455 research outputs found

    QCD corrections to Upsilon production via color-octet states at the Tevatron and LHC

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    The NLO QCD corrections to Upsilon production via S-wave color-octet states Upsilon(^1S_0^8,^3S_1^8) at the Tevatron and LHC is calculated. The K factors of total cross section (ratio of NLO to LO) are 1.313 and 1.379 for Upsilon(^1S_0^8) and Upsilon(^3S_1^8) at the Tevatron, while at the LHC they are 1.044 and 1.182, respectively. By fitting the experimental data from the D0, the matrix elements for S-wave color-octet states are obtained. And new predictions for Upsilon production are presented. The prediction for the polarization of inclusive Upsilon contains large uncertainty rising from the polarization of Upsilon from feed-down of chi_b. To further clarify the situation, new measurements on the production and polarization for direct Upsilon are expected.Comment: 13 pages, 10 Figure

    Fractional Quantum Hall Effect in Topological Flat Bands with Chern Number Two

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    Recent theoretical works have demonstrated various robust Abelian and non-Abelian fractional topological phases in lattice models with topological flat bands carrying Chern number C=1. Here we study hard-core bosons and interacting fermions in a three-band triangular-lattice model with the lowest topological flat band of Chern number C=2. We find convincing numerical evidence of bosonic fractional quantum Hall effect at the ν=1/3\nu=1/3 filling characterized by three-fold quasi-degeneracy of ground states on a torus, a fractional Chern number for each ground state, a robust spectrum gap, and a gap in quasihole excitation spectrum. We also observe numerical evidence of a robust fermionic fractional quantum Hall effect for spinless fermions at the ν=1/5\nu=1/5 filling with short-range interactions.Comment: 5 pages, 7 figures, with Supplementary Materia

    Non-Abelian Quantum Hall Effect in Topological Flat Bands

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    Inspired by recent theoretical discovery of robust fractional topological phases without a magnetic field, we search for the non-Abelian quantum Hall effect (NA-QHE) in lattice models with topological flat bands (TFBs). Through extensive numerical studies on the Haldane model with three-body hard-core bosons loaded into a TFB, we find convincing numerical evidence of a stable ν=1\nu=1 bosonic NA-QHE, with the characteristic three-fold quasi-degeneracy of ground states on a torus, a quantized Chern number, and a robust spectrum gap. Moreover, the spectrum for two-quasihole states also shows a finite energy gap, with the number of states in the lower energy sector satisfying the same counting rule as the Moore-Read Pfaffian state.Comment: 5 pages, 7 figure

    Genetic elimination of field-cage populations of Mediterranean fruit flies

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    The Mediterranean fruit fly (medfly, Ceratitis capitata Wiedemann) is a pest of over 300 fruits, vegetables and nuts. The sterile insect technique (SIT) is a control measure used to reduce the reproductive potential of populations through the mass release of sterilized male insects that mate with wild females. However, SIT flies can display poor field performance, due to the effects of mass-rearing and of the irradiation process used for sterilization. The development of female-lethal RIDL (release of insects carrying a dominant lethal) strains for medfly can overcome many of the problems of SIT associated with irradiation. Here, we present life-history characterizations for two medfly RIDL strains, OX3864A and OX3647Q. Our results show (i) full functionality of RIDL, (ii) equivalency of RIDL and wild-type strains for life-history characteristics, and (iii) a high level of sexual competitiveness against both wild-type and wild-derived males. We also present the first proof-of-principle experiment on the use of RIDL to eliminate medfly populations. Weekly releases of OX3864A males into stable populations of wild-type medfly caused a successive decline in numbers, leading to eradication. The results show that genetic control can provide an effective alternative to SIT for the control of pest insects

    Thermal-Resistivity Characteristics of Carbon Fabric Reinforced Cementitious Matrix

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    The thermal-resistivity effect of the carbon fiber reinforced cement (CFRC) has been successfully applied to monitor the temperature of concrete structures. There are insufficient studies on the thermal-resistivity effect of the carbon fabric reinforced cementitious matrix (CFRCM). In this paper, the resistance change of CFRCM from room temperature to 120℃ and the thermal-resistivity characteristics during repeated heating have been studied. It was showed that during the heating process, with the continuous increasement of the carrier concentration, the specimen exhibited obvious negative temperature coefficient (NTC) effect, and a temperature rise of 10℃ lessened relative resistance change by about 0.4%. However, some carriers stayed in the conduction band after the first cooling. Then, the resistance cannot return to the original value, and the curves of subsequent heating processes had a good repeatability
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