4,302 research outputs found
CP-violating Supersymmetric Higgs at the Tevatron and LHC
We analyze the prospect for observing the intermediate neutral Higgs boson
() in its decay to two lighter Higgs bosons () at the presently
operating hadron colliders in the framework of the CP violating MSSM using the
PYTHIA event generator. We consider the lepton+ 4-jets+ \met channel from
associate production, with W h_2 \ra W h_1 h_1 \ra \ell \nu_\ell b
\bar b b\bar b. We require two, three or four tagged -jets. We explicitly
consider all relevant Standard Model backgrounds, treating -jets separately
from light flavor and gluon jets and allowing for mistagging. We find that it
is very hard to observe this signature at the Tevatron, even with 20 fb
of data, in the LEP--allowed region of parameter space due to the small signal
efficiency, even though the background is manageable. At the LHC, a priori huge
SM backgrounds can be suppressed by applying judiciously chosen kinematical
selections. After all cuts, we are left with a signal cross section of around
0.5 fb, and a signal to background ratio between 1.2 and 2.9. According to our
analysis this Higgs signal should be viable at the LHC in the vicinity of
present LEP exclusion once 20 to 50 fb of data have been accumulated at
TeV.Comment: 27 pages, 12 figure
Mitigation of the LHC Inverse Problem
The LHC inverse problem refers to the difficulties in determining the
parameters of an underlying theory from data (to be) taken by the LHC
experiments: if they find signals of new physics, and an underlying theory is
assumed, could its parameters be determined uniquely, or do different parameter
choices give indistinguishable experimental signatures? This inverse problem
was studied before for a supersymmetric Standard Model with 15 free parameters.
This earlier study found 283 indistinguishable pairs of parameter choices,
called degenerate pairs, even if backgrounds are ignored. We can resolve all
but 23 of those pairs by constructing a true \chi^2 distribution using mostly
counting observables. The elimination of systematic errors would even allow
separating the residual degeneracies. Taking the Standard Model background into
account we still can resolve 237 of the 283 "degenerate" pairs. This indicates
that (some of) our observables should also be useful for the purpose of
determining the values of SUSY parameters.Comment: 32 pages, 13 figures, typo in (3.6) corrected, version to appear in
Phys. Rev.
Direct and Indirect Detection of Neutralino Dark Matter and Collider Signatures in an Model with Two Intermediate Scales
We investigate the detectability of neutralino Dark Matter via direct and
indirect searches as well as collider signatures of an model with two
intermediate scales. We compare the direct Dark Matter detection cross section
and the muon flux due to neutralino annihilation in the Sun that we obtain in
this model with mSUGRA predictions and with the sensitivity of current and
future experiments. In both cases, we find that the detectability improves as
the model deviates more from mSUGRA. In order to study collider signatures, we
choose two benchmark points that represent the main phenomenological features
of the model: a lower value of and reduced third generation sfermion
masses due to extra Yukawa coupling contributions in the Renormalization Group
Equations, and increased first and second generation slepton masses due to new
gaugino loop contributions. We show that measurements at the LHC can
distinguish this model from mSUGRA in both cases, by counting events containing
leptonically decaying bosons, heavy neutral Higgs bosons, or like--sign
lepton pairs.Comment: 21 pages, 16 figure
MRI and clinical resolution of a suspected intracranial toxoplasma granuloma with medical treatment in a domestic short hair cat
A two-year-old cat was presented with a left paradoxical vestibular syndrome. MRI of the brain revealed an extra-axial homogenously contrast enhancing mass in the region of the left caudal cerebellar peduncle. Toxoplasma serology was consistent with active infection and the lesion was suspected to be a toxoplasma granuloma. Following eight weeks of tapering oral prednisolone and 11 weeks of oral clindamycin treatment, repeat MRI revealed resolution of the lesion. Eighteen months after initial diagnosis, the cat remained neurologically normal. Differential diagnoses for a solitary, extra-axial, contrast enhancing mass lesion in the feline brain should include toxoplasma granuloma, which can undergo MRI and clinical resolution with medical treatment
Weighing the universe with accelerators and detectors
Suppose the lightest superpartner (LSP) is observed at colliders, and WIMPs
are detected in explicit experiments. We point out that one cannot immediately
conclude that cold dark matter (CDM) of the universe has been observed, and we
determine what measurements are necessary before such a conclusion is
meaningful. We discuss the analogous situation for neutrinos and axions; in the
axion case we have not found a way to conclude axions are the CDM even if
axions are detected.Comment: 15 pages, 3 figures; minor changes included and typos fixe
SUSY darkmatter at the LHC - 7 TeV
We have analysed the early LHC signatures of the minimal supergravity
(mSUGRA) model. Our emphasis is on the 7 - run corresponding to an
integrated luminosity of although we have also discussed
briefly the prospects at LHC-10 . We focus on the parameter space yielding
relatively light squark and gluinos consistent with the darkmatter relic
density data and the LEP bounds on the lightest Higgs scalar mass. This
parameter space is only allowed for non-vanishing trilinear soft breaking term
. A significant region of the parameter space with large to moderate
negative values of consistent with the stability of the scalar potential
and relic density production via neutralino annihilation and/or neutralino -
stau coannihilation yields observable signal via the jets + missing transverse
energy channel. The one lepton + jets + missing energy signal is also viable
over a smaller but non-trivial parameter space. The ratio of the size of the
two signals - free from theoretical uncertainties - may distinguish between
different relic density generating mechanisms. With efficient -tagging
facilities at 7 the discriminating power may increase significantly. We
also comment on other dark matter relic density allowed mSUGRA scenarios and
variants there of in the context of LHC-7 .Comment: Brief comments on signals at 7 TeV in the Higgs funnel region of
mSUGRA, models with non universal scalar and gaugino masses have been added.
Accepted for publication in PR
Inference on the tail process with application to financial time series modelling
To draw inference on serial extremal dependence within heavy-tailed Markov
chains, Drees, Segers and Warcho{\l} [Extremes (2015) 18, 369--402] proposed
nonparametric estimators of the spectral tail process. The methodology can be
extended to the more general setting of a stationary, regularly varying time
series. The large-sample distribution of the estimators is derived via
empirical process theory for cluster functionals. The finite-sample performance
of these estimators is evaluated via Monte Carlo simulations. Moreover, two
different bootstrap schemes are employed which yield confidence intervals for
the pre-asymptotic spectral tail process: the stationary bootstrap and the
multiplier block bootstrap. The estimators are applied to stock price data to
study the persistence of positive and negative shocks.Comment: 22 page
Determining the Mass of Dark Matter Particles with Direct Detection Experiments
In this article I review two data analysis methods for determining the mass
(and eventually the spin-independent cross section on nucleons) of Weakly
Interacting Massive Particles with positive signals from direct Dark Matter
detection experiments: a maximum likelihood analysis with only one experiment
and a model-independent method requiring at least two experiments.
Uncertainties and caveats of these methods will also be discussed.Comment: 24 pages, 10 figures, 1 reference added, typos fixed, published
version, to appear in the NJP Focus Issue on "Dark Matter and Particle
Physics
Comparison of clinical signs and outcomes between dogs with presumptive ischemic myelopathy and dogs with acute non compressive nucleus pulposus extrusion
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