3,732 research outputs found

    The Viscous Lengths in Hydrodynamic Turbulence are Anomalous Scaling Functions

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    It is shown that the idea that scaling behavior in turbulence is limited by one outer length LL and one inner length η\eta is untenable. Every n'th order correlation function of velocity differences \bbox{\cal F}_n(\B.R_1,\B.R_2,\dots) exhibits its own cross-over length ηn\eta_{n} to dissipative behavior as a function of, say, R1R_1. This length depends on nn {and on the remaining separations} R2,R3,R_2,R_3,\dots. One result of this Letter is that when all these separations are of the same order RR this length scales like ηn(R)η(R/L)xn\eta_n(R)\sim \eta (R/L)^{x_n} with xn=(ζnζn+1+ζ3ζ2)/(2ζ2)x_n=(\zeta_n-\zeta_{n+1}+\zeta_3-\zeta_2)/(2-\zeta_2), with ζn\zeta_n being the scaling exponent of the nn'th order structure function. We derive a class of scaling relations including the ``bridge relation" for the scaling exponent of dissipation fluctuations μ=2ζ6\mu=2-\zeta_6.Comment: PRL, Submitted. REVTeX, 4 pages, I fig. (not included) PS Source of the paper with figure avalable at http://lvov.weizmann.ac.il/onlinelist.htm

    Micro-Capsules in Shear Flow

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    This paper deals with flow-induced shape transitions of elastic capsules. The state of the art concerning both theory and experiments is briefly reviewed starting with dynamically induced small deformation of initially spherical capsules and the formation of wrinkles on polymerized membranes. Initially non-spherical capsules show tumbling and tank-treading motion in shear flow. Theoretical descriptions of the transition between these two types of motion assuming a fixed shape are at variance with the full capsule dynamics obtained numerically. To resolve the discrepancy, we expand the exact equations of motion for small deformations and find that shape changes play a dominant role. We classify the dynamical phase transitions and obtain numerical and analytical results for the phase boundaries as a function of viscosity contrast, shear and elongational flow rate. We conclude with perspectives on timedependent flow, on shear-induced unbinding from surfaces, on the role of thermal fluctuations, and on applying the concepts of stochastic thermodynamics to these systems.Comment: 34 pages, 15 figure

    Resonance structure in the {\gamma}{\gamma} and π0π0\pi^0\pi^0 systems in dC interactions

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    Along with π0\pi^0 and {\eta} mesons, a resonance structure in the invariant mass spectrum of two photons at M{\gamma}{\gamma} = 360 \pm 7 \pm 9 MeV is observed in the reaction d + C \rightarrow {\gamma} + {\gamma} + X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are {\Gamma} = 64 \pm 18 MeV and σγγ\sigma_{\gamma\gamma} = 98 \pm 24 {\mu}b, respectively. The collected statistics amount to 2339 \pm 340 events of 1.5 \cdot 10^6 triggered interactions of a total number ~ 10^12 of dC-interactions. The results on observation of the resonance in the invariant mass spectra of two π0\pi^0 mesons are presented: the data obtained in the d + C \rightarrow {\gamma} + {\gamma} reaction is confirmed by the d + C \rightarrow π0\pi^0 + π0\pi^0 reaction: Mπ0π0M_{\pi^0\pi^0} = 359.2 \pm 1.9 MeV, {\Gamma} = 48.9 \pm 4.9 MeV; the ratio of Br(R\rightarrow{\gamma}{\gamma}) / Br(R\rightarrowπ0π0\pi^0\pi^0) = (1.8 {\div} 3.7)\cdot10^-3.Comment: 10 pages, 11 figure

    Bulk viscosity of superfluid neutron stars

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    The hydrodynamics, describing dynamical effects in superfluid neutron stars, essentially differs from the standard one-fluid hydrodynamics. In particular, we have four bulk viscosity coefficients in the theory instead of one. In this paper we calculate these coefficients, for the first time, assuming they are due to non-equilibrium beta-processes (such as modified or direct Urca process). The results of our analysis are used to estimate characteristic damping times of sound waves in superfluid neutron stars. It is demonstrated that all four bulk viscosity coefficients lead to comparable dissipation of sound waves and should be considered on the same footing.Comment: 11 pages, 1 figure, this version with some minor stylistic changes is published in Phys. Rev.

    Spontaneous Violation of the CP Symmetry in the Higgs Sector of the Next-to-Minimal Supersymmetric Model

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    The spontaneous violation of the CP symmetry in the next-to-minimal supersymmetric standard Model (NMSSM) is investigated. It is found that the spontaneous violation of the CP symmetry can occur in the Higgs sector of the NMSSM for a wide region of the parameter space of the model, at the 1-loop level where the radiative corrections due to the top quark and scalar-top quark loops are found to generate the scalar-pseudoscalar mixings between the two Higgs doublets of the NMSSM. In our model, we assume that the masses of the left-handed and the right-handed scalar-top quarks are not degenerate. And we investigate our model anaytically: We derive analytical formulae of the 1-loop mass matrix for the neutral Higgs bosons. We calculate the upper bound on the lightest neutral Higgs boson mass under the assumption. It is found to be about 140 GeV for our choice of parameter values in the presence of the spontaneous violation of the CP symmetry in the NMSSM. Thus, the possibility of the spontaneous violation of the CP symmetry is not completely ruled out in the Higgs sector of the NMSSM if the masses of the left-handed and the right-handed scalar-top quarks are not degenerate. Further, the phenomenology of the KK-Kˉ{\bar K} mixing within the context of our model is studied. The lower bound on CP violating phase in the KK-Kˉ{\bar K} mixing is found to increase if either tanβ\tan\beta decreases or AtA_t increases.Comment: 21 pages, 5 figures, To appear in Phys. Rev.

    Possibility of spontaneous CP violation in the nonminimal supersymmetric standard model with two neutral Higgs singlets

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    A supersymmetric standard model with two Higgs doublets and two Higgs singlets is investigated if it can accommodate the possibility of spontaneous CP violation. Assuming the degeneracy of the scalar quark masses of the third generation, we find that spontaneous CP violation in the Higgs sector is viable in our model. In the case of spontaneous CP violation, the masses of the lightest two neutral Higgs bosons are estimated to be 80 and 125 GeV for some parameter values in our model, which, are consistent with LEP2 data.Comment: 18 pages, 3figure

    Neutral Higgs sector of the next-to-minimal supersymmetric standard model with explicit CP violation

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    The neutral Higgs sector of the next-to-minimal supersymmetric standard model (NMSSM) with explicit CP violation is investigated at the 1-loop level, using the effective potential method; not only the loops involving the third generation of quarks and scalar quarks, but also the loops involving WW boson, charged Higgs boson, and chargino are taken into account. It is found that for some parameter values of the NMSSM the contributions from the WW boson, charged Higgs boson, and chargino loops may modify the masses of the neutral Higgs bosons and the mixings among them significantly, depending on the CP phase. In e+ee^+e^- collisions, the prospects for discovering neutral Higgs bosons are investigated within the context of the NMSSM with explicit CP violation when the dominant component of the lightest neutral Higgs boson is the Higgs singlet field of the NMSSM.Comment: Latex, 23 pages, 6 figure

    Electron injection in a nanotube with leads: finite frequency noise-correlations and anomalous charges

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    The non-equilibrium transport properties of a carbon nanotube which is connected to Fermi liquid leads, where electrons are injected in the bulk, are computed. A previous work which considered an infinite nanotube showed that the zero frequency noise correlations, measured at opposite ends of the nanotube, could be used to extract the anomalous charges of the chiral excitations which propagate in the nanotube. Here, the presence of the leads have the effect that such-noise cross-correlations vanish at zero frequency. Nevertheless, information concerning the anomalous charges can be recovered when considering the spectral density of noise correlations at finite frequencies, which is computed perturbatively in the tunneling amplitude. The spectrum of the noise cross-correlations is shown to depend crucially on the ratio of the time of flight of quasiparticles traveling in the nanotube to the ``voltage'' time which defines the width of the quasiparticle wave-packets injected when an electron tunnels. Potential applications toward the measurement of such anomalous charges in non-chiral Luttinger liquids (nanotubes or semiconductor quantum wires) are discussed.Comment: 11 pages, 5 figure

    Invisible Higgs and Scalar Dark Matter

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    In this proceeding, we show that when we combined WMAP and the most recent results of XENON100, the invisible width of the Higgs to scalar dark matter is negligible(<10%), except in a small region with very light dark matter (< 10 GeV) not yet excluded by XENON100 or around 60 GeV where the ratio can reach 50% to 60%. The new results released by the Higgs searches of ATLAS and CMS set very strong limits on the elastic scattering cross section.Comment: 4 pages, 2 figures, proceeding TAUP2011 References adde
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