1,509 research outputs found

    AdS/QCD, Light-Front Holography, and Sublimated Gluons

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    Gauge/gravity duality leads to a simple, analytical, and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian. This approach, called "Light-Front Holography", successfully describes the spectroscopy of light-quark meson and baryons, their elastic and transition form factors, and other hadronic properties. The bound-state Schrodinger and Dirac equations of the soft-wall AdS/QCD model predict linear Regge trajectories which have the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. Light-front holography connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable zeta in 3+1 space at fixed light-front time. A key feature is the determination of the frame-independent light-front wavefunctions of hadrons -- the relativistic analogs of the Schrodinger wavefunctions of atomic physics which allow one to compute form factors, transversity distributions, spin properties of the valence quarks, jet hadronization, and other hadronic observables. One thus obtains a one-parameter color-confining model for hadron physics at the amplitude level. AdS/QCD also predicts the form of a non-perturbative effective running coupling and its beta-function with an infrared fixed point which agrees with the effective coupling extracted from measurements of the Bjorken sum rule below 1 GeV^2. This is consistent with a flux-tube interpretation of QCD where soft gluons are sublimated into a color-confining potential for quarks. We discuss a number of phenomenological hadronic properties which support this picture.Comment: Invited talk, presented by SJB at the International Workshop on QCD Green's Functions, Confinement and Phenomenology, 5-9 September 2011, Trento, Ital

    AdS/QCD, Light-Front Holography, and Color Confinement

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    A remarkable holographic feature of dynamics in AdS space in five dimensions is that it is dual to Hamiltonian theory in physical space-time, quantized at fixed light-front time {\tau} = t+z/c. This light-front holographic principle provides a precise relation between the bound-state amplitudes in AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. The fifth dimension coordinate z is dual to the light front variable {\zeta} describing the invariant separation of the quark constituents. The resulting valence Fock-state wavefunction eigensolutions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schr\"odinger equation. The soft-wall dilaton profile exp ({\kappa}^2 {\zeta}^2) provides a model for the light-front potential which is color-confining and reproduces well the linear Regge behavior of the light-quark hadron spectrum in both L, the orbital angular momentum, and n, the radial node number. The pion mass vanishes in the chiral limit and other features of chiral symmetry are satisfied. The resulting running QCD coupling displays an infrared fixed point. The elastic and transition form factors of the pion and the nucleons are also found to be well described in this framework. The light-front AdS/QCD holographic approach thus gives a frame-independent analytic first approximation of the color-confining dynamics, spectroscopy, and excitation spectra of relativistic light-quark bound states in QCD.Comment: Contribution to the Proceedings of the conference, Xth Quark Confinement and the Hadron Spectrum, October 8-12, 2012, TUM Campus Garching, Munich, German

    Ninetieth Regular Meeting of the Committee on Agriculture of the World Trade Organization

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    En esta nota se dan a conocer los principales temas que se discutieron durante la Nonagésima Primera Reunión Ordinaria del Comité de Agricultura de la Organización Mundial del Comercio (OMC)2, a la que el Instituto Interamericano de Cooperación para la Agricultura (IICA) asistió como miembro observador

    Reference frame on youth

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    Potato Zebra Chip

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    A look to successful experiences of agrotourism in Latin America

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    Este documento describe algunos de los agroturismos Experiencias de los ganadores del Programa Hemisférico de Agroindustria Rural – concursos PRODAR. Estas experiencias se han dividido en tres tramos: i) Rutas y circuitos temáticos de gestión local; ii) Gastronomía, producción agrícola y actividades al aire libre, motores del turismo local; y iii) Programas y proyectos de apoyo a la agroturismo desarrolloThis document describes some of the agrotourism experiences of the winners of the Rural Agroindustry Hemispheric Program – PRODAR contests. These experiences have been divided into three sections: i) Routes and theme tours locally managed; ii) Gastronomy, agricultural production and outdoor activities, motors of local tourism; and iii) Programs and support projects for agrotouristic development

    Letter from Geraldine Ferraro to the Red Cross of San Juan de Dios in Costa Rica

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    Letter from Geraldine Ferraro to the Red Cross of San Juan de Dios in Costa Rica. Letter has handwritten notes.https://ir.lawnet.fordham.edu/vice_presidential_campaign_correspondence_1984_international/1342/thumbnail.jp
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