4,422 research outputs found
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
On Gauge Symmetry Breaking via Euclidean Time Component of Gauge Fields
We study gauge theories with/without an extra dimension at finite
temperature, in which there are two kinds of order parameters of gauge symmetry
breaking. The one is the zero mode of the gauge field for the Euclidean time
direction and the other is that for the direction of the extra dimension. We
evaluate the effective potential for the zero modes in one-loop approximation
and investigate the vacuum configuration in detail. Our analyses show that
gauge symmetry can be broken only through the zero mode for the direction of
the extra dimension and no nontrivial vacuum configuration of the zero mode for
the Euclidean time direction is found.Comment: 22 pages, 6 figures, references and typos corrected, version to
appear in PR
Dairy production and sources of cellular variability of milk of cow's in two large farms in semi-arid environment (Tunisia coastal)
This investigation, referring to a description of the Individual Counts Cellular (CCI) of milk, accompanied by an analysis , so some quantitative and qualitative milk parameters that a number of physiological and zootechnical factors of cellular evolution, was performed on two large cattle farms conducted in semi-arid coastal environment (region of Sousse, Tunisia), subject tri-daily in mechanical milking room. It is especially striking that the arithmetic mean (MA) of the CCI cows's was 371000 cell. / ml, while the geometric mean (MG) of the CCI cows's was only 107500 cell. / ml. The median was 73,000 cells. / ml, value close to the MG and widely spaced from the MA, thus telling the usefulness of the MG. A great heterogeneity of cell quality of the milk was noted, however, without clearly identify correlation with the chemical composition of milk. In two large herds followed, the variation of CCI was inversely related to dairy productions. On the other hand, the CCI found an increase with the rank of lactation, the stage of lactation and the spring season of calving.Keywords: Dairy cattle, Cellular Counts Individual, milk production level, quality milk, Factors of cellular variation, semi-arid coastal environmen
Probing Lepton Flavor Violation at Future Colliders
Supersymmetric theories with significant lepton flavor violation have
and nearly degenerate. In this case, pair production
of and at LEPII and at
the Next Linear Collider leads to the phenomenon of slepton oscillations, which
is analogous to neutrino oscillations. The reach in and gives a probe of lepton flavor violation which is significantly more
powerful than the current bounds from rare processes, such as . Polarizable beams and the mode at the NLC are found to
be promising options.Comment: 10 pages, 3 figures, RevTeX, minor corrections, published versio
Solutions to large B and L breaking in the Randall-Sundrum model
The stability of proton and neutrino masses are discussed in the
Randall-Sundrum model. We show that relevant operators should be suppressed, if
the hierarchical Yukawa matrices are explained only by configurations of
wavefunctions for fermions and the Higgs field along the extra dimension. We
assume a discrete gauge symmetry to suppress those operators. In the
Dirac neutrino case, there is an infinite number of symmetries which may forbid
the dangerous operators. In the Majorana neutrino case, the discrete gauge
symmetries should originate from gauge symmetries which are broken on
the Planck brane. We also comment on the oscillation as a
phenomenon which can distinguish those discrete gauge symmetries.Comment: 12 pages, No figures, Added reference
A possible minimal gauge-Higgs unification
A possible minimal model of the gauge-Higgs unification based on the higher
dimensional spacetime M^4 X (S^1/Z_2) and the bulk gauge symmetry SU(3)_C X
SU(3)_W X U(1)_X is constructed in some details. We argue that the Weinberg
angle and the electromagnetic current can be correctly identified if one
introduces the extra U(1)_X above and a bulk scalar triplet. The VEV of this
scalar as well as the orbifold boundary conditions will break the bulk gauge
symmetry down to that of the standard model. A new neutral zero-mode gauge
boson Z' exists that gains mass via this VEV. We propose a simple fermion
content that is free from all the anomalies when the extra brane-localized
chiral fermions are taken into account as well. The issues on recovering a
standard model chiral-fermion spectrum with the masses and flavor mixing are
also discussed, where we need to introduce the two other brane scalars which
also contribute to the Z' mass in the similar way as the scalar triplet. The
neutrinos can get small masses via a type I seesaw mechanism. In this model,
the mass of the Z' boson and the compactification scale are very constrained as
respectively given in the ranges: 2.7 TeV < m_Z' < 13.6 TeV and 40 TeV < 1/R <
200 TeV.Comment: 20 pages, revised versio
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
Verifiable Model of Neutrino Masses from Large Extra Dimensions
We propose a new scenario of neutrino masses with a Higgs triplet
in a theory of large extra dimensions. Lepton number
violation in a distant brane acts as the source of a very small trilinear
coupling of to the standard Higgs doublet in our brane. Small realistic
Majorana neutrino masses are \underline{naturally} obtained with the
fundamental scale TeV, foretelling the possible
discovery of (m_\xi\lsim M_*) at future colliders. Decays of
into same-sign dileptons are fixed by the neutrino mass matrix. Observation of
conversion in nuclei is predicted.Comment: A comment on Tevatron reach and two references added. Discussion and
conclusions unchange
A Higgs Mechanism for Gravity
In this paper we elaborate on the idea of an emergent spacetime which arises
due to the dynamical breaking of diffeomorphism invariance in the early
universe. In preparation for an explicit symmetry breaking scenario, we
consider nonlinear realizations of the group of analytical diffeomorphisms
which provide a unified description of spacetime structures. We find that
gravitational fields, such as the affine connection, metric and coordinates,
can all be interpreted as Goldstone fields of the diffeomorphism group. We then
construct a Higgs mechanism for gravity in which an affine spacetime evolves
into a Riemannian one by the condensation of a metric. The symmetry breaking
potential is identical to that of hybrid inflation but with the non-inflaton
scalar extended to a symmetric second rank tensor. This tensor is required for
the realization of the metric as a Higgs field. We finally comment on the role
of Goldstone coordinates as a dynamical fluid of reference.Comment: 15 pages, 2 figures, 3 tables, appendix C on on-shell d.o.f. added,
references adde
Stability analysis and response of nonlinear rotor-seal system
In this paper, we study the stability of the nonlinear rotor-seal system using Liapunov’s first method. The mathematical solutions using multiple scales up to and including second order approximations is investigated. We extract all resonance cases from analytical solution and investigated. It is quite clear that some of the simultaneous resonance cases are undesirable in the design of such system as they represent some of the worst behavior of the system. The effects of various parameters on the behavior of the system and stability of the system are investigated numerically by response curve. Poincaré maps are used to determine stability and plot bifurcation diagrams
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