4,146 research outputs found
Integrating out Holographic QCD back to Hidden Local Symmetry
We develop a previously proposed gauge-invariant method to integrate out
infinite towers of vector and axialvector mesons arising as Kaluza-Klein (KK)
modes in a class of holographic models of QCD (HQCD). We demonstrate that HQCD
can be reduced to the chiral perturbation theory (ChPT) with the hidden local
symmetry (HLS) (so-called HLS-ChPT) having only the lowest KK mode identified
as the HLS gauge boson, and the Nambu-Goldstone bosons. The
terms in the HLS-ChPT are completely determined by integrating out infinite
towers of vector/axialvector mesons in HQCD: Effects of higher KK modes are
fully included in the coefficients. As an example, we apply our method to the
Sakai-Sugimoto model.Comment: To appear in proceedings of SCGT09, Nagoya, Japan, 8 page
Conformal Barrier and Hidden Local Symmetry Constraints: Walking Technirhos in LHC Diboson Channels
We expand the previous analyses of the conformal barrier on the walking
technirho for the 2 TeV diboson excesses reported by the ATLAS collaboration,
with a special emphasis on the hidden local symmetry (HLS) constraints. We
first show that the Standard Model (SM) Higgs Lagrangian is equivalent to the
scale-invariant nonlinear chiral Lagrangian, which is further gauge equivalent
to the scale-invariant HLS model, with the scale symmetry realized nonlinearly
via SM Higgs as a (pseudo-) dilaton. The scale symmetry forbids the new vector
boson decay to the 125 GeV Higgs plus W/Z boson, in sharp contrast to the
conventional "equivalence theorem" which is invalidated by the conformality.
The HLS forbids mixing between the iso-triplet technirho's, rho_{Pi} and
rho_{P}, of the one-family walking technicolor (with four doublets
N_D=N_F/2=4), which, without the HLS, would be generated when switching on the
standard model gauging. We also present updated analyses of the walking
technrho's for the diboson excesses by fully incorporating the constraints from
the conformal barrier and the HLS as well as possible higher order effects:
still characteristic of the one-family walking technirho is its smallness of
the decay width, roughly of order Gamma/M_rho ~ [3/N_C x 1/N_D] x
[Gamma/M_rho]_{QCD} ~ 70 GeV/2TeV (N_D= N_C=4), in perfect agreement with the
expected diboson resonance with Gamma<100 GeV. The model is so sharply
distinguishable from other massive spin 1 models without the conformality and
HLS that it is clearly testable at the LHC Run II. If the 2 TeV boson decay to
WH/ZH is not observed in the ongoing Run II, then the conformality is operative
on the 125 GeV Higgs, strongly suggesting that the 2 TeV excess events are
responsible for the walking technirhos and the 125 GeV Higgs is the
technidilaton.Comment: latex, 12 eps figures, 36 pages; minor corrections made in theory
part, version published in NP
Phase Transition in a One-Dimensional Extended Peierls-Hubbard Model with a Pulse of Oscillating Electric Field: II. Linear Behavior in Neutral-to-Ionic Transition
Dynamics of charge density and lattice displacements after the neutral phase
is photoexcited is studied by solving the time-dependent Schr\"odinger equation
for a one-dimensional extended Peierls-Hubbard model with alternating
potentials. In contrast to the ionic-to-neutral transition studied previously,
the neutral-to-ionic transition proceeds in an uncooperative manner as far as
the one-dimensional system is concerned. The final ionicity is a linear
function of the increment of the total energy. After the electric field is
turned off, the electronic state does not significantly change, roughly keeping
the ionicity, even if the transition is not completed, because the ionic
domains never proliferate. As a consequence, an electric field with frequency
just at the linear absorption peak causes the neutral-to-ionic transition the
most efficiently. These findings are consistent with the recent experiments on
the mixed-stack organic charge-transfer complex, TTF-CA. We artificially modify
or remove the electron-lattice coupling to discuss the origin of such
differences between the two transitions.Comment: 17 pages, 9 figure
Quantum Zeno effect with a superconducting qubit
Detailed schemes are investigated for experimental verification of Quantum
Zeno effect with a superconducting qubit. A superconducting qubit is affected
by a dephasing noise whose spectrum is 1/f, and so the decay process of a
superconducting qubit shows a naturally non-exponential behavior due to an
infinite correlation time of 1/f noise. Since projective measurements can
easily influence the decay dynamics having such non-exponential feature, a
superconducting qubit is a promising system to observe Quantum Zeno effect. We
have studied how a sequence of projective measurements can change the dephasing
process and also we have suggested experimental ways to observe Quantum Zeno
effect with a superconducting qubit. It would be possible to demonstrate our
prediction in the current technology
2 TeV Walking Technirho at LHC?
The ATLAS collaboration has recently reported an excess of about 2.5
global significance at around 2 TeV in the diboson channel with the
boson-tagged fat dijets, which may imply a new resonance beyond the standard
model. We provide a possible explanation of the excess as the isospin-triplet
technivector mesons (technirhos, denoted as ) of the walking
technicolor in the case of the one-family model as a benchmark. As the
effective theory for the walking technicolor at the scales relevant to the LHC
experiment, we take a scale-invariant version of the hidden local symmetry
model so constructed as to accommodate technipions, technivector mesons, and
the technidilaton in such a way that the model respects spontaneously broken
chiral and scale symmetries of the underlying walking technicolor. In
particular, the technidilaton, a (pseudo) Nambu-Goldstone boson of the
(approximate) scale symmetry predicted in the walking technicolor, has been
shown to be successfully identified with the 125 GeV Higgs. Currently available
LHC limits on those technihadrons are used to fix the couplings of technivector
mesons to the standard-model fermions and weak gauge bosons. We find that the
technirho's are mainly produced through the Drell-Yan process and predominantly
decay to the dibosons, which accounts for the currently reported excess at
around 2 TeV. The consistency with the electroweak precision test and other
possible discovery channels of the 2 TeV technirhos are also addressed.Comment: 8 pages, 4 eps figures, latex; version to appear in PL
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