102 research outputs found

    Photon emission in Pb+Pb collisions at SpS and LHC

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    Yield of direct photons in Pb+Pb collisions at SpS and LHC energy is evaluated with emphasis on estimate of possible uncertainty. Possibility of experimental observation of direct photons at LHC is discussed. Predictions of several models at SpS energy are compared with experimental data.Comment: 19 pages, 13 figure

    Direct emission of light mesons from quark-gluon plasma surface

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    On the basis of hydrodynamic model of evolution of heavy ion collision we consider emission of π,K,η,ρ,ω,K\pi,K,\eta,\rho,\omega,K^* mesons directly from the surface of quark-gluon plasma, with accounting of their absorption by surrounding plasma hadronic gas. We evaluate upper and lower limits on yields of these direct mesons in Pb+Pb collision at 158 AGeV (SpS) and 3150+3150 AGeV (LHC), and find, that even in the case of the lowest yield, direct η\eta and heavier mesons dominate at LHC energy at soft ptp_t (pt0.5GeV/cp_t\le 0.5 GeV/c). This enhancement of the low ptp_t meson production can be considered as a quark-gluon plasma signature.Comment: Submitted to PR

    Phases of Josephson Junction Ladders

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    We study a Josephson junction ladder in a magnetic field in the absence of charging effects via a transfer matrix formalism. The eigenvalues of the transfer matrix are found numerically, giving a determination of the different phases of the ladder. The spatial periodicity of the ground state exhibits a devil's staircase as a function of the magnetic flux filling factor ff. If the transverse Josephson coupling is varied a continuous superconducting-normal transition in the transverse direction is observed, analogous to the breakdown of the KAM trajectories in dynamical systems.Comment: 12 pages with 3 figures, REVTE

    Universal mechanism of discontinuity of commensurate-incommensurate transitions in three-dimensional solids: Strain dependence of soliton self-energy

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    We show that there exists a universal mechanism of long-range soliton attraction in three-dimensional solids and, therefore, of discontinuity of any commensurate-incommensurate (C-IC) phase transition. This mechanism is due to the strain dependence of the soliton self-energy and specific features of the solid-state elasticity. The role of this mechanism is studied in detail for a class of C-IC transitions where the IC modulation is one-dimensional, the anisotropy in the order parameter space is small, and the symmetry of the systems allows the existence of the Lifshitz invariant. Two other mechanisms of soliton attraction are operative here but the universal mechanism considered in this paper is found to be the most important one in some cases. Comparison with the most extensively studied C-IC transition in K2SeO4\rm K_2SeO_4 shows that the experimentally observed thermal anomalies can be understood as a result of the smearing of the theoretically predicted discontinuous transition.Comment: 8 pages (extended version, title changed

    Thermal Radiation from Au + Au Collisions at \sqrt{s} = 200 GEV/A Energy

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    The transverse momentum distribution of the direct photons measured by the PHENIX collaboration in Au+AuAu + Au collisions at s=200\sqrt{s}=200 GeV/A has been analyzed. It has been shown that the data can be reproduced reasonably well assuming a deconfined state of thermalized quarks and gluons with initial temperature more than the transition temperature for deconfinement inferred from lattice QCD. The value of the initial temperature depends on the equation of state of the evolving matter. The sensitivities of the results on various input parameters have been studied. The effects of the modifications of hadronic properties at non-zero temperature have been discussed.Comment: minor modifications in the text, accepted for publicatio

    Lipoprotein(a) concentration and the blood content of INFγ-producing T-helpers 17 (Th17/1) in males with premature coronary artery disease

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    Aim. To analyze the relationship of blood lipid profile parameters, including the level of lipoprotein(a) (Lp(a)), and the content of circulating CD4+ T-lymphocytes with premature coronary artery disease (CAD).Material and methods. This retrospective cross-sectional study included 76 men aged 40 to 79 years. Patients were divided into following groups: main group — patients with CAD (58 [54;64] years, n=56) onset before the age of 55; control group — patients (62 [57;66] years, n=20) without CAD and obstructive CAD and peripheral arterial disease. Statins were taken by 51 (91%) and 9 (45%) patients in the main and control groups, respectively. In serum and plasma samples, lipid spectrum parameters and Lp(a) concentration were determined. Cellular phenotyping was performed by direct immunofluorescence in a culture of mononuclear leukocytes isolated from blood. To determine cytokines, cells were in vitro activated with inhibitor of intracellular transport of secretory proteins. Cell fluorescence was determined using flow cytometry.Results. Patients of both groups were comparable in age, body mass index, prevalence of hypertension and diabetes. Blood Lp(a) concentrations were higher in the CAD group than in the control group (49 [10;102] mg/dL vs 12 [4,3;32] mg/ dL, p<0,05). The content of INFγ-producing T-helpers 17 (Th17/1) was also higher in the CAD group (19 [15;24] vs 13 [11;22], % of Th17, p=0,05). Logistic regression revealed that elevated Lp(a) levels (≥30 mg/dL) and relative amounts of Th17/1 (>14% of Th17) independently of each other, atherogenic lipoprotein cholesterol levels, classical risk factors, and statin use were associated with premature CAD in the general group of patients with odds ratio (OR) of 4,6 (95% confidence interval (CI), 1,1-20,2) and 10,9 (2,1-56,7), p<0,05, respectively. The combination of Lp(a) >30 mg/dl and Th17/1 over 14% significantly increased the risk of premature CAD (OR, 28,0, 95% CI, 4,31-181,75, p=0,0005).Conclusion. We have shown for the first time that an increased Lp(a) concentration with an increased Th17/1 content is associated with the premature CAD in men