共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Jersák 《Nuclear Physics B》1974,80(2):322-340
Assuming that the scaling law interpolates the non-forward Compton amplitude in the resonance region, the threshold behaviour of the non-forward scaling function is determined from the threshold behaviour of the electroproduction scaling function. In addition the threshold behaviour of the deep inelastic annihilation scaling function is determined and found to be equal to that of the electroproduction scaling function. A Veneziano-like pole model for the non-forward Compton amplitude with these properties is constructed. In this model the scaling law interpolates the annihilation amplitude in the resonance region, too. 相似文献
2.
3.
A study of the spatial and temporal evolution of auto-ignition kernels using time-resolved tomographic OH-LIF 总被引:1,自引:0,他引:1
Jhon Pareja Ayane Johchi Tao Li Andreas Dreizler Benjamin Böhm 《Proceedings of the Combustion Institute》2019,37(2):1321-1328
In this paper, the spatial and temporal evolution of auto-ignition kernels from methane jets propagating into a NOx-vitiated, high-turbulence, hot air co-flow was studied by means of time-resolved tomographic laser-induced fluorescence of OH (Tomo OH-LIF). Measurements were performed using a burst dye laser system at 10 kHz for volumetric laser illumination and a multi-camera arrangement (8-views) for detection of the fluorescence signal. Auto-ignition kernels were detected three-dimensionally and tracked using a robust algorithm based on the intensity gradient of the volumetrically reconstructed signals. The size and location of the detected kernels were evaluated for operating conditions with different Reynolds numbers of the fuel jet. Results showed that auto-ignition randomly occurred with high probability in a well defined fairly axisymmetric radial region with strong fluctuations in the main direction of the flow. The increase of the Reynolds number of the fuel jet resulted in a radial spread of the location of auto-ignition events. The statistical evaluation of the orientation and growth of auto-ignition kernels with respect to the mean flow field showed that the kernels were oriented tangentially to the flow and temporally evolve towards this preferential direction as the ignition events progressed. 相似文献
4.
M. Göckeler R. Horsley H. Perlt P.E.L. Rakow A. Schäfer G. Schierholz A. Schiller 《The European Physical Journal C - Particles and Fields》2006,48(2):523-530
We consider the renormalisation of lattice QCD operators with one and two covariant derivatives related to the first and second
moments of generalised parton distributions and meson distribution amplitudes. Employing the clover fermion action we calculate
their non-forward quark matrix elements in one-loop lattice perturbation theory. For some representations of the hypercubic
group commonly used in simulations we determine the sets of all possible mixing operators and compute the matrices of the
renormalisation factors in one-loop approximation. We describe how tadpole improvement is applied to the results.
PACS 11.15.Ha; 12.38.Bx; 12.38.Gc
An erratum to this article can be found at 相似文献
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W. M. Tulczyjew 《Journal of Geometry and Physics》1984,1(3):79-120
Symplectic relations and their generating functions have found extensive applications in classical mechanics. In the present paper we undertake the study of the correspondence between generating functions of symplectic relations and kernels of integral operators of quantum theories. As a first step we study this correspondence in the case of linear symplectic relations generated by quadratic functions. The theory is sufficiently complicated even in this simple case. Additional complications must be expected in the general nonlinear theory due to the fact that the composition of regular nonlinear symplectic relations is in general singular and that nonlinear symplectic relations in general do not have global generating functions. The present paper is a continuation of the study of linear symplectic relations undertaken in [2]. 相似文献
7.
A.W. Fisher 《Physics letters. [Part B]》1985,159(1):42-44
A method for evaluating the asymptotic expansions of supersymmetric heat kernels is presented. 相似文献
8.
《Physics letters. A》2019,383(30):125874
Ulmer and Kaissl formulas for the deconvolution of one-dimensional Gaussian kernels are generalized to the three-dimensional case. The generalization is based on the use of the scalar version of the Grad's multivariate Hermite polynomials which can be expressed through ordinary Hermite polynomials. 相似文献
9.
B.R. Wienke 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,24(5):385-389
Taylor series expansions of collision terms occuring in transport equations (Boltzmann, Spencer-Lewis, Fokker-Planck, etc.) lead to tensor products which are often complicated and ambiguous in actual applications. We describe a simple reduction technique for azimuthally symmetric collision kernels and apply the method to reduce the second order (dyadic) expansion of the linear Boltzmann and relativistic Fokker-Planck relationships. 相似文献
10.
We introduce an analytical kernel, the "cusp" kernel, to model the effects of velocity-changing collisions on optically pumped atoms in low-pressure buffer gases. Like the widely used Keilson-Storer kernel [J. Keilson and J.?E. Storer, Q. Appl. Math. 10, 243 (1952)], cusp kernels are characterized by a single parameter and preserve a Maxwellian velocity distribution. Cusp kernels and their superpositions are more useful than Keilson-Storer kernels, because they are more similar to real kernels inferred from measurements or theory and are easier to invert to find steady-state velocity distributions. 相似文献
11.
Alessandro Dionisi Vici 《Letters in Mathematical Physics》1979,3(6):533-541
We characterize integral operators belonging to B(L
2 (ℝ3))which are dilatation analytic in the Cartesian product of two sectors S
a ⊂ ℂ as analytic functions from S
a×Sa into B(L
2(Ω)), the space of bounded operators on square integrable functions on the unit sphere Ω, which satisfy certain norm estimates
uniformly on every subsector. 相似文献
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13.
Anatol Odzijewicz 《Communications in Mathematical Physics》1988,114(4):577-597
Quantization of a mechanical system with the phase space a Kähler manifold is studied. It is shown that the calculation of the Feynman path integral for such a system is equivalent to finding the reproducing kernel function. The proposed approach is applied to a scalar massive conformal particle interacting with an external field which is described by deformation of a Hermitian line bundle structure. 相似文献
14.
Christian Schindler 《International Journal of Theoretical Physics》1991,30(11):1409-1430
Every convex subset of a locally convex Hausdorff space (X, ) is equipped with the (-algebra generated by its-relatively open subsets. Within the set () of probability measures on two particular convex subsets are considered: (a) the set
s
() of probability measures with a separable support, and (b) the set
c
() of probability measures with a compact convex support. If is the base of a cone inX, then there exists an affine barycenter map from
c
() onto whose composition with the natural embedding of in
c
() yields the identity map on , and every-continuous affine transformation of can be represented by an affine transformation of
c
() that is induced by a Markov kernel. If (X, ) is a Banach space and is a closed, bounded, generating cone base inX that is contained in a hyperplane, then analogous results are obtained with respect to
s
(). Since the state spaces considered in noncommutative measure theory are cone bases and every change in time of an empirical system can be thought of as an affine transformation of the associated state space (Schrödinger picture), the existence of these representation theorems implies that the time evolution of general empirical systems can be described by dynamical concepts borrowed from classical probability theory. 相似文献
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Previously, to solve the Boltzmann equation by the moments method with expansion of the distribution function by spherical
Hermit polynomials, a new computational method was suggested which allowed to construct nonlinear matrix elements of the collision
integral with very large indices. This made it possible to substantially advance in construction of the distribution function.
Limitations to convergence of the distribution function that appear in moment method are eliminated if we come to expansion
by spherical harmonics from expansion by spherical Hermit polynomials. In this case, a complex five-fold collision integral
is replaced by a set of comparatively simple integral operators, and kernels G
l1,l2
l
(c, c
1, c
2) of these operators become the analog of matrix elements. We found the relations between expansions of the distribution function
in the reference frames with various velocities of motion along marked axis. Starting from the invariance condition of the
collision integral with respect to selection of such reference frames, we derived recurrent relations between the kernels
with various indices. These relations allow us to construct any nonlinear kernel G
l1, l2
l
(c, c
1, c
2), if the kernel G
0,00(c, c
1, c
2) is known. 相似文献
17.
Th. Kirst H. V. von Geramb K. A. Amos 《Zeitschrift für Physik A Hadrons and Nuclei》1990,336(4):365-367
A new integral equation which relates the output kernels of the Gel'fand-Levitan and Marchenko inverse scattering equations in a continuous range of their variables is specified. Structural details of this integral equation are studied when theS-matrix is a rational function, and the output kernels are separable in terms of Bessel, Hankel and Jost solutions. 相似文献
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19.
LetU be a basis representation of an irreducible unitary representation of a nilpotent Lie groupG inL
2(R
k) and letdU denote the representation of the Lie algebrag obtained by differentiation. Ifb
1,...,b
d
is a basis ofg andB
i
=dU(b
i
) we consider the operators
相似文献
20.
Raghukumar K Cornuelle BD Hodgkiss WS Kuperman WA 《The Journal of the Acoustical Society of America》2008,124(1):98-112
Sensitivity kernels for receptions of broadband sound transmissions are used to study the effect of the transmitted signal on the sensitivity of the reception to environmental perturbations. A first-order Born approximation is used to obtain the pressure sensitivity of the received signal to small changes in medium sound speed. The pressure perturbation to the received signal caused by medium sound speed changes is expressed as a linear combination of single-frequency sensitivity kernels weighted by the signal in the frequency domain. This formulation can be used to predict the response of a source transmission to sound speed perturbations. The stability of time-reversal is studied and compared to that of a one-way transmission using sensitivity kernels. In the absence of multipath, a reduction in pressure sensitivity using time reversal is only obtained with multiple sources. This can be attributed both to the presence of independent paths and to cancellations that occur due to the overlap of sensitivity kernels for different source-receiver paths. The sensitivity kernel is then optimized to give a new source transmission scheme that takes into account knowledge of the medium statistics and is related to the regularized inverse filter. 相似文献
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