93 research outputs found

    The Relativistic Linear Singular Oscillator

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    Exactly-solvable model of the linear singular oscillator in the relativistic configurational space is considered. We have found wavefunctions and energy spectrum for the model under study. It is shown that they have correct non-relativistic limits.Comment: 14 pages, 12 figures in eps format, IOP style LaTeX file (revised taking into account referees suggestions

    Measurement of the e+eK+Kπ+πe^+e^- \to K^+K^-\pi^+\pi^- cross section with the CMD-3 detector at the VEPP-2000 collider

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    The process e+eK+Kπ+πe^+e^- \to K^+K^-\pi^+\pi^- has been studied in the center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23 pb1^{-1} collected with the CMD-3 detector at the VEPP-2000 e+ee^+e^- collider. Using about 24000 selected events, the e+eK+Kπ+πe^+e^- \to K^+K^-\pi^+\pi^- cross section has been measured with a systematic uncertainty decreasing from 11.7\% at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of K+Kπ+πK^+K^-\pi^+\pi^- production dynamics has been performed

    Study of the process e+eppˉe^+e^-\to p\bar{p} in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector

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    Using a data sample of 6.8 pb1^{-1} collected with the CMD-3 detector at the VEPP-2000 e+ee^+e^- collider we select about 2700 events of the e+eppˉe^+e^- \to p\bar{p} process and measure its cross section at 12 energy ponts with about 6\% systematic uncertainty. From the angular distribution of produced nucleons we obtain the ratio GE/GM=1.49±0.23±0.30|G_{E}/G_{M}| = 1.49 \pm 0.23 \pm 0.30

    Electroproduction, photoproduction, and inverse electroproduction of pions in the first resonance region

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    Methods are set forth for determining the hadron electromagnetic structure in the sub-NNˉN\bar{N}-threshold timelike region of the virtual-photon ``mass'' and for investigating the nucleon weak structure in the spacelike region from experimental data on the process πNe+eN\pi N\to e^+e^- N at low energies. These methods are formulated using the unified description of photoproduction, electroproduction, and inverse electroproduction of pions in the first resonance region in the framework of the dispersion-relation model and on the basis of the model-independent properties of inverse electroproduction. Applications of these methods are also shown.Comment: The revised published version; Revtex4, 18 pages, 6 figure

    Finite-size effect on two-particle production in continuous and discrete spectrum

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    The formalism allowing one to account for the effect of a finite space-time extent of particle production region is given. Its applications to the lifetime measurement of hadronic atoms produced by a high-energy beam in a thin target, as well as to the femtoscopy techniques widely used to measure space-time characteristics of the production processes, are discussed. Particularly, it is found that the neglect of the finite-size effect on the pionium lifetime measurement in the experiment DIRAC at CERN could lead to the lifetime overestimation comparable with the 10% statistical error. The theoretical systematic errors arising in the calculation of the finite-size effect due to the neglect of non-equal emission times in the pair center-of-mass system, the space-time coherence and the residual charge are shown to be negligible.Comment: LaTeX, 77 pages including 5 tables and 18 figures. Somewhat extended version to be published in Phys. El. Part. At. Nuc

    The Red Sea, Coastal Landscapes, and Hominin Dispersals

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    This chapter provides a critical assessment of environment, landscape and resources in the Red Sea region over the past five million years in relation to archaeological evidence of hominin settlement, and of current hypotheses about the role of the region as a pathway or obstacle to population dispersals between Africa and Asia and the possible significance of coastal colonization. The discussion assesses the impact of factors such as topography and the distribution of resources on land and on the seacoast, taking account of geographical variation and changes in geology, sea levels and palaeoclimate. The merits of northern and southern routes of movement at either end of the Red Sea are compared. All the evidence indicates that there has been no land connection at the southern end since the beginning of the Pliocene period, but that short sea crossings would have been possible at lowest sea-level stands with little or no technical aids. More important than the possibilities of crossing the southern channel is the nature of the resources available in the adjacent coastal zones. There were many climatic episodes wetter than today, and during these periods water draining from the Arabian escarpment provided productive conditions for large mammals and human populations in coastal regions and eastwards into the desert. During drier episodes the coastal region would have provided important refugia both in upland areas and on the emerged shelves exposed by lowered sea level, especially in the southern sector and on both sides of the Red Sea. Marine resources may have offered an added advantage in coastal areas, but evidence for their exploitation is very limited, and their role has been over-exaggerated in hypotheses of coastal colonization
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