668 research outputs found

    Overdamping Phenomena near the Critical Point in O(NN) Model

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    We consider the dynamic critical behavior of the propagating mode for the order parameter fluctuation of the O(NN) Ginzburg-Landau theory, involving the canonical momentum as a degree of freedom. We reexamine the renormalization group analysis of the Langevin equation for the propagating mode. We find the fixed point for the propagating mode as well as that for the diffusive one, the former of which is unstable to the latter. This indicates that the propagating mode becomes overdamped near the critical point. We thus can have a sufficient understanding of the phonon mode in the structural phase transition of solids. We also discuss the implication for the chiral phase transition.Comment: 5 pages, 1 figure;v3 modification for correcting a misleading description, conclusion unchange

    Derivation of Covariant Dissipative Fluid Dynamics in the Renormalization-group Method

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    We derive generic relativistic hydrodynamical equations with dissipative effects from the underlying Boltzmann equation in a mechanical and systematic way on the basis of so called the renormalization-group (RG) method. A macroscopic frame vector is introduced to specify the frame on which the macroscopic dynamics is described. Our method is so mechanical with only few ansatz that our method give a microscopic foundation of the available hydrodynamical equations, and also can be applied to make a reduction of the kinetic equations other than the simple Boltzmann equation.Comment: Serious typos and a minor one are corrected in p.6 and 7, and in p.1, respectivel

    Important Factors on Sidewalks with Vendor Activities Based on Pedestrian Perception by Gender and Age

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    This paper presents an investigation of important factors relating sidewalk performance based on pedestrian perceptions by gender and age. Exploratory factor analysis technique and reliability test of the variables are performed on 45 items of sidewalk current condition in order to extract dimensions of pedestrian perceptions in Jakarta and Bangkok. Based on age, male respondents reveals that eight factors are identified as important on sidewalk performance, and labeled on the basis of the attributed covered as sidewalk interaction, comfort, space availability, safety, vendor problems, walking path, vendor regulation, and vendor's attraction. On the other hand, the first seven factors are similarly stated by female respondents. Grouped by age, young respondents reveal nine factors are considered important and arbitrarily named as comfort, sidewalk interaction, safety, vendor's attraction, vendor problems, vendor regulation, walking path, space availability, and sidewalk condition. The presence of vendors are often deemed as obstruction for walking flow, but their activities should be accommodated by establishing policies and management to accept high performance of the sidewalks and to support the city's economy

    Roles of axial anomaly on neutral quark matter with color superconducting phase

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    We investigate effects of the axial anomaly term with a chiral-diquark coupling on the phase diagram within a two-plus-one-flavor Nambu-Jona-Lasinio (NJL) model under the charge-neutrality and β\beta-equilibrium constraints. We find that when such constraints are imposed, the new anomaly term plays a quite similar role as the vector interaction does on the phase diagram, which the present authors clarified in a previous work. Thus, there appear several types of phase structures with multiple critical points at low temperature TT, although the phase diagrams with intermediate-TT critical point(s) are never realized without these constraints even within the same model Lagrangian. This drastic change is attributed to an enhanced interplay between the chiral and diquark condensates due to the anomaly term at finite temperature; the u-d diquark coupling is strengthened by the relatively large chiral condensate of the strange quark through the anomaly term, which in turn definitely leads to the abnormal behavior of the diquark condensate at finite TT, inherent to the asymmetric quark matter. We note that the critical point from which the crossover region extends to zero temperature appears only when the strength of the vector interaction is larger than a critical value. We also show that the chromomagnetic instability of the neutral asymmetric homogenous two-flavor color superconducting(2CSC) phase is suppressed and can be even completely cured by the enhanced diquark coupling due to the anomaly term and/or by the vector interaction.Comment: 15 pages, 5 figures, typos corrected, new references and some statements adde

    Phase diagram at finite temperature and quark density in the strong coupling limit of lattice QCD for color SU(3)

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    We study the phase diagram of quark matter at finite temperature (T) and finite chemical potential (mu) in the strong coupling limit of lattice QCD for color SU(3). We derive an analytical expression of the effective free energy as a function of T and mu, including baryon effects. The finite temperature effects are evaluated by integrating over the temporal link variable exactly in the Polyakov gauge with anti-periodic boundary condition for fermions. The obtained phase diagram shows the first order phase transition at low temperatures and the second order phase transition at high temperatures separated by the tri-critical point in the chiral limit. Baryon has effects to reduce the effective free energy and to extend the hadron phase to a larger mu direction at low temperatures.Comment: 18 pages, 10 figure

    Two-photon decays of vector mesons and dilepton decays of scalar mesons in dense matter

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    Two-photon decays of vector mesons and dilepton decays of scalar mesons which are forbidden in vacuum and can occur in dense baryonic matter due to the explicit violation of Lorentz symmetry are described within a quark model of the Nambu--Jona-Lasinio type. The temperature and chemical potential dependence of these processes is investigated. It is found that their contribution to the production of photons and leptons in heavy-ion collisions is enhanced near the conditions corresponding to the restoration of chiral symmetry. Moreover, in the case of the a_0 meson and especially the \rho-meson, a resonant behaviour (an additional amplification) is observed due to the degeneration of \rho and a_0 masses when a hot hadron matter is approaching a chirally symmetric phase.Comment: 20 figures, IOP styl

    Concentration of meteoritic free organic matter by fluid transport and adsorption

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    Carbonaceous chondrites contain many abiotic organic compounds, some of which are found in life on Earth. Both the mineral and organic matter phases, of these meteorites, have been affected by aqueous alteration processes. Whilst organic matter is known to be associated with phyllosilicate phases, no such relationship has yet been identified for specific organic compound classes. Furthermore, ongoing sample return missions, Hyabusa 2 and OSIRIS-Rex, are set to return potentially organic rich C-type asteroid samples to the Earth. Consequently, strategies to investigate organic-mineral relationships are required. Here we report spatial data for free/soluble organic matter (FOM/SOM) components (akylimidazole and alkylpyridine homologues) and mineral phases. Low and intermediate molecular weight alkylimidazole homologues are more widely distributed than higher molecular weight members, likely due to their affinity for the aqueous phase. On aqueous alteration of anhydrous mineral phases, transported FOM is adsorbed onto the surface or into the interlayers of the resulting phyllosilicates and thus concentrated and protected from oxidising fluids. Therefore, aiding the delivery of biologically relevant molecules to earth, shortly preceding the origin of life

    Scalar Particles in Lattice QCD

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    We report a project to study scalar particles by lattice QCD simulations. After a brief introduction of the current situation of lattice study of the sigma meson, we describe our numerical simulations of scalar mesons, σ\sigma and κ\kappa. We observe a low sigma mass, mπ<mσmρm_\pi<m_\sigma\le m_\rho, for which the disconnected diagram plays an important role. For the kappa meson, we obtain higher mass than the experimental value, i.e., mκ2mKm_\kappa\sim 2m_{K^*}.Comment: 4 figures, to be published in Proceedings of `International Symposium on Hadron Spectroscopy, Chiral Symmetry and Relativistic Description of Bound Systems' (in a series of KEK proceedings
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