8,081 research outputs found
Twisted supersymmetry and the topology of theory space
We present examples of four dimensional, non-supersymmetric field theories in
which ultraviolet supersymmetry breaking effects, such as bose-fermi splittings
and the vacuum energy, are suppressed by , where
is a weak coupling factor and can be made arbitrarily large. The particle
content and interactions of these models are conveniently represented by a
graph with sites and links, describing the gauge theory space structure. While
the theories are supersymmetric ``locally'' in theory space, supersymmetry can
be explicitly broken by topological obstructions.Comment: 9 pages, revtex
Dynamically Warped Theory Space and Collective Supersymmetry Breaking
We study deconstructed gauge theories in which a warp factor emerges
dynamically and naturally. We present nonsupersymmetric models in which the
potential for the link fields has translational invariance, broken only by
boundary effects that trigger an exponential profile of vacuum expectation
values. The spectrum of physical states deviates exponentially from that of the
continuum for large masses; we discuss the effects of such exponential towers
on gauge coupling unification. We also present a supersymmetric example in
which a warp factor is driven by Fayet-Iliopoulos terms. The model is peculiar
in that it possesses a global supersymmetry that remains unbroken despite
nonvanishing D-terms. Inclusion of gravity and/or additional messenger fields
leads to the collective breaking of supersymmetry and to unusual phenomenology.Comment: 28 pages LaTeX, JHEP format, 7 eps figures (v2: reference added
The Long Range Gravitational Potential Energy Between Strings
We calculate the gravitational potential energy between infinitely long
parallel strings with tensions \tau_1 and \tau_2. Classically, it vanishes, but
at one loop, we find that the long range gravitational potential energy per
unit length is U/L = 24G_N^2\tau_1\tau_2/(5 \pi a^2) + ..., where a is the
separation between the strings, G_N is Newton's constant, and we set \hbar = c
=1. The ellipses represent terms suppressed by more powers of G_N \tau_i.
Typically, massless bulk fields give rise at one loop to a long range potential
between p-branes in space-times of dimension p+2+1. The contribution to this
potential from bulk scalars is computed for arbitrary p (strings correspond to
p=1) and in the case of three-branes its possible relevance for cosmological
quintessence is commented on.Comment: 10 pages, 6 figure
W physics at the ILC with polarized beams as a probe of the Littlest Higgs Model
We study the possibility of using W pair production and leptonic decay of one
of the W's at the ILC with polarized beams as a probe of the Littlest Higgs
Model. We consider cross-sections, polarization fractions of the W's, leptonic
decay energy and angular distributions, and left-right polarization asymmetry
as probes of the model. With parameter values allowed by present experimental
constraints detectable effects on these observables at typical ILC energies of
500 GeV and 800 GeV will be present. Beam polarization is further found to
enhance the sensitivity.Comment: 17 pages, plain latex, 6 figures, replaced with version accepted by
JHEP, typographical errors removed, notation and references improved, new
references added, explanation added in appendix regarding beam polarization
dependenc
Gravity in Dynamically Generated Dimensions
A theory of gravity in dimensions is dynamically generated from a
theory in dimensions. As an application we show how dynamically coupled
gravity theories can reduce the effective Planck mass.Comment: 7 pages, LaTeX (Revtex
Little Technicolor
Inspired by the AdS/CFT correspondence, we show that any G/H symmetry
breaking pattern can be described by a simple two-site moose diagram. This
construction trivially reproduces the CCWZ prescription in the context of
Hidden Local Symmetry. We interpret this moose in a novel way to show that many
little Higgs theories can emerge from ordinary chiral symmetry breaking in
scaled-up QCD. We apply this reasoning to the simple group little Higgs to see
that the same low energy degrees of freedom can arise from a variety of UV
complete theories. We also show how models of holographic composite Higgs
bosons can turn into brane-localized little technicolor theories by
"integrating in" the IR brane.Comment: 26 pages, 2 figures; v2: references added; v3: added section on
vacuum alignment to match JHEP versio
The Minimal Moose for a Little Higgs
Recently a new class of theories of electroweak symmetry breaking have been
constructed. These models, based on deconstruction and the physics of theory
space, provide the first alternative to weak-scale supersymmetry with naturally
light Higgs fields and perturbative new physics at the TeV scale. The Higgs is
light because it is a pseudo-Goldstone boson, and the quadratically divergent
contributions to the Higgs mass are cancelled by new TeV scale ``partners'' of
the {\em same} statistics. In this paper we present the minimal theory space
model of electroweak symmetry breaking, with two sites and four link fields,
and the minimal set of fermions. There are very few parameters and degrees of
freedom beyond the Standard Model. Below a TeV, we have the Standard Model with
two light Higgs doublets, and an additional complex scalar weak triplet and
singlet. At the TeV scale, the new particles that cancel the 1-loop quadratic
divergences in the Higgs mass are revealed. The entire Higgs potential needed
for electroweak symmetry breaking--the quartic couplings as well as the
familiar negative mass squared--can be generated by the top Yukawa coupling,
providing a novel link between the physics of flavor and electroweak symmetry
breaking.Comment: 15 pages. References added. Included clarifying comments on the
origin of quartic couplings, and on power-counting. More elegant model for
generating Higgs potential from top Yukawa coupling presente
Horava-Lifshitz Cosmology: A Review
This article reviews basic construction and cosmological implications of a
power-counting renormalizable theory of gravitation recently proposed by
Horava. We explain that (i) at low energy this theory does not exactly recover
general relativity but instead mimic general relativity plus dark matter; that
(ii) higher spatial curvature terms allow bouncing and cyclic universes as
regular solutions; and that (iii) the anisotropic scaling with the dynamical
critical exponent z=3 solves the horizon problem and leads to scale-invariant
cosmological perturbations even without inflation. We also comment on issues
related to an extra scalar degree of freedom called scalar graviton. In
particular, for spherically-symmetric, static, vacuum configurations we prove
non-perturbative continuity of the lambda->1+0 limit, where lambda is a
parameter in the kinetic action and general relativity has the value lambda=1.
We also derive the condition under which linear instability of the scalar
graviton does not show up.Comment: 28 pages, invited review for CQG; version to be published (v2
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