共查询到20条相似文献,搜索用时 15 毫秒
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Abstract To resolve the controversy on the occurrence of a b.c.c.–h.c.p. transition in shock as well as static measurements in Mo, we have done more accurate total energy electronic structure calculations. Our results show that this phasetransition should occur at much higher pressures than suggested by earlier calculations. 相似文献
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《Solid State Communications》1982,41(12):939-942
The influence of a 〈110〉-screw dislocation in a f.c.c. crystal on nearly free electrons is analysed by means of the deformation potential theory. The Fermi surface is assumed to intersect the faces of the first Brillouin zone and electrons near those faces are considered in the two wave approximation. The pure shear strain around the screw dislocation yields the deformation potential. The phase-dismatching caused by the deformation operator takes the value π when the incident electron is on one of four faces of the first zone. 相似文献
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For finite values of the parameter and in the presence of small
structural asymmetry and inhomogeneity of the junctions parameters, the
two-junction interferometer model can be described by means of a single
non-linear differential equation in such a way that a ratchet potential for
SQUIDs can be deduced. The resulting dynamical equation, derived for
first-order corrections with respect to a symmetric and homogeneous model
with =0, presents an additional second-harmonic term and a cosine
term in the expression for the effective current-phase relation. For
opportune values of the perturbation parameters a ratchet potential with
pre-definite characteristics can be obtained. 相似文献
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We present an analysis of nonannihilation channels in four-pronged
interactions at 5·68 GeV/c. The transverse momenta and azimuthal angles distributions of nucléons and -mesons are compared with phase space. No essential influence of
production on azimuthal correlation has been found. The seen difference of azimuthal angle distributions for like and unlike charged pions in annihilations appears to be more pronounced for small transverse momenta and for small transverse masses. For 10971 events of the reaction ¯pp¯pp–+ we present cross sections for
production and differential cross sections. The reaction is dominated by the strong quasi-two-body channel
with cross section (1·66 ±±0·10) mb. We study in detail the production mechanism of this channel in terms of the absorption model.Dedicated to Academician Václav Votruba on the occasion of his seventieth birthday.The authors are indebted to the CERN-Prague collaboration on ¯pp interactions at 5·7 GeV/c for experimental data used in this paper and to Dr. M. Novak for valuable comments. 相似文献
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Lei-Lei Shen Xiao-Lin Chen Zhi-Gang Luo Peng-Zhi Huang Shi-Lin Zhu Peng-Fei Yu Xiang Liu 《The European Physical Journal C - Particles and Fields》2010,70(1-2):183-217
We study the possible heavy molecular states composed of a pair of charm mesons in the H and S doublets. Since the P-wave charm-strange mesons D s0(2317) and D s1(2460) are extremely narrow, the future experimental observation of the possible heavy molecular states composed of $D_{s}/D_{s}^{\ast}$ and D s0(2317)/D s1(2460) may be feasible if they really exist. Especially the possible J PC =1?? states may be searched for via the initial state radiation technique. 相似文献
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We calculate the inclusive decay rates of ηb into charmonium via double cc pairs for S- and P-wave states ηc, J/ψ and χcJ within the framework of non-relativistic QCD (NRQCD) factorization at leading order in αs. Besides calculating the contributions of the color-singlet channels ηb→c(c)[2S+1Sl(1)]+c(c), the effects of c(c) pair in the color-octet configurations are also considered. We find that ηb→c(c)[3S1(8)]+c(c) make a small contribution to Br(ηb→J/ψ(ηc)+c(c)). While in ther ηb→χcJ+c(c) case, the color octet contributions are significant, for they are of the same αs4vc5 order as the color-singlet processes. We predict Br(ηb → J/ψ(ηc)+c(c)) = 2.99(2.75) × 10-5 for S-vrave states J/ψ and ηc, and Br(ηb→χcJ +c(c))= (4.37,3.40,2.83)×10-5 (for J = 0,1,2) for P-wave states χcJ. In the end, we also find Br(ηb → c(c)c(c)) is almost saturated by ηb decay into charmonium in association with cc pair from the point of view of duality. 相似文献
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We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak.At the sec... 相似文献
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《Journal of Physics and Chemistry of Solids》1987,48(12):1165-1171
Laser Raman spectroscopy on samples across which a d.c. field has been applied is suggested as a new technique for studying ionic solids. As an example, the laser Raman spectra of a solid state proton conductor MoO3 · 2H2Ois reported with the d.c. field “on”. Two new peaks at 795 and 414 cm−1 appear in the laser Raman spectra and their intensities grow with increasing time and applied d.c. voltage. Their appearance has been explained by assuming that H3O+ ions are created by the d.c. field as the mobile charged ionic species. By monitoring the peak intensities of the 795 and 414cm−1 bands at different places in the sample between the cathode and the anode, the diffusion coefficient has been estimated. 相似文献
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Charmonium ( \({c \bar{c}}\) ) bound states in few-nucleon systems, 2H, 4He and 8Be, are studied via Gaussian Expansion Method (GEM). We adopt a Gaussian potential as an effective \({(c \bar{c})}\) –nucleon (N) interaction. The relation between two-body \({(c \bar{c})}\) –N scattering length \({a_{c\bar{c}-N}}\) and the binding energies B of \({(c \bar{c})}\) –nucleus bound states are given. Recent lattice QCD data of \({a_{c\bar{c}-N}}\) corresponds to \({B \simeq 0.5}\) MeV for \({(c \bar{c})-^{4}}\) He and 2 MeV for \({(c \bar{c})-^{8}}\) Be in our results. 相似文献
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V. V. Abramov A. A. Volkov P. I. Goncharov A. Yu. Kalinin A. V. Korablev Yu. P. Korneev A. V. Kostritsky A. N. Krinitsyn V. I. Kryshkin A. A. Markov V. V. Talov L. K. Turchanovich A. V. Khmelnikov 《Physics of Atomic Nuclei》2007,70(9):1515-1526
The transverse single-spin asymmetry for charged hadrons (π ±, K ±, p, $\bar p$ ) produced in proton-nucleus collisions was measured for c.m. production angles in the range 40°–79°. The measurements were performed with the FODS-2 setup by using a 40-GeV polarized proton beam originating from the accelerator of the Institute for High Energy Physics (Protvino) and hitting carbon and copper nuclear targets. The data in question were obtained in the polarized-proton-fragmentation region (0.0 < x F < 0.7, 0.6 < p T < 2.5 GeV/c). In agreement with data obtained at other energies, the single-spin asymmetry for π ± mesons is significant at high x F. For the first time, a sizable analyzing power, which changes sign at x F = 0.43, is observed for protons. The dependence of the analyzing power on the target-nucleus mass is insignificant. 相似文献
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《Nuclear Physics A》1988,489(2):284-302
The neutron-proton spin correlation coefficient Ayy was measured at 90° c.m. by elastic scattering of 13.7 MeV polarized neutrons from a polarized proton target. The target polarization of about 60% was produced in a LMN single crystal by dynamic nuclear orientation using 70 GHz microwaves. The target was thin enough to allow the detection of the recoil protons in coincidence with the associated scattered neutrons. Our result for Ayy is the first experimental determination of a neutron-proton spin correlation parameter at such a low energy. To determine the influence of Ayy on the 3S1-3D1 mixing parameter ε1, a single-energy n-p phase shift analysis was performed using the experimentally determined value of Ayy= 0.078 ± 0.014 along with analyzing power and cross section data. As expected, the result for ε1 changes drastically upon the inclusion of Ayy. An unexpectedly small value of ε1 = −0.16°±0.54° has been obtained in the present analysis. 相似文献
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The effects of structural asymmetries and of inhomogeneities in the junction
parameters on the electrodynamic response of conventional d.c. SQUIDs are
studied both analytically and numerically. By a first-order perturbative
expansion with respect to the parameter and to the deviation parameters
describing structural asymmetry and inhomogeneity, we write the reduced
dynamical equation for the average superconducting phase difference of a
conventional d.c. SQUID. As in homogeneous and symmetric SQUIDs, the
resulting dynamical equation is seen to be similar to that of a single
junction with an unconventional current-phase relation characterized by a
second harmonic contribution; in addition, a cosine term appears as a
consequence of superconducting coupling inhomogeneity. By means of the
reduced dynamical equation, the I-V characteristics in the presence of an
external rf field and the critical current of the device are studied in the
absence of noise. 相似文献
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Microwave induced d.c. voltage due to inverse a.c. Josephson effect has been observed across bulk samples of Y-Ba-Cu-O and Y-Ba-Sr-Cu-O. The d.c. voltage is found to vary with microwave power, frequency and also with small external magnetic fields. Although the resistivity curve of Y-Ba-Cu-O does not show any appreciable resistance drop around 230 K, the microwave induced d.c. voltage due to the inverse a.c. Josephson effect has been found to exist upto 230 K. The resistivity behaviour of Y-Ba-Sr-Cu-O shows a sharp resistivity drop above 230 K. In this sample the inverse Josephson effect is found to exist upto +26 °C, indicating the presence of a phase having a superconducting onset around this temperature. 相似文献