11,663 research outputs found

    OPE analysis of the nucleon scattering tensor including weak interaction and finite mass effects

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    We perform a systematic operator product expansion of the most general form of the nucleon scattering tensor WμνW_{\mu \nu} including electro-magnetic and weak interaction processes. Finite quark masses are taken into account and a number of higher-twist corrections are included. In this way we derive relations between the lowest moments of all 14 structure functions and matrix elements of local operators. Besides reproducing well-known results, new sum rules for parity-violating polarized structure functions and new mass correction terms are obtained.Comment: 50 pages, additional references adde

    Higgs boson production in high energy proton-nucleus collisions

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    We study Higgs boson production from gluon-gluon fusion at mid-rapidity in high energy proton-nucleus collisions. For this process the presently still little known gluon distribution function h1⊥gh_1^{\perp g} gives a numerically relevant contribution. We show by explicite calculation that using CGC (color glass condensate) model input the result obtained in the naive k_t factorization approach matches the result obtained in the TMD factorization framework for a dilute medium. We also verify the earlier finding that the k_t factorization formalism for Higgs production breaks down in a dense medium. In doing so we formulate a hybrid model which allows one to treat such reactions theoretically.Comment: a few more references added, vision

    QCD at Finite Density and Color Superconductivity

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    Brief review of current status of the field.Comment: Invited talk at Lattice 99, Pisa, July 1999. 5 pages, 7 fig

    Diffractive charged meson pair production

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    We investigate the possibility to measure the nonforward gluon distribution function by means of diffractively produced \pi^+\pi^- and K^+K^- pairs in polarized lepton nucleon scattering. The resulting cross sections are small and are dominated by the gluonic contribution. We find relatively large spin asymmetries, both for \pi^+\pi^- and for K^+K^- pairs.Comment: 15 pages, version with changed kinematical cuts, to be pubished in Phys.Lett.

    Seasonal changes in microbial dissolved organic sulfur transformations in coastal waters

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    The marine trace gas dimethylsulfide (DMS) is the single most important biogenic source of atmospheric sulfur, accounting for up to 80% of global biogenic sulfur emissions. Approximately 300 million tons of DMS are produced annually, but the majority is degraded by microbes in seawater. The DMS precursor dimethylsulfoniopropionate (DMSP) and oxidation product dimethylsulphoxide (DMSO) are also important organic sulfur reservoirs. However, the marine sinks of dissolved DMSO remain unknown. We used a novel combination of stable and radiotracers to determine seasonal changes in multiple dissolved organic sulfur transformation rates to ascertain whether microbial uptake of dissolved DMSO was a significant loss pathway. Surface concentrations of DMS ranged from 0.5 to 17.0 nM with biological consumption rates between 2.4 and 40.8 nM·d−1. DMS produced from the reduction of DMSO was not a significant process. Surface concentrations of total DMSO ranged from 2.3 to 102 nM with biological consumption of dissolved DMSO between 2.9 and 111 nM·d−1. Comparisons between 14C2-DMSO assimilation and dissimilation rates suggest that the majority of dissolved DMSO was respired (>94%). Radiotracer microbial consumption rates suggest that dissimilation of dissolved DMSO to CO2 can be a significant loss pathway in coastal waters, illustrating the significance of bacteria in controlling organic sulfur seawater concentrations

    On the Stability of Λ(1405)\Lambda(1405) Matter

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    A hypothesis of absolutely stable strange hadronic matter composed of Λ(1405)\Lambda(1405) baryons, here denoted Λ∗\Lambda^*, is tested within many-body calculations performed using the Relativistic Mean-Field approach. In our calculations, we employed the Λ∗Λ∗\Lambda^*\Lambda^* interaction compatible with the Λ∗Λ∗\Lambda^*\Lambda^* binding energy BΛ∗Λ∗=40B_{\Lambda^*\Lambda^*}=40~MeV given by the phenomenological energy-independent KˉN\bar{K}N interaction model by Yamazaki and Akaishi (YA). We found that the binding energy per Λ∗\Lambda^*, as well as the central density in Λ∗\Lambda^* many-body systems saturates for mass number A≥120A\geq120, leaving Λ∗\Lambda^* aggregates highly unstable against strong interaction decay. Moreover, we confronted the YA interaction model with kaonic atom data and found that it fails to reproduce the K−K^- single-nucleon absorption fractions at rest from bubble chamber experiments.Comment: Proceedings of the HYP2018 conference, Norfolk/Portsmouth, USA, June 24 - 29, 2018, submitted to AIP Conference Proceeding

    Diquark Bose Condensates in High Density Matter and Instantons

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    Instantons lead to strong correlations between up and down quarks with spin zero and anti-symmetric color wave functions. In cold and dense matter, nb>nc≃1fm−3n_b>n_c\simeq 1 fm^{-3} and T<Tc∼T<T_c\sim 50 MeV, these pairs Bose-condense, replacing the usual condensateandrestoringchiralsymmetry.Athighdensity,thegroundstateisacolorsuperconductorinwhichdiquarksplaytheroleofCooperpairs.AninterestingtoymodelisprovidedbyQCDwithtwocolors:ithasaparticle−anti−particlesymmetrywhichrelates condensate and restoring chiral symmetry. At high density, the ground state is a color superconductor in which diquarks play the role of Cooper pairs. An interesting toy model is provided by QCD with two colors: it has a particle-anti-particle symmetry which relates and condensates.Comment: 4 pages ReVTeX, 2 eps-figures included using epsf.st
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