410 research outputs found

    Diquark Bose-Einstein condensation

    Full text link
    Bose-Einstein condensation (BEC) of composite diquarks in quark matter (the color superconductor phase) is discussed using the quasi-chemical equilibrium theory at a relatively low density region near the deconfinement phase transition, where dynamical quark-pair fluctuations are assumed to be described as bosonic degrees of freedom (diquarks). A general formulation is given for the diquark formation and particle-antiparticle pair-creation processes in the relativistic flamework, and some interesting properties are shown, which are characteristic for the relativistic many-body system. Behaviors of transition temperature and phase diagram of the quark-diquark matter are generally presented in model parameter space, and their asymptotic behaviors are also discussed. As an application to the color superconductivity, the transition temperatures and the quark and diquark density profiles are calculated in case with constituent/current quarks, where the diquark is in bound/resonant state. We obtained TC6080T_C \sim 60-80 MeV for constituent quarks and TC130T_C \sim 130 MeV for current quarks at a moderate density (ρb3ρ0\rho_b \sim 3 \rho_0). The method is also developed to include interdiquark interactions into the quasi-chemical equilibrium theory within a mean-field approximation, and it is found that a possible repulsive diquark-diquark interaction lowers the transition temperature by nearly 50%.Comment: 21 pages, 23 figure

    Baryons in Holographic QCD

    Get PDF
    We study the baryon in holographic QCD with D4/D8/D8ˉD4/D8/\bar{D8} multi-DD brane system. In holographic QCD, the baryon appears as a topologically non-trivial chiral soliton in a four-dimensional effective theory of mesons. We call this topological soliton as Brane-induced Skyrmion. Some review of D4/D8/D8ˉD4/D8/\bar{D8} holographic QCD is presented from the viewpoints of recent hadron physics and phenomenologies. Four-dimensional effective theory with pions and ρ\rho mesons is uniquely derived from the non-abelian Dirac-Born-Infeld (DBI) action of D8D8 brane with D4D4 supergravity background, without small amplitude expansion of meson fields to discuss chiral solitons. For the hedgehog configuration of pion and ρ\rho-meson fields, we derive the energy functional and the Euler-Lagrange equation of Brane-induced Skyrmion from the meson effective action induced by holographic QCD. Performing the numerical calculation, we obtain the pion profile F(r)F(r) and the ρ\rho-meson profile G(r)G(r) of the Brane-induced Skyrmion, and estimate its total energy, energy density distribution, and root-mean-square radius. These results are compared with the experimental quantities of baryons and also with the profiles of standard Skyrmion without ρ\rho mesons. We analyze interaction terms of pions and ρ\rho mesons in Brane-induced Skyrmion, and consider the role of ρ\rho-meson component appearing in baryons.Comment: 28 pages, 11 figure

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

    Get PDF
    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

    A note on fermions in holographic QCD

    Full text link
    We study the fermionic sector of a probe D8-brane in the supergravity background made of D4-branes compactified on a circle with supersymmetry broken explicitly by the boundary conditions. At low energies the dual field theory is effectively four-dimensional and has proved surprisingly successful in recovering qualitative and quantitative properties of QCD. We investigate fluctuations of the fermionic fields on the probe D8-brane and interpret these as mesinos (fermionic superpartners of mesons). We demonstrate that the masses of these modes are comparable to meson masses and show that their interactions with ordinary mesons are not suppressed.Comment: 21+1 pp, 1 figure; v2: typos corrected, refs. adde

    Skyrmions with holography and hidden local symmetry

    Get PDF
    We study baryons as Skyrmions in holographic QCD with D4/D8/D8-bar multi-D brane system in type IIA superstring theory, and also in the non-linear sigma model with hidden local symmetry (HLS). Comparing these two models, we find that the extra-dimension and its nontrivial curvature can largely change the role of (axial) vector mesons for baryons in four-dimensional space-time. In the HLS approach, the rho-meson field as a massive Yang-Mills field has a singular configuration in Skyrmion, which gives a strong repulsion for the baryon as a stabilizer. When a_1 meson is added in this approach, the stability of Skyrmion is lost by the cancellation of rho and a_1 contributions. On the contrary, in holographic QCD, the rho-meson field does not appear as a massive Yang-Mills field due to the extra-dimension and its nontrivial curvature. We show that the rho-meson field has a regular configuration in Skyrmion, which gives a weak attraction for the baryon in holographic QCD. We argue that Skyrmion with pi, rho and a_1 mesons become stable due to the curved extra-dimension and also the presence of the Skyrme term in holographic QCD. From this result, we also discuss the features of our truncated-resonance analysis on baryon properties with pi and rho mesons below the cutoff scale M_KK about 1GeV in holographic QCD, which is compared with other 5D instanton analysis.Comment: 7 pages, 7 figure

    Dynamics of Baryons from String Theory and Vector Dominance

    Get PDF
    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

    Expression of the SmB′ splicing protein in rodent cells capable of following an alternative RNA splicing pathway

    Get PDF
    AbstractThe expression of the SmB and SmB′ spliceosome proteins in a variety of cell types and tissues has been investigated. Although SmB is found in all cells studied, the SmB′ protein is found only in a small number of rodent cell types. The presence of this protein is correlated with the ability to utilize an alternative pathway of RNA splicing which is not available in most cell types. This is the first demonstration of tissue specific expression of a protein component of the spliceosome and suggests a role for SmB′ in the regulation of some cases of alternative RNA splicing

    Holographic aspects of three dimensional QCD from string theory

    Full text link
    We study two aspects of 3D QCD with massless fermions in a holographic set-up from string theory, based on D3/D7 branes; parity anomaly and baryons as baby Skyrmions. We first give a novel account of parity anomaly of 3D QCD with odd number of flavors from the IR holographic viewpoint by observing a subtle point in D7 brane embeddings with a given fixed UV theory. We also discuss its UV origin in terms of weakly coupled D-brane pictures. We then focus on the parity-symmetric case of even number of N_F flavors, and study baryons in the holographic model. We identify the monopoles of U(N_F) gauge theory dynamically broken down to U(N_F/2)x U(N_F/2) in the holographic 4 dimensional bulk as a holographic counter-part of 3D baby-Skyrmions for baryons in large N limit, and work out some details how the mapping goes. In particular, we show that the correct baryon charges emerge from the Witten effect with a space-varying theta angle.Comment: 33 pages, 10 figures; v2: references added with comments, typos corrected; v3: more references added; v4: holographic baryon profile and the analysis of its baryon charge is significantly revised, correcting errors in the previous discussio

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

    Full text link
    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

    UPAYA PENCEGAHAN PENYEBARAN AFRICAN SWINE FEVER DI NUSA TENGGARA TIMUR

    Get PDF
    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
    corecore