1,509 research outputs found
AdS/QCD, Light-Front Holography, and Sublimated Gluons
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
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
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
A look to successful experiences of agrotourism in Latin America
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) GastronomÃa, producción agrÃcola 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
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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