22,531 research outputs found

    Spontaneous Nambu-Goldstone Currents Generation Driven by Mismatch

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    We review recent progress of understanding and resolving instabilities driven by mismatch between the Fermi surfaces of the pairing quarks in 2-flavor color superconductor. With the increase of mismatch, the 2SC phase exhibits chromomagnetic instability as well as color neutral baryon current instability. We describe the 2SC phase in the nonlinear realization framework, and show that each instability indicates the spontaneous generation of the corresponding pseudo Nambu-Golstone current. The Nambu-Goldstone currents generation state covers the gluon phase as well as the one-plane wave LOFF state. We further point out that, when charge neutrality condition is required, there exists a narrow unstable LOFF (Us-LOFF) window, where not only off-diagonal gluons but the diagonal 8-th gluon cannot avoid the magnetic instability. In this Us-LOFF window, the diagonal magnetic instability cannot be cured by off-diagonal gluon condensate in the color superconducting phase.Comment: 22 pages, no figures; contribution to the proceedings of the INT workshop "Pairing in fermionic systems", Seattle, September 19-23, 200

    Understanding magnetic instability in gapless superconductors

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    Magnetic instability in gapless superconductors still remains as a puzzle. In this article, we point out that the instability might be caused by using BCS theory in mean-field approximation, where the phase fluctuation has been neglected. The mean-field BCS theory describes very well the strongly coherent or rigid superconducting state. With the increase of mismatch between the Fermi surfaces of pairing fermions, the phase fluctuation plays more and more important role, and "soften" the superconductor. The strong phase fluctuation will eventually quantum disorder the superconducting state, and turn the system into a phase-decoherent pseudogap state.Comment: Proceeding for the "International Conference on QCD and Hadronic Physics", Jun. 16-20, Beijing, Chin

    Holographic description of total hadronic cross sections at high energies

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    We investigate the hadron-hadron total cross sections at high energies in the framework of holographic QCD. In our model setup, the involved strong interaction is described by the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel, and the two form factors are obtained from the bottom-up AdS/QCD models. We show that the resulting nucleon-nucleon total cross section is consistent with the experimental data recently measured by the TOTEM collaboration at the LHC. As examples to see the general versatility of the model, we also present our analysis on the pion-nucleon and pion-pion cases, which can be predicted because all the adjustable parameters are fixed by the nucleon-nucleon data.Comment: 7 pages, 2 figures, prepared for the proceedings of QCD@Work 2018 - International Workshop on Quantum Chromodynamics, 25 - 28 June 2018, Matera, Ital

    Dynamical holographic QCD model

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    We develop a dynamical holographic QCD model, which resembles the renormalization group from ultraviolet (UV) to infrared (IR). The dynamical holographic model is constructed in the graviton-dilaton-scalar framework with the dilaton background field Φ\Phi and scalar field XX responsible for the gluodynamics and chiral dynamics, respectively. We summarize our results on hadron spectra, QCD phase transition and transport properties including the jet quenching parameter and the shear/bulk viscosity in the framework of the dynamical holographic QCD model.Comment: 8 pages, 5 figures, proceedings for QCD@Work2014, June 16-19,2014, Bari, Ital

    Endophytic Fungi of Bitter Melon \u3ci\u3e(Momordica Charantia)\u3c/i\u3e in Guangdong Province, China

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    Endophytic fungi can mutualistically interact with their host plants by deterring herbivores. Overall 1172 endophytic fungal isolates were recovered from roots, stems, leaves, flowers and fruits of bitter melon, Momordica charantia, at five sites in Guangdong Province. These isolates were identified to 25 genera using morphological and molecular characteristics. The endophyte communities at the five sites were similar. Alternaria alternata, Aspergillus spp., Cladosporium spp., Colletotrichum spp., Nigrospora spp., Penicillium spp., Arthrinium spp., Chaetimium spp., Curvularia spp., Fusarium spp., Phoma spp., and Phomopsis spp. were isolated from at least three of the five sites. The coefficient of similarity for endophytes ranged from 60.6% to 83.3% between any two sites. There were significant differences in the species composition of endophytes recovered from different tissues of bitter melon. Fusarium spp. was the most frequent in root and stem samples, Colletotrichum spp. in leaf samples, A. alternata in flower samples, and Cladosporium spp. in fruit samples. The coefficients of similarity for endophytes were between 42.9% and 80.0% from any two tissues. We found that the composition of endophytes of bitter melon was relatively stable across sites, but differed greatly among tissues. We also found that there were fewer insects such as aphids (Homoptera: Aphididae), leafminers (Lepidoptera, Gracillariidae), and cotton leafworms Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) collected from the leaves of bitter melon at the Huadu site compared to those collected at the Yunfu site. Whether this is related to the endophyte communities isolated from different sites requires further research
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