1,353 research outputs found
Holographic QCD Integrated back to Hidden Local Symmetry
We develop a previously proposed gauge-invariant method to integrate out
infinite tower of Kaluza-Klein (KK) modes of vector and axialvector mesons in a
class of models of holographic QCD (HQCD). The HQCD is reduced by our method to
the chiral perturbation theory with the hidden local symmetry (HLS) having only
the lowest KK mode identified as the HLS gauge boson. We take the
Sakai-Sugimoto model as a concrete HQCD, and completely determine the terms as well as the terms from the DBI part and the
anomaly-related (intrinsic parity odd) gauge-invariant terms from the CS part.
Effects of higher KK modes are fully included in these terms. To demonstrate
power of our method, we compute momentum-dependences of several form factors
such as the pion electromagnetic form factors, the - and
- transition form factors compared with experiment, which was
not achieved before due to complication to handle infinite sums. We also study
other anomaly-related quantities like --- and
--- vertex functions.Comment: 4 eps figures, 37 pages, latex, typos fixed; some discussions and
references added; fig.4 replace
Dimension-six top-Higgs interaction and its effect in collider phenomenology
Measurement of the Yukawa interaction between the top quark and the Higgs
boson should be useful to clarify the mechanism of fermion mass generation.
We discuss the impact of non-standard interactions characterized by
dimension-six operators on the effective top Yukawa coupling.
The cross section of the process is calculated including these operators, and possible deviation
from the standard model prediction is evaluated under the constraint from
perturbative unitarity and current experimental data.
We find that if the new physics scale is in a TeV region, the cross section
can be significantly enhanced due to the non-standard interactions.
Such a large effect should be detectable at the International Linear
Collider.Comment: 22 pages, RevTex4, 20 eps figure
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
Can WIMP Dark Matter overcome the Nightmare Scenario?
Even if new physics beyond the Standard Model (SM) indeed exists, the energy
scale of new physics might be beyond the reach at the Large Hadron Collider
(LHC) and the LHC could find only the Higgs boson but nothing else. This is the
so-called "nightmare scenario". On the other hand, the existence of the dark
matter has been established from various observations. One of the promising
candidates for thermal relic dark matter is a stable and electric
charge-neutral Weakly Interacting Massive Particle (WIMP) with the mass below
the TeV scale. In the nightmare scenario, we introduce a WIMP dark matter
singlet under the SM gauge group, which only couples to the Higgs doublet at
the lowest order, and investigate a possibility that such WIMP dark matter can
be a clue to overcome the nightmare scenario via various phenomenological tests
such as the dark matter relic abundance, the direct detection experiments for
the dark matter particle, and the production of the dark matter particle at the
LHC.Comment: 14 pages, 10 figure
Does the three site Higgsless model survive the electroweak precision tests at loop?
We complete the list of one loop renormalization group equations and matching
conditions relevant for the computation of the electroweak precision parameters
and in the three site Higgsless model. We obtain one-loop formulas for
and expressed in terms of physical observables such as the KK gauge
boson mass , the KK fermion mass , and the KK gauge boson ()
couplings with light quarks and leptons . It is shown that these
physical observables, , and are severely constrained by
the electroweak precision data. Unlike the tree level analysis on the ideally
delocalized fermion, we find that perfect fermiophobity of is ruled out by
the precision data. We also study the cutoff dependence of our analysis.
Although the model is non-renormalizable, the dependence on the cutoff
parameter is shown to be non-significant.Comment: 13pages, 5figures, minor corrections made, references adde
Kaluza-Klein bubble like structure and celestial sphere in inflationary universe
We consider five dimensional deSitter spacetimes with a deficit angle due to
the presence of a closed 2-brane and identify one dimension as an extra
dimension. From the four dimensional viewpoint we can see that the spacetime
has a structure similar to a Kaluza-Klein bubble of nothing, that is, four
dimensional spacetime ends at the 2-brane. Since a spatial section of the full
deSitter spacetime has the topology of a sphere, the boundary surface surrounds
the remaining four dimensional spacetime, and can be considered as the
celestial sphere. After the spacetime is created from nothing via an instanton
which we describe, some four dimensional observers in it see the celestial
sphere falling down, and will be in contact with a 2-brane attached on it.Comment: 5pages, 4figures, to be published in GR
New approach to solution generation using SL(2,R)-duality of a dimensionally reduced space in five-dimensional minimal supergravity and new black holes
The dimensional reduction of (the bosonic sector of) five-dimensional minimal
supergravity to four dimensions leads to a theory with a massless axion and a
dilaton coupled to gravity and two U(1) gauge fields (one of which has
Chern-Simons coupling), whose field equations have SL(2,R)-invariance.
Utilizing this SL(2,R)-duality, we provide a new formalism for solution
generation. As an example, applying it to the Rasheed solution, which are known
to describe dyonic rotating black holes (from the four-dimensional point of
view) of five-dimensional pure gravity, we obtain rotating Kaluza-Klein black
hole solutions in five-dimensional minimal supergravity. We also show that the
solutions have six charges: mass, angular momentum, Kaluza-Klein
electric/magnetic charges and electric/magnetic charges of the Maxwell field,
four of which are related by a constraint.Comment: 17 pages, a few references and comments added, to be published in PR
One-Loop Corrections to the S and T Parameters in a Three Site Higgsless Model
In this paper we compute the the one-loop chiral logarithmic corrections to
the S and T parameters in a highly deconstructed Higgsless model with only
three sites. In addition to the electroweak gauge bosons, this model contains a
single extra triplet of vector states (which we denote \rho^{\pm} and \rho^0),
rather than an infinite tower of "KK" modes. We compute the corrections to S
and T in 'tHooft-Feynman gauge, including the ghost, unphysical
Goldstone-boson, and appropriate "pinch" contributions required to obtain
gauge-invariant results for the one-loop self-energy functions. We demonstrate
that the chiral-logarithmic corrections naturally separate into two parts, a
model-independent part arising from scaling below the \rho mass, which has the
same form as the large Higgs-mass dependence of the S or T parameter in the
standard model, and a second model-dependent contribution arising from scaling
between the \rho mass and the cutoff of the model. The form of the universal
part of the one-loop result allows us to correctly interpret the
phenomenologically derived limits on the S and T parameters (which depend on a
"reference" Higgs-boson mass) in this three-site Higgsless model. Higgsless
models may be viewed as dual to models of dynamical symmetry breaking akin to
"walking technicolor", and in these terms our calculation is the first to
compute the subleading 1/N corrections to the S and T parameters. We also
discuss the reduction of the model to the ``two-site'' model, which is the
usual electroweak chiral lagrangian, noting the ``non-decoupling''
contributions present in the limit as M_\rho goes to infinity.Comment: 58 pages; uses JHEP and axodraw. Extensively corrected to incorporate
consistent perturbative expansion, additional pinch contributions, and
running of delocalization parameter. Footnotes adde
The Three Site Model at One-Loop
In this paper we compute the one-loop chiral logarithmic corrections to all
O(p^4) counterterms in the three site Higgsless model. The calculation is
performed using the background field method for both the chiral- and
gauge-fields, and using Landau gauge for the quantum fluctuations of the gauge
fields. The results agree with our previous calculations of the
chiral-logarithmic corrections to the S and T parameters in 't Hooft-Feynman
gauge. The work reported here includes a complete evaluation of all one-loop
divergences in an SU(2) x U(1) nonlinear sigma model, corresponding to an
electroweak effective Lagrangian in the absence of custodial symmetry.Comment: 40 pages, nine included eps figures. Minor corrections mad
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