624 research outputs found

    Excited State Contributions to the Heavy Baryon Fragmentation Functions in a Quark-Diquark Model

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    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting Λb\Lambda_b production rate and polarization at LEP energies are in agreement with experiment. The Λc\Lambda_c and Ξc\Xi_c functions are also obtained. The spin independent f1(z)f_1(z) is compared to data. The integrated values for production rates agree with the data

    Decay of the classical Loschmidt echo in integrable systems

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    We study both analytically and numerically the decay of fidelity of classical motion for integrable systems. We find that the decay can exhibit two qualitatively different behaviors, namely an algebraic decay, that is due to the perturbation of the shape of the tori, or a ballistic decay, that is associated with perturbing the frequencies of the tori. The type of decay depends on initial conditions and on the shape of the perturbation but, for small enough perturbations, not on its size. We demonstrate numerically this general behavior for the cases of the twist map, the rectangular billiard, and the kicked rotor in the almost integrable regime.Comment: 8 pages, 3 figures, revte

    Spin Dependent Fragmentation Functions for Heavy Flavor Baryons and Single Heavy Hyperon Polarization

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    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. Λb\Lambda_b , Λc\Lambda_c and Ξc\Xi_c production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted Λc\Lambda_c polarization is roughly in agreement with experiment.Comment: LaTeX2e 11 pages with 4 PostScript figures. To be published in Proceedings of the International Workshop ``Symmetries and spin'', Praha-SPIN-200

    Measurement of the cosmic ray hadron spectrum up to 30 TeV at mountain altitude: the primary proton spectrum

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    The flux of cosmic ray hadrons at the atmospheric depth of 820 g/cm^2 has been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore, National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well described by a single power law : S(E_h) = (2.25 +- 0.21 +- 0.34(sys)) 10^(-7)(E_h/1000)^(-2.79 +- 0.05) m^(-2) s^(-1) sr^(-1) GeV^(-1) over the energy range 30 GeV-30 TeV. The procedure and the accuracy of the measurement are discussed. The primary proton spectrum is derived from the data by using the CORSIKA/QGSJET code to compute the local hadron flux as a function of the primary proton spectrum and to calculate and subtract the heavy nuclei contribution (basing on direct measurements). Over a wide energy range E_0 = 0.5-50 TeV its best fit is given by a single power law : S(E_0) = (9.8 +- 1.1 +- 1.6(sys)) 10^(-5) (E_0/1000)^(-2.80 +- 0.06) m^(-2) s^(-1) sr^(-1) GeV^(-1). The validity of the CORSIKA/QGSJET code for such application has been checked using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the measured hadron fluxes at the two experimental depths (820 and 1030 g/cm^2 respectively) at better than 10% in the considered energy range.Comment: 16 pages, 9 figures, accepted for publication in Astroparticle Physic

    Loschmidt Echo and Lyapunov Exponent in a Quantum Disordered System

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    We investigate the sensitivity of a disordered system with diffractive scatterers to a weak external perturbation. Specifically, we calculate the fidelity M(t) (also called the Loschmidt echo) characterizing a return probability after a propagation for a time tt followed by a backward propagation governed by a slightly perturbed Hamiltonian. For short-range scatterers we perform a diagrammatic calculation showing that the fidelity decays first exponentially according to the golden rule, and then follows a power law governed by the diffusive dynamics. For long-range disorder (when the diffractive scattering is of small-angle character) an intermediate regime emerges where the diagrammatics is not applicable. Using the path integral technique, we derive a kinetic equation and show that M(t) decays exponentially with a rate governed by the classical Lyapunov exponent.Comment: 9 pages, 7 figure

    Universality of the Lyapunov regime for the Loschmidt echo

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    The Loschmidt echo (LE) is a magnitude that measures the sensitivity of quantum dynamics to perturbations in the Hamiltonian. For a certain regime of the parameters, the LE decays exponentially with a rate given by the Lyapunov exponent of the underlying classically chaotic system. We develop a semiclassical theory, supported by numerical results in a Lorentz gas model, which allows us to establish and characterize the universality of this Lyapunov regime. In particular, the universality is evidenced by the semiclassical limit of the Fermi wavelength going to zero, the behavior for times longer than Ehrenfest time, the insensitivity with respect to the form of the perturbation and the behavior of individual (non-averaged) initial conditions. Finally, by elaborating a semiclassical approximation to the Wigner function, we are able to distinguish between classical and quantum origin for the different terms of the LE. This approach renders an understanding for the persistence of the Lyapunov regime after the Ehrenfest time, as well as a reinterpretation of our results in terms of the quantum--classical transition.Comment: 33 pages, 17 figures, uses Revtex

    Изучение влияния аланина на накопление фенольных соединений в листьях цикория обыкновенного (Cichorium intybus L.)

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    Common chicory (Cichorium intybus L.) is a promising source of raw materials for both food (roots) and pharmaceutical industries (leaves). One of the ways to increase the biologically active compounds content in medicinal plant materials is the use of various growth stimulants, which include amino acids. The article presents the results of an experimental study conducted in 2021-2022 which study the effect of of L-alanine and a racemic mixture of alanine (DL) on the accumulation and qualitative composition of phenolic compounds (PC) in the leaves of chicory.Results. It was found that the use of alanine in different concentrations did not have a significant effect on the increase of phenolic compounds content, and also did not affect the on their accumulation dynamics. The use of alanine enantiomers did not affect the qualitative composition of phenolic compounds, but led to a change in the ratio of hydroxycinnamic acids to each other. It has been established that during the growing season the percentage ratio between the main phenolic compounds in chicory leaves changes - the content of chlorogenic acid increases in proportion to the decrease in chicory acid. Treatment with L-alanine at a concentration of 25 mg/l during the study period in both varieties led to the largest reduction in the content of chicory acid compared to others. It was noted that the total content of PC is higher in a year with warmer and more arid weather, it was higher on average by 0,7 %.Цикорий обыкновенный (Cichorium intybus L.) является перспективным источником получения сырья для нужд как пищевой (корни), так и фармацевтической промышленности (листья). Одним из способов увеличения содержания биологически активных соединений в лекарственном растительном сырье является использование различных стимуляторов роста, к которым относятся аминокислоты. В статье приведены результаты экспериментального исследования, проводившегося в 2021-2022 годов по изучению действия раствора L-аланина и рацемической смеси аланина (DL) на накопление и качественный состав фенольных соединений (ФС) в листьях цикория обыкновенного.Было установлено, что применение аланина в разных концентрациях не оказало значительного влияния на увеличение содержания фенольных соединений, а также не повлияло на динамику их накопления. Применение растворов энантиомеров аланина не повлияло на качественный состав фенольных соединений, но привело к изменению соотношения гидроксикоричных кислот между собой. Установлено, что в течение вегетационного периода в листьях цикория изменяется процентное соотношение между основными фенольными соединениями – содержание хлорогеновой кислоты увеличивается пропорционально снижению цикориевой кислоты. Обработка L-аланином в концентрации 25 мг/л за период исследования на обоих сортах привела к наибольшему снижению содержания цикориевой кислоты по сравнению с другими вариантами. Отмечено, что общее содержание ФС выше в год с более теплой и засушливой погодой – в среднем на 0,7 %

    The effect of caffeine, metronidazole, and ibuprofen on continuous flow activated sludge process

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    BACKGROUND: The aim of this work was to study the biological treatment of a synthetic wastewater containing emerging contaminants. The 95-day experiment was conducted in an 81 L continuous flow conventional activated sludge apparatus consisting of anoxic and aerobic reactors with internal recycling, and a clarifier with activated sludge recycling. Real activated sludge from the municipal wastewater treatment plant in the Nur-Sultan city was used. The degradation efficiencies of caffeine, metronidazole, and ibuprofen in the synthetic wastewater were studied either separately or in combination. RESULTS: When treated separately at the concentration of 30 mg/L, the degradation of caffeine and ibuprofen was up to 100%, while the degradation of metronidazole was in the range of 12–27%. Caffeine and ibuprofen inhibited the nitrification process, while the presence of metronidazole in the system suppressed the activity of denitrifying microorganisms. The biological treatment of the synthetic wastewater containing all three compounds (at the concentration of 10 mg/L each) resulted in degradation of caffeine and ibuprofen up to 100%, and 56% in the case of metronidazole. As both nitrification and denitrification processes were affected, the total nitrogen removal was significantly reduced from 53% to 22%. CONCLUSION: Complete degradation of caffeine and ibuprofen, and partial degradation of metronidazole were observed in a synthetic wastewater using the activated sludge process. As the presence of emerging pollutants in a wastewater affects the general efficiency of the wastewater treatment plants, other physical or chemical pre-treatment should be utilized to minimize the harmful effect of contaminants on the biological processes

    Low exposure long-baseline neutrino oscillation sensitivity of the DUNE experiment

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    The Deep Underground Neutrino Experiment (DUNE) will produce world-leading neutrino oscillation measurements over the lifetime of the experiment. In this work, we explore DUNE\u27s sensitivity to observe charge-parity violation (CPV) in the neutrino sector, and to resolve the mass ordering, for exposures of up to 100 kiloton-megawatt-calendar years (kt-MW-CY), where calendar years include an assumption of 57% accelerator uptime based on past accelerator performance at Fermilab. The analysis includes detailed uncertainties on the flux prediction, the neutrino interaction model, and detector effects. We demonstrate that DUNE will be able to unambiguously resolve the neutrino mass ordering at a 4σ (5σ) level with a 66 (100) kt-MW-CY far detector exposure, and has the ability to make strong statements at significantly shorter exposures depending on the true value of other oscillation parameters, with a median sensitivity of 3σ for almost all true δCP values after only 24 kt-MW-CY. We also show that DUNE has the potential to make a robust measurement of CPV at a 3σ level with a 100 kt-MW-CY exposure for the maximally CP-violating values δCP=±π/2. Additionally, the dependence of DUNE\u27s sensitivity on the exposure taken in neutrino-enhanced and antineutrino-enhanced running is discussed. An equal fraction of exposure taken in each beam mode is found to be close to optimal when considered over the entire space of interest
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