1,770 research outputs found
Probing the Universal Randall-Sundrum Model at the ILC
The Randall-Sundrum model with all Standard Model (SM) fields in the bulk,
including the Higgs, can be probed by precision measurements at the ILC. In
particular, the couplings of the Higgs to the gauge bosons of the SM can be
determined with high accuracy at the ILC. Here we examine the deviations in
these couplings from their SM values within the framework of the Universal
Randall-Sundrum Model (URSM) as well as the corresponding couplings of the
first Higgs Kaluza-Klein excitation.Comment: 3 pages, 2 figs, contributed to the 2005 ALCPG and ILC Workshops,
Snowmass, CO, 8/14-8/27 2005; small typos remove
Production of a large, rolled ring forging of ''200'' grade maraging steel Final technical report
Manufacturing process for seamless, thin walled maraging steel cylinder by roll formin
Top Compositeness at the Tevatron and LHC
We explore the possibility that the right-handed top quark is composite. We
examine the consequences that compositeness would have on
production at the Tevatron, and derive a weak constraint on the scale of
compositeness of order a few hundred GeV from the inclusive cross
section. More detailed studies of differential properties of
production could potentially improve this limit. We find that a composite top
can result in an enhancement of the production rate at
the LHC (of as much as compared to the Standatd Model four top rate). We
explore observables which allow us to extract the four top rate from the
backgrounds, and show that the LHC can either discover or constrain top
compositeness for wide ranges of parameter space.Comment: 9 pages, 4 figure
Observing Ultra High Energy Cosmic Particles from Space: SEUSO, the Super Extreme Universe Space Observatory Mission
The experimental search for ultra high energy cosmic messengers, from eV to beyond eV, at the very end of the known energy
spectrum, constitutes an extraordinary opportunity to explore a largely unknown
aspect of our universe. Key scientific goals are the identification of the
sources of ultra high energy particles, the measurement of their spectra and
the study of galactic and local intergalactic magnetic fields. Ultra high
energy particles might, also, carry evidence of unknown physics or of exotic
particles relics of the early universe. To meet this challenge a significant
increase in the integrated exposure is required. This implies a new class of
experiments with larger acceptances and good understanding of the systematic
uncertainties. Space based observatories can reach the instantaneous aperture
and the integrated exposure necessary to systematically explore the ultra high
energy universe. In this paper, after briefly summarising the science case of
the mission, we describe the scientific goals and requirements of the SEUSO
concept. We then introduce the SEUSO observational approach and describe the
main instrument and mission features. We conclude discussing the expected
performance of the mission
Charged Lepton Flavor Physics and Extra Dimensions
We estimate the charged lepton electric dipole moments and the branching
ratios of radiative lepton flavor violating decays in the framework of the two
Higgs doublet model with the inclusion two extra dimensions. Here, we consider
that the new Higgs doublet is accessible to one of the extra dimensions with a
Gaussian profile and the fermions are accessible to the other extra dimension
with uniform zero mode profile. We observe that the numerical values of the
physical quantities studied enhance with the additional effects due to the
extra dimensions and they are sensitive to the new Higgs localization.Comment: 23 pages, 13 page
Spin properties of dense near-surface ensembles of nitrogen-vacancy centres in diamond
We present a study of the spin properties of dense layers of near-surface
nitrogen-vacancy (NV) centres in diamond created by nitrogen ion implantation.
The optically detected magnetic resonance contrast and linewidth, spin
coherence time, and spin relaxation time, are measured as a function of
implantation energy, dose, annealing temperature and surface treatment. To
track the presence of damage and surface-related spin defects, we perform in
situ electron spin resonance spectroscopy through both double electron-electron
resonance and cross-relaxation spectroscopy on the NV centres. We find that,
for the energy (~keV) and dose (~ions/cm)
ranges considered, the NV spin properties are mainly governed by the dose via
residual implantation-induced paramagnetic defects, but that the resulting
magnetic sensitivity is essentially independent of both dose and energy. We
then show that the magnetic sensitivity is significantly improved by
high-temperature annealing at C. Moreover, the spin properties
are not significantly affected by oxygen annealing, apart from the spin
relaxation time, which is dramatically decreased. Finally, the average NV depth
is determined by nuclear magnetic resonance measurements, giving
-17~nm at 4-6 keV implantation energy. This study sheds light on the
optimal conditions to create dense layers of near-surface NV centres for
high-sensitivity sensing and imaging applications.Comment: 12 pages, 7 figure
After the Standard Model: New Resonances at the LHC
Experiments will soon start taking data at CERN's Large Hadron Collider (LHC)
with high expectations for discovery of new physics phenomena. Indeed, the
LHC's unprecedented center-of-mass energy will allow the experiments to probe
an energy regime where the standard model is known to break down. In this
article, the experiments' capability to observe new resonances in various
channels is reviewed.Comment: Preprint version of a Brief Review for Modern Physics Letters A.
Changes w.r.t. the fully corrected version are smal
Charge asymmetries of top quarks: a window to new physics at hadron colliders
With the next start of LHC, a huge production of top quarks is expected.
There are several models that predict the existence of heavy colored resonances
decaying to top quarks in the TeV energy range. A peak in the differential
cross section could reveal the existence of such a resonance, but this is
experimentally challenging, because it requires selecting data samples where
top and antitop quarks are highly boosted. Nonetheless, the production of such
resonances might generate a sizable charge asymmetry of top versus antitop
quarks. We consider a toy model with general flavour independent couplings of
the resonance to quarks, of both vector and axial-vector kind. The charge
asymmetry turns out to be a more powerful observable to detect new physics than
the differential cross section, because its highest statistical significance is
achieved with data samples of top-antitop quark pairs of low invariant masses
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