70) and Rb1?xBixF1+2x (0.50 ? × ? 0.60). The distribution of the fluorine atoms between normal and interstitial sites is given as a function of substitution rate. A substition mechanism is proposed. Electrical and NMR results on one side and structural data on the other side are correlated. A study of the background as a function of temperature has allowed to determine the static origin of its modulation. By inelastic neutron diffusion, it has been shown that the number of carriers is weak, which involves a high mobility. 相似文献
10.
N. Mamouni M. Belaiche A. Benyoussef A. El Kenz H. Ez-Zahraouy M. Loulidi E. H. Saidi E. K. Hlil 《中国物理 B》2011,20(8):87504-087504
Electronic and magnetic structures of zinc blende ZnO doped with V impurities are studied by first-principles calculations based on the Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA).Calculations for the substitution of O by N or P are performed and the magnetic moment is found to be sensitive to the N or P content.Furthermore,the system exhibits a half-metallic band structure accompanied by the broadening of vanadium bands.The mechanism responsible for ferromagnetism is also discussed and the stability of the ferromagnetic state compared with that of the paramagnetic state is systematically investigated by calculating the total energy difference between them by using supercell method. 相似文献
11.
The bottleneck effect arising in the electron paramagnetic resonance of Gd in GdBe13 and GdxCe-xBe13 with x ? 0.001 is removed by additions of CeBe13 which displays a high electron lattice relaxation rate, tentatively attributed to an interconfiguration fluctuation of the 4f electron of Ce. 相似文献
12.
13.
The thermodynamical properties of hot asymmetric nuclear matter are shown to be quite independent of the nuclear potentials currently in use. However, there is a sizeable effect of the nuclear compressibility on the critical and maximum temperatures. 相似文献
14.
J.Michael Hollas Barry J Langham Hamdan Musa Trevor Ridley 《Journal of Molecular Spectroscopy》1983,97(2):405-419
The two-photon fluorescence excitation spectrum of 1,2-difluorobenzene was obtained with a tunable dye laser calibrated using a combination of the neon optogalvanic spectrum and etalon fringes. The spectrum consists only of A1-A1 bands but the use of linear and circular polarization divides the bands into two types. The 000 type retains its intensity in circular polarization and, rotationally, shows little or no zero-rank contribution. The 510 (or 1410) type loses much of its intensity in circular polarization and, rotationally, shows a large zero-rank contribution. These observations all accord with the trace of the two-photon transition tensor being close to zero for the 000 type and large for the 510 type, the latter type being involved in vibronic interaction which mixes the and states. There is strong evidence for Fermi resonance between the 51 and 61101 levels. Parts of the one-photon absorption spectrum have been photographed to aid sequence identification and also to look for the 510, A1-A1 transition. This transition is not observed: nor is there any evidence for intensity stealing by b2 vibrations. 相似文献
15.
The system of 1,3-difluorobenzene has been observed using the technique of two-photon fluorescence excitation obtained with a pulsed dye laser. Calibration was achieved by a combination of the neon optogalvanic spectrum and etalon fringes. In circular, compared to linear, polarization the bands divide into two groups, those which are B2-A1 and which retain their intensity with circular polarization, and those which are A1-A1 and lose about 60% of their intensity under the same conditions. These two kinds of bands also show characteristic rotational contours. All of the A1-A1 bands whose assignments are established obtain their intensity through vibronic interaction in which the vibration ν′25 (ν′14 in the Wilson numbering) mixes the with, presumably, the state. There is an important Fermi resonance between the 91 and 101111 levels. Parts of the one-photon absorption spectrum have been photographed to identify sequences associated with the 000 band for comparison with those observed in the two-photon spectrum, and to search for bands involving odd quanta of b2 vibrations, including ν′25 (ν′14); none was found. 相似文献
16.
G.V. Dass 《Physics letters. [Part B]》1974,49(2):181-184
The amplitude ratio 〈3π|T|KS〉/〈3π|T|KL〉 can be well determined in e+e? (or low energy from the decay time-distribution when each produced kaon→3π, other unknown parameters of the distribution being obtainable from corresponding observations involving known channels like ππ. 相似文献
17.
O. Häusser D.B. Fossan A. Olin D. Ward W. Witthuhn R.E. Warner 《Nuclear Physics A》1974,225(3):425-428
The branching ratio for the transition from the 0.90 MeV second excited to the 0.57 MeV first excited state in 207Pb has been measured to be (0.59 ± 0.09)%. The corresponding B(M1) exceeds recent theoretical predictions. 相似文献
18.
Lifetimes of 24 different levels (v′, J′) in the B1Πu state of Na2 have been measured with an accuracy of about 1% using a modelocked Ar+ laser and a modified delayed coincidence single-photon counting technique. With these lifetimes, the variation of the transition moment R(r) with internuclear distance r has been determined. The necessary Franck-Condon factors and r centroids have been calculated from spectroscopic data obtained by previous interferometric measurements of laser-induced fluorescence. The squared transition moment |R(r)|2 increases between and by about 30%. Our measurements confirm the results of M. M. Hessel, E. W. Smith, and R. E. Drullinger, who used intensity measurements of Na2 fluorescence lines for the determination of R(r). 相似文献
19.
T. Groń E. Malicka A.W. Pacyna R. Sitko 《Journal of Physics and Chemistry of Solids》2009,70(8):1175-1180
The magnetic and electrical properties of the Al-doped polycrystalline spinels ZnxCryAlzSe4 (0.13≤z≤0.55) with the antiferromagnetic (AFM) order and semiconducting behavior were investigated. A complex antiferromagnetic structure below a Néel temperature TN≈23 K for the samples with z up to 0.4 contrasting with the strong ferromagnetic (FM) interactions evidenced by a large positive Curie-Weiss temperature θCW decreasing from 62.2 K for z=0.13 to 37.5 K for z=0.55 was observed. Detailed investigations revealed a divergence between the zero-field-cooling (ZFC) and field-cooling (FC) susceptibilities at temperature less than TN suggesting bond frustration due to competing ferromagnetic and antiferromagnetic exchange interactions in the compositional range 0.13≤z≤0.4. Meanwhile, for z=0.55 a spin-glass-like behavior of cluster type with randomly oriented magnetic moments is observed as the ZFC-FC splitting goes up to the freezing temperature Tf=11.5 K and the critical fields connected both with a transformation of the antiferromagnetic spin spiral via conical magnetic structure into ferromagnetic phase disappear. 相似文献
20.
Rydberg absorption series of N2 converging to the state of N2+ have been reinvestigated with a 6.65-m normal incidence vacuum spectrograph in the second order. Previously known A ← X series (I) and (II) have been extended to higher members with m ~ 40 and up to v′ = 7. 相似文献