共查询到20条相似文献,搜索用时 15 毫秒
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Alexander Gersten 《Foundations of Physics Letters》1998,11(2):165-178
By applying projection operators to state vectors of coordinates, we obtain subspaces in which these states are no longer normalized according to Dirac's delta function but normalized according to what we call incomplete delta functions. We show that this class of functions satisfy identities similar to those satisfied by the Dirac delta function. The incomplete delta functions may be employed advantageously in projected subspaces and in the link between functions defined on the whole space and the projected subspace. We apply a similar procedure to finite-dimensional vector spaces for which we define incomplete Kronecker deltas. Dispersion relations for the momenta are obtained and sums over poles are defined and obtained with the aid of differences of incomplete delta functions. 相似文献
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P. D. Morley 《Nuclear Physics A》1987,470(3-4):547-557
We compute delta electroproduction in nuclei using a relativistic nuclear model. Iron is predicted to have the largest per nucleon cross section and narrowest width, but the variation in A is no larger than an 18% effect. Predictions are made for the SLAC NPAS NE5 experiment and a recently completed Bates laboratory experiment. 相似文献
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Two-dimensional doping sheets (“δ-doping”) are integral parts of many novel semiconductor device concepts. Their practical realization in silicon (Si), however, was long delayed by the difficulty to introduce dopants into Si in a well-controlled way during epitaxial growth. Recent advances in the understanding of epitaxial growth and the incorporation of dopants in Si have overcome these difficulties and opened a new field in Si materials and device research. In this article, we review the growth, processing, and characterization of epitaxially grown 5-doped Si. Furthermore, we discuss the electronic subband states of such structures. Finally, we give an overview of device concepts that use 5-doping and analyze their properties. 相似文献
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Andrzej J. Buras Jean-Marc Gérard William A. Bardeen 《The European Physical Journal C - Particles and Fields》2014,74(5):1-30
We review and update our results for $K\rightarrow \pi \pi $ decays and $K^0$ – $\bar{K}^0$ mixing obtained by us in the 1980s within an analytic approximate approach based on the dual representation of QCD as a theory of weakly interacting mesons for large $N$ , where $N$ is the number of colors. In our analytic approach the Standard Model dynamics behind the enhancement of $\hbox {Re}A_0$ and suppression of $\hbox {Re}A_2$ , the so-called $\Delta I=1/2$ rule for $K\rightarrow \pi \pi $ decays, has a simple structure: the usual octet enhancement through the long but slow quark–gluon renormalization group evolution down to the scales $\mathcal{O}(1\, {\hbox { GeV}})$ is continued as a short but fast meson evolution down to zero momentum scales at which the factorization of hadronic matrix elements is at work. The inclusion of lowest-lying vector meson contributions in addition to the pseudoscalar ones and of Wilson coefficients in a momentum scheme improves significantly the matching between quark–gluon and meson evolutions. In particular, the anomalous dimension matrix governing the meson evolution exhibits the structure of the known anomalous dimension matrix in the quark–gluon evolution. While this physical picture did not yet emerge from lattice simulations, the recent results on $\hbox {Re}A_2$ and $\hbox {Re}A_0$ from the RBC-UKQCD collaboration give support for its correctness. In particular, the signs of the two main contractions found numerically by these authors follow uniquely from our analytic approach. Though the current–current operators dominate the $\Delta I=1/2$ rule, working with matching scales $\mathcal{O}(1 \, {\hbox { GeV}})$ we find that the presence of QCD-penguin operator $Q_6$ is required to obtain satisfactory result for $\hbox {Re}A_0$ . At NLO in $1/N$ we obtain $R=\hbox {Re}A_0/\hbox {Re}A_2= 16.0\pm 1.5$ which amounts to an order of magnitude enhancement over the strict large $N$ limit value $\sqrt{2}$ . We also update our results for the parameter $\hat{B}_K$ , finding $\hat{B}_K=0.73\pm 0.02$ . The smallness of $1/N$ corrections to the large $N$ value $\hat{B}_K=3/4$ results within our approach from an approximate cancelation between pseudoscalar and vector meson one-loop contributions. We also summarize the status of $\Delta M_K$ in this approach. 相似文献
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A. Sibirtsev K. Tsushima Amand Faessler 《Zeitschrift für Physik A Hadrons and Nuclei》1996,354(1):215-218
TheΔ-excitation in $\bar pd$ annihilation at rest was studied. The annihilation amplitude from the statistical model and theπN amplitude from the resonance model were adopted in our calculations. We analyze the invariant mass of theπ +p andπ ?p systems selecting the protons with momenta above 400 MeV/c and with respect to the different final reaction channels. Our model reproduces reasonably the experimental data. 相似文献
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International Journal of Theoretical Physics - Dirac delta function of matrix argument is employed frequently in the development of diverse fields such as Random Matrix Theory, Quantum Information... 相似文献
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LIU Guang-Zhou LIU Wei ZHAO En-Guang 《理论物理通讯》2004,42(7)
In this paper a new phase structure of neutron star matter including nucleons and delta isobars is presented.Particle fractions populated and pion condensations in neutron star matter are investigated in this model. The existence of the pion condensations can postpone the appearance of delta isobars. We found that both the pion condensation and reduce of the ratio of delta isobar to nucleons couplings can soften the corresponding equation of state. The maximum masses and their corresponding radii of neutron stars are calculated, and the obtained values are in observational region. 相似文献
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LIUGuang-Zhou LIUWei ZHAOEn-Guang 《理论物理通讯》2004,42(1):99-102
In this paper a new phase structure of neutron star matter including nucleons and delta isobars is presented. Particle fractions populated and pion condensations in neutron star matter are investigated in this model. The existence of the pion condensations can postpone the appearance of delta isobars. We found that both the pion condensation and reduce of the ratio of delta isobar to nucleons couplings can soften the corresponding equation of state. The maximum masses and their corresponding radii of neutron stars are calculated, and the obtained values are in observational region. 相似文献
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Justin Holmer Jeremy Marzuola Maciej Zworski 《Communications in Mathematical Physics》2007,274(1):187-216
We study the Gross-Pitaevskii equation with a repulsive delta function potential. We show that a high velocity incoming soliton
is split into a transmitted component and a reflected component. The transmitted mass (L
2 norm squared) is shown to be in good agreement with the quantum transmission rate of the delta function potential. We further
show that the transmitted and reflected components resolve into solitons plus dispersive radiation, and quantify the mass
and phase of these solitons. 相似文献
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This paper studies the effect of perturbation to the breakdown of the leading-edge vortices over delta wings. The passive
perturbation in the normal direction is achieved by installing the hemisphere-like bulges on the delta wing along the projection
of the vortices. The key purpose of this perturbation is to delay or suppress vortex breakdown over delta wings according
to the self-induction mechanism theory. The design of bulge-like surface for delta wings offers a minimization of initial
vorticity gradient and an elimination of linearly mutual induction within the vortex core. Three delta wings with swept angles
of 60°, 65dg and 70° have been used. Dye flow visualization and force measurement in different water tunnels are performed
at the water speed of U=0.10, 0.15, 0.20 and 0.25 m/s. In flow visualization, the results show contributions of bulges as
perturbation to leading-edge vortices. The best outcome of perturbing the vortex core occurs in the case of the 65° delta
wing. The breakdown positions on the 65° delta wing are delayed in almost the entire range of angles of attack, and that,
the results are presented here. 相似文献
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ZHU Ren-Gui WANG An-Min 《理论物理通讯》2008,50(12):1265-1268
In order to analyze a limiting case of the 1D delta anyon model, the coupling strength of the δ interaction c is modified to become a function of the anyonic parameter κ. A pedagogic derivation of the solution for this modified model using the method of anyon-boson mapping plus Bethe ansatz is presented. The limiting case as κ → π and simultaneously c → 0, which was previously neglected, is analyzed. Some unexpected properties of this limiting case are discovered. The BAEs are compared with previous results. 相似文献