86 research outputs found

    Evidence for the two pole structure of the Lambda(1405) resonance

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    The K^- p --> pi^0 pi^0 Sigma^0 reaction is studied within a chiral unitary model. The distribution of pi^0 Sigma^0 states forming the Lambda(1405) shows, in agreement with a recent experiment, a peak at 1420 MeV and a relatively narrow width of Gamma = 38 MeV. The mechanism for the reaction is largely dominated by the emission of a pi^0 prior to the K^- p interaction leading to the Lambda(1405). This ensures the coupling of the Lambda(1405) to the K^- p channel, thus maximizing the contribution of the second state found in chiral unitary theories, which is narrow and of higher energy than the nominal Lambda(1405). This is unlike the pi^- p --> K^0 \pi Sigma reaction, which gives more weight to the pole at lower energy and with a larger width. The data of these two experiments, together with the present theoretical analysis, provides a firm evidence of the two pole structure of the Lambda(1405).Comment: 4 pages, 6 figure

    Dual-Regge Approach to High-Energy, Low-Mass Diffraction Dissociation

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    A dual-Regge model with a nonlinear proton Regge trajectory in the missing mass channel, describing the experimental data on low-mass single diffraction dissociation, is constructed. Predictions for the LHC energies are given.Comment: 14 pages, 12 figure

    Covariant description of kinetic freeze out through a finite time-like layer

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    The Freeze Out (FO) problem is addressed for a covariant FO probability and a finite FO layer with a time-like normal vector continuing the line of studies introduced in Ref. [1]. The resulting post FO momentum distribution functions are presented and discussed. We show that in general the post FO distributions are non-thermal and asymmetric distributions even for time-like FO situations.Comment: 10 pages, 12 figures, major rewrite with changed content, corrected typos and new references adde

    A Kinematically Complete Analysis of the CLAS data on the Proton Structure Function F2F_2 in a Regge-Dual model

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    The recently measured inclusive electron-proton cross section in the nucleon resonance region, performed with the CLAS detector at the Thomas Jefferson Laboratory, has provided new data for the nucleon structure function F2F_2 with previously unavailable precision. In this paper we propose a description of these experimental data based on a Regge-dual model for F2F_2. The basic inputs in the model are nonlinear complex Regge trajectories producing both isobar resonances and a smooth background. The model is tested against the experimental data, and the Q2Q^2- dependence of the moments is calculated. The fitted model for the structure function (inclusive cross section) is a limiting case of the more general scattering amplitude equally applicable to deeply virtual Compton scattering (DVCS). The connection between the two is discussed.Comment: 21 pages, 12 figures, revtex style. Misprints in eqs. (15,17) are corrected. To appear in Phys. Rev.

    International Distribution of Equity Funds and Market Efficiency

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    The network of international capital markets is modeled as a global communications system, where information flows in one channel and funds flow in the other. Based on the fundamental logic of the measurement of information (Reza, 1992) and on the standard assumptions of the Capital Asset Pricing Model (CAPM) (Shapiro, 1999), we demonstrate that these markets operate at very large losses. Global markets are far less efficient than long-established domestic capital markets of developed countries, which do relatively well in transmitting information and funds. Along with the integration of national capital markets into a more tightly knit international network, however, major improvements in efficiency can be expected. Integration, though, implies a need for some kind of global regulations to help standardize the flow of information and the routines of pricing risk. Standardization in turn can be expected to decrease risks and increase the efficiency of distributing funds. From an information-theoretical perspective the introduction of mutually accepted regulations is desired, since it would boost the capacity utilization of the distribution system as such. A better-utilized communications system will bring faster clearing international markets and cheaper funds

    Can supercooling explain the HBT puzzle?

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    Possible hadronization of supercooled QGP, created in heavy ion collisions at RHIC and SPS, is discussed within a Bjorken hydrodynamic model. Such a hadronization is expected to be a very fast shock-like process, what, if hadronization coincides or shortly followed by freeze out, could explain a part of the HBT puzzle, i.e. the flash-like particle emission (Rout/Rside1R_{out}/R_{side}\approx 1). HBT data also show that the expansion time before freeze out is very short (610fm/c\sim 6-10 fm/c). In this work we discuss question of supercooled QGP and the timescale of the reaction.Comment: 9 pages, 2 figure

    Nonideal particle distributions from kinetic freeze-out models

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    In fluid dynamical models the freeze-out of particles across a three-dimensional space-time hypersurface is discussed. The calculation of final momentum distribution of emitted particles is described for freeze-out surfaces, with both spacelike and timelike normals, taking into account conservation laws across the freeze-out discontinuity

    Pneumonia in patients with chronic kidney disease V D stage: pathogenetic aspects of complex therapy and outcomes

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    Abstract.The aim of our study was to increase the effectiveness of treatment of comorbid pneumonia in patients with CKD VD stage. Materials and Methods. 73 patients with CKD VD st. (59 on HD and 14 on PD) with mild to moderate comorbid pneumonia who received renal replacement therapy (RRT) during 2013-2016 were included in the observational prospective open-label randomized trial. Patients were randomized into two groups: group 1 (n = 42) included patients who in addition to the conventional therapy of pneumonia received medication «Lipin» as a complex therapy; group 2 included patients (n = 31) who received only basic (traditional) therapy. The groups were representative by the main demographic, social and clinical-laboratory findings, severity of pneumonia, duration and modality of RRT. The primary endpoints were death from any cause and episodes of rehospitalization. The overall assessment of the clinical efficacy of the therapy was based on a comparison of the duration of hospitalization, antibiotic therapy, intoxication syndrome, and regression of X-ray changes. Survival in observation groups was determined by the Kaplan-Meier method. Analyzed cases were included to October 31, 2018. The markers of oxidative stress (OS) were determined in 29 patients of group 1 and 14 patients of group 2 before treatment and after 14 days while treatment of  pneumonia was started. Results. The analysis demonstrated that during a 1-year period a 17 (25,76%) episodes of rehospitalization were recorded: 11 causes (35.5%) in group 1 and 6 (14.3%) in group 2 (χ² = 4.486, p = 0.035). In total, 29 deaths were recorded during the study period: 10 (23.8%) cases in group 1, and 19 (61.3%) - in group 2 (χ² = 8.957, p = 0.003, RR - 2.574, 95% CI: 1.400-4.733). The three- and five-year cumulative survival rates were 83% vs. 21% and 59% vs. 21%, in the group 1 and group 2, respectively (p = 0.00003). It was stated that the duration of hospitalization, antibiotic therapy, intoxication syndrome and X-ray regression were significantly lower in group 1 compared with group 2 (p <0.05). The comparative analysis of dynamics in the groups shows that increasing the treatment effectiveness at complex therapy background accompanied by a significant positive dynamics of OS markers (p <0,05). Conclusions Thus, the results of this study demonstrated the effectiveness of complex method of pneumonia treatment in patients with CKD stage 5D including Lipin medication compared traditional therapy. There is a significant difference in patient survival depending on the proposed and generally accepted treatment
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