273,910 research outputs found
Self-tuning of cosmological constant and exit from inflation
I review the recent 5D self-tuning solutions of the cosmological constant
problem, and try to unify two cosmological constant problems within the
framework of the self-tuning solutions. One problem, the large cosmological
constant needed for inflation, is interpreted by starting with the parameters
allowing only the dS vacuum, and the vanishing cosmological constant at a true
vacuum is realized by changing parameters by exit from inflation at the brane
such that the self-tuning solution is allowed.Comment: Latex file of 8 pages, including 2 figures. Talk presented at
COSPA-03, Taipei, Taiwan, Nov. 13-15, 200
Non-Abelian statistics in the interference noise of the Moore-Read quantum Hall state
We propose noise oscillation measurements in a double point contact,
accessible with current technology, to seek for a signature of the non-abelian
nature of the \nu=5/2 quantum Hall state. Calculating the voltage and
temperature dependence of the current and noise oscillations, we predict the
non-abelian nature to materialize through a multiplicity of the possible
outcomes: two qualitatively different frequency dependences of the nonzero
interference noise. Comparison between our predictions for the Moore-Read state
with experiments on \nu=5/2 will serve as a much needed test for the nature of
the \nu=5/2 quantum Hall state.Comment: 4 pages, 4 figures v2: typo's corrected, discussions clarified,
references adde
R-parity from string compactification
In this paper, we embed the parity as a discrete subgroup of a
global symmetry \UoR\,obtained from compactification of heterotic
string \EE8. A part of \UoR\,transformation is the shift of the anticommuting
variable to which necessarily incoorporate
the transformation of internal space coordinate. Out of six internal spaces, we
identify three U(1)'s whose charges are denoted as , and
. The \UoR~is defined as \UEE\UKK~where \UEE~is the part from
\EE8 and \UKK~is the part generated by , and . We
propose a method to define a \UoR~direction. The needed vacuum expectation
values for breaking gauge U(1)'s except U(1) of the standard model carry
\UoR~charge 4 modulo 4 such that \UoR~is broken down to at the grand
unification scale. is broken to between the intermediate
(\sim 10^{11\,}\gev) and the electroweak scales (100\,\gev\sim 1\,\tev).
The conditions we impose are proton longevity, a large top quark mass, and
acceptable magnitudes for the term and neutrino masses.Comment: 21 pages with 3 figure
Is an axizilla possible for di-photon resonance?
Heavy axion-like particles, called axizillas, are simple extensions of the
standard model(SM). An axizilla is required not to couple to the quarks,
leptons, and Brout-Englert-Higgs doublets of the SM, but couple to the gauge
anomalies of the and photon. It is possible to have its branching
ratios(BRs) to two photons greater than 10% and to two 's less than 10%. To
have a (production cross section)(BR to di-photons) at a
level, a TeV scale heavy quark is required for
the gluon--quark fusion process. The decay of to axizilla plus quark, and
the subsequent decay of the axizilla to two photons can be fitted at the
required level of .Comment: 9 pages of latex file with 3 figure
Brane gravity, massless bulk scalar and self-tuning of the cosmological constant
We show that a self-tuning mechanism of the cosmological constant could work
in 5D non-compact space-time with a symmetry in the presence of a
massless scalar field. The standard model matter fields live only on the 4D
brane. The change of vacuum energy on the brane (brane cosmological constant)
by, for instance, electroweak and QCD phase transitions, just gives rise to
dynamical shifts of the profiles of the background metric and the scalar field
in the extra dimension, keeping 4D space-time flat without any fine-tuning. To
avoid naked singularities in the bulk, the brane cosmological constant should
be negative. We introduce an additional brane-localized 4D Einstein-Hilbert
term so as to provide the observed 4D gravity with the non-compact extra
dimension. With a general form of brane-localized gravity term allowed by the
symmetries, the low energy Einstein gravity is successfully reproduced on the
brane at long distances. We show this phenomenon explicitly for the case of
vanishing bulk cosmological constant.Comment: 1+15 pages, no figure, Version to appear in PR
QCD Axion and Dark Energy
String allowed discrete symmetry is the mother of acceptable effective global
symmetries at low energy. With this philosophy, we discuss dark energy, QCD
axion, and inflation, and speculate some implications of the recent BICEP2
data.Comment: 5 pages, 2 figures. Talk presented at PATRAS 2014, CERN, 30 June 201
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