19,567,583 research outputs found

    The Elusive p-air Cross Section

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    For the \pbar p and pppp systems, we have used all of the extensive data of the Particle Data Group[K. Hagiwara {\em et al.} (Particle Data Group), Phys. Rev. D 66, 010001 (2002).]. We then subject these data to a screening process, the ``Sieve'' algorithm[M. M. Block, physics/0506010.], in order to eliminate ``outliers'' that can skew a χ2\chi^2 fit. With the ``Sieve'' algorithm, a robust fit using a Lorentzian distribution is first made to all of the data to sieve out abnormally high \delchi, the individual ith^{\rm th} point's contribution to the total χ2\chi^2. The χ2\chi^2 fits are then made to the sieved data. We demonstrate that we cleanly discriminate between asymptotic lns\ln s and ln2s\ln^2s behavior of total hadronic cross sections when we require that these amplitudes {\em also} describe, on average, low energy data dominated by resonances. We simultaneously fit real analytic amplitudes to the ``sieved'' high energy measurements of pˉp\bar p p and pppp total cross sections and ρ\rho-values for s6\sqrt s\ge 6 GeV, while requiring that their asymptotic fits smoothly join the the σpˉp\sigma_{\bar p p} and σpp\sigma_{pp} total cross sections at s=\sqrt s=4.0 GeV--again {\em both} in magnitude and slope. Our results strongly favor a high energy ln2s\ln^2s fit, basically excluding a lns\ln s fit. Finally, we make a screened Glauber fit for the p-air cross section, using as input our precisely-determined pppp cross sections at cosmic ray energies.Comment: 15 pages, 6 figures, 2 table,Paper delivered at c2cr2005 Conference, Prague, September 7-13, 2005. Fig. 2 was missing from V1. V3 fixes all figure

    Supersymmetric CP-violating Currents and Electroweak Baryogenesis

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    In this work we compute the CP-violating currents of the right-handed stops and Higgsinos, induced by the presence of non-trivial vacuum expectation values of the Higgs fields within the context of the minimal supersymmetric extension of the Standard Model (MSSM) with explicit CP-violating phases. Using the Keldysh formalism, we perform the computation of the currents at finite temperature, in an expansion of derivatives of the Higgs fields. Contrary to previous works, we implement a resummation of the Higgs mass insertion effects to all orders in perturbation theory. While the components of the right-handed stop current j^\mu_{\widetilde t_R} become proportional to the difference H_2 \partial^{\mu}H_1-H_1 \partial^{\mu} H_2 (suppressed by \Delta\beta), the Higgsino currents, j^\mu_{\widetilde{H}_i}, present contributions proportional to both H_2 \partial^{\mu}H_1\pm H_1 \partial^{\mu} H_2. For large values of the charged Higgs mass and moderate values of \tan\beta the contribution to the source proportional to H_2 \partial^{\mu}H_1+H_1 \partial^{\mu} H_2 in the diffusion equations become sizeable, although it is suppressed by the Higgsino number violating interaction rate \Gamma_\mu^{-1/2}. For small values of the wall velocity, 0.04\simlt v_\omega \simlt 0.1, the total contribution leads to acceptable values of the baryon asymmetry for values of the CP-violating phases \phi_{CP} in the range 0.04\simlt|\sin\phi_{CP}|\simlt 1. Finally, we comment on the relevance of the latest results of Higgs searches at LEP2 for the mechanism of electroweak baryogenesis within the MSSM.Comment: 27 pages, 4 figures, latex2e. Typo corrected and references adde

    Effect of a Pipe Number on the Heat Transfer Rate for a Granit Stone Absorber Solar Collector

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    As the fossil energy has been getting depletion, it is important to utilize alternative energies such as solar energy. An equipment that can be used for capturing and converting solar energy is solar collector. Two identical collectors used in this study were placed facing to the North with an inclination angle of 15°. The collector dimension was 0.8 m x 1 m x 0.05 m. One collector contained 5 parallel pipes and the other contained 7 parallel pipes. The water used in the test was flowed naturally due to the gravity force from a higher tank and was adjusted using a valve fitted at the end of the collector. The water flow rates employed were 200, 250 and 300 cc/minutes and measured using a volume meter and a stop watch. The results showed that the energy coming into the collector, energy absorbed by the absorber and water, increased with an increase in the observation time and reached the peak value at about 2.30 pm. After that, they decreased. The effect of the pipe number is significant and the performance of the collector containing 7 pipes is better than that containing 5 pipes

    Laboratory glassware rack for seismic safety

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    A rack for laboratory bottles and jars for chemicals and medicines has been designed to provide the maximum strength and security to the glassware in the event of a significant earthquake. The rack preferably is rectangular and may be made of a variety of chemically resistant materials including polypropylene, polycarbonate, and stainless steel. It comprises a first plurality of parallel vertical walls, and a second plurality of parallel vertical walls, perpendicular to the first. These intersecting vertical walls comprise a self-supporting structure without a bottom which sits on four legs. The top surface of the rack is formed by the top edges of all the vertical walls, which are not parallel but are skewed in three dimensions. These top edges form a grid matrix having a number of intersections of the vertical walls which define a number of rectangular compartments having varying widths and lengths and varying heights
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