4,773 research outputs found

    Pi N sigma-term and chiral-odd twist-3 distribution function e(x) of the nucleon in the chiral quark soliton model

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    The isosinglet combination of the chiral-odd twist-3 distribution function eu(x)+ed(x)e^u(x)+e^d(x) of the nucleon has outstanding properties that its first moment is proportional to the well-known πN\pi N sigma-term and that it contains a δ\delta-function singularity at x=0x=0. These two features are inseparably connected in that the above sum rule would be violated, if there is no such a singularity in eu(x)+ed(x)e^u(x)+e^d(x). Very recently, we found that the physical origin of this δ\delta-function singularity can be traced back to the long-range quark-quark correlation of scalar type, which signals the spontaneous chiral symmetry breaking of the QCD vacuum. The main purpose of the present paper is to give complete theoretical predictions for the chiral-odd twist-3 distribution function ea(x)e^a(x) of each flavor aa on the basis of the chiral quark soliton model, without recourse to the derivative expansion type approximation. These theoretical predictions are then compared with the empirical information extracted from the CLAS data of the semi-inclusive DIS processes by assuming the Collins mechanism only. A good agreement with the CLAS data is indicative of a sizable violation of the πN\pi N sigma-term sum rule, or equivalently, the existence of a δ\delta-function singularity in eu(x)+ed(x)e^u(x) + e^d(x).Comment: 35 pages, 10 figure

    Belle II iTOP Optics: Design, Construction and Performance

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    The imaging-Time-of-Propogation (iTOP) counter is a new type of ring-imaging Cherenkov counter developed for particle identification at the Belle II experiment. It consists of 16 modules arranged azimuthally around the beam line. Each module consists of one mirror, one prism and two quartz bar radiators. Here we describe the design, acceptance test, alignment, gluing and assembly of the optical components. All iTOP modules have been successfully assembled and installed in the Belle II detector by the middle of 2016. After installation, laser and cosmic ray data have been taken to test the performance of the modules. First results from these tests are presented.Comment: Proceedings of TIPP 2017, May 22 - 26, Beijing, China, 2017; University of Cincinnati preprint UCHEP-17-07. arXiv admin note: text overlap with arXiv:1709.0993

    Jet-fluid string formation and decay in high-energy heavy-ion collisions

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    We propose a new hadronization mechanism, jet-fluid string (JFS) formation and decay, to understand observables in intermediate to high-pTp_{T} regions comprehensively. In the JFS model, hard partons produced in jet lose their energy in traversing the QGP fluid, which is described by fully three-dimensional hydrodynamic simulations. When a jet parton escapes from the QGP fluid, it picks up a partner parton from a fluid and forms a color singlet string, then it decays to hadrons. We find that high-pTp_T v2v_2 values in JFS are about two times larger than in the independent fragmentation model.Comment: 6 pages, 2 figures; Proceeding for poster sessions at Quark Matter 2006, Shanghai, China, 14-20 November 2006; to appear in Int. J. of Mod. Phys.

    Indication of intrinsic spin Hall effect in 4d and 5d transition metals

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    We have investigated spin Hall effects in 4dd and 5dd transition metals, Nb, Ta, Mo, Pd and Pt, by incorporating the spin absorption method in the lateral spin valve structure; where large spin current preferably relaxes into the transition metals, exhibiting strong spin-orbit interactions. Thereby nonlocal spin valve measurements enable us to evaluate their spin Hall conductivities. The sign of the spin Hall conductivity changes systematically depending on the number of dd electrons. This tendency is in good agreement with the recent theoretical calculation based on the intrinsic spin Hall effect.Comment: 5 pages, 4 figure

    Mechanical Behavior of Cohesive Soil under Repeated Loading

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    A new triaxial apparatus which can control the stress condition automatically in a constant mean principal stress under repeated loading was developed, Mechanical behavior of cohesive soils under repeated loading was investigated. Excess pore water pressure generated in loading cycles was measured and the experimental results were interpreted in terms of effective stress by using elasto-plastic models

    Search for a Ridge Structure Origin with Shower Broadening and Jet Quenching

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    We investigate the role of jet and shower parton broadening by the strong colour field in the Δη\Delta\eta-Δϕ\Delta\phi correlation of high pTp_T particles. When anisotropic momentum broadening (Δpz>ΔpT\Delta p_z > \Delta p_T) is given to jet and shower partons in the initial stage, a ridge-like structure is found to appear in the two hadron correlation. The ratio of the peak to the pedestal yield is overestimated.Comment: Talk given at 20th Int. Conf. on Ultra-Relativistic Nucleus-Nucleus Collisions, Jaipur, India, Feb.4-10, 200

    Nucleosynthesis in novae: experimental progress in the determination of nuclear reaction rates

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    The sources of nuclear uncertainties in nova nucleosynthesis have been identified using hydrodynamical nova models. Experimental efforts have followed and significantly reduced those uncertainties. This is important for the evaluation of nova contribution to galactic chemical evolution, gamma--ray astronomy and possibly presolar grain studies. In particular, estimations of expected gamma-ray fluxes are essential for the planning of observations with existing or future satellites.Comment: Invited contribution to the "Origin of Matter and Evolution of Galaxies" conference (OMEG07) with additional and color figure

    SuprimeCam Observation of Sporadic Meteors during Perseids 2004

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    We report the serendipitous findings of 13 faint meteors and 44 artificial space objects by Subaru SuprimeCam imaging observations during 11-16 August 2004. The meteors, at about 100km altitude, and artificial satellites/debris in orbit, at 500km altitude or higher, were clearly discriminated by their apparent defocused image sizes. CCD photometry of the 13 meteors, including 1 Perseid, 1 Aquarid, and 11 sporadic meteors, was performed. We defined a peak video-rate magnitude by comparing the integrated photon counts from the brightest portion of the track traversed within 33ms to those from a 0-mag star during the same time duration. This definition gives magnitudes in the range 4.0< V_{vr} <6.4 and 4.1< I_{vr}<5.9 for these 13 meteors. The corresponding magnitude for virtual naked-eye observers could be somewhat fainter especially for the V-band observation, in which the [OI] 5577 line lasting about 1 sec as an afterglow could contribute to the integrated flux of the present 5-10 min CCD exposures. Although the spatial resolution is insufficient to resolve the source size of anything smaller than about 1 m, we developed a new estimate of the collisionally excited column diameter of these meteors. A diameter as small as a few mm was derived from their collisionally excited photon rates, meteor speed, and the volume density of the oxygen atoms at the 100km altitude. The actual column diameter of the radiating zone, however, could be as large as few 100m because the excited atoms travel that distance before they emit forbidden lines in 0.7 sec of its average lifetime. Among the 44 artificial space objects, we confirmed that 17 were cataloged satellites/space debris.Comment: 14 pages, 13 figures, 5 tables, submitted to PAS
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