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The dynamical gluon mass in the massless bound-state formalism
We describe the phenomenon of dynamical gluon mass generation within the
massless bound-state formalism, which constitutes the general framework for the
systematic implementation of the Schwinger mechanism in non-Abelian gauge
theories. The main ingredient of this formalism is the dynamical formation of
bound states with vanishing mass, which gives rise to effective vertices
containing massless poles; these vertices, in turn, trigger the Schwinger
mechanism, and allow for the gauge-invariant generation of an effective gluon
mass. In this particular approach, the gluon mass is directly related to
quantities that are intrinsic to the bound-state formation itself, such as the
"transition amplitude" and the corresponding "bound-state wave-function".
Specifically, a set of powerful relations discussed in the text, allows one to
determine the dynamical evolution of the gluon mass through a Bethe-Salpeter
equation, which controls the dynamics of the relevant wave-function. In
addition, it is possible to demonstrate that the massless bound-state formalism
is equivalent to the standard approach based on Schwinger-Dyson equations, thus
establishing a formal connection between two different nonperturbative
formalisms.Comment: 12 pages, 8 figures. Talk presented at the QCD-TNT-III-From quarks
and gluons to hadronic matter: A bridge too far? 2-6 September, 2013 - ECT*
Trento, Ital
Caffeine improves anaerobic performance in 30s Wingate test
Graduate
Applie
Standard Model Engineering with Intersecting Branes
I briefly describe the recent construction of the first specific string
D-brane models yielding just the SM massless fermion spectrum. One of the most
remarkable facts predicted by these constructions is that the global symmetries
of the SM like Baryon and Lepton numbers as well as the axial are
gauged symmetries whose anomalies are cancelled by a Green-Schwarz mechanism
only in the case of three quark-lepton generations. Proton stability and the
Dirac nature of neutrino masses are thus a prediction of these theories. This
is work done in collaboration with Fernando Marchesano and Raul Rabadan.Comment: 10 pages, Latex file, no figures. Contribution to the proceedings of
SUSY-01, Dubna (Russia), June 200
Topics in String Unification
I discuss several aspects of strings as unified theories. After recalling the
difficulties of the simplest supersymmetric grand unification schemes I
emphasize the distinct features of string unification. An important role in
constraining the effective low energy physics from strings is played by
symmetries. The discussed topics include the unification of coupling
constants (computation of and at the weak
scale), supersymmetry breaking through gaugino condensation, and properties of
the induced SUSY-breaking soft terms. I remark that departures from
universality in the soft terms are (in contrast to the minimal SUSY model)
generically expected.Comment: 22 pages. Talk given at the ``Workshop on Electroweak Physics Beyond
the Standard Model'', Valencia, 3-5 October 199
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