13,644 research outputs found

    Quark Condensates in Nuclear Matter in the Global Color Symmetry Model of QCD

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    With the global color symmetry model being extended to finite chemical potential, we study the density dependence of the local and nonlocal scalar quark condensates in nuclear matter. The calculated results indicate that the quark condensates increase smoothly with the increasing of nuclear matter density before the critical value (about 12ρ0\rho_0) is reached. It also manifests that the chiral symmetry is restored suddenly as the density of nuclear matter reaches its critical value. Meanwhile, the nonlocal quark condensate in nuclear matter changes nonmonotonously against the space-time distance among the quarks.Comment: 15 pages, 3 figure

    Reevaluation of the density dependence of nucleon radius and mass in the global color symmetry model of QCD

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    With the global color symmetry model (GCM) at finite chemical potential, the density dependence of the bag constant, the total energy and the radius of a nucleon in nuclear matter is investigated. A relation between the nuclear matter density and the chemical potential with the action of QCD being taken into account is obtained. A maximal nuclear matter density for the existence of the bag with three quarks confined within is given. The calculated results indicate that, before the maximal density is reached, the bag constant and the total energy of a nucleon decrease, and the radius of a nucleon increases slowly, with the increasing of the nuclear matter density. As the maximal nuclear matter density is reached, the mass of the nucleon vanishes and the radius becomes infinite suddenly. It manifests that a phase transition from nucleons to quarks takes place.Comment: 18 pages, 3 figure

    Building environment assessment methods and social studies of rural villages in Yunnan and urban development in Chongqing City, Southwest China

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    Recent urbanization processes and corresponding government policies in China have highlighted the need for much greater understanding of sustainable development and the requirements for sustainability in settings that are very different in rural and urban regions. This paper examines practice and knowledge linked to typical vernacular houses constructed since 1950 in Yunnan Province and regional buildings in Chongqing City in Southwest China. Both areas have played crucial roles in contributing to regional architectural design since the beginning of the 20th Century because of the diversity arising from numerous ethnic groups and various climate types and topography features in the region. The study explores how academic and end-user knowledge accumulated and developed, and how this has revealed social, cultural and political influences on how designers and consumers were motivated towards sustainable design over the same time period. It is argued that locally shared knowledge bases should be considered important for informing governmental policies, planning strategy and consumers’ preferences, as well as influencing actions and social acceptance in relation to sustainable development. Furthermore, sustainable design should not be regarded as a contemporary new idea, but one that has its roots in the historical changes in built environment design and practice

    1-(2-Ureidoeth­yl)quinolinium tetra­phenyl­borate

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    In the cation of the title salt, C12H14N3O+·C24H20B−, the dihedral angle between the quinoline ring and the mean plane of the urea fragment is 61.51 (5)°. In the crystal, the cations inter­act through weak C—H⋯O hydrogen bonding, forming a zigzag chain along the c-axis direction; the cations and anions are involved in weak inter­molecular C—H⋯π and N—H⋯π inter­actions as donors and acceptors, respectively

    The Schrodinger-like Equation for a Nonrelativistic Electron in a Photon Field of Arbitrary Intensity

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    The ordinary Schrodinger equation with minimal coupling for a nonrelativistic electron interacting with a single-mode photon field is not satisfied by the nonrelativistic limit of the exact solutions to the corresponding Dirac equation. A Schrodinger-like equation valid for arbitrary photon intensity is derived from the Dirac equation without the weak-field assumption. The "eigenvalue" in the new equation is an operator in a Cartan subalgebra. An approximation consistent with the nonrelativistic energy level derived from its relativistic value replaces the "eigenvalue" operator by an ordinary number, recovering the ordinary Schrodinger eigenvalue equation used in the formal scattering formalism. The Schrodinger-like equation for the multimode case is also presented.Comment: Tex file, 13 pages, no figur
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