1,051 research outputs found
Analysis of the Neutralino System in Three--Body Leptonic Decays of Neutralinos
Neutralinos in supersymmetric theories, the spin--1/2
Majorana--type superpartners of the U(1) and SU(2) neutral electroweak gauge
bosons and SU(2) neutral Higgs bosons, are expected to be among light
supersymmetric particles so that they can be produced copiouslyvia direct pair
production and/or from cascade decays of other sparticles such as sleptons at
the planned Large Hadron Collider and the prospective International Linear
Collider. Considering the prospects of having both highly polarized neutralinos
and possibility of reconstructing their decay rest frames, we provide a
systematic investigation of the three--body leptonic decays of the neutralinos
in the minimal supersymmetric standard model and demonstrate alternative ways
for probing the Majorana nature of the neutralinos and CP violation in the
neutralino system.Comment: Version to appear in Eur.Phys.J.
Magnetization reversal and magnetic anisotropy in Co network nanostructures
The magnetization reversal and magnetic anisotropy in Co network structures have been studied using magneto-optic Kerr effect (MOKE). An enhancement of the coercivity is observed in the network structures and is attributed to the pinning of domain walls by the hole edges in the vicinity of which the demagnetizing field spatially varies. We find that the magnetization reversal process is dominated by the intrinsic unaxial anisotropy (2K(u)/M(s)approximate to 200 Oe) in spite of the shape anisotropy induced by the hole edges. The influence of the cross-junction on the competition between the intrinsic uniaxial anisotropy and the induced shape anisotropy is discussed using micromagnetic simulations
Requirements on collider data to match the precision of WMAP on supersymmetric dark matter
If future colliders discover supersymmetric particles and probe their
properties, one could predict the dark matter density of the Universe and would
constrain cosmology with the help of precision data provided by WMAP and
PLANCK.
We investigate how well the relic density can be predicted in minimal
supergravity (mSUGRA), with and without the assumption of mSUGRA when analysing
data. We determine the parameters to which the relic density is most sensitive,
and quantify the collider accuracy needed. Theoretical errors in the prediction
are investigated in some detail.Comment: 42 pages, 16 figures. v2 incorporates referee's comments: minor
corrections/clarifications with additional figures to show regions of m12-m0
plane considere
Gaugino and Scalar Masses in the Landscape
In this letter we demonstrate the genericity of suppressed gaugino masses M_a
\sim m_{3/2}/ln(M_P/m_{3/2}) in the IIB string landscape, by showing that this
relation holds for D7-brane gauginos whenever the associated modulus is
stabilised by nonperturbative effects. Although m_{3/2} and M_a take many
different values across the landscape, the above small mass hierarchy is
maintained. We show that it is valid for models with an arbitrary number of
moduli and applies to both the KKLT and exponentially large volume approaches
to Kahler moduli stabilisation. In the latter case we explicitly calculate
gaugino and moduli masses for compactifications on the two-modulus Calabi-Yau
P^4_[1,1,1,6,9]. In the large-volume scenario we also show that soft scalar
masses are approximately universal with m_i^2 \sim m_{3/2}^2 (1 + \epsilon_i),
with the non-universality parametrised by \epsilon_i \sim 1/ln (M_P/m_{3/2})^2
\sim 1/1000. We briefly discuss possible phenomenological implications of our
results.Comment: 15 pages, JHEP style; v2. reference adde
Continuity of generalized parton distributions for the pion virtual Compton scattering
We discuss a consistent treatment of the light-front gauge-boson and meson
wave functions in the analyses of the generalized parton distributions(GPDs)
and the scattering amplitudes in deeply virtual Compton scattering(DVCS) for
the pion. The continuity of the GPDs at the crossover, where the longitudinal
momentum fraction of the probed quark is same with the skewedness parameter,
and the finiteness of the DVCS amplitude are ensured if the same light-front
radial wave function as that of the meson bound state wave function is used for
the gauge boson bound state arising from the pair-creation(or nonvalence)
diagram. The frame-independence of our model calculation is also guaranteed by
the constraint from the sum rule between the GPDs and the form factors.Comment: 14 pages, 9 figures, we (1) changed the title, (2) added references,
(3) discussed the GPD value at the crossover in Sec. III, version to appear
in Phys. Rev.
Phenomenology of Mixed Modulus-Anomaly Mediation in Fluxed String Compactifications and Brane Models
In some string compactifications, for instance the recently proposed KKLT
set-up, light moduli are stabilized by nonperturbative effects at
supersymmetric AdS vacuum which is lifted to a dS vacuum by supersymmetry
breaking uplifting potential. In such models, soft supersymmetry breaking terms
are determined by a specific mixed modulus-anomaly mediation in which the two
mediations typically give comparable contributions to soft parameters. Similar
pattern of soft terms can arise also in brane models to stabilize the radion by
nonperturbative effects. We examine some phenomenological consequences of this
mixed modulus-anomaly mediation, including the pattern of low energy sparticle
spectrum and the possibility of electroweak symmetry breaking. It is noted that
adding the anomaly-mediated contributions at amounts to replacing the
messenger scale of the modulus mediation by a mirage messenger scale
where
for denoting the
modulus-mediated contribution to the gaugino mass at . The minimal
KKLT set-up predicts . As a consequence, for ,
the model can lead to a highly distinctive pattern of sparticle masses at TeV
scale, particularly when .Comment: 20 pages, 15 figures, some notations are changed, typos are corrected
and discussions on the CP phase from and B are adde
SUSY Parameter Analysis at TeV and Planck Scales
Coherent analyses at future LHC and LC experiments can be used to explore the
breaking mechanism of supersymmetry and to reconstruct the fundamental theory
at high energies, in particular at the grand unification scale. This will be
exemplified for minimal supergravity.Comment: 7 pages, 3 figures, uses espcrc2.sty (included), Proceedings, Loops
and Legs 2004, Zinnowitz on Usedo
Neutralino Pair Production and 3-Body Decays at Linear Colliders as Probes of CP Violation in the Neutralino System
In the CP-invariant supersymmetric theories, the steep S-wave (slow P-wave)
rise of the cross section for any non-diagonal neutralino pair production in
annihilation, (), near threshold is accompanied by the slow P-wave (steep S-wave) decrease
of the fermion invariant mass distribution of the 3-body neutralino decay,
( or ), near the end
point. These selection rules, unique to the neutralino system due to its
Majorana nature, guarantee that the observation of simultaneous sharp S-wave
excitations of the production cross section near threshold and the lepton and
quark invariant mass distribution near the end point is a qualitative,
unambiguous evidence for CP violation in the neutralino system.Comment: 11 pages, 1 eps figure, a reference adde
Reduced order models for control of fluids using the Eigensystem Realization Algorithm
In feedback flow control, one of the challenges is to develop mathematical
models that describe the fluid physics relevant to the task at hand, while
neglecting irrelevant details of the flow in order to remain computationally
tractable. A number of techniques are presently used to develop such
reduced-order models, such as proper orthogonal decomposition (POD), and
approximate snapshot-based balanced truncation, also known as balanced POD.
Each method has its strengths and weaknesses: for instance, POD models can
behave unpredictably and perform poorly, but they can be computed directly from
experimental data; approximate balanced truncation often produces vastly
superior models to POD, but requires data from adjoint simulations, and thus
cannot be applied to experimental data.
In this paper, we show that using the Eigensystem Realization Algorithm (ERA)
\citep{JuPa-85}, one can theoretically obtain exactly the same reduced order
models as by balanced POD. Moreover, the models can be obtained directly from
experimental data, without the use of adjoint information. The algorithm can
also substantially improve computational efficiency when forming reduced-order
models from simulation data. If adjoint information is available, then balanced
POD has some advantages over ERA: for instance, it produces modes that are
useful for multiple purposes, and the method has been generalized to unstable
systems. We also present a modified ERA procedure that produces modes without
adjoint information, but for this procedure, the resulting models are not
balanced, and do not perform as well in examples. We present a detailed
comparison of the methods, and illustrate them on an example of the flow past
an inclined flat plate at a low Reynolds number.Comment: 22 pages, 7 figure
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Off-Gas Analysis During the Vitrification of Hanford Radioactive Waste Samples
This paper describes the off-gas analysis of samples collected during the radioactive vitrification experiments. Production and characterization of the Hanford waste-containing LAW and HAW glasses are presented in related reports from this conference
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