966 research outputs found
Semi-Bounded Restrictions of Dirac Type Operators and the Unique Continuation Property
Let M be a connected Riemannian manifold and let D be a Dirac type operator
acting on smooth compactly supported sections in a Hermitian vector bundle over
M. Suppose D has a self-adjoint extension A in the Hilbert space of
square-integrable sections. We show that any -section contained in
a closed A-invariant subspace onto which the restriction of A is semi-bounded
has the unique continuation property: if vanishes on a non-empty open
subset of M, then it vanishes on all of M.Comment: 10 pages, LaTeX, minor corrections, reference adde
Associated neutralino-neutralino-photon production at NLC
We study the potential of an linear collider to search for
neutralino-neutralino-photon production. Our analysis shows that this signal is
not viable under realistic expectations for electron beam polarization due to
large Standard Model backgrounds. Such a search would be possible only if beam
polarizations of near 100% could be achieved.Comment: 3 pages, 6 figures, uses RevTeX4. Contribution to Snowmass 200
Relic density of neutralinos in minimal supergravity
We evaluate the relic density of neutralinos in the minimal supergravity
(mSUGRA) model. All 2->2 neutralino annihilation diagrams, as well as all
initial states involving sleptons, charginos, neutralinos and third generation
squarks are included. Relativistic thermal averaging of the velocity times
cross sections is performed. We find that co-annihilation effects are only
important on the edges of the model parameter space, where some amount of
fine-tuning is necessary to obtain a reasonable relic density. Alternatively,
at high tan(beta), annihilation through the broad Higgs resonances gives rise
to an acceptable neutralino relic density over broad regions of parameter space
where little or no fine-tuning is needed.Comment: LaTeX, 10 pages. Talk given by Alexander Belyaev at SUSY'02, "The
10th International Conference on Supersymmetry and Unification of Fundamental
Interactions", DESY, Hamburg, Germany, 17-23 June 200
Adoption of E-Marketing by Direct-Market Farms in the Northeastern United States
Many farms have begun operating websites in order to promote their businesses. This study uses data from a 2005 survey of farms in the northeastern United States to identify characteristics of farmers, farms, and farm businesses associated with website adoption. Following a technology-adoption framework, a probit model of website use is estimated to identify significant relationships. Sales location, product type, number of advertising methods used, high-speed Internet connection, land tenure arrangement, and gross farm sales is found to be significantly related to website adoption.Marketing,
Exploring neutralino dark matter resonance annihilation via bA,bH -> b mu^+ mu^- at the LHC
One of the main channels which allows for a large rate of neutralino dark
matter annihilation in the early Universe is via the pseudoscalar Higgs
A-resonance. In this case, the measured dark matter abundance can be obtained
in the minimal supergravity (mSUGRA) model when tan(beta)\sim 50 and
2m_{\tz_1}\sim m_A. We investigate the reaction pp\to b\phi\to b\mu^+\mu^- +X
(where \phi =A or H) at the CERN LHC where requiring the tag of a single b-jet
allows for amplification of the signal-to-background ratio. The rare but
observable Higgs decay to muon pairs allows for a precise measurement of the
Higgs boson mass and decay width. We evaluate signal and background using
CalcHEP, with muon energy smearing according to the CMS detector. We find that
the Higgs width (\Gamma_A) can typically be determined with the accuracy up to
\sim 8% (\sim 17%) for m_A\sim 400 (600) GeV assuming 10^3 fb^{-1} of
integrated luminosity. Therefore, the pp\to b\phi\to b\mu^+\mu^- +X process
provides a unique possibility for direct \Gamma_A measurement at the LHC. While
the Higgs width is correlated with the parameter \tan\beta for a given value of
m_A, extracting \tan\beta is complicated by an overlap of the A and H peaks,
radiative corrections to the b and \tau Yukawa couplings, and the possibility
that SUSY decay modes of the Higgs may be open. In the case where a dilepton
mass edge from \tz_2\to\ell^+\ell^-\tz_1 is visible, it should be possible to
test the relation that 2m_{\tz_1}\sim m_A.Comment: 19 pages with 25 .eps figure
Local Index Theory for Lorentzian Manifolds
We prove a local version of the index theorem for Lorentzian Dirac-type
operators on globally hyperbolic Lorentzian manifolds with Cauchy boundary. In
case the Cauchy hypersurface is compact we do not assume self-adjointness of
the Dirac operator on the spacetime or the associated elliptic Dirac operator
on the boundary. In this case integration of our local index theorem results in
a generalization of previously known index theorems for globally hyperbolic
spacetimes that allows for twisting bundles associated with non-compact gauge
groups.Comment: 39 pages, 1 figur
The Reach of the Fermilab Tevatron and CERN LHC for Gaugino Mediated SUSY Breaking Models
In supersymmetric models with gaugino mediated SUSY breaking (inoMSB), it is
assumed that SUSY breaking on a hidden brane is communicated to the visible
brane via gauge superfields which propagate in the bulk. This leads to GUT
models where the common gaugino mass is the only soft SUSY breaking
term to receive contributions at tree level. To obtain a viable phenomenology,
it is assumed that the gaugino mass is induced at some scale beyond the
GUT scale, and that additional renormalization group running takes place
between and as in a SUSY GUT. We assume an SU(5) SUSY GUT above
the GUT scale, and compute the SUSY particle spectrum expected in models with
inoMSB. We use the Monte Carlo program ISAJET to simulate signals within the
inoMSB model, and compute the SUSY reach including cuts and triggers approriate
to Fermilab Tevatron and CERN LHC experiments. We find no reach for SUSY by the
Tevatron collider in the trilepton channel. %either with or without %identified
tau leptons. At the CERN LHC, values of (1160) GeV can be probed
with 10 (100) fb of integrated luminosity, corresponding to a reach in
terms of of 2150 (2500) GeV. The inoMSB model and mSUGRA can likely
only be differentiated at a linear collider with sufficient energy to
produce sleptons and charginos.Comment: 17 page revtex file with 9 PS figure
Linear Collider Capabilities for Supersymmetry in Dark Matter Allowed Regions of the mSUGRA Model
Recent comparisons of minimal supergravity (mSUGRA) model predictions with
WMAP measurements of the neutralino relic density point to preferred regions of
model parameter space. We investigate the reach of linear colliders (LC) with
and 1 TeV for SUSY in the framework of the mSUGRA model. We find
that LCs can cover the entire stau co-annihilation region provided \tan\beta
\alt 30. In the hyperbolic branch/focus point (HB/FP) region of parameter
space, specialized cuts are suggested to increase the reach in this important
``dark matter allowed'' area. In the case of the HB/FP region, the reach of a
LC extends well past the reach of the CERN LHC. We examine a case study in the
HB/FP region, and show that the MSSM parameters and can be
sufficiently well-measured to demonstrate that one would indeed be in the HB/FP
region, where the lightest chargino and neutralino have a substantial higgsino
component.Comment: 29 pages, 15 EPS figures; updated version slightly modified to
conform with published versio
Reconciling Neutralino Relic Density with Yukawa Unified Supersymmetric Models
Supersymmetric grand unified models based on the gauge group SO(10) are
especially attractive in light of recent data on neutrino masses. The simplest
SO(10) SUSY GUT models predict unification of third generation Yukawa couplings
in addition to the usual gauge coupling unification. Recent surveys of Yukawa
unified SUSY GUT models predict an inverted scalar mass hierarchy in the
spectrum of sparticle masses if the superpotential mu term is positive. In
general, such models tend to predict an overabundance of dark matter in the
universe. We survey several solutions to the dark matter problem in Yukawa
unified supersymmetric models. One solution-- lowering the GUT scale mass value
of first and second generation scalars-- leads to u_R and c_R squark masses in
the 90-120 GeV regime, which should be accessible to Fermilab Tevatron
experiments. We also examine relaxing gaugino mass universality which may solve
the relic density problem by having neutralino annihilations via the Z or h
resonances, or by having a wino-like LSP.Comment: 21 page file plus 9 figures; updated version to coincide with
published versio
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