Journal articles: 'Lorentzian function'

1

Azzerboni, B., E. Cardelli, E. Della Torre, and G. Finocchio. "Reversible magnetization and Lorentzian function approximation." Journal of Applied Physics 93, no. 10 (2003): 6635–37. http://dx.doi.org/10.1063/1.1557698.

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Ida, T., M. Ando, and H. Toraya. "Extended pseudo-Voigt function for approximating the Voigt profile." Journal of Applied Crystallography 33, no. 6 (2000): 1311–16. http://dx.doi.org/10.1107/s0021889800010219.

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The formula of the pseudo-Voigt function expressed by a weighted sum of Gaussian and Lorentzian functions is extended by adding two other types of peak functions in order to improve the accuracy when approximating the Voigt profile. The full width at half-maximum (FWHM) values and mixing parameters of the Gaussian, the Lorentzian and the other two component functions in the extended formula can be approximated by polynomials of a parameter ρ = ΓL/(ΓG+ ΓL), where ΓGand ΓLare the FWHM values of the deconvoluted Gaussian and Lorentzian functions, respectively. The maximum deviation of the extended pseudo-Voigt function from the Voigt profile is within 0.12% relative to the peak height when sixth-order polynomial expansions are used. The systematic errors of the integrated intensity ΓGand ΓL, estimated by fitting the extended formula to Voigt profiles, are typically less than 1/10 of the errors arising from the application of the original formula of the pseudo-Voigt approximation proposed by Thompsonet al.[J. Appl. Cryst.(1987),20, 79–83], while the time required for computation of the extended formula is only about 2.5 relative to the computation time required for the original formula.

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Alomar, Abdulazeez S. "Impact of Faddeeva–Voigt broadening on line-shape analysis at critical points of dielectric functions." AIP Advances 12, no. 6 (2022): 065127. http://dx.doi.org/10.1063/5.0092287.

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Faddeeva–Voigt broadening (FVB) couples the physical characteristics of both Lorentzian and Gaussian profiles as a combined analytic function shaping the dielectric response. Accurate extraction of the Gaussian and Lorentzian broadening contents in line-shape analysis is essential for reliable optical characterization of semiconductors and dielectrics. By adding the Gaussian-broadening width to each Lorentzian width, we investigate how FVB affects critical-point (CP) analysis. We revisit a selection of earlier work based on classical Lorentz broadening in modulation spectroscopy and spectral ellipsometry. To generalize CP analysis, we derive the FVB’s analytical representation in terms of fractional derivatives of the Faddeeva function and apply the twenty-pole Martin–Donoso–Zamudio approximation for its precise and efficient computation of the FVB of model dielectric functions and derivatives. We investigate the FVB of the electroreflectance line shape of HgCdTe for three-dimensional M0 transitions and of the photoreflectance line shape of InP excitonic E0 transitions. Furthermore, we explore how FVB affects the dielectric functions of three-dimensional excitonic and two-dimensional M0 transitions vs Tanguy’s analytical two-dimensional exciton E1 and E1+Δ1 fits of GaAs to the second-order derivatives. We use the Akaike information criterion to quantitatively estimate the goodness of fit that statistically penalizes overfitting due to extraneous parameters. By consolidating both Gaussian and Lorentzian broadenings, the FVB significantly affects the CP analysis of modulation-spectroscopy line shapes and second-order derivatives of the dielectric function.

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MORETTI, VALTER. "ASPECTS OF NONCOMMUTATIVE LORENTZIAN GEOMETRY FOR GLOBALLY HYPERBOLIC SPACETIMES." Reviews in Mathematical Physics 15, no. 10 (2003): 1171–217. http://dx.doi.org/10.1142/s0129055x03001886.

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Connes' functional formula of the Riemannian distance is generalized to the Lorentzian case using the so-called Lorentzian distance, the d'Alembert operator and the causal functions of a globally-hyperbolic spacetime. As a step of the presented machinery, a proof of the almost-everywhere smoothness of the Lorentzian distance considered as a function of one of the two arguments is given. Afterwards, using a C*-algebra approach, the spacetime causal structure and the Lorentzian distance are generalized into noncommutative structures giving rise to a Lorentzian version of part of Connes' noncommutative geometry. The generalized noncommutative spacetime consists of a direct set of Hilbert spaces and a related class of C*-algebras of operators. In each algebra a convex cone made of self-adjoint elements is selected which generalizes the class of causal functions. The generalized events, called loci, are realized as the elements of the inductive limit of the spaces of the algebraic states on the C*-algebras. A partial-ordering relation between pairs of loci generalizes the causal order relation in spacetime. A generalized Lorentz distance of loci is defined by means of a class of densely-defined operators which play the role of a Lorentzian metric. Specializing back the formalism to the usual globally-hyperbolic spacetime, it is found that compactly-supported probability measures give rise to a non-pointwise extension of the concept of events.

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Dillen, Franki, and Luc Vrancken. "Lorentzian isotropic Lagrangian immersions." Filomat 30, no. 10 (2016): 2857–67. http://dx.doi.org/10.2298/fil1610857d.

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In this note we are interested in isotropic totally real Lorentzian submanifolds of indefinite complex space forms. We show that such submanifolds are always H-umbilical warped product immersions and we determine also the warping function.

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Amini, Roya, Mehdi Sharifzadeh, and Yousof Bahrampour. "Bartnik’s splitting conjecture and Lorentzian Busemann function." Classical and Quantum Gravity 35, no. 10 (2018): 105009. http://dx.doi.org/10.1088/1361-6382/aaba66.

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Erkekoğlu, F., E. García-Río, and D. N. Kupeli. "On Level Sets of Lorentzian Distance Function." General Relativity and Gravitation 35, no. 9 (2003): 1597–615. http://dx.doi.org/10.1023/a:1025779017980.

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KAWAI, HIKARU, and TAKASHI OKADA. "ASYMPTOTICALLY VANISHING COSMOLOGICAL CONSTANT IN THE MULTIVERSE." International Journal of Modern Physics A 26, no. 18 (2011): 3107–20. http://dx.doi.org/10.1142/s0217751x11053730.

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We study the problem of the cosmological constant in the context of the multiverse in Lorentzian space–time, and show that the cosmological constant will vanish in the future. This sort of argument was started by Sidney Coleman in 1989, and he argued that the Euclidean wormholes make the multiverse partition function a superposition of various values of the cosmological constant Λ, which has a sharp peak at Λ = 0. However, the implication of the Euclidean analysis to our Lorentzian space–time is unclear. With this motivation, we analyze the quantum state of the multiverse in Lorentzian space–time by the WKB method, and calculate the density matrix of our universe by tracing out the other universes. Our result predicts vanishing cosmological constant. While Coleman obtained the enhancement at Λ = 0 through the action itself, in our Lorentzian analysis the similar enhancement arises from the front factor of eiS in the universe wave function, which is in the next leading order in the WKB approximation.

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Benisty, David, and Eduardo I. Guendelman. "Lorentzian quintessential inflation." International Journal of Modern Physics D 29, no. 14 (2020): 2042002. http://dx.doi.org/10.1142/s021827182042002x.

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From the assumption that the slow-roll parameter [Formula: see text] has a Lorentzian form as a function of the e-folds number [Formula: see text], a successful model of a quintessential inflation is obtained. The form corresponds to the vacuum energy both in the inflationary and in the dark energy epochs. The form satisfies the condition to climb from small values of [Formula: see text] to [Formula: see text] at the end of the inflationary epoch. At the late universe, [Formula: see text] becomes small again and this leads to the dark energy epoch. The observables that the models predict fits with the latest Planck data: [Formula: see text]. Naturally, a large dimensionless factor that exponentially amplifies the inflationary scale and exponentially suppresses the dark energy scale appearance, producing a sort of cosmological seesaw mechanism. We find the corresponding scalar Quintessential Inflationary potential with two flat regions — one inflationary and one as a dark energy with slow-roll behavior.

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10

Torkington, P. "Gaussian Band Shape Derived from Finite-Rate Oscillator Growth." Applied Spectroscopy 41, no. 1 (1987): 139–41. http://dx.doi.org/10.1366/0003702874868188.

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The accepted classical model for derivation of the frequency spectrum from the time-dependence of oscillator activity is considered. The exponential decay function giving rise to a Lorentzian band is modified to allow for a finite rate of growth of the oscillator, the resulting frequency spectrum is obtained, and the form normalized to unit band half-width is compared to the equivalent Lorentzian and Gaussian bands. It is shown that as the rate of oscillator growth decreases from infinity to one approximating the rate of decay, the resulting band contour changes from Lorentzian to near-Gaussian. At sufficiently fast growth-rates the band closely approximates a linear combination of Lorentzian and Gaussian.

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11

Turner, Jacob E., Daniel R. Stinebring, Maura A. McLaughlin, Anne M. Archibald, Timothy Dolch, and Ryan S. Lynch. "Scattering Delay Mitigation in High-accuracy Pulsar Timing: Cyclic Spectroscopy Techniques." Astrophysical Journal 944, no. 2 (2023): 191. http://dx.doi.org/10.3847/1538-4357/acb6fd.

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Abstract We simulate scattering delays from the interstellar medium to examine the effectiveness of three estimators in recovering these delays in pulsar timing data. Two of these estimators use the more traditional process of fitting autocorrelation functions to pulsar dynamic spectra to extract scintillation bandwidths, while the third estimator uses the newer technique of cyclic spectroscopy on baseband pulsar data to recover the interstellar medium’s impulse response function. We find that either fitting a Lorentzian or Gaussian distribution to an autocorrelation function or recovering the impulse response function from the cyclic spectrum are, on average, accurate in recovering scattering delays, although autocorrelation function estimators have a large variance, even at high signal-to-noise ratio (S/N). We find that, given sufficient S/N, cyclic spectroscopy is more accurate than both Gaussian and Lorentzian fitting for recovering scattering delays at specific epochs, suggesting that cyclic spectroscopy is a superior method for scattering estimation in high-quality data.

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12

Trieu, Tuan, and Jianlin Cheng. "3D genome structure modeling by Lorentzian objective function." Nucleic Acids Research 45, no. 3 (2016): 1049–58. http://dx.doi.org/10.1093/nar/gkw1155.

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13

Nagel, W., and W. Van Driessche. "Effect of forskolin on conductive anion pathways of toad skin." American Journal of Physiology-Cell Physiology 263, no. 1 (1992): C166—C171. http://dx.doi.org/10.1152/ajpcell.1992.263.1.c166.

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The effect of the diterpene, forskolin, on pathways for conductive Cl- transport was analyzed using isolated skins of Bufo viridis. Forskolin did not stimulate the voltage-activated Cl- movement from mucosa to serosa; the Lorentzian component in the power density spectrum, which was present at serosa positive clamp potentials under control conditions, decreased significantly. The observation that stimulation of cytosolic adenosine 3'-5'-cyclic monophosphate (cAMP) by forskolin has no effect on the voltage-activated Cl- transport argues against control of this pathway by cAMP. Our data further demonstrate that the forskolin-activated Cl- conductive pathway is also permeable for NO3-. This pathway was studied in absence of mucosal Cl-, which eliminates Cl- movement through the voltage-activated pathway. With SO4(2-) and Cl- on the mucosal and serosal sides, respectively, this forskolin-induced pathway displayed a linear current-voltage relationship. The associated Lorentzians increased at serosa negative clamp potentials. Transepithelial current and plateau value of the Lorentzian were related by a quadratic function, which suggests voltage-independence of number and open-close probability of these conductance sites. Morphological sites for voltage-activated and forskolin-induced conductive Cl- transport remain to be identified.

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Al-Dayel, Ibrahim, Sharief Deshmukh, and Mohd Danish Siddiqi. "A Characterization of GRW Spacetimes." Mathematics 9, no. 18 (2021): 2209. http://dx.doi.org/10.3390/math9182209.

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We show presence a special torse-forming vector field (a particular form of torse-forming of a vector field) on generalized Robertson–Walker (GRW) spacetime, which is an eigenvector of the de Rham–Laplace operator. This paves the way to showing that the presence of a time-like special torse-forming vector field ξ with potential function ρ on a Lorentzian manifold (M,g), dimM>5, which is an eigenvector of the de Rham Laplace operator, gives a characterization of a GRW-spacetime. We show that if, in addition, the function ξ(ρ) is nowhere zero, then the fibers of the GRW-spacetime are compact. Finally, we show that on a simply connected Lorentzian manifold (M,g) that admits a time-like special torse-forming vector field ξ, there is a function f called the associated function of ξ. It is shown that if a connected Lorentzian manifold (M,g), dimM>4, admits a time-like special torse-forming vector field ξ with associated function f nowhere zero and satisfies the Fischer–Marsden equation, then (M,g) is a quasi-Einstein manifold.

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15

Jakeš, Jaromír. "A Simple Numerical Method for Calculating Gaussian NMR Spectral Line Shapes Partially Narrowed Due to a Motion with the Exponential Spectral Autocorrelation Function." Collection of Czechoslovak Chemical Communications 67, no. 4 (2002): 405–28. http://dx.doi.org/10.1135/cccc20020405.

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A simple numerical method for calculating NMR spectral line shapes resulting from a Gaussian line by a partial narrowing due to a motion with the exponential spectral autocorrelation function of the form exp (-|τ|/τc) was developed. It was found that the partially narrowed line is narrower not only than the parent Gaussian line with the second moment of ωp2 but also than the Lorentzian line with the half-width of 2ωp2τc obtained from the extreme narrowing approximation. The central intensity increase compared with the closer of these two lines is less than 50.2%. Asymptotic developments for large values of ω - ω0 and for large values of ωpτc were derived. Two-term approximation applied to the extreme narrowing case led to a very simple modification of the Lorentzian line having the correct second moment ωp2. Analysis of this modified Lorentzian line showed that attempts to estimate ωp2 from truncated second moments of Lorentzian lines without knowledge of τc are hopeless. The case of the polyexponential spectral autocorrelation function with all but one correlation times fast enough to allow for the extreme narrowing, modelling the case of an anisotropic motion, is also considered.

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Khmou, Youssef. "A case study in bifurcation theory." International Journal of Modern Physics C 28, no. 08 (2017): 1750104. http://dx.doi.org/10.1142/s0129183117501042.

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This short paper is focused on the bifurcation theory found in map functions called evolution functions that are used in dynamical systems. The most well-known example of discrete iterative function is the logistic map that puts into evidence bifurcation and chaotic behavior of the topology of the logistic function. We propose a new iterative function based on Lorentizan function and its generalized versions, based on numerical study, it is found that the bifurcation of the Lorentzian function is of second-order where it is characterized by the absence of chaotic region.

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Gómez i Blanch, G., and And M. J. Fullana i Alfonso. "On geometro dynamics in atomic stationary states." Revista Mexicana de Física 65, no. 2 (2019): 148. http://dx.doi.org/10.31349/revmexfis.65.148.

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In a previous paper [G.Gomez Blanch and M.J.Fullana, 2017] we dened, in the frame of a geometro-dynamic approach, a metric corresponding to a lorentzian spacetime were the electron stationary trajectories in an hydrogenoid atom, derived from the de Broglie-Bohm model, are geodesics. In this paper we want to complete this purpose: we will determinate the remaining relevant geometrical elements of that approach and we will calculate the energetic density component of the energy-momentum tensor. We will discuss the meaning of the obtained results and their relationship with other geometro-dynamic approaches.Furthermore, we will derive a more general relationship between the lorentzian metric tensor and the wave function for general stationary states. The electron description by the wave function ψ in the Euclidean space and time is shown equivalent to the description by a metric tensor in an lorentzian manifold. In our approach, the particle acquires a determining role over thewave function, in a similar manner as the wave function determines the movement of the particle. This dialectic approach overcomes the de Broglie-Bohm model. And furthermore, a non local element (the quantum potential) is introduced in the model, that therefore goes beyond the relativistic locality.

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ROMERO-DEPABLOS, A., J. L. PAZ, A. MENDOZA-GARCÍA, P. MARTÍN, and E. CASTRO. "OPTICAL PROPERTIES OF MOLECULAR SYSTEM COUPLED TO THE SOLVENT." International Journal of Modern Physics B 23, no. 31 (2009): 5801–9. http://dx.doi.org/10.1142/s021797920905434x.

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Analytic approximations for the absorption coefficient and refraction index have been obtained for a two-level molecular system in the presence of a four-wave mixing signal. Stochastic collisions among solute–solvent molecules produce a broadening of the upper level of energy. In this work, we have used four generalized Lorentzian approximants of the Voigt function as probability distribution, calculated by the two-point quasi-rational approximant method previously denoted as asymptotical Padé technique, for the evaluation of the average values of the Fourier components associated to the induced coherences. The innovation of this type of distributions allows us, by taking appropriate limits, to find similar profiles of optical properties as those using Gaussian and Lorentzian distribution functions.

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PLUJKO, V. A., O. M. GORBACHENKO, and E. V. KULICH. "LORENTZIAN-LIKE MODELS OF E1 RADIATIVE STRENGTH FUNCTIONS." International Journal of Modern Physics E 18, no. 04 (2009): 996–1001. http://dx.doi.org/10.1142/s0218301309013142.

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Photoabsorption cross sections and dipole γ-decay strength functions are calculated and compared with experimental data to test Lorentzian-like models of their description in the middle-weight and heavy atomic nuclei. Approaches with asymmetric shape of the radiative strength function are recommended for overall estimation of the dipole γ-strengths. The ready-to-use table of giant dipole resonance parameters and their errors are obtained from fitting the theoretical calculations for photoabsorption cross sections to the experimental data. Systematics for giant dipole resonance parameters are given.

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Ida, Takashi. "Continuous series of symmetric peak profile functions determined by standard deviation and kurtosis." Powder Diffraction 36, no. 4 (2021): 222–32. http://dx.doi.org/10.1017/s0885715621000567.

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A mathematical system for modeling the effects of symmetrized instrumental aberrations has been developed. The system is composed of the truncated Gaussian, sheared Gaussian, and Rosin-Rammler-type functions. The shape of the function can uniquely be determined by the standard deviation and kurtosis. A practical method to evaluate the convolution with the Lorentzian function and results of application to the analysis of experimental powder diffraction data are briefly described.

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Alías, Luis J., Ana Hurtado, and Vicente Palmer. "Geometric analysis of Lorentzian distance function on spacelike hypersurfaces." Transactions of the American Mathematical Society 362, no. 10 (2010): 5083. http://dx.doi.org/10.1090/s0002-9947-2010-04992-x.

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NOH*, Heung-Ryoul. "On the Lorentzian-like Function in Saturated Absorption Spectroscopy." New Physics: Sae Mulli 68, no. 5 (2018): 578–82. http://dx.doi.org/10.3938/npsm.68.578.

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Treumann, Rudolf A., and Wolfgang Baumjohann. "Generalised partition functions: inferences on phase space distributions." Annales Geophysicae 34, no. 6 (2016): 557–64. http://dx.doi.org/10.5194/angeo-34-557-2016.

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Abstract. It is demonstrated that the statistical mechanical partition function can be used to construct various different forms of phase space distributions. This indicates that its structure is not restricted to the Gibbs–Boltzmann factor prescription which is based on counting statistics. With the widely used replacement of the Boltzmann factor by a generalised Lorentzian (also known as the q-deformed exponential function, where κ = 1∕|q − 1|, with κ, q ∈ R) both the kappa-Bose and kappa-Fermi partition functions are obtained in quite a straightforward way, from which the conventional Bose and Fermi distributions follow for κ → ∞. For κ ≠ ∞ these are subject to the restrictions that they can be used only at temperatures far from zero. They thus, as shown earlier, have little value for quantum physics. This is reasonable, because physical κ systems imply strong correlations which are absent at zero temperature where apart from stochastics all dynamical interactions are frozen. In the classical large temperature limit one obtains physically reasonable κ distributions which depend on energy respectively momentum as well as on chemical potential. Looking for other functional dependencies, we examine Bessel functions whether they can be used for obtaining valid distributions. Again and for the same reason, no Fermi and Bose distributions exist in the low temperature limit. However, a classical Bessel–Boltzmann distribution can be constructed which is a Bessel-modified Lorentzian distribution. Whether it makes any physical sense remains an open question. This is not investigated here. The choice of Bessel functions is motivated solely by their convergence properties and not by reference to any physical demands. This result suggests that the Gibbs–Boltzmann partition function is fundamental not only to Gibbs–Boltzmann but also to a large class of generalised Lorentzian distributions as well as to the corresponding nonextensive statistical mechanics.

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Alshehri, Norah, and Mohammed Guediri. "Gradient Ricci Solitons on Spacelike Hypersurfaces of Lorentzian Manifolds Admitting a Closed Conformal Timelike Vector Field." Mathematics 12, no. 6 (2024): 842. http://dx.doi.org/10.3390/math12060842.

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In this article, we investigate Ricci solitons occurring on spacelike hypersurfaces of Einstein Lorentzian manifolds. We give the necessary and sufficient conditions for a spacelike hypersurface of a Lorentzian manifold, equipped with a closed conformal timelike vector field ξ¯, to be a gradient Ricci soliton having its potential function as the inner product of ξ¯ and the timelike unit normal vector field to the hypersurface. Moreover, when the ambient manifold is Einstein and the hypersurface is compact, we establish that, under certain straightforward conditions, the hypersurface is an extrinsic sphere, that is, a totally umbilical hypersurface with a non-zero constant mean curvature. In particular, if the ambient Lorentzian manifold has a constant sectional curvature, we show that the compact spacelike hypersurface is essentially a round sphere.

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Liao, Xichang, and Yingke Lei. "Modified Variable Step Size FLOM-CMA Based on Lorentzian Function under Impulse Noise." MATEC Web of Conferences 232 (2018): 04061. http://dx.doi.org/10.1051/matecconf/201823204061.

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Aiming at the problem that the traditional equalization algorithm under impulse noise is difficult to suppress impulse noise and achieve equalization, a new modified variable step size FLOM-CMA algorithm based on Lorentzian function is proposed in this paper. The proposed algorithm has modified the cost function to made full use of the phase information of signal to correct the phase rotation. Also, by adjusting the FLOM of cost function, that impulse noise is restrained effectively. Furthermore, the Lorentzian function is use to update the step size to make sure it is is appropriate for each equalization point. Simulation experiments show that, compared with FLOM-CMA and VS-FLOM-CMA, the proposed algorithm that the proposed algorithm achieves higher convergence accuracy with similar convergence speed. And under different impulse noise conditions, the robustness of the algorithm is better.

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Farasat Shamir, M., G. Mustafa, and Saad Waseem. "Study of non-commutative wormhole solutions in f(R,G) gravity." International Journal of Geometric Methods in Modern Physics 17, no. 09 (2020): 2050129. http://dx.doi.org/10.1142/s0219887820501297.

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In this paper, we investigate some feasible regions for the existence of wormholes by introducing non-commutative geometry in terms of Gaussian and Lorentzian distributions in [Formula: see text] modified theory of gravity. We explore wormhole solutions by assuming a viable model [Formula: see text], where [Formula: see text] is assumed to be a linear function of Ricci scalar and [Formula: see text] is chosen to be a power law model. For [Formula: see text] model under discussion, we select suitable form of redshift and shape functions, which is necessary for the existence of wormholes. We discuss mainly two types of solutions corresponding to different values of free parameters and obtain numerical results. The stability condition for numerical solutions is discussed via TOV equations and it is proved that gravitational and hydrostatic forces show opposite behavior to anisotropic force and hence cancel each other’s effect, which provides a stable wormhole configuration. By using graphical evolution, it has been found that null energy conditions (NEC) are violated for non-commutative Gaussian and Lorentzian distributions. However, some feasible regions have been found for the existence of wormhole solutions with Gaussian and Lorentzian distributions in the context of [Formula: see text] gravity.

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Karmanova, M. B. "Метрические характеристики классов компактных множеств на группах Карно с сублоренцевой структурой". Владикавказский математический журнал 26, № 3 (2024): 56–64. http://dx.doi.org/10.46698/d9212-8277-5800-l.

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We consider classes of mappings of Carnot groups that are intrinsically Lipschitz and defined on compact subsets, and describe the metric characteristics of their images under the condition that a~sub-Lorentzian structure is introduced on the image. This structure is a sub-Riemannian generalization of Minkowski geometry. One of its features is the unlimitedness of the balls constructed with respect to the~intrinsic distance. In sub-Lorentzian geometry, the study of spacelike surfaces whose intersections with such balls are limited, is of independent interest. If the mapping is defined on an open set, then the formulation of space-likeness criterion reduces to considering the connectivity component of the intersection containing the center of the ball and analyzing the properties of the sub-Riemannian differential matrix. If the domain of definition of the mapping is not an open set, then the question arises what conditions can be set on the mapping that guarantee the boundedness of the intersection of the image of a compact set with a sub-Lorentzian ball. In this article, this problem is resolved: we consider that part of the intersection that can be parameterized by the connectivity component of the~intersection of the image of the sub-Riemannian differential and the ball. In addition, using such local parameterizations, a set function is introduced, which is constructed similarly to Hausdorff measure. We show that this set function is also a measure. As an application, the sub-Lorentzian area formula is established.

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Gillioz, Marc. "Conformal 3-Point Functions and the Lorentzian OPE in Momentum Space." Communications in Mathematical Physics 379, no. 1 (2020): 227–59. http://dx.doi.org/10.1007/s00220-020-03836-8.

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Abstract In conformal field theory in Minkowski momentum space, the 3-point correlation functions of local operators are completely fixed by symmetry. Using Ward identities together with the existence of a Lorentzian operator product expansion (OPE), we show that the Wightman function of three scalar operators is a double hypergeometric series of the Appell $$F_4$$ F 4 type. We extend this simple closed-form expression to the case of two scalar operators and one traceless symmetric tensor with arbitrary spin. Time-ordered and partially-time-ordered products are constructed in a similar fashion and their relation with the Wightman function is discussed.

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Kesrarat, Darun, and Vorapoj Patanavijit. "Noise resistance evaluation of spatial-field optical flow using modifying Lorentzian function." Bulletin of Electrical Engineering and Informatics 11, no. 5 (2022): 2603–10. http://dx.doi.org/10.11591/eei.v11i5.3815.

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This paper presents the evaluation of the modifying Lorentzian function on the spatial-field optical flow to examine the validity in the noisy domain of motion estimation. In the routine of the motion estimation, the frame’s motion vector is estimated by the optical flow approach where the flow of the image’s frames is caught to estimate the motion vector. Nevertheless, in the noisy domain, the preciseness of the motion vector is weakened. We operated the measurement along with several non-Gaussian noises standards through several styles of the standard image frame. The determination on error vector magnitude (EVM) was taken into account to consider the preciseness of direction and length of the motion vector (MV) in comparison with various noise resistance techniques in spatial-field optical flow approach. In the achievement results, we found that this modifying Lorentzian norm function added up in the optical flow strengthen the degree of preciseness in the estimation of the spatial-field optical flow approach in the noisy domain.

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Mustafa, G., M. Farasat Shamir, Asifa Ashraf та Tie-Cheng Xia. "Noncommutative wormholes solutions with conformal motion in the background of f(𝔾, 𝕋) gravity". International Journal of Geometric Methods in Modern Physics 17, № 07 (2020): 2050103. http://dx.doi.org/10.1142/s0219887820501030.

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This study explores the wormhole solutions in [Formula: see text] Gravity. For this purpose we assume two sorts of matter density profiles, which satisfy the Gaussian and Lorentzian noncommutative distributions. Further, we employ the conformal motions in the back ground of nonzero conformal killing vectors to find the shape-function from the modified field equations of [Formula: see text] gravity. By defining the connection between Gaussian and Lorentzian noncommutative distributions with conformal Killing vectors, it has been investigated that wormhole solutions would exist under the particular values of involved parameters in [Formula: see text] gravity.

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Acciai, Matteo, Alessio Calzona, Matteo Carrega, and Maura Sassetti. "Spectral features of voltage pulses in interacting helical channels." EPJ Web of Conferences 230 (2020): 00009. http://dx.doi.org/10.1051/epjconf/202023000009.

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We investigate the interplay of voltage-driven excitations and electron-electron interactions in a pair of counterpropagating helical channels capacitively coupled to a time-dependent gate. By focusing on the non-equilibrium spectral properties of the system, we show how the spectral function is modified by external drives with different time profile in presence of Coulomb interactions. In particular, we focus on a Lorentzian drive and a square single pulse. In presence of strong enough electron-electron interactions, we find that both drives can result in minimal excitations, i.e. characterized by an excess spectral function with a definite sign. This is in contrast with what happens in the non-interacting case, where only properly quantized Lorentzian pulses are able to produce minimal excitations.

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32

Schmidt-Grund, Rüdiger, Steffen Richter, Stefan G. Ebbinghaus, Michael Lorenz, Carsten Bundesmann, and Marius Grundmann. "Electronic transitions and dielectric function tensor of a YMnO3 single crystal in the NIR-VUV spectral range." RSC Adv. 4, no. 63 (2014): 33549–54. http://dx.doi.org/10.1039/c4ra05036c.

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The dielectric function tensor elements of an YMnO<sub>3</sub> single crystal yield M0 critical point like band-band absorption with discrete spectrally localized Lorentzian transitions within the band gaps.

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Berton, Marco. "AGN evolution as seen in spectral lines: The case of narrow-line Seyfert 1s." Proceedings of the International Astronomical Union 15, S356 (2019): 94. http://dx.doi.org/10.1017/s1743921320002653.

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AbstractLine profiles can provide fundamental information on the physics of active galactic nuclei (AGN). In the case of narrow-line Seyfert 1 galaxies (NLS1s) this is of particular importance since past studies revealed how their permitted line profiles are well reproduced by a Lorentzian function instead of a Gaussian. This has been explained with different properties of the broad-line region (BLR), which may present more pronounced turbulent motions in NLS1s with respect to other AGN. We investigated the line profiles in a recent large NLS1 sample classified using SDSS, and we divided the sources into two subsamples according to their line shapes, Gaussian or Lorentzian. The line profiles seem to separate all the properties of NLS1s. Black hole mass, Eddington ratio, [OIII] luminosity, and Fe II strength are all very different in the Lorentzian and Gaussian samples, as well as their position on the quasar main sequence. We interpret this in terms of evolution within the class of NLS1s. The Lorentzian sources may be the youngest objects, while Gaussian profiles may be typically associated to more evolved objects. Further detailed spectroscopic studies are needed to fully confirm our hypothesis.

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Finocchio, G., M. Carpentieri, E. Cardelli, and B. Azzerboni. "Analytical solution of Everett integral using Lorentzian Preisach function approximation." Journal of Magnetism and Magnetic Materials 300, no. 2 (2006): 451–70. http://dx.doi.org/10.1016/j.jmmm.2005.05.032.

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Alías, Luis J., G. Pacelli Bessa, and Jorge H. S. de Lira. "Geometric analysis of the Lorentzian distance function on trapped submanifolds." Classical and Quantum Gravity 33, no. 12 (2016): 125007. http://dx.doi.org/10.1088/0264-9381/33/12/125007.

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McVoy, K. W., P. A. Mello, and X. T. Tang. "Detectability of non-lorentzian corrections to the Ericson correlation function." Nuclear Physics A 454, no. 2 (1986): 365–73. http://dx.doi.org/10.1016/0375-9474(86)90274-5.

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Plujko, V. A., O. M. Gorbachenko, E. P. Rovenskykh, and V. O. Zheltonoshskii. "E1 gamma-transitions in hot atomic nuclei." Nuclear Physics and Atomic Energy 13, no. 4 (2012): 340–45. https://doi.org/10.15407/jnpae2012.04.340.

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New version of the modified Lorentzian approach for radiative strength function is proposed. Renewed systematics for giant dipole resonance (GDR) parameters is given. The gamma-decay strength functions are calculated using renewed GDR parameters and compared with experimental data. It is demonstrated that closed-form approaches with asymmetric shape of the gamma strength, as a rule, provide the reliable simple method for description of gamma-decay processes.

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McNemar, Charles W., and William Dew Horrocks. "The Resolution of Laser-Induced Europium(III) Ion Excitation Spectra through the Use of the Marquardt Nonlinear Regression Method." Applied Spectroscopy 43, no. 5 (1989): 816–21. http://dx.doi.org/10.1366/0003702894202256.

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The ability to resolve a 7 F0 → 5 D0 spectrum into individual peaks is important in the study of Eu(III) complexes where the wavelength of the transition is sensitive to the environment of the ion. This paper describes a computer program, based upon the Marquardt nonlinear regression algorithm, developed to resolve such spectra. Several different line shapes were examined, with the Lorentzian function providing the most accurate description for solid complexes and the Lorentzian-Gaussian product function being the most acceptable for species in solution. The program can resolve a spectrum into as many as five peaks with the option to hold any of the parameters constant. The best fit is determined by evaluation of the sum of the squares of the differences between the calculated and the experimental values.

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Lee, Myoung-Jae, and Young-Dae Jung. "Resonant flow instability of space-charge waves in self-gravitating Lorentzian dusty plasma columns." Canadian Journal of Physics 97, no. 6 (2019): 651–55. http://dx.doi.org/10.1139/cjp-2018-0530.

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The dispersion characteristics and the resonant instability mode of the space-charge wave are investigated in a streaming Lorentzian dusty plasma column by using the normal mode analysis. The result shows that the non-thermal character of the Lorentzian cylindrical dusty plasma enhances the unstable property of the space-charge wave due to the beam–plasma interaction. It is found that the resonant growth rates of the space-charge wave increase with an increase of the harmonic-order of the root of the Bessel function. It is also found that the influence of the self-gravitation enhances the resonant growth rate of the space-charge wave of the Lorentzian cylindrical dusty plasma. In addition, it is found the resonant growth rate decreases with an increase of the radius of the dusty plasma column. The variation of the resonant instability mode due to the non-thermal character and geometric effects is also discussed.

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JUNG, YOUNG-DAE, and WOOPYO HONG. "Elastic electron–ion collisions in a Lorentzian plasma." Journal of Plasma Physics 63, no. 1 (2000): 79–88. http://dx.doi.org/10.1017/s0022377899008090.

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Plasma screening effects on elastic electron–ion collision processes in a Lorentzian (kappa)-distribution plasma are investigated using the eikonal method. The electron–ion interaction potential is obtained by introducing a plasma dielectric function εκ. The semiclassical straight-line trajectory method is applied to the path of a projectile electron in order to investigate the variation of the eikonal phase as a function of impact parameter and spectral index κ. In the first-order eikonal approximation, the dynamic plasma screening effect on the eikonal phase is found to be a static screening effect, and depends only on the Debye length and spectral index. The position of the maximum of the differential elastic eikonal cross-section recedes from the ion core with increasing spectral index. The plasma screening effect on the eikonal cross-section increases with decreasing spectral index.

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41

Meng, Zhaoyue, Richard M. Thorne, and Danny Summers. "Ion-acoustic wave instability driven by drifting electrons in a generalized Lorentzian distribution." Journal of Plasma Physics 47, no. 3 (1992): 445–64. http://dx.doi.org/10.1017/s002237780002434x.

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A generalized Lorentzian (kappa) particle distribution function is useful for modelling plasma distributions with a high-energy tail that typically occur in space. The modified plasma dispersion function is employed to study the instability of ion-acoustic waves driven by electron drift in a hot isotropic unmagnetized plasma modelled by a kappa distribution. The real and imaginary parts of the wave frequency ω0 + ιγ are obtained as functions of the normalized wavenumber kλD, where λD is the electron Debye length. Marginal stability conditions for instability are obtained for different ion-to-electron temperature ratios. The results for a kappa distribution are compared with the classical results for a Maxwellian. In all cases studied the ion-acoustic waves are strongly damped at short wavelengths, kλD ≫ 1, but they can be destabilized at long wavelengths. The instability for both the kappa and Maxwellian distributions can be quenched by increasing the ion-electron temperature ratio Ti/Te. However, both the marginally unstable electron drift velocities and the growth rates of unstable waves can differ significantly between a generalized Lorentzian and a Maxwellian plasma; these differences are also influenced by the value of Ti/Te.

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CHEN, HSING-TA, TAK-SAN HO, and SHIH-I. CHU. "EXPLORATION OF THE MEMORY EFFECT ON THE PHOTON-ASSISTED TUNNELING VIA A SINGLE QUANTUM DOT: A GENERALIZED FLOQUET THEORETICAL APPROACH." International Journal of Modern Physics B 25, no. 17 (2011): 2251–70. http://dx.doi.org/10.1142/s0217979211100989.

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The generalized Floquet approach is developed to study memory effect on electron transport phenomena through a periodically driven single quantum dot in an electrode–multi-level dot–electrode nanoscale quantum device. The memory effect is treated using a multi-function Lorentzian spectral density (LSD) model that mimics the spectral density of each electrode in terms of multiple Lorentzian functions. For the symmetric single-function LSD model involving a single-level dot, the underlying single-particle propagator is shown to be related to a 2×2 effective time-dependent Hamiltonian that includes both the periodic external field and the electrode memory effect. By invoking the generalized Van Vleck (GVV) nearly degenerate perturbation theory, an analytical Tien-Gordon-like expression is derived for arbitrary order multi-photon resonance d.c. tunneling current. Numerically converged simulations and the GVV analytical results are in good agreement, revealing the origin of multi-photon coherent destruction of tunneling and accounting for the suppression of the staircase jumps of d.c. current due to the memory effect. Specially, a novel blockade phenomenon is observed, showing distinctive oscillations in the field-induced current in the large bias voltage limit.

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Azzerboni, B., E. Cardelli, G. Finocchio, and F. La Foresta. "Remarks about preisach function approximation using lorentzian function and its identification for nonoriented steels." IEEE Transactions on Magnetics 39, no. 5 (2003): 3028–30. http://dx.doi.org/10.1109/tmag.2003.815879.

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Buishvili, L. L., and G. V. Kobakhidze. "On the shape of EPR line in magnetodilute crystals." Low Temperature Physics 20, no. 11 (1994): 935–36. https://doi.org/10.1063/10.0033739.

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The shape of the absorption line in magnetodilute samples at low temperatures is analyzed by the memory function method. It is shown that, in contrast to the approximation of the cut-off Lorentzian shape of the line, the memory function method gives the Gaussian decrease in absorption for a detuning above the cut-off parameter.

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45

Park, Seung Nam, Jae Won Hahn, and Chunghi Rhee. "Effect of the Slit Function of the Detection System and a Fast-Fitting Algorithm on Accuracy of CARS Temperature." Applied Spectroscopy 48, no. 6 (1994): 737–41. http://dx.doi.org/10.1366/000370294774368866.

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The effect of the erroneous functional forms of the slit functions on the best-fit temperature in CARS (coherent anti-Stokes Raman spectroscopy) thermometry has been investigated. When the shape of the slit function is described as a Lorentzian or a Gaussian function and its width adjusted with the room-temperature CARS spectrum, the maximum systematic errors due to the slit functions reach 1.5–2.5% in the temperature range from 300 to 2100 K. A fast-fitting algorithm exponentially interpolating the CARS spectrum at an intermediate temperature with two precalculated spectra has been proposed, and its validity has been assessed by calculating the error due to the fitting algorithm.

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46

PLUJKO, V. A., I. M. KADENKO, O. M. GORBACHENKO, and E. V. KULICH. "THE SIMPLIFIED DESCRIPTION OF DIPOLE RADIATIVE STRENGTH FUNCTION." International Journal of Modern Physics E 17, no. 01 (2008): 240–44. http://dx.doi.org/10.1142/s0218301308009744.

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The gamma-decay strength function is calculated and compared with experimental data to test simple methods of the descriptions of the dipole radiative strength function (RSF) of gamma-decay in the middle-weight and heavy atomic nuclei. Simplified version of the modified Lorentzian model is proposed. It is shown that the phenomenological closed-form models with asymmetric shape can be used for overall estimates of the dipole RSF in the gamma-ray energy region up to about 20 MeV when giant dipole resonance (GDR) parameters are known or the GDR systematics can be adopted.

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Abdul Rahim, Amir Nazren, Shahrul Nizam Yaakob, Lee Yeng Seng, Mohd Wafi Nasrudin, and Iszaidy Ismail. "Improving the iterative back projection estimation through Lorentzian sharp infinite symmetrical filter." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 3 (2022): 2539. http://dx.doi.org/10.11591/ijece.v12i3.pp2539-2552.

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<span>This study proposed an enhancement technique for improvising the estimation technique in iterative back projection (IBP) by using the Lorentzian error function with a sharp infinite symmetrical filter (SISEF). The IBP estimation is an iteratively based error correction that can minimize the error reconstruction significantly. However, the IBP has a drawback in that it suffers from jaggy and ringing artifacts as a result of the iterative reconstruction method and the absence of edge guidance. Furthermore, because the IBP estimator tended to oscillate at the same solution frequently, numerous iterations were required. Therefore, this study proposed edge enhancement to enhance the estimator by using the combination of the IBP with Lorentzian SISEF to produce a finer high-resolution output image. As a result, the SISEF is used to improvise the estimator by providing high accuracy of edge detail information for enhancing the edge image. At the same time, the Lorentzian error norm helps to increase the robustness of the IBP algorithm from contamination of additional noise and the ringing artifacts.</span>

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48

Amir, Nazren Abdul Rahim, Nizam Yaakob Shahrul, Yeng Seng Lee, Wafi Nasrudin Mohd, and Ismail Iszaidy. "Improving the iterative back projection estimation through Lorentzian sharp infinite symmetrical filter." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 3 (2022): 2539–52. https://doi.org/10.11591/ijece.v12i3.pp2539-2552.

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This study proposed an enhancement technique for improvising the estimation technique in iterative back projection (IBP) by using the Lorentzian error function with a sharp infinite symmetrical filter (SISEF). The IBP estimation is an iteratively based error correction that can minimize the error reconstruction significantly. However, the IBP has a drawback in that it suffers from jaggy and ringing artifacts as a result of the iterative reconstruction method and the absence of edge guidance. Furthermore, because the IBP estimator tended to oscillate at the same solution frequently, numerous iterations were required. Therefore, this study proposed edge enhancement to enhance the estimator by using the combination of the IBP with Lorentzian SISEF to produce a finer high-resolution output image. As a result, the SISEF is used to improvise the estimator by providing high accuracy of edge detail information for enhancing the edge image. At the same time, the Lorentzian error norm helps to increase the robustness of the IBP algorithm from contamination of additional noise and the ringing artifacts.

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Vijay, Amrendra, Donald J. Kouri, and David K. Hoffman. "Scattering and Bound States: A Lorentzian Function-Based Spectral Filter Approach†." Journal of Physical Chemistry A 108, no. 41 (2004): 8987–9003. http://dx.doi.org/10.1021/jp040356n.

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Azzerboni, B., M. Carpentieri, G. Finocchio, and M. Ipsale. "Super-Lorentzian Preisach function and its applicability to model scalar hysteresis." Physica B: Condensed Matter 343, no. 1-4 (2004): 121–26. http://dx.doi.org/10.1016/j.physb.2003.08.082.

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Journal articles on the topic 'Lorentzian function'

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