69 research outputs found
Vacuum Alignment with more Flavors
We study the alignment of the vacuum in gauge theories with Dirac
fermions transforming according to a complex representation of the gauge group.
The alignment of the vacuum is produced by adding a small mass perturbation to
the theory. We study in detail the and case. For and
we reproduce earlier known results including the Dashen phase with
spontaneous violation of the combined charge conjugation and parity symmetry,
CP. For we find regions with and without spontaneous CP violation.
We then generalize to an arbitrary number of flavors. Here it is shown that
at the point where flavors are degenerate with positive mass and
the mass of the 'th flavor becomes negative and equal to CP breaks
spontaneously.Comment: Coincides with published version. Several new results for an
arbitrary number of flavors. New plot adde
Physics of the Non-Abelian Coulomb Phase: Insights from Pad\'e Approximants
We consider a vectorial, asymptotically free SU() gauge theory with
fermions in a representation having an infrared (IR) fixed point. We
calculate and analyze Pad\'e approximants to scheme-independent series
expansions for physical quantities at this IR fixed point, including the
anomalous dimension, , to , and the
derivative of the beta function, , to , where
is an -dependent expansion variable. We consider the
fundamental, adjoint, and rank-2 symmetric tensor representations. The results
are applied to obtain further estimates of and
for several SU() groups and representations , and
comparisons are made with lattice measurements. We apply our results to obtain
new estimates of the extent of the respective non-Abelian Coulomb phases in
several theories. For , the limit and
with fixed is considered. We assess the accuracy of the
scheme-independent series expansion of in comparison
with the exactly known expression in an supersymmetric gauge
theory. It is shown that an expansion of to
is quite accurate throughout the entire non-Abelian Coulomb
phase of this supersymmetric theory.Comment: 28 pages, 3 figure
Conformal House
We investigate the gauge dynamics of nonsupersymmetric SU(N) gauge theories
featuring the simultaneous presence of fermionic matter transforming according
to two distinct representations of the underlying gauge group. We bound the
regions of flavors and colors which can yield a physical infrared fixed point.
As a consistency check we recover the previously investigated conformal windows
bounds when restricting to a single matter representation. The earlier
conformal windows can be imagined to be part now of the new conformal house. We
predict the nonperturbative anomalous dimensions at the infrared fixed points.
We further investigate the effects of adding mass terms to the condensates on
the conformal house chiral dynamics and construct the simplest instanton
induced effective Lagrangian terms
Ultra Minimal Technicolor and its Dark Matter TIMP
We introduce an explicit model with technifermion matter transforming
according to multiple representations of the underlying technicolor gauge
group. The model features simultaneously the smallest possible value of the
naive S parameter and the smallest possible number of technifermions. The
chiral dynamics is extremely rich. We construct the low-energy effective
Lagrangian. We provide both the linearly and non-linearly realized ones. We
then embed, in a natural way, the Standard Model (SM) interactions within the
global symmetries of the underlying gauge theory. Several low-energy composite
particles are SM singlets. One of these Technicolor Interacting Massive
Particles (TIMP)s is a natural cold dark matter (DM) candidate. We estimate the
fraction of the mass in the universe constituted by our DM candidate over the
baryon one. We show that the new TIMP, differently from earlier models, can be
sufficiently light to be directly produced and studied at the Large Hadron
Collider (LHC).Comment: RevTeX, 31 pages. 9 figure
Duality in a Supersymmetric Gauge Theory From a Perturbative Viewpoint
We study duality in supersymmetric QCD in the non-Abelian
Coulomb phase, order-by-order in scheme-independent series expansions. Using
exact results, we show how the dimensions of various fundamental and composite
chiral superfields, and the quantities , , and at superconformal
fixed points of the renormalization group emerge in scheme-independent series
expansions in the electric and magnetic theories. We further demonstrate that
truncations of these series expansions to modest order yield very accurate
approximations to these quantities.Comment: 4 figure
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