6,707 research outputs found

    Weighing the Neutrino

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    We investigate the potential of short-baseline experiments in order to measure the dispersion relation of the (muon) neutrino, with a prospect of eventually measuring the neutrino mass. As a byproduct, the experiment would help to constrain parameters of Lorentz-violating effects in the neutrino sector. The potential of a high-flux laser-accelerated proton beam (e.g., at the upcoming ELI facility), incident on a thick target composed of a light element to produce pions, with a subsequent decay to muons and muon-neutrinos, is discussed. We find a possibility for a muon neutrino mass measurement of unprecedented accuracy.Comment: 12 pages; RevTe

    On the applicability of the layered sine-Gordon model for Josephson-coupled high-T_c layered superconductors

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    We find a mapping of the layered sine-Gordon model to an equivalent gas of topological excitations and determine the long-range interaction potentials of the topological defects. This enables us to make a detailed comparison to the so-called layered vortex gas, which can be obtained from the layered Ginzburg-Landau model. The layered sine-Gordon model has been proposed in the literature as a candidate field-theoretical model for Josephson-coupled high-T_c superconductors, and the implications of our analysis for the applicability of the layered sine-Gordon model to high-T_c superconductors are discussed. We are led to the conjecture that the layered sine--Gordon and the layered vortex gas models belong to different universality classes. The determination of the critical temperature of the layered sine-Gordon model is based on a renormalization-group analysis.Comment: 7 pages, accepted for publication in J. Phys.: Condens. Matte

    Interplay of fixed points in scalar models

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    We performed the renormalization group analysis of scalar models exhibiting spontaneous symmetry breaking. It is shown that an infrared fixed point appears in the broken symmetric phase of the models, which induces a dynamical scale, that can be identified with the correlation length. This enables one to identify the type of the phase transition which shows similarity to the one appearing in the crossover scale. The critical exponent Μ\nu of the correlation length also proved to be equal in the crossover and the infrared scaling regimes.Comment: 11 pages, 4 figure

    Including nonlocality in exchange-correlation kernel from time-dependent current density functional theory: Application to the stopping power of electron liquids

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    We develop a scheme for building the scalar exchange-correlation (xc) kernel of time-dependent density functional theory (TDDFT) from the tensorial kernel of time-dependent {\em current} density functional theory (TDCDFT) and the Kohn-Sham current density response function. Resorting to the local approximation to the kernel of TDCDFT results in a nonlocal approximation to the kernel of TDDFT, which is free of the contradictions that plague the standard local density approximation (LDA) to TDDFT. As an application of this general scheme, we calculate the dynamical xc contribution to the stopping power of electron liquids for slow ions to find that our results are in considerably better agreement with experiment than those obtained using TDDFT in the conventional LDA.Comment: 6 pages, 3 figures, accepted to Phys. Rev.

    Secondary metabolites from Stachys palustris L.

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    In this work we report the first total analysis of the secondary metabolites from a sample of Stachys palustris L., an herbaceous perennial plant belonging to Lamiaceae, collected in Hungary. The phytochemical analysis, performed by means of classical column chromatography and NMR spectroscopy and Mass spectrometry (MS), allowed us to isolate and identify eight compounds such as verbascoside (1) [1], echinacoside (2) [1], two isoscutellarein derivatives (3, 4) [2,3], chlorogenic acid (5) [3], harpagide (6) [4], 8-O-acetyl-harpagide (7) [4] and monomelittoside (8) [4]. These compounds belong to four different classes of chemical compounds namely phenyl-ethanoid glycosides (PhGs) (compounds 1, 2), flavonoids (compounds 3,4), caffeoyl-quinic acids (compound 5) and iridoids (compounds 6,7 and 8). From a chemosystematic point of view, these compounds are all important: compounds (6) and (7) are considered as the major chemotaxonomic markers of the genus; compound (1) and (8) resulted new constituents in this species and compound (2) is even new in the genus. In addition to this, the co-occurrence of iridoids and PhGs has a chemosystematic importance since it is widely demonstrated their presence in Asterids [1, 3]. Lastly, compounds (3) and (4) such as compounds (5),(6) and (7) have already been found in Stachys species, giving, this way, evidence of a phytochemical pattern perfectly in accordance with those reported in literature for other members of this genus. Nevertheless, it’s worth to underline the fact that compounds (3) and (4), like all isoscutellarein derivatives containing allose, seem to have a restricted distribution in only some genera of Lamiaceae

    Secondary metabolites from Stachys palustris L.

    Get PDF
    In this work we report the first total analysis of the secondary metabolites from a sample of Stachys palustris L., an herbaceous perennial plant belonging to Lamiaceae, collected in Hungary. The phytochemical analysis, performed by means of classical column chromatography and NMR spectroscopy and Mass spectrometry (MS), allowed us to isolate and identify eight compounds such as verbascoside (1) [1], echinacoside (2) [1], two isoscutellarein derivatives (3, 4) [2,3], chlorogenic acid (5) [3], harpagide (6) [4], 8-O-acetyl-harpagide (7) [4] and monomelittoside (8) [4]. These compounds belong to four different classes of chemical compounds namely phenyl-ethanoid glycosides (PhGs) (compounds 1, 2), flavonoids (compounds 3,4), caffeoyl-quinic acids (compound 5) and iridoids (compounds 6,7 and 8). From a chemosystematic point of view, these compounds are all important: compounds (6) and (7) are considered as the major chemotaxonomic markers of the genus; compound (1) and (8) resulted new constituents in this species and compound (2) is even new in the genus. In addition to this, the co-occurrence of iridoids and PhGs has a chemosystematic importance since it is widely demonstrated their presence in Asterids [1, 3]. Lastly, compounds (3) and (4) such as compounds (5),(6) and (7) have already been found in Stachys species, giving, this way, evidence of a phytochemical pattern perfectly in accordance with those reported in literature for other members of this genus. Nevertheless, it’s worth to underline the fact that compounds (3) and (4), like all isoscutellarein derivatives containing allose, seem to have a restricted distribution in only some genera of Lamiaceae

    Occurrence statistics of cold, streaming ions in the near‐Earth magnetotail: Survey of Polar‐TIDE observations

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95347/1/jgra17705.pd

    Time-dependent density-functional theory approach to nonlinear particle-solid interactions in comparison with scattering theory

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    An explicit expression for the quadratic density-response function of a many-electron system is obtained in the framework of the time-dependent density-functional theory, in terms of the linear and quadratic density-response functions of noninteracting Kohn-Sham electrons and functional derivatives of the time-dependent exchange-correlation potential. This is used to evaluate the quadratic stopping power of a homogeneous electron gas for slow ions, which is demonstrated to be equivalent to that obtained up to second order in the ion charge in the framework of a fully nonlinear scattering approach. Numerical calculations are reported, thereby exploring the range of validity of quadratic-response theory.Comment: 14 pages, 3 figures. To appear in Journal of Physics: Condensed Matte

    Hidden symmetries in the asymmetric exclusion process

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    We present a spectral study of the evolution matrix of the totally asymmetric exclusion process on a ring at half filling. The natural symmetries (translation, charge conjugation combined with reflection) predict only two fold degeneracies. However, we have found that degeneracies of higher order also exist and, as the system size increases, higher and higher orders appear. These degeneracies become generic in the limit of very large systems. This behaviour can be explained by the Bethe Ansatz and suggests the presence of hidden symmetries in the model. Keywords: ASEP, Markov matrix, symmetries, spectral degeneracies, Bethe Ansatz.Comment: 16 page
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