288 research outputs found

    Process Modeling of Soil Thermal and Hydrological Dynamics

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    To explicitly simulate the soil thermal state effects on hydrological response, the soil thermal regime, frozen soil, and permafrost simulation capability in the Geophysical Institute Permafrost Laboratory (GIPL) model have been included into the physically based, distributed watershed model Gridded Surface Subsurface Hydrologic Analysis (GSSHA). The GIPL model is used to compute a vertical soil temperature profile in every lateral two-dimensional GSSHA computational element using the soil moisture information from hydrologic simulations in GSSHA; GSSHA, in turn, uses this temperature and phase, ice content, and information to adjust hydraulic conductivities for both the vertical unsaturated soil flow and lateral saturated groundwater flow. This two-way coupling increases computational accuracy in both models by providing additional information and processes not previously included in either. The soil moisture physical state is defined by the Richards Equation, and the soil thermal state is defined by the numerical model of phase change based on quasi-linear heat conduction equation. Results from the demonstration site, a head water sub-catchment at the peak of the Caribou-Poker Creeks Research Watershed, representing Alaskan woodland and tundra ecosystem in permafrost-active region, indicated that freezing temperatures reduce soil thermal conductivity and soil storage capacity, thereby increasing overland flow and peak discharges

    Brane-induced Skyrmion on S^3: baryonic matter in holographic QCD

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    We study baryonic matter in holographic QCD with D4/D8/\bar{D8} multi-D brane system in type IIA superstring theory. The baryon is described as the "brane-induced Skyrmion", which is a topologically non-trivial chiral soliton in the four-dimensional meson effective action induced by holographic QCD. We employ the "truncated-resonance model" approach for the baryon analysis, including pion and \rho meson fields below the ultraviolet cutoff scale M_KK \sim 1GeV, to keep the holographic duality with QCD. We describe the baryonic matter in large N_c as single brane-induced Skyrmion on the three-dimensional closed manifold S^3 with finite radius R. The interactions between baryons are simulated by the curvature of the closed manifold S^3, and the decrease of the size of S^3 represents the increase of the total baryon-number density in the medium in this modeling. We investigate the energy density, the field configuration, the mass and the root-mean-square radius of single baryon on S^3 as the function of its radius R. We find a new picture of "pion dominance" near the critical density in the baryonic matter, where all the (axial) vector meson fields disappear and only the pion field survive. We also find the "swelling" phenomena of the baryons as the precursor of the deconfinement, and propose the mechanism of the swelling in general context of QCD. The properties of the deconfinement and the chiral symmetry restoration in the baryonic matter are examined by taking the proper order parameters. We also compare our truncated-resonance model with another "instanton" description of the baryon in holographic QCD, considering the role of cutoff scale M_KK.Comment: 25 pages, 12 figure

    Dynamics of Baryons from String Theory and Vector Dominance

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    We consider a holographic model of QCD from string theory, a la Sakai and Sugimoto, and study baryons. In this model, mesons are collectively realized as a five-dimensional \U(NF)=U(1)×SU(NF)U(N_F)=U(1)\times SU(N_F) Yang-Mills field and baryons are classically identified as SU(NF)SU(N_F) solitons with a unit Pontryagin number and NcN_c electric charges. The soliton is shown to be very small in the large 't Hooft coupling limit, allowing us to introduce an effective field B{\cal B}. Its coupling to the mesons are dictated by the soliton structure, and consists of a direct magnetic coupling to the SU(NF)SU(N_F) field strength as well as a minimal coupling to the U(NF)U(N_F) gauge field. Upon the dimensional reduction, this effective action reproduces all interaction terms between nucleons and an infinite tower of mesons in a manner consistent with the large NcN_c expansion. We further find that all electromagnetic interactions, as inferred from the same effective action via a holographic prescription, are mediated by an infinite tower of vector mesons, rendering the baryon electromagnetic form factors completely vector-dominated as well. We estimate nucleon-meson couplings and also the anomalous magnetic moments, which compare well with nature.Comment: 65pages, 3 figures, vector mesons and axial-vector mesons are now canonically normalized (comparisons with data and conclusions unaffected

    Confront Holographic QCD with Regge Trajectories of vectors and axial-vectors

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    We derive the general 5-dimension metric structure of the DpDqDp-Dq system in type II superstring theory, and demonstrate the physical meaning of the parameters characterizing the 5-dimension metric structure of the \textit{holographic} QCD model by relating them to the parameters describing Regge trajectories. By matching the spectra of vector mesons ρ1\rho_1 with deformed DpDqDp-Dq soft-wall model, we find that the spectra of vector mesons ρ1\rho_1 can be described very well in the soft-wall D3DqD3-Dq model, i.e, AdS5AdS_5 soft-wall model. We then investigate how well the AdS5AdS_5 soft-wall model can describe the Regge trajectory of axial-vector mesons a1a_1. We find that the constant component of the 5-dimension mass square of axial-vector mesons plays an efficient role to realize the chiral symmetry breaking in the vacuum, and a small negative z4z^4 correction in the 5-dimension mass square is helpful to realize the chiral symmetry restoration in high excitation states.Comment: 9 pages, 3 figure and 3 tables, one section adde

    Nuclear matter to strange matter transition in holographic QCD

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    We construct a simple holographic QCD model to study nuclear matter to strange matter transition. The interaction of dense medium and hadrons is taken care of by imposing the force balancing condition for stable D4/D6/D6 configuration. By considering the intermediate and light flavor branes interacting with baryon vertex homogeneously distributed along R^3 space and requesting the energy minimization, we find that there is a well defined transition density as a function of current quark mass. We also find that as density goes up very high, intermediate (or heavy) and light quarks populate equally as expected from the Pauli principle. In this sense, the effect of the Pauli principle is realized as dynamics of D-branes.Comment: 13 pages, 14 figure

    UPAYA PENCEGAHAN PENYEBARAN AFRICAN SWINE FEVER DI NUSA TENGGARA TIMUR

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    The outbreak of African Swine Fever (ASF) disease as a disease that can affect the swine has distributed in many countries including Indonesia. The Province of Nusa Tenggara Timur (NTT) is the biggest swine population in Indonesia being risk because Timor Island directly bordered Timor Leste, which an area that affected ASF. The outbreak of ASF caused a big loss to the economy and the public's fear of consumption of pork and other swine products. The purpose of this activity is to given information about characteristics of good pork quality and appeal public to control and prevent dissemination of ASF. According to this activity, the public knowing ASF as a danger and zoonotic disease, which caused public anxiety to consumption pork and other swine products. Although the public knowing about the danger of ASF, there is no preventive action they know. This activity is a tool for breeders to prevent ASF in their animal husbandry and for the public to know that ASF, not a zoonotic disease. However, consumption of pork and other swine products infected with ASF can spread ASF continuously

    Baryonic Popcorn

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    In the large N limit cold dense nuclear matter must be in a lattice phase. This applies also to holographic models of hadron physics. In a class of such models, like the generalized Sakai-Sugimoto model, baryons take the form of instantons of the effective flavor gauge theory that resides on probe flavor branes. In this paper we study the phase structure of baryonic crystals by analyzing discrete periodic configurations of such instantons. We find that instanton configurations exhibit a series of "popcorn" transitions upon increasing the density. Through these transitions normal (3D) lattices expand into the transverse dimension, eventually becoming a higher dimensional (4D) multi-layer lattice at large densities. We consider 3D lattices of zero size instantons as well as 1D periodic chains of finite size instantons, which serve as toy models of the full holographic systems. In particular, for the finite-size case we determine solutions of the corresponding ADHM equations for both a straight chain and for a 2D zigzag configuration where instantons pop up into the holographic dimension. At low density the system takes the form of an "abelian anti-ferromagnetic" straight periodic chain. Above a critical density there is a second order phase transition into a zigzag structure. An even higher density yields a rich phase space characterized by the formation of multi-layer zigzag structures. The finite size of the lattices in the transverse dimension is a signal of an emerging Fermi sea of quarks. We thus propose that the popcorn transitions indicate the onset of the "quarkyonic" phase of the cold dense nuclear matter.Comment: v3, 80 pages, 18 figures, footnotes 5 and 7 added, version to appear in the JHE

    Singular values of the Dirac operator in dense QCD-like theories

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    We study the singular values of the Dirac operator in dense QCD-like theories at zero temperature. The Dirac singular values are real and nonnegative at any nonzero quark density. The scale of their spectrum is set by the diquark condensate, in contrast to the complex Dirac eigenvalues whose scale is set by the chiral condensate at low density and by the BCS gap at high density. We identify three different low-energy effective theories with diquark sources applicable at low, intermediate, and high density, together with their overlapping domains of validity. We derive a number of exact formulas for the Dirac singular values, including Banks-Casher-type relations for the diquark condensate, Smilga-Stern-type relations for the slope of the singular value density, and Leutwyler-Smilga-type sum rules for the inverse singular values. We construct random matrix theories and determine the form of the microscopic spectral correlation functions of the singular values for all nonzero quark densities. We also derive a rigorous index theorem for non-Hermitian Dirac operators. Our results can in principle be tested in lattice simulations.Comment: 3 references added, version published in JHE
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