3,139 research outputs found
QCD corrections to stoponium production at hadron colliders
If the lighter top squark has no kinematically allowed two-body decays that
conserve flavor, then it will live long enough to form hadronic bound states.
The observation of the diphoton decays of stoponium could then provide a
uniquely precise measurement of the top squark mass. In this paper, we
calculate the cross section for the production of stoponium in a hadron
collider at next-to-leading order (NLO) in QCD. We present numerical results
for the cross section for production of stoponium at the LHC and study the
dependence on beam energy, stoponium mass, and the renormalization and
factorization scale. The cross-section is substantially increased by the NLO
corrections, counteracting a corresponding decrease found earlier in the NLO
diphoton branching ratio.Comment: 24 page
Super No-Scale F-SU(5): A Dynamic Determination of M_{1/2} and tan beta
We study the Higgs potential in No-Scale F-SU(5), a model built on the
tripodal foundations of the Flipped SU(5) x U(1)_X Grand Unified Theory, extra
F-theory derived TeV scale vector-like particle multiplets, and the high scale
boundary conditions of No-Scale Supergravity. V_min, the minimum of the
potential following radiative electroweak symmetry breaking, is a function at
fixed Z-Boson mass of the universal gaugino boundary mass M_{1/2} and
tan{\beta}, the ratio of Higgs vacuum expectation values. The No-Scale
nullification of the bilinear Higgs soft term B_mu at the boundary reduces
V_min(M_{1/2}) to a one dimensional dependency, which may be secondarily
minimized. This "Super No-Scale" condition dynamically fixes tan beta and
M_{1/2} at the local minimum minimorum of V_min. Fantastically, the walls of
this theoretically established secondary potential coalesce in descent to a
striking concurrency with the previously phenomenologically favored "golden
point" and "golden strip".Comment: V2, As accepted to Physics Letters B; 8 Pages, 2 Plots, 1 Tabl
A Higgs Mass Shift to 125 GeV and A Multi-Jet Supersymmetry Signal: Miracle of the Flippons at the \sqrt{s} = 7 TeV LHC
We describe a model named No-Scale F-SU(5) which is simultaneously capable of
explaining the dual signals emerging at the LHC of i) a 124-126 GeV Higgs boson
mass m_h, and ii) tantalizing low-statistics excesses in the multi-jet data
which may attributable to supersymmetry. These targets tend to be mutually
exclusive in more conventional approaches. The unified mechanism responsible
for both effects is the introduction of a rather unique set of vector-like
multiplets at the TeV scale, dubbed flippons, which i) can elevate m_h by
around 3-4 GeV via radiative loop corrections, and ii) flatten the running of
the strong coupling and color-charged gaugino, resulting in a prominent
collider signal from production of light gluino pairs. This well motivated
theoretical framework maintains consistency with all key phenomenological
constraints, and all residual parameterization freedom may in principle be
fixed by a combination of the two experiments described. We project that the
already collected luminosity of 5 fb^-1 may be sufficient to definitively
establish the status of this model, given appropriate data selection cuts.Comment: Physics Letters B version, 10 pages, 3 figures, 2 tables. arXiv admin
note: text overlap with arXiv:1105.398
Testing No-Scale F-SU(5): A 125 GeV Higgs Boson and SUSY at the 8 TeV LHC
We celebrate the recent Higgs discovery announcement with our experimental
colleagues at the LHC and look forward to the implications that this success
will bring to bear upon the continuing search for supersymmetry (SUSY). The
model framework named No-Scale F-SU(5) possesses the rather unique capacity to
provide a light CP-even Higgs boson mass in the favored 124-126 GeV window
while simultaneously retaining a testably light SUSY spectrum that is
consistent with emerging low-statistics excesses beyond the Standard Model
expectation in the ATLAS and CMS multijet data. In this letter we review the
distinctive F-SU(5) mechanism that forges the physical 125 GeV Higgs boson and
make a specific assessment of the ATLAS multijet SUSY search observables that
may be expected for a 15/fb delivery of 8 TeV data in this model context. Based
on our Monte Carlo study, we anticipate that the enticing hints of a SUSY
signal observed in the 7 TeV data could be amplified in the 8 TeV results.
Moreover, if the existing signal is indeed legitimate, we project that the
rendered gains in significance will be sufficient to conclusively rule out an
alternative attribution to statistical fluctuation at that juncture.Comment: Physics Letters B Version, 7 Pages, 1 Figur
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Field-structured composite studies.
Field-structured composites (FSCs) were produced by hosting micron-sized gold-coated nickel particles in a pre-polymer and allowing the mixture to cure in a magnetic field environment. The feasibility of controlling a composite's electrical conductivity using feedback control applied to the field coils was investigated. It was discovered that conductivity in FSCs is primarily determined by stresses in the polymer host matrix due to cure shrinkage. Thus, in cases where the structuring field was uniform and unidirectional so as to produce chainlike structures in the composite, no electrical conductivity was measured until well after the structuring field was turned off at the gel point. In situations where complex, rotating fields were used to generate complex, three-dimensional structures in a composite, very small, but measurable, conductivity was observed prior to the gel point. Responsive, sensitive prototype chemical sensors were developed based on this technology with initial tests showing very promising results
Natural Predictions for the Higgs Boson Mass and Supersymmetric Contributions to Rare Processes
In the context of No-Scale F-SU(5), a model defined by the convergence of the
F-lipped SU(5) Grand Unified Theory, two pairs of hypothetical TeV scale
vector-like supersymmetric multiplets with origins in F-theory, and the
dynamically established boundary conditions of No-Scale Supergravity, we
predict that the lightest CP-even Higgs boson mass lies within the range of
119.0 GeV to 123.5 GeV, exclusive of the vector-like particle contribution to
the mass. With reports by the CMS, ATLAS, CDF, and D0 Collaborations detailing
enticing statistical excesses in the vicinity of 120 GeV in searches for the
Standard Model Higgs boson, all signs point to an imminent discovery. While
basic supersymmetric constructions such as mSUGRA and the CMSSM have already
suffered overwhelming reductions in viable parameterization during the LHC's
initial year of operation, about 80% of the original No-Scale F-SU(5) model
space remains viable after analysis of the first 1.1 fb^{-1} of integrated
luminosity. This model is moreover capable of handily explaining the small
excesses recently reported in the CMS multijet supersymmetry search, and also
features a highly favorable "golden" subspace which may simultaneously account
for the key rare process limits on the muon anomalous magnetic moment (g - 2)
and the branching ratio of the flavor-changing neutral current decay b to
s\gamma. In addition, the isolated mass parameter responsible for the global
particle mass normalization, the gaugino boundary mass M_{1/2}, is dynamically
determined at a secondary local minimization of the minimum of the Higgs
potential V_{min}, in a manner which is deeply consistent with all precision
measurements at the physical electroweak scale.Comment: Physics Letters B Version, 10 pages, 2 figures, 2 table
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Higgs Bosons Strongly Coupled to the Top Quark
Several extensions of the Standard Model require the burden of electroweak
symmetry breaking to be shared by multiple states or sectors. This leads to the
possibility of the top quark interacting with a scalar more strongly than it
does with the Standard Model Higgs boson. In top-quark condensation this
possibility is natural. We also discuss how this might be realized in
supersymmetric theories. The properties of a strongly coupled Higgs boson in
top-quark condensation and supersymmetry are described. We comment on the
difficulties of seeing such a state at the Tevatron and LEPII, and study the
dramatic signatures it could produce at the LHC. The four top quark signature
is especially useful in the search for a strongly coupled Higgs boson. We also
calculate the rates of the more conventional Higgs boson signatures at the LHC,
including the two photon and four lepton signals, and compare them to
expectations in the Standard Model.Comment: 18 pages, latex, 9 figure
Do Deep Inelastic Scattering Data Favor a Light Gluino
A next--to--leading order QCD analysis of deep inelastic scattering data is
performed allowing for contributions due to a light gluino. We obtain the
values of for QCD, SUSY QCD with a Majorana gluino and a
Dirac gluino respectively. The value of \alsm obtained in SUSY QCD with a
Majorana gluino best agrees with the direct measurements of
at LEP.Comment: 8 pages with 7 pages of figures, DESY 94-00
Understanding the Astrophysics of Galaxy Evolution: the role of spectroscopic surveys in the next decade
Over the last decade optical spectroscopic surveys have characterized the low
redshift galaxy population and uncovered populations of star-forming galaxies
back to z ~ 7. This work has shown that the primary epoch of galaxy building
and black hole growth occurs at redshifts of 2 to 3. The establishment of the
concordance LCDM cosmology shifted the focus of galaxy population studies from
constraining cosmological parameters to characterizing the processes which
regulate the formation and evolution of galaxies.In the next decade, high
redshift observers will attempt to formulate a coherent evolutionary picture
connecting galaxies in the high redshift Universe to galaxies today. In order
to link galaxy populations at different redshifts, we must not only
characterize their evolution in a systematic way, we must establish which
physical processes are responsible for it. Considerable progress has already
been made in understanding how galaxies evolved from z ~ 1 to the present day.
Large spectroscopic surveys in the near infrared are required to push these
studies back towards the main epoch of galaxy building. Only then will we
understand the full story of the formation of L* galaxies like our own Milky
Way. A large near-IR spectroscopic survey will also provide the calibration
needed to avoid systematics in the large photometric programs proposed to study
the nature of dark matter and dark energy. We provide an outline design for a
multi-object 0.4 to 1.8 micron spectrograph, which could be placed on an
existing telescope, and which would allow a full characterization of the galaxy
population out to z ~ 2. We strongly recommend a serious further study to
design a real instrument, which will be required for galaxy formation studies
to advance to the next frontier.Comment: White paper, primary author J.E. Gunn, submitted to Astro2010 Decadal
Survey, see http://www7.nationalacademies.org/bpa/Astro2010_SWP_byTitle.htm
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