752 research outputs found

    Space-time correlation and momentum exchanges in compound open-channel flow by simultaneous measurements of two-sets of ADVs

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    River hydrodynamicsOverbank flows and vegetatio

    Techni-dilaton at Conformal Edge

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    Techni-dilaton (TD) was proposed long ago in the technicolor (TC) near criticality/conformality. To reveal the critical behavior of TD, we explicitly compute the nonperturbative contributions to the scale anomaly andtothetechnigluoncondensate and to the techni-gluon condensate , which are generated by the dynamical mass m of the techni-fermions. Our computation is based on the (improved) ladder Schwinger-Dyson equation, with the gauge coupling α\alpha replaced by the two-loop running one α(μ)\alpha(\mu) having the Caswell-Banks-Zaks IR fixed point α\alpha_*: α(μ)α=α\alpha(\mu) \simeq \alpha = \alpha_* for the IR region m<μ<ΛTCm < \mu < \Lambda_{TC}, where ΛTC\Lambda_{TC} is the intrinsic scale (analogue of ΛQCD\Lambda_{QCD} of QCD) relevant to the perturbative scale anomaly. We find that /m4const0-/m^4\to const \ne 0 and /m4(α/αcr1)3/2/m^4\to (\alpha/\alpha_{cr}-1)^{-3/2}\to\infty in the criticality limit m/ΛTCexp(π/(α/αcr1)1/2)0m/\Lambda_{TC}\sim\exp(-\pi/(\alpha/\alpha_{cr}-1)^{1/2})\to 0 (α=ααcr\alpha=\alpha_* \to \alpha_{cr}) ("conformal edge"). Our result precisely reproduces the formal identity =(β(α)/4α)=(\beta(\alpha)/4 \alpha) , where β(α)=(2αcr/π)(α/αcr1)3/2\beta(\alpha)=-(2\alpha_{cr}/\pi) (\alpha/\alpha_{cr}-1)^{3/2} is the nonperturbative beta function corresponding to the above essential singularity scaling of m/ΛTCm/\Lambda_{TC}. Accordingly, the PCDC implies (MTD/m)2(FTD/m)2=4/m4const0(M_{TD}/m)^2 (F_{TD}/m)^2=-4/m^4 \to const \ne 0 at criticality limit, where MTDM_{TD} is the mass of TD and FTDF_{TD} the decay constant of TD. We thus conclude that at criticality limit the TD could become a "true (massless) Nambu-Goldstone boson" MTD/m0M_{TD}/m\to 0, only when m/FTD0m/F_{TD}\to 0, namely getting decoupled, as was the case of "holographic TD" of Haba-Matsuzaki-Yamawaki. The decoupled TD can be a candidate of dark matter.Comment: 17 pages, 14 figures; discussions clarified, references added, to appear in Phys.Rev.

    The Brieva-Rook Localization of the Microscopic Nucleon-Nucleus Potential

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    The nonlocality of the microscopic nucleon-nucleus optical potential is commonly localized by the Brieva-Rook approximation. The validity of the localization is tested for the proton+90^{90}Zr scattering at the incident energies from 65 MeV to 800 MeV. The localization is valid in the wide incident-energy range.Comment: 20 pages, 8 figure

    A qq-anaolg of the sixth Painlev\'e equation

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    A qq-difference analog of the sixth Painlev\'e equation is presented. It arises as the condition for preserving the connection matrix of linear qq-difference equations, in close analogy with the monodromy preserving deformation of linear differential equations. The continuous limit and special solutions in terms of qq-hypergeometric functions are also discussed.Comment: 8 pages, LaTeX file (Two misprints corrected

    Collective excitations, instabilities, and ground state in dense quark matter

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    We study the spectrum of light plasmons in the (gapped and gapless) two-flavor color superconducting phases and its connection with the chromomagnetic instabilities and the structure of the ground state. It is revealed that the chromomagnetic instabilities in the 4-7th and 8th gluonic channels correspond to two very different plasmon spectra. These spectra lead us to the unequivocal conclusion about the existence of gluonic condensates (some of which can be spatially inhomogeneous) in the ground state. We also argue that spatially inhomogeneous gluonic condensates should exist in the three-flavor quark matter with the values of the mass of strange quark corresponding to the gapless color-flavor locked state.Comment: Revtex, 5 pages, 4 figures, two figures and clarifications added, to appear in PRD (Rapid Communications

    Neutral Larkin--Ovchinnikov--Fulde--Ferrell state and chromomagnetic instability in two-flavor dense QCD

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    In two-flavor dense quark matter, we describe the dynamics in the single plane wave Larkin--Ovchinnikov--Fulde--Ferrell (LOFF) state satisfying the color and electric neutrality conditions. We find that because the neutral LOFF state itself suffers from a chromomagnetic instability in the whole region where it coexists with the (gapped/gapless) two-flavor superconducting (2SC/g2SC) phases, it cannot cure this instability in those phases. This is unlike the recently revealed gluonic phase which seems to be able to resolve this problem.Comment: Revtex4, 5 pages, 3 figures, clarifications added, to appear in Phys.Rev.Let

    Gluonic phases, vector condensates, and exotic hadrons in dense QCD

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    We study the dynamics in phases with vector condensates of gluons (gluonic phases) in dense two-flavor quark matter. These phases yield an example of dynamics in which the Higgs mechanism is provided by condensates of gauge (or gauge plus scalar) fields. Because vacuum expectation values of spatial components of vector fields break the rotational symmetry, it is naturally to have a spontaneous breakdown both of external and internal symmetries in this case. In particular, by using the Ginzburg-Landau approach, we establish the existence of a gluonic phase with both the rotational symmetry and the electromagnetic U(1) being spontaneously broken. In other words, this phase describes an anisotropic medium in which the color and electric superconductivities coexist. It is shown that this phase corresponds to a minimum of the Ginzburg-Landau potential and, unlike the two-flavor superconducting (2SC) phase, it does not suffer from the chromomagnetic instability. The dual (confinement) description of its dynamics is developed and it is shown that there are light exotic vector hadrons in the spectrum, some of which condense. Because most of the initial symmetries in this system are spontaneously broken, its dynamics is very rich.Comment: 33 pages, RevTeX; v.2: Published PRD versio

    Ultra-violet Behavior of Bosonic Quantum Membranes

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    We treat the action for a bosonic membrane as a sigma model, and then compute quantum corrections by integrating out higher membrane modes. As in string theory, where the equations of motion of Einstein's theory emerges by setting β=0\beta = 0, we find that, with certain assumptions, we can recover the equations of motion for the background fields. Although the membrane theory is non-renormalizable on the world volume by power counting, the investigation of the ultra-violet behavior of membranes may give us insight into the supersymmetric case, where we hope to obtain higher order M-theory corrections to 11 dimensional supergravity.Comment: 25 pages, Latex, no figure

    Gauged Nambu-Jona-Lasinio model with extra dimensions

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    We investigate phase structure of the D (> 4)-dimensional gauged Nambu-Jona-Lasinio (NJL) model with δ(=D4)\delta(=D-4) extra dimensions compactified on TeV scale, based on the improved ladder Schwinger-Dyson (SD) equation in the bulk. We assume that the bulk running gauge coupling in the SD equation for the SU(N_c) gauge theory with N_f massless flavors is given by the truncated Kaluza-Klein effective theory and hence has a nontrivial ultraviolet fixed point (UVFP). We find the critical line in the parameter space of two couplings, the gauge coupling and the four-fermion coupling, which is similar to that of the gauged NJL model with fixed (walking) gauge coupling in four dimensions. It is shown that in the presence of such walking gauge interactions the four-fermion interactions become ``nontrivial'' even in higher dimensions, similarly to the four-dimensional gauged NJL model. Such a nontriviality holds only in the restricted region of the critical line (``nontrivial window'') with the gauge coupling larger than a non-vanishing value (``marginal triviality (MT)'' point), in contrast to the four-dimensional case where such a nontriviality holds for all regions of the critical line except for the pure NJL point. In the nontrivial window the renormalized effective potential yields a nontrivial interaction which is conformal invariant. The exisitence of the nontrivial window implies ``cutoff insensitivity'' of the physics prediction in spite of the ultraviolet dominance of the dynamics. In the formal limit D -> 4, the nontrivial window coincides with the known condition of the nontriviality of the four-dimensional gauged NJL model, 9/(2Nc)<NfNc<9/2Nc9/(2N_c) < N_f - N_c < 9/2 N_c.Comment: 34 pages, 6 figures, references added, to appear in Phys.Rev.D. The title is changed in PR

    Coulomb Blockade and Coherent Single-Cooper-Pair Tunneling in Single Josephson Junctions

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    We have measured the current-voltage characteristics of small-capacitance single Josephson junctions at low temperatures (T < 0.04 K), where the strength of the coupling between the single junction and the electromagnetic environment was controlled with one-dimensional arrays of dc SQUIDs. We have clearly observed Coulomb blockade of Cooper-pair tunneling and even a region of negative differential resistance, when the zero-bias resistance of the SQUID arrays is much higher than the quantum resistance h/e^2 = 26 kohm. The negative differential resistance is evidence of coherent single-Cooper-pair tunneling in the single Josephson junction.Comment: RevTeX, 4 pages with 6 embedded figure
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