14,699 research outputs found

    On the Application of Gluon to Heavy Quarkonium Fragmentation Functions

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    We analyze the uncertainties induced by different definitions of the momentum fraction zz in the application of gluon to heavy quarkonium fragmentation function. We numerically calculate the initial gJ/ψg \to J / \psi fragmentation functions by using the non-covariant definitions of zz with finite gluon momentum and find that these fragmentation functions have strong dependence on the gluon momentum k\vec{k}. As k| \vec{k} | \to \infty, these fragmentation functions approach to the fragmentation function in the light-cone definition. Our numerical results show that large uncertainties remains while the non-covariant definitions of zz are employed in the application of the fragmentation functions. We present for the first time the polarized gluon to J/ψJ/\psi fragmentation functions, which are fitted by the scheme exploited in this work.Comment: 11 pages, 7 figures;added reference for sec.

    Critical behaviours of contact near phase transitions

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    A central quantity of importance for ultracold atoms is contact, which measures two-body correlations at short distances in dilute systems. It appears in universal relations among thermodynamic quantities, such as large momentum tails, energy, and dynamic structure factors, through the renowned Tan relations. However, a conceptual question remains open as to whether or not contact can signify phase transitions that are insensitive to short-range physics. Here we show that, near a continuous classical or quantum phase transition, contact exhibits a variety of critical behaviors, including scaling laws and critical exponents that are uniquely determined by the universality class of the phase transition and a constant contact per particle. We also use a prototypical exactly solvable model to demonstrate these critical behaviors in one-dimensional strongly interacting fermions. Our work establishes an intrinsic connection between the universality of dilute many-body systems and universal critical phenomena near a phase transition.Comment: Final version published in Nat. Commun. 5:5140 doi: 10.1038/ncomms6140 (2014

    Research on UBI auto insurance pricing model based on parameter adaptive SAPSO optimal fuzzy controller

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    Aiming at the problem of “dynamic” accurate determination of rates in UBI auto insurance pricing, this paper proposes a UBI auto insurance pricing model based on fuzzy controller and optimizes it with a parameter adaptive SASPO. On the basis of the SASPO algorithm, the movement direction of the particles can be mutated and the direction can be dynamically controlled, the inertia weight value is given by the distance between the particle and the global optimal particle, and the learning factor is calculated according to the change of the fitness value, which realizes the parameter in the running process. Effective self-adjustment. A five-dimensional fuzzy controller is constructed by selecting the monthly driving mileage, the number of violations, and the driving time at night in the UBI auto insurance data. The weights are used to form fuzzy rules, and a variety of algorithms are used to optimize the membership function and fuzzy rules and compare them. The research results show that, compared with other algorithms, the parameter adaptive SAPAO algorithm can calculate more reasonable, accurate and high-quality fuzzy rules and membership functions when processing UBI auto insurance data. The accuracy and robustness of UBI auto insurance rate determination can realize dynamic and accurate determination of UBI auto insurance rates

    Quantum simulation of artificial Abelian gauge field using nitrogen-vacancy center ensembles coupled to superconducting resonators

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    We propose a potentially practical scheme to simulate artificial Abelian gauge field for polaritons using a hybrid quantum system consisting of nitrogen-vacancy center ensembles (NVEs) and superconducting transmission line resonators (TLR). In our case, the collective excitations of NVEs play the role of bosonic particles, and our multiport device tends to circulate polaritons in a behavior like a charged particle in an external magnetic field. We discuss the possibility of identifying signatures of the Hofstadter "butterfly" in the optical spectra of the resonators, and analyze the ground state crossover for different gauge fields. Our work opens new perspectives in quantum simulation of condensed matter and many-body physics using hybrid spin-ensemble circuit quantum electrodynamics system. The experimental feasibility and challenge are justified using currently available technology.Comment: 6 papes+supplementary materia

    Molecular evolution of H3N8 EIV in China, phylogenetic and structural analyses

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    Inst.de VirologíaFil: Miño, Samuel. Chinese Academy of Agricultural Sciences. Harbin Veterinary Research Institute. National Key Laboratory of Veterinary Biotechnology; China. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología; ArgentinaFil: Qi, T. Chinese Academy of Agricultural Sciences. Harbin Veterinary Research Institute. National Key Laboratory of Veterinary Biotechnology; ChinaFil: Guo, W. Chinese Academy of Agricultural Sciences. Harbin Veterinary Research Institute. National Key Laboratory of Veterinary Biotechnology; ChinaFil: Wang, X. Chinese Academy of Agricultural Sciences. Harbin Veterinary Research Institute. National Key Laboratory of Veterinary Biotechnology; Chin

    Minimizing the Average Delay at Intersections via Presignals and Speed Control

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    © 2018 Mina Ghanbarikarekani et al. Urban intersections have been well recognized as bottlenecks of urban transport systems. It is thus important to propose and implement strategies for increasing the efficiency of public and private transportation systems as a whole. In order to achieve this goal, an additional signal could be set up near the intersection to give priority to buses through stopping vehicles in advance of the main intersection as a presignal. It has been increasingly popular in urban cities. While presignals indeed reduce the average delay per traveler, they cause extra stops of private vehicles, which might compromise the overall efficiency, safety, and sustainability. This paper aims to propose a model to improve presignals by reducing the vehicles' number of stops behind the presignals. By applying the method, vehicles would be able to adjust their speed based on traffic conditions as well as buses' speed and approach. Numerical analyses have been conducted to determine the conditions required for implementing this method
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