207 research outputs found

    Gluon-propagator functional form in the Landau gauge in SU(3) lattice QCD: Yukawa-type gluon propagator and anomalous gluon spectral function

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    We study the gluon propagator Dμνab(x)D_{\mu\nu}^{ab}(x) in the Landau gauge in SU(3) lattice QCD at β\beta = 5.7, 5.8, and 6.0 at the quenched level. The effective gluon mass is estimated as 400600400 \sim 600MeV for r(xαxα)1/2=0.51.0r \equiv (x_\alpha x_\alpha)^{1/2} = 0.5 \sim 1.0 fm. Through the functional-form analysis of Dμνab(x)D_{\mu\nu}^{ab}(x) obtained in lattice QCD, we find that the Landau-gauge gluon propagator Dμμaa(r)D_{\mu\mu}^{aa}(r) is well described by the Yukawa-type function emr/re^{-mr}/r with m600m \simeq 600MeV for r=0.11.0r = 0.1 \sim 1.0 fm in the four-dimensional Euclidean space-time. In the momentum space, the gluon propagator D~μμaa(p2)\tilde D_{\mu\mu}^{aa}(p^2) with (p2)1/2=0.53(p^2)^{1/2}= 0.5 \sim 3 GeV is found to be well approximated with a new-type propagator of (p2+m2)3/2(p^2+m^2)^{-3/2}, which corresponds to the four-dimensional Yukawa-type propagator. Associated with the Yukawa-type gluon propagator, we derive analytical expressions for the zero-spatial-momentum propagator D0(t)D_0(t), the effective mass Meff(t)M_{\rm eff}(t), and the spectral function ρ(ω)\rho(\omega) of the gluon field. The mass parameter mm turns out to be the effective gluon mass in the infrared region of \sim 1fm. As a remarkable fact, the obtained gluon spectral function ρ(ω)\rho(\omega) is almost negative-definite for ω>m\omega >m, except for a positive δ\delta-functional peak at ω=m\omega=m.Comment: 20 pages, 15 figure

    A terahertz vibrational molecular clock with systematic uncertainty at the 101410^{-14} level

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    Neutral quantum absorbers in optical lattices have emerged as a leading platform for achieving clocks with exquisite spectroscopic resolution. However, the studies of these clocks and their systematic shifts have so far been limited to atoms. Here, we extend this architecture to an ensemble of diatomic molecules and experimentally realize an accurate lattice clock based on pure molecular vibration. We evaluate the leading systematics, including the characterization of nonlinear trap-induced light shifts, achieving a total systematic uncertainty of 4.6×10144.6\times10^{-14}. The absolute frequency of the vibrational splitting is measured to be 31 825 183 207 592.8(5.1) Hz, enabling the dissociation energy of our molecule to be determined with record accuracy. Our results represent an important milestone in molecular spectroscopy and THz-frequency standards, and may be generalized to other neutral molecular species with applications for fundamental physics, including tests of molecular quantum electrodynamics and the search for new interactions.Comment: 17 pages, 8 figure

    Enumerative aspects of the Gross-Siebert program

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    We present enumerative aspects of the Gross-Siebert program in this introductory survey. After sketching the program's main themes and goals, we review the basic definitions and results of logarithmic and tropical geometry. We give examples and a proof for counting algebraic curves via tropical curves. To illustrate an application of tropical geometry and the Gross-Siebert program to mirror symmetry, we discuss the mirror symmetry of the projective plane.Comment: A version of these notes will appear as a chapter in an upcoming Fields Institute volume. 81 page

    Landau-Ginzburg/Calabi-Yau correspondence, global mirror symmetry and Orlov equivalence

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    We show that the Gromov-Witten theory of Calabi-Yau hypersurfaces matches, in genus zero and after an analytic continuation, the quantum singularity theory (FJRW theory) recently introduced by Fan, Jarvis and Ruan following ideas of Witten. Moreover, on both sides, we highlight two remarkable integral local systems arising from the common formalism of Gamma-integral structures applied to the derived category of the hypersurface {W=0} and to the category of graded matrix factorizations of W. In this setup, we prove that the analytic continuation matches Orlov equivalence between the two above categories.Comment: 72pages, v2: Appendix B and references added. Typos corrected, v3: several mistakes corrected, final versio

    Dynamic contrast-enhanced magnetic resonance imaging of tumor-induced lymph flow.

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    The growth of metastatic tumors in mice can result in markedly increased lymph flow through tumor-draining lymph nodes (LNs), which is associated with LN lymphangiogenesis. A dynamic magnetic resonance imaging (MRI) assay was developed, which uses low-molecular weight gadolinium contrast agent to label the lymphatic drainage, to visualize and quantify tumor-draining lymph flow in vivo in mice bearing metastatic melanomas. Tumor-bearing mice showed greatly increased lymph flow into and through draining LNs and into the bloodstream. Quantitative analysis established that both the amount and the rate of lymph flow through draining LNs are significantly increased in melanoma-bearing mice. In addition, the rate of appearance of contrast media in the bloodstream was significantly increased in mice bearing melanomas. These results indicate that gadolinium-based contrast-enhanced MRI provides a noninvasive assay for high-resolution spatial identification and mapping of lymphatic drainage and for dynamic measurement of changes in lymph flow associated with cancer or lymphatic dysfunction in mice. Low-molecular weight gadolinium contrast is already used for 1.5-T MRI scanning in humans, which should facilitate translation of this imaging assay

    Keeping Adolescent Orphans in School to Prevent Human Immunodeficiency Virus Infection: Evidence From a Randomized Controlled Trial in Kenya

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    We report findings from a pilot study in western Kenya, using an experimental design to test whether comprehensive support to keep adolescent orphans in school can reduce HIV risk factors

    Excited States in 52Fe and the Origin of the Yrast Trap at I=12+

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    Excited states in 52Fe have been determined up to spin 10\hbar in the reaction 28Si + 28Si at 115 MeV by using \gamma-ray spectroscopy methods at the GASP array. The excitation energy of the yrast 10+ state has been determined to be 7.381 MeV, almost 0.5 MeV above the well known \beta+-decaying yrast 12+ state, definitely confirming the nature of its isomeric character. The mean lifetimes of the states have been measured by using the Doppler Shift Attenuation method. The experimental data are compared with spherical shell model calculations in the full pf-shell.Comment: 9 pages, RevTeX, 7 figures include

    The Infrared Behaviour of the Pure Yang-Mills Green Functions

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    We review the infrared properties of the pure Yang-Mills correlators and discuss recent results concerning the two classes of low-momentum solutions for them reported in literature; i.e. decoupling and scaling solutions. We will mainly focuss on the Landau gauge and pay special attention to the results inferred from the analysis of the Dyson-Schwinger equations of the theory and from "{\it quenched}" lattice QCD. The results obtained from properly interplaying both approaches are strongly emphasized.Comment: Final version to be published in FBS (54 pgs., 11 figs., 4 tabs

    Resurrection of a Bull by Cloning from Organs Frozen without Cryoprotectant in a −80°C Freezer for a Decade

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    Frozen animal tissues without cryoprotectant have been thought to be inappropriate for use as a nuclear donor for somatic cell nuclear transfer (SCNT). We report the cloning of a bull using cells retrieved from testicles that had been taken from a dead animal and frozen without cryoprotectant in a −80°C freezer for 10 years. We obtained live cells from defrosted pieces of the spermatic cords of frozen testicles. The cells proliferated actively in culture and were apparently normal. We transferred 16 SCNT embryos from these cells into 16 synchronized recipient animals. We obtained five pregnancies and four cloned calves developed to term. Our results indicate that complete genome sets are maintained in mammalian organs even after long-term frozen-storage without cryoprotectant, and that live clones can be produced from the recovered cells
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