353 research outputs found

    Spectroscopy of Baryons Containing Two Heavy Quarks in Nonperturbative Quark Dynamics

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    We have studied the three quark systems in an Effective Hamiltonian approach in QCD. With only two parameters: the string tension sigma and the strong coupling constant alpha_s we obtain a good description of the ground state light and heavy baryons. The prediction of masses of the doubly heavy baryons not discovered yet are also given. In particular, a mass of 3620 MeV for the lightest (ccu) baryon is found by employing the hyperspherical formalism to the three quark confining potential with the string junction.Comment: 8 pages, LaTe

    Fine structure splittings of excited P and D states in charmonium

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    It is shown that the fine structure splittings of the 23PJ2 ^3P_J and 33PJ3 ^3P_J excited states in charmonium are as large as those of the 13PJ1^3P_J state if the same αs(μ)0.36\alpha_s(\mu)\approx 0.36 is used. The predicted mass M(23P0)=3.84M(2 ^3P_0)=3.84 GeV appears to be 120 MeV lower that the center of gravity of the 23PJ2 ^3P_J multiplet and lies below the DDˉD\bar D^* threshold. Our value of M(23P0)M(2 ^3P_0) is approximately 80 MeV lower than that from the paper by Godfrey and Isgur while the differences in the other masses are \la 20 MeV. Relativistic kinematics plays an important role in our analysis.Comment: 12 page

    Ground-state baryons in nonperturbative quark dynamics

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    We review the results obtained in an Effective Hamiltonian (EH) approach for the three-quark systems. The EH is derived starting from the Feynman--Schwinger representation for the gauge-invariant Green function of the three quarks propagating in the nonperturbative QCD vacuum and assuming the minimal area law for the asymptotic of the Wilson loop. It furnishes the QCD consistent framework within which to study baryons. The EH has the form of the nonrelativistic three-quark Hamiltonian with the perturbative Coulomb-like and nonperturbative string interactions and the specific mass term. After outlining the approach, methods of calculations of the baryon eigenenergies and some simple applications are explained in details. With only two parameters: the string tension σ=0.15GeV2\sigma=0.15 GeV^2 and the strong coupling constant αs=0.39\alpha_s=0.39 a unified quantitative description of the ground state light and heavy baryons is achieved. The prediction of masses of the doubly heavy baryons not discovered yet are also given. In particular, a mass of 3660MeV3660 MeV for the lightest Ξcc\Xi_{cc} baryon is found by employing the hyperspherical formalism to the three quark confining potential with the string junction.Comment: 25 pages, 4 figures included, LaTeX 2e; to be published in Phys. Atom. Nuc

    Selection and reconstruction of the top quarks in the all-hadronic decays at a Linear Collider

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    A method of reconstruction of the top quarks produced in the process E+E- -> t\bar{t} -> 6 jets at a Linear Collider (LC) is proposed. The approach does not involve a kinematic fit, as well as assumptions on the invariant masses of the dijets originating from the decays of W bosons and, therefore, the method is expected to be less sensitive to theoretical and experimental uncertainties on the top-mass measurement than traditional reconstruction methods. For the first time, the reconstruction of the top quarks was investigated using the full LC detector simulation after taking into account the background arising from QCD multi-jet production.Comment: 22 pages, including 13 figures and 3 table

    Pentaquarks in the Jaffe-Wilczek approximation

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    The masses of uuddsˉuudd\bar s , uudddˉuudd\bar d and uussdˉuuss\bar d pentaquarks are evaluated in a framework of both the Effective Hamiltonian approach to QCD and spinless Salpeter using the Jaffe--Wilczek diquark approximation and the string interaction for the diquark--diquark--antiquark system. The pentaquark masses are found to be in the region above 2 GeV. That indicates that the Goldstone boson exchange effects may play an important role in the light pentaquarks. The same calculations yield the mass of [ud]2cˉ[ud]^2\bar c pentaquark \sim 3250 MeV and [ud]2bˉ[ud]^2\bar b pentaquark \sim 6509 MeV.Comment: 14 pages, 2 tables, LaTeX2e. References correcte

    A Thin-Layer Chromatography Method for the Determination of Essential Oil Components in Anise and Fennel Fruits

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    Scientific relevance. The State Pharmacopoeia of the Russian Federation, edition XIV, requires the identification of aniseed and fennel fruits by the same thin-layer chromatography (TLC) procedure using Sudan III and menthol. These markers are neither specific nor related to the therapeutic effects of these herbal drug products. The visual interpretation of chromatograms is complicated because of the low intensity of adsorption zones. Moreover, the corresponding compendial monographs do not characterise the adsorption zones specific to each of the plants. The most abundant component in aniseed and fennel essential oils, trans-anethole, would make a better reference standard from a methodological point of view.Aim. This study aimed to optimise the TLC procedure for essential oil determination in herbal drugs and herbal medicinal products of aniseed and fennel fruits and subsequently recommend it for inclusion in the relevant compendial monographs.Materials and methods. The study examined samples from several batches of herbal drugs, including aniseed and common fennel fruits, sourced from Russian manufacturers. The reference standards comprised commercial reagents, including trans-anethole, anise oil, and linalool, as well as fresh essential oils that had been steam distilled from the test samples in a Clevenger apparatus. The study was conducted by TLC. Sample preparation involved using Merck aluminium TLC plates, an IKA KS-501 digital orbital shaker, and a CAMAG Linomat 5 semi-automatic sample application system. The authors heated the plates in either a Binder ED53 drying oven or a CAMAG TLC plate heater. For visualisation, the authors selected a CAMAG TLC VISUALIZER 2 UV imaging and documentation system.Results. The informational and experimental research showed the feasibility of using trans-anethole as an identification reference standard for common anise and fennel fruits. The authors selected the optimal solvent for extracting active substances from the test products (hexane) and a detection reagent for improving visual evaluation of the chromatograms (1% sulfovanillin). The authors established characteristic adsorption zones for differentiating between aniseed and fennel fruits.Conclusions. The optimised procedure identifies the main components in the essential oils of aniseed and fennel fruits with a specific reference standard. This procedure may be recommended for inclusion in draft monographs for the corresponding herbal medicinal products

    Изготовление элементов проточной части модели бустерного s-насоса двустороннего действия

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    The article describes a new design of the primary pump to run in powerful units (more than 1 GW) of power plants. The new construction has some advantages such as compactness, theoretical lack of radial and axial forces, and high efficiency in a wide range of flow. The abovementioned advantages can be possible owing to applying an innovative shape of the pump flow path. An impeller with the guide vanes forms the three-row single stage in the each row axial double entry blade system. The inlet and outlet parts have a shape of the involute that can ensure (according to calculated data) the efficiency and stability in a wide range of flow because of a lack of the spiral parts. The results of numerical calculations of the pump working flow theoretically confirm that demanding parameters of the pump (H=286 m; Q=1,15 m3 /s) can be obtained with competitive efficiency. To verify the proposed advantages of the construction, there was decision made to conduct the real physical experiment. For this purpose the small model of a real pump was designed with parameters H=14 m, Q=13 l/s. Construction of the pump model has a cartridge conception. In addition, there is a possibility for quick replacement of the some parts of the blade system in case of operational development of the pump. In order to obtain hydraulic characteristics of the pump to say nothing of the electromotor the torque gauge coupling is used. Numerical calculations for the pump model were also performed which confirm the operability. For manufacturing of the blade system the new perspective technology is applied. The main hydraulic components (impellers and guide vanes) are made of ABS plastic by using 3D-printer. According to this technology parts are made layer by layer by means of welded plastic filament. Using this method the satisfactory tolerance (approximately ±0,3 mm) of the parts was obtained. At that moment, it is possible to create the parts with the maximum size no higher than 150 mm. Immersing finished parts in acetone vapor enable us to increase the surface strength and reduce roughness. At this stage of the work some plastic parts are ready for assembling operation. Now manufacturing of other plastic parts of the blade system is under way along with pre-production of the rotor and stator components.Излагается процесс изготовления элементов проточной части полирядного лопастного насоса с s-образной меридиональной проекцией и элементами подвода и отвода в форме эвольвенты. Приведена конструкция опытной модели бустерного s-насоса двустороннего действия. В основу конструкции заложена картриджная концепция агрегата. Изложены результаты численного моделирования рабочего процесса проточной части модели. Описана технология изготовления элементов проточной части насоса из высокопрочного ABS пластика с применением 3D-принтера с последующей процедурой поверхностного упрочнения готовых изделий в парах ацетона. Показаны изготовленные детали рабочих органов активной части насоса: колесо рабочее, аппарат направляющий, шнек. DOI: 10.7463/aplts.0415.079327

    QCD string in light-light and heavy-light mesons

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    The spectra of light-light and heavy-light mesons are calculated within the framework of the QCD string model, which is derived from QCD in the Wilson loop approach. Special attention is payed to the proper string dynamics that allows us to reproduce the straight-line Regge trajectories with the inverse slope being 2\pi\sigma for light-light and twice as small for heavy-light mesons. We use the model of the rotating QCD string with quarks at the ends to calculate the masses of several light-light mesons lying on the lowest Regge trajectories and compare them with the experimental data as well as with the predictions of other models. The masses of several low-lying orbitally and radially excited heavy--light states in the D, D_s, B, and B_s meson spectra are calculated in the einbein (auxiliary) field approach, which has proven to be rather accurate in various calculations for relativistic systems. The results for the spectra are compared with the experimental and recent lattice data. It is demonstrated that an account of the proper string dynamics encoded in the so-called string correction to the interquark interaction leads to an extra negative contribution to the masses of orbitally excited states that resolves the problem of the identification of the D(2637) state recently claimed by the DELPHI Collaboration. For the heavy-light system we extract the constants \bar\Lambda, \lambda_1, and \lambda_2 used in Heavy Quark Effective Theory (HQET) and find good agreement with the results of other approaches.Comment: RevTeX, 42 pages, 7 tables, 7 EPS figures, uses epsfig.sty, typos corrected, to appear in Phys.Rev.

    Nonperturbative hyperfine contribution to the b1b_1 and h1h_1 meson masses

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    Due to the nonperturbative contribution to the hyperfine splitting the mass of the n1P1n^1P_1 state is strongly correlated with the center of gravity Mcog(n3PJ)M_{\rm cog}(n^3P_J) of the n3PJn^3P_J multiplet: M(n1P1)M(n^1P_1) is less than Mcog(n3PJ)M_{\rm cog}(n^3P_J) by about 40 MeV (20 MeV) for the 1P (2P) state. For b1(1235)b_1(1235) the agreement with experiment is reached only if a0(980)a_0(980) belongs to the 13PJ1^3P_J multiplet. The predicted mass of b1(21P1)b_1(2^1P_1) is 1620\approx 1620 MeV. For the isoscalar meson a correlation between the mass of h1h_1(1170) (h1(1380))(h_1(1380)) and Mcog(13PJ)M_{cog}(1^3P_J) composed from light (strange) quarks also takes place.Comment: 22 pages RevTe

    Determination of the Total Alkaloid Content of Thermopsis Dry Extract by HPTLC-Densitometry

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    When used to quantify alkaloids in thermopsis dry extract, acidimetric titration has several limitations, including insufficient specificity of the method and arbitrary selection of a titration endpoint. Different parts of the Thermopsis lanceolata plant produce alkaloids in different proportions: the herb is rich in thermopsine, whereas the seeds are rich in cytisine. Since thermopsine and cytisine have different pharmacological effects, it is important to identify and quantify individual alkaloids in thermopsis dry extract.The aim of the study was to develop and validate an analytical procedure for identifying and quantifying total alkaloids in thermopsis dry extract by high-performance thin-layer chromatography (HPTLC) with densitometric detection.Materials and methods. The study included samples from two pilot-scale batches of thermopsis dry extract and reference standards for cytisine and thermopsine. The authors used Merck HPTLС Silica Gel 60 F254 20×10 cm plates for chromato-graphic separation and analysed the results with a CAMAG® TLC Scanner 4 densitometer and the winCATS software.Results. The authors identified thermopsis dry extract using HPTLC separation followed by spectrodensitometry. The alkaloid-specific solution applied to chromatography plates helped to identify the three most abundant and four minor alkaloids of thermopsis. The most abundant alkaloids were thermopsine, cytisine, and an unidentified alkaloid with a retention factor of approximately 0.2. These three alkaloids accounted for almost 80% of the total alkaloid content of the dry extract. The authors quantified cytisine, thermopsine, and total alkaloids expressed as thermopsine.Conclusions. The authors developed and validated an analytical procedure for identifying and quantifying total alkaloids in thermopsis dry extract. This procedure offers the possibility of reducing the analysis time from 4–5 hours to 2–2.5 hours
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