296 research outputs found
Bounds on Dark Matter Interactions with Electroweak Gauge Bosons
We investigate scenarios in which dark matter interacts with the Standard
Model primarily through electroweak gauge bosons. We employ an effective field
theory framework wherein the Standard Model and the dark matter particle are
the only light states in order to derive model-independent bounds. Bounds on
such interactions are derived from dark matter production by weak boson fusion
at the LHC, indirect detection searches for the products of dark matter
annihilation and from the measured invisible width of the . We find that
limits on the UV scale, , reach weak scale values for most operators
and values of the dark matter mass, thus probing the most natural scenarios in
the WIMP dark matter paradigm. Our bounds suggest that light dark matter
(m_{\chi}\lsim m_Z/2 or m_{\chi}\lsim 100-200\gev, depending on the
operator) cannot interact only with the electroweak gauge bosons of the
Standard Model, but rather requires additional operator contributions or dark
sector structure to avoid overclosing the universe.Comment: 45 pages, 26 figure
Higgs Properties in the Fourth Generation MSSM: Boosted Signals Over the 3G Plan
The generalization of the MSSM to the case of four chiral fermion generations
(4GMSSM) can lead to significant changes in the phenomenology of the otherwise
familiar Higgs sector. In most of the 3GMSSM parameter space, the lighter
CP-even is GeV and mostly Standard Model-like while
are all relatively heavy. Furthermore, the ratio of Higgs vevs,
, is relatively unconstrained. In contrast to this, in the 4GMSSM,
heavy fourth generation fermion loops drive the masses of to large
values while the CP-odd boson, , can remain relatively light and is restricted to the range 1/2 \lsim \tan \beta \lsim 2 due to
perturbativity requirements on Yukawa couplings. We explore this scenario in
some detail, concentrating on the collider signatures of the light CP-odd Higgs
at both the Tevatron and LHC. We find that while may lead to a
potential signal in the channel at the LHC, may first be
observed in the channel due to a highly loop-enhanced cross
section that can be more than an order of magnitude greater than that of a SM
Higgs for masses of and . We find that the
CP-even states are highly mixed and can have atypical branching
fractions. Precision electroweak constraints, particularly for the light
parameter space region, are examined in detail.Comment: 20 pages, 7 figures; typos fixed, refs adde
No Prejudice in Space
We present a summary of recent results obtained from a scan of the
19-dimensional parameter space of the pMSSM and its implications for dark
matter searches.Comment: 12 pgs, Presented at the Dark Matter Conference, 9-11 Feb 2009,
Arcetri, Florence, Ital
Pharmacokinetics and bioavailability of different acetylsalicylic acid formulations assessed by liquid chromatography-tandem mass spectrometry in healthy subjects
Low-dose acetylsalicylic acid (ASA, 100 mg/die) is used in thromboprophylaxis. Enteric-coated formulation (EC-ASA) is commonly used for its lower risk of side effects. Some patients on EC-ASA do not respond appropriately and recent studies showed that poor responsiveness is more frequent with EC-ASA [1]. Aim of this study was to validate a method useful to study the pharmacokinetics (PK) of ASA in healthy subjects treated with two different aspirin formulations
Warped Phenomenology of Higher-Derivative Gravity
We examine the phenomenological implications at colliders for the existence
of higher-derivative gravity terms as extensions to the Randall-Sundrum model.
Such terms are expected to arise on rather general grounds, e.g., from string
theory. In 5-d, if we demand that the theory be unitary and ghost free, these
new contributions to the bulk action are uniquely of the Gauss-Bonnet form. We
demonstrate that the usual expectations for the production cross section and
detailed properties of graviton Kaluza-Klein resonances and TeV-scale black
holes can be substantially altered by existence of these additional
contributions. It is shown that measurements at future colliders will be highly
sensitive to the presence of such terms.Comment: 29 pages, 8 figure
Constraints on the pMSSM from LAT Observations of Dwarf Spheroidal Galaxies
We examine the ability for the Large Area Telescope (LAT) to constrain
Minimal Supersymmetric Standard Model (MSSM) dark matter through a combined
analysis of Milky Way dwarf spheroidal galaxies. We examine the Lightest
Supersymmetric Particles (LSPs) for a set of ~71k experimentally valid
supersymmetric models derived from the phenomenological-MSSM (pMSSM). We find
that none of these models can be excluded at 95% confidence by the current
analysis; nevertheless, many lie within the predicted reach of future LAT
analyses. With two years of data, we find that the LAT is currently most
sensitive to light LSPs (m_LSP < 50 GeV) annihilating into tau-pairs and
heavier LSPs annihilating into b-bbar. Additionally, we find that future LAT
analyses will be able to probe some LSPs that form a sub-dominant component of
dark matter. We directly compare the LAT results to direct detection
experiments and show the complementarity of these search methods.Comment: 24 pages, 9 figures, submitted to JCA
Black Hole Chromosphere at the LHC
If the scale of quantum gravity is near a TeV, black holes will be copiously
produced at the LHC. In this work we study the main properties of the light
descendants of these black holes. We show that the emitted partons are closely
spaced outside the horizon, and hence they do not fragment into hadrons in
vacuum but more likely into a kind of quark-gluon plasma. Consequently, the
thermal emission occurs far from the horizon, at a temperature characteristic
of the QCD scale. We analyze the energy spectrum of the particles emerging from
the "chromosphere", and find that the hard hadronic jets are almost entirely
suppressed. They are replaced by an isotropic distribution of soft photons and
hadrons, with hundreds of particles in the GeV range. This provides a new
distinctive signature for black hole events at LHC.Comment: Incorporates changes made for the version to be published in Phys.
Rev. D. Additional details provided on the effect of the chromosphere in
cosmic ray shower
Supersymmetry Without Prejudice at the LHC
The discovery and exploration of Supersymmetry in a model-independent fashion
will be a daunting task due to the large number of soft-breaking parameters in
the MSSM. In this paper, we explore the capability of the ATLAS detector at the
LHC ( TeV, 1 fb) to find SUSY within the 19-dimensional
pMSSM subspace of the MSSM using their standard transverse missing energy and
long-lived particle searches that were essentially designed for mSUGRA. To this
end, we employ a set of k previously generated model points in the
19-dimensional parameter space that satisfy all of the existing experimental
and theoretical constraints. Employing ATLAS-generated SM backgrounds and
following their approach in each of 11 missing energy analyses as closely as
possible, we explore all of these k model points for a possible SUSY
signal. To test our analysis procedure, we first verify that we faithfully
reproduce the published ATLAS results for the signal distributions for their
benchmark mSUGRA model points. We then show that, requiring all sparticle
masses to lie below 1(3) TeV, almost all(two-thirds) of the pMSSM model points
are discovered with a significance in at least one of these 11 analyses
assuming a 50\% systematic error on the SM background. If this systematic error
can be reduced to only 20\% then this parameter space coverage is increased.
These results are indicative that the ATLAS SUSY search strategy is robust
under a broad class of Supersymmetric models. We then explore in detail the
properties of the kinematically accessible model points which remain
unobservable by these search analyses in order to ascertain problematic cases
which may arise in general SUSY searches.Comment: 69 pages, 40 figures, Discussion adde
Pharmacokinetic of myriocin in rabbit’s eyes
Myriocin (Myr) is a suicide inactivator of ceramide synthesis with a complex lipid multifunctional structure. Its biological activity is exerted at very low doses, and thus highly performing quantitative method are
needed [1]. The pharmacological development of Myr to modulate ceramide levels also requires currently unavailable ADME information in healthy and pathological animal models
Quantum Radiation from a 5-Dimensional Rotating Black Hole
We study a massless scalar field propagating in the background of a
five-dimensional rotating black hole. We showed that in the Myers-Perry metric
describing such a black hole the massless field equation allows the separation
of variables. The obtained angular equation is a generalization of the equation
for spheroidal functions. The radial equation is similar to the radial
Teukolsky equation for the 4-dimensional Kerr metric. We use these results to
quantize the massless scalar field in the space-time of the 5-dimensional
rotating black hole and to derive expressions for energy and angular momentum
fluxes from such a black hole.Comment: references added, accepted for publication in Physical Review
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