2,108 research outputs found
Higgs-gauge unification without tadpoles
In orbifold gauge theories localized tadpoles can be radiatively generated at
the fixed points where U(1) subgroups are conserved. If the Standard Model
Higgs fields are identified with internal components of the bulk gauge fields
(Higgs-gauge unification) in the presence of these tadpoles the Higgs mass
becomes sensitive to the UV cutoff and electroweak symmetry breaking is
spoiled. We find the general conditions, based on symmetry arguments, for the
absence/presence of localized tadpoles in models with an arbitrary number of
dimensions D. We show that in the class of orbifold compactifications based on
T^{D-4}/Z_N (D even, N>2) tadpoles are always allowed, while on T^{D-4}/\mathbb
Z_2 (arbitrary D) with fermions in arbitrary representations of the bulk gauge
group tadpoles can only appear in D=6 dimensions. We explicitly check this with
one- and two-loops calculationsComment: 19 pages, 3 figures, axodraw.sty. v2: version to appear in Nucl.
Phys.
Tadpoles and Symmetries in Higgs-Gauge Unification Theories
In theories with extra dimensions the Standard Model Higgs fields can be
identified with internal components of bulk gauge fields (Higgs-gauge
unification). The bulk gauge symmetry protects the Higgs mass from quadratic
divergences, but at the fixed points localized tadpoles can be radiatively
generated if U(1) subgroups are conserved, making the Higgs mass UV sensitive.
We show that a global symmetry, remnant of the internal rotation group after
orbifold projection, can prevent the generation of such tadpoles. In particular
we consider the classes of orbifold compactifications T^d/Z_N (d even, N>2) and
T^d/Z_2 (arbitrary d) and show that in the first case tadpoles are always
allowed, while in the second they can appear only for d=2 (six dimensions).Comment: 10 pages, based on talks given by M.Q. at String Phenomenology 2004,
University of Michigan, Ann Arbor, August 1-6, 2004 and 10th International
Symposium on Particles, Strings and Cosmology (PASCOS'04 and Nath Fest),
Northeastern University, Boston, August 16-22, 200
Asymptotic Behavior for a Nonlocal Diffusion Equation in Domains with Holes
The paper deals with the asymptotic behavior of solutions to a non-local
diffusion equation, , in an exterior domain, , which
excludes one or several holes, and with zero Dirichlet data on
. When the space dimension is three or more this
behavior is given by a multiple of the fundamental solution of the heat
equation away from the holes. On the other hand, if the solution is scaled
according to its decay factor, close to the holes it behaves like a function
that is -harmonic, , in the exterior domain and vanishes in its
complement. The height of such a function at infinity is determined through a
matching procedure with the multiple of the fundamental solution of the heat
equation representing the outer behavior. The inner and the outer behavior can
be presented in a unified way through a suitable global approximation
Brassica genomics: a complement to, and early beneficiary of, the Arabidopsis sequence.
Those studying the genus Brassica will be among the early beneficiaries of the now-completed Arabidopsis sequence. The remarkable morphological diversity of Brassica species and their relatives offers valuable opportunities to advance our knowledge of plant growth and development, and our understanding of rapid phenotypic evolution
ON GAUGINO CONDENSATION WITH FIELD-DEPENDENT GAUGE COUPLINGS
We study in detail gaugino condensation in globally and locally
supersymmetric Yang-Mills theories. We focus on models for which gauge-neutral
matter couples to the gauge bosons only through nonminimal gauge kinetic terms,
for the cases of one and several condensing gauge groups. Using only symmetry
arguments, the low-energy expansion, and general properties of supersymmetry,
we compute the low energy Wilson action, as well as the (2PI) effective action
for the composite {\it classical} superfield U\equiv\langle \Tr\WW \rangle,
with the supersymmetric gauge field strength. The 2PI effective
action provides a firmer foundation for the approach of Veneziano and
Yankielowicz, who treated the composite superfield, , as a quantum degree of
freedom. We show how to rederive the Wilson action by minimizing the 2PI action
with respect to . We determine, in both formulations and for global and
local supersymmetry, the effective superpotential, , the non-perturbative
contributions to the low-energy K\"ahler potential , and the leading higher
supercovariant derivative terms in an expansion in inverse powers of the
condensation scale. As an application of our results we include the string
moduli dependence of the super- and K\"ahler potentials for simple orbifold
models.Comment: 54 pages, plain te
A decomposition of the increased stability of GDP growth
Since 1984, the U.S. economy has grown at a remarkably steady pace. An analysis of this increased stability shows that every major component of GDP has exhibited smoother growth. However, two components--inventory investment and consumer spending--are responsible for the bulk of the decline in overall volatility.Gross domestic product ; Capital investments ; Inventories ; Consumption (Economics)
A light Higgs scenario based on the TeV-scale supersymmetric strong dynamics
We consider a model based on the supersymmetric QCD theory with N_c=2 and
N_f=3. The theory is strongly coupled at the infrared scale \Lambda_H. Its low
energy effective theory below \Lambda_H is described by the supersymmetric
standard model with the Higgs sector that contains four iso-spin doublets, two
neutral iso-spin singlets and two charged iso-spin singlets. If \Lambda_H is at
the multi-TeV to 10 TeV, coupling constants for the F-terms of these composite
fields are relatively large at the electroweak scale. Nevertheless, the SM-like
Higgs boson is predicted to be as light as 125 GeV because these F-terms
contribute to the mass of the SM-like Higgs boson not at the tree level but at
the one-loop level. A large non-decoupling effect due to these F-terms appears
in the one-loop correction to the triple Higgs boson coupling, which amounts to
a few tens percent. Such a non-decoupling property in the Higgs potential
realizes the strong first order phase transition, which is required for a
successful scenario of electroweak baryogenesis
Supersymmetric CP-violating Currents and Electroweak Baryogenesis
In this work we compute the CP-violating currents of the right-handed stops
and Higgsinos, induced by the presence of non-trivial vacuum expectation values
of the Higgs fields within the context of the minimal supersymmetric extension
of the Standard Model (MSSM) with explicit CP-violating phases. Using the
Keldysh formalism, we perform the computation of the currents at finite
temperature, in an expansion of derivatives of the Higgs fields. Contrary to
previous works, we implement a resummation of the Higgs mass insertion effects
to all orders in perturbation theory. While the components of the right-handed
stop current j^\mu_{\widetilde t_R} become proportional to the difference H_2
\partial^{\mu}H_1-H_1 \partial^{\mu} H_2 (suppressed by \Delta\beta), the
Higgsino currents, j^\mu_{\widetilde{H}_i}, present contributions proportional
to both H_2 \partial^{\mu}H_1\pm H_1 \partial^{\mu} H_2. For large values of
the charged Higgs mass and moderate values of \tan\beta the contribution to the
source proportional to H_2 \partial^{\mu}H_1+H_1 \partial^{\mu} H_2 in the
diffusion equations become sizeable, although it is suppressed by the Higgsino
number violating interaction rate \Gamma_\mu^{-1/2}. For small values of the
wall velocity, 0.04\simlt v_\omega \simlt 0.1, the total contribution leads to
acceptable values of the baryon asymmetry for values of the CP-violating phases
\phi_{CP} in the range 0.04\simlt|\sin\phi_{CP}|\simlt 1. Finally, we comment
on the relevance of the latest results of Higgs searches at LEP2 for the
mechanism of electroweak baryogenesis within the MSSM.Comment: 27 pages, 4 figures, latex2e. Typo corrected and references adde
Echoes of the electroweak phase transition: discovering a second Higgs doublet through A0 â ZH0
The existence of a second Higgs doublet in nature could lead to a cosmological first-order electroweak
phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We obtain the
spectrum and properties of the new scalars H0, A0, and Hïżœ that signal such a phase transition and show that
the observation of the decay A0 â ZH0 at LHC would be a âsmoking gunâ signature of these scenarios. We
analyze the LHC search prospects for this decay in the llbbÂŻ and llWĂŸWâ final states, arguing that current
data may be sensitive to this signature in the former channel as well as there being great potential for a
discovery in either channel at the very early stages of the 14 TeV run
Higher Order Stability of a Radiatively Induced 220 GeV Higgs Mass
The effective potential for radiatively broken electroweak symmetry in the
single Higgs doublet Standard Model is explored to four sequentially subleading
logarithm-summation levels (5-loops) in the dominant Higgs self-interaction
couplant . We augment these results with all contributing leading
logarithms in the remaining large but sub-dominant Standard Model couplants
(t-quark, QCD and gauge couplants) as well as next to
leading logarithm contributions from the largest of these, the t-quark and QCD
couplants. Order-by-order stability is demonstrated for earlier leading
logarithm predictions of an order 220 GeV Higgs boson mass in conjunction with
fivefold enhancement of the value for over that anticipated from
conventional spontaneous symmetry breaking.Comment: revtex, 6 pages. Analysis and text is expanded in revised versio
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