589 research outputs found
QCD Dual
We uncover a novel solution of the 't Hooft anomaly matching conditions for
QCD. Interestingly in the perturbative regime the new gauge theory, if
interpreted as a possible QCD dual, predicts the critical number of flavors
above which QCD in the nonperturbative regime, develops an infrared stable
fixed point. Remarkably this value is identical to the maximum bound predicted
in the nonpertubative regime via the all-orders conjectured beta function for
nonsupersymmetric gauge theories.Comment: RevTeX, 13 pages. Added discussion on operator matching and flavor
decoupling. Version to match the published on
Aspects of the Quantum Chromo Dynamics Phase Diagram
I briefly review some aspects of the Quantum Chromo Dynamics phase diagram at
non zero temperature and quark chemical potential. I then suggest new possible
phases which can appear in strongly interacting theories at non zero chemical
potential. Finally I describe the phase diagram as function of the number of
flavors and colors at zero quark chemical potential and zero temperature.Comment: 16 pp. 6 eps-figs. Invited review talk for the GISELDA Meeting held
in Frascati, 14-18 January 200
The Standard Model is Natural as Magnetic Gauge Theory
We suggest that the Standard Model can be viewed as the magnetic dual of a
gauge theory featuring only fermionic matter content. We show this by first
introducing a Pati-Salam like extension of the Standard Model and then relating
it to a possible dual electric theory featuring only fermionic matter. The
absence of scalars in the electric theory indicates that the associated
magnetic theory is free from quadratic divergences. Our novel solution to the
Standard Model hierarchy problem leads also to a new insight on the mystery of
the observed number of fundamental fermion generations by naturally explaining
why it has to be at least three.Comment: RevTeX, 5 pages. Version to match the published one. Added several
paragraphs suggesting how nonsupersymmetric gauge-gauge duality can work.
This work opens the doors to a new way to address the hierarchy problem of
the Standard Mode
Magnetic S-parameter
We propose a direct test of the existence of gauge duals for
nonsupersymmetric asymptotically free gauge theories developing an infrared
fixed point by computing the S-parameter in the electric and dual magnetic
description. In particular we show that at the lower bound of the conformal
window the magnetic S-parameter, i.e. the one determined via the dual magnetic
gauge theory, assumes a simple expression in terms of the elementary magnetic
degrees of freedom. The results further support our recent conjecture of the
existence of a universal lower bound on the S parameter and indicates that it
is an ideal operator for counting the active physical degrees of freedom within
the conformal window. Our results can be directly used to unveil possible four
dimensional gauge duals and constitute the first explicit computation of a
nonperturbative quantity, in the electric variables, via nonsupersymmetric
gauge duality.Comment: RevTeX 4, 4 pages, two columns. Version to match the published
version in Phys. Rev. Let
Large N Scalars: From Glueballs to Dynamical Higgs Models
We construct effective Lagrangians, and corresponding counting schemes, valid
to describe the dynamics of the lowest lying large N stable massive composite
state emerging in strongly coupled theories. The large N counting rules can now
be employed when computing quantum corrections via an effective Lagrangian
description. The framework allows for systematic investigations of composite
dynamics of non-Goldstone nature. Relevant examples are the lightest glueball
states emerging in any Yang-Mills theory. We further apply the effective
approach and associated counting scheme to composite models at the electroweak
scale. To illustrate the formalism we consider the possibility that the Higgs
emerges as: the lightest glueball of a new composite theory; the large N scalar
meson in models of dynamical electroweak symmetry breaking; the large N
pseudodilaton useful also for models of near-conformal dynamics. For each of
these realisations we determine the leading N corrections to the electroweak
precision parameters. The results nicely elucidate the underlying large N
dynamics and can be used to confront first principle lattice results featuring
composite scalars with a systematic effective approach.Comment: 15 pages ReVTeX, 3 figure
Chiral Phase Transition for SU(N) Gauge Theories
We describe the chiral phase transition for vector-like SU(N) gauge theories
as a function of the number of quark flavors Nf by making use of an
anomaly-induced effective potential. The potential depends explicitly on the
full beta-function and the anomalous dimension \gamma of the quark mass
operator. By using this potential we argue that chiral symmetry is restored for
\gamma <1. A perturbative computation of \gamma then leads to an estimate of
the critical value Nf^c for the transition.Comment: 7 pages, LaTeX AIP style. Conf. Proc. "New Directions in Quantum
Chromodynamics
Anomaly Matching and Low Energy Theories at High Matter Density
I provide new arguments supporting the validity of the t'Hooft anomaly
conditions at non zero quark chemical potential. These constraints strengthen
the quark-hadron continuity scenario. Finally I review the 2SC effective
Lagrangian for color superconductivity
Jumping Dynamics
We propose an alternative paradigm to the conjectured Miransky scaling
potentially underlying the physics describing the transition from the
conformally broken to the conformally restored phase when tuning certain
parameters such as the number of flavors in gauge theories. According to the
new paradigm the physical scale and henceforth also the massive spectrum of the
theory jump at the lower boundary of the conformal window. In particular we
propose that a theory can suddenly jump from a Quantum Chromodynamics type
spectrum, at the lower boundary of the conformal window, to a conformal one
without particle interpretation. The jumping scenario, therefore, does not
support a near-conformal dynamics of walking type. We will also discuss the
impact of jumping dynamics on the construction of models of dynamical
electroweak symmetry breaking.Comment: 4 pages. 6 Figure
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