Search results for " Spectra"
showing 10 items of 709 documents
Scattering resonances and Pseudospectrum : stability and completeness aspects in optical and gravitational systems
2022
The general context of this thesis is an effort to establish a bridge between gravitational andoptical physics, specifically in the context of scattering problems using as a guideline concepts andtools taken from the theory of non-self-adjoint operators. Our focus is on Quasi-Normal Modes(QNMs), namely the natural resonant modes of open leaky structures under linear perturbationssubject to outgoing boundary conditions. They also are referred to as scattering resonances.In the conservative self-adjoint case the spectral theorem guarantees the completeness andspectral stability of the associated normal modes. In this sense, a natural question in the non-self-adjoint setting refers to the char…
Lévy flights in an infinite potential well as a hypersingular Fredholm problem.
2016
We study L\'evy flights {{with arbitrary index $0< \mu \leq 2$}} inside a potential well of infinite depth. Such problem appears in many physical systems ranging from stochastic interfaces to fracture dynamics and multifractality in disordered quantum systems. The major technical tool is a transformation of the eigenvalue problem for initial fractional Schr\"odinger equation into that for Fredholm integral equation with hypersingular kernel. The latter equation is then solved by means of expansion over the complete set of orthogonal functions in the domain $D$, reducing the problem to the spectrum of a matrix of infinite dimensions. The eigenvalues and eigenfunctions are then obtained numer…
Non-self-adjoint graphs
2013
On finite metric graphs we consider Laplace operators, subject to various classes of non-self-adjoint boundary conditions imposed at graph vertices. We investigate spectral properties, existence of a Riesz basis of projectors and similarity transforms to self-adjoint Laplacians. Among other things, we describe a simple way how to relate the similarity transforms between Laplacians on certain graphs with elementary similarity transforms between matrices defining the boundary conditions.
Secondary interactions as driving force in heterocomplex formation of 2,7-disubstituted-1,8-naphthyridines: Quantum chemical, NMR and mass spectral i…
2009
Abstract Tautomerism and dimerization of 2,7-disubstituted-1,8-naphtyridines has been studied theoretically by quantum chemical methods and experimentally by liquid and solid state NMR and ESI-TOF mass spectral techniques. The heterocomplex formation has been proven in solution by variable temperature 1H NMR and in solid state by 13C CPMAS NMR spectra of a grinded mixture of two congeners. Secondary interactions have been proposed as driving forces in the heterocomplex formation. The energy differences between homo- and heterocomplexes were calculated with recently developed DFT + D methods. The energy data obtained by the quantum chemical methods are in agreement with the concept of second…
On the temperature dependence of the electrical conductivity in hot quenched lattice QCD
2011
Extending our recent work, we report on a calculation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD in the temperature range 1.16Tc<T<2.98Tc. After performing a systematic analysis of the in fluence of cut-off effects on light quark meson correlators using clover improved Wilson fermions, we discuss resulting constraints on the electrical conductivity in a quark gluon plasma.
Faddeev study of heavy baryon spectroscopy
2007
16 pages, 3 figures.-- PACS nrs.: 12.39.Jh, 12.39.Pn, 14.20.-c.-- ISI Article Identifier: 000246249100015.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0703257
The Scale Dependence of the Hadron Multiplicity in Quark and Gluon Jets and a Precise Determination of $C_{A}/C_{F}$
1999
\frac{C_A}{C_F} = 2.246 \pm 0.062~(stat.) \pm 0.080~(syst.) \pm 0.095~(theo.) Data collected at the Z resonance using the DELPHI detector at LEP are used to determine the charged hadron multiplicity in gluon and quark jets as a function of a transverse momentum-like scale. The colour factor ratio, \cacf, is directly observed in the increase of multiplicities with that scale. The smaller than expected multiplicity ratio in gluon to quark jets is understood by differences in the hadronization of the leading quark or gluon. From the dependence of the charged hadron multiplicity on the opening angle in symmetric three-jet events the colour factor ratio is measured to be: C_A/C_F = 2.246 \pm 0.0…
On Commuting Quasi-Nilpotent Operators that are Injective
2022
Banach space operators that commute with an injective quasi-nilpotent operator, 11 such as the Volterra operator, inherit spectral and Fredholm properties, relating in 12 particular to the Weyl spectra.
Self-broadening coefficients and improved line intensities for the ν7 band of ethylene near 10.5μm, and impact on ethylene retrievals from Jungfraujo…
2014
Relying on high-resolution Fourier transform infrared (FTIR) spectra, the present work involved extensive measurements of individual line intensities and self-broadening coefficients for the ν7 band of 12C2H4. The measured self-broadening coefficients exhibit a dependence on both J and Ka. Compared to the corresponding information available in the latest edition of the HITRAN spectroscopic database, the measured line intensities were found to be higher by about 10% for high J lines in the P branch and lower by about 5% for high J lines of the R branch, varying between these two limits roughly linearly with the line positions. The impact of the presently measured line intensities on retrieva…
Raman spectroscopy and crystal-field split rotational states of photoproducts CO and H2 after dissociation of formaldehyde in solid argon
2012
Raman signal is monitored after 248 nm photodissociation of formaldehyde in solid Ar at temperatures of 9–30 K. Rotational transitions J = 2 ← 0 for para-H2 fragments and J = 3 ← 1 for ortho-H2 are observed as sharp peaks at 347.2 cm−1 and 578.3 cm−1, respectively, which both are accompanied by a broader shoulder band that shows a split structure. The rovibrational spectrum of CO fragments has transitions at 2136.5 cm−1, 2138.3 cm−1, 2139.9 cm−1, and 2149 cm−1. To explain the observations, we performed adiabatic rotational potential calculations to simulate the Raman spectrum. The simulations indicate that the splitting of rotational transitions is a site effect, where H2 molecules can resi…