1,269 research outputs found
Signatures for flow effects in s**(1/2) = 200 GeV proton-proton collisions
A simple model based on relativistic geometry and final-state hadronic
rescattering is used to predict pion source parameters extracted in two-pion
femtoscopy studies of proton-proton collisions at s**(1/2) = 200 GeV. From
studying the momentum and particle multiplicity dependences of these parameters
in the context of this model and assuming a very short hadronization time,
flow-like behavior is seen which resembles the flow behavior commonly observed
in relativistic heavy-ion collisions.Comment: 10 pages, 3 figures, submitted to Physical Revie
Measurements of the CKM angle
In this report we summarize the most recent results of measurements of the
angle of the Unitarity Triangle.Comment: 4 pages proceedings for CIPANP'09 conferenc
Analysis of co-located MODIS and CALIPSO observations near clouds
This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS (MODerate resolution Imaging Spectroradiometer) imager can refine our perceptions based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar measurements about the systematic aerosol changes that occur near clouds. <br><br> The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies – due mainly to wind drift and differences in view angle – do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. In maritime areas perceived cloud free, the global median distance to clouds below 3 km altitude is in the 4–5 km range
Regge-model predictions for K+Sigma photoproduction from the nucleon
We present Regge-model predictions for the p(gamma,K+)Sigma0 and
n(gamma,K+)Sigma- differential cross sections and photon-beam asymmetries in
the resonance region. The reaction amplitude encompasses the exchange of
K+(494) and K*+(892) Regge-trajectories, introducing a mere three free
parameters. These are fitted to the available p(gamma,K+)Sigma0 data beyond the
resonance region. The n(gamma,K+)Sigma- amplitude is obtained from the
p(gamma,K+)Sigma0 one through SU(2) isospin symmetry considerations.Comment: 4 pages, 2 figures; Proceedings Tenth Conference on the Intersections
of Particle and Nuclear Physics, San Diego, 200
Observation-Based Study on Aerosol Optical Depth and Particle Size in Partly Cloudy Regions
This study seeks to help better understand aerosol-cloud interactions by examining statistical relationships between aerosol properties and nearby low-altitude cloudiness using satellite data. The analysis of a global dataset of MODIS (Moderate Resolution Imaging Spectroradiometer) observations reveals that the positive correlation between cloudiness and aerosol optical depth (AOD) reported in earlier studies is strong throughout the globe and during both winter and summer. Typically, AOD is 30-50 higher on cloudier-than-average days than on less cloudy days. A combination of satellite observations and MERRA-2 global reanalysis data reveals that the correlation between cloud cover and AOD is strong for all aerosol types considered: sulfate, dust, carbon, and sea salt. The observations also indicate that in the presence of nearby clouds, aerosol size distributions tend to shift toward smaller particles over large regions of the Earth. This is consistent with a greater cloud-related increase in the AOD of fine mode than of coarse mode particles. The greater increase in fine mode AOD implies that the cloudiness-AOD correlation does not come predominantly from cloud detection uncertainties. Additionally, the results show that aerosol particle size increases near clouds even in regions where it decreases with increasing cloudiness. This suggests that the decrease with cloudiness comes mainly from changes in large-scale environment, rather than from clouds increasing the number or the size of fine mode aerosols. Finally, combining different aerosol retrieval algorithms demonstrated that quality assessment flags based on local variability can help identifying when the observed aerosol populations are affected by surrounding clouds
Extended-soft-core Baryon-Baryon Model II. Hyperon-Nucleon Interaction
The YN results are presented from the Extended-soft-core (ESC) interactions.
They consist of local- and non-local-potentials due to (i) One-boson-exchange
(OBE), with pseudoscalar-, vector-, scalar-, and axial-vector-nonets, (ii)
Diffractive exchanges, (iii) Two-pseudoscalar exchange, and (iv)
Meson-pair-exchange (MPE). This model, called ESC04, describes NN and YN in a
unified way using broken flavor SU(3)-symmetry. Novel ingredients are the
inclusion of (i) the axial-vector-mesons, (ii) a zero in the scalar- and
axial-vector meson form factors. We describe simultaneous fits to the NN- and
YN-data, using four options in the ESC-model. Very good fits were obtained.
G-matrix calculations with these four options are also reported. The obtained
well depths (U_\Lambda, U_\Sigma, U_\Xi) reveal distinct features of ESC04a-d.
The \Lambda\Lambda-interactions are demonstrated to be consistent with the
observed data of_{\Lambda\Lambda}^6He. The possible three-body effects are
investigated by considering phenomenologically the changes of the vector-meson
masses in a nuclear medium.Comment: preprint vesion 66 pages, two-column version 27 pages, 17 figure
Electroweak Symmetry Breaking and Proton Decay in SO(10) SUSY-GUT with TeV W_R
In a recent paper, we proposed a new class of supersymmetric SO(10) models
for neutrino masses where the TeV scale electroweak symmetry is SU(2)_L\times
SU(2)_R\times U(1)_{B-L} making the associated gauge bosons W_R and Z'
accessible at the Large Hadron Collider. We showed that there exists a domain
of Yukawa coupling parameters and symmetry breaking patterns which give an
excellent fit to all fermion masses including neutrinos. In this sequel, we
discuss an alternative Yukawa pattern which also gives good fermion mass fit
and then study the predictions of both models for proton lifetime. Consistency
with current experimental lower limits on proton life time require the squark
masses of first two generations to be larger than ~ 1.2 TeV. We also discuss
how one can have simultaneous breaking of both SU(2)_R\times U(1)_{B-L} and
standard electroweak symmetries via radiative corrections.Comment: 31 pages, 5 figures, 4 tables
Effects of an Adolescent Asthma Education Intervention on Knowledge, Intention, Behavior, Self-Efficacy and Self-Consciousness
In this study, we evaluated the effects of an asthma education intervention, guided by social cognitive theory, on knowledge, intention, behavior, self-efficacy, and self-consciousness. The sample consisted of 87 asthmatic adolescents in six middle and/or high schools in California. A non-equivalent comparison group design, with delayed intervention in the comparison group, was utilized. We implemented a modified version of the American Lung Association’s Kickin Asthma curriculum. Self-report questionnaires assessing the key study variables were administered at baseline, at immediate postintervention, and five weeks after the intervention. There were no statistically significant differences at post-test, controlling for pre-test values, for any of the study variables between the intervention (n = 51) and comparison groups (n = 35). After collapsing across groups, however, there were statistically significant improvements following the intervention for knowledge, intention, selected behavior variables, and self-efficacy. The evaluation of this theory-based asthma education intervention demonstrates the positive impact this curriculum can have on a sample of asthmatic adolescents
Remote sensing of cloud sides of deep convection: towards a three-dimensional retrieval of cloud particle size profiles
International audienceThe cloud scanner sensor is a central part of a recently proposed satellite remote sensing concept ? the three-dimensional (3-D) cloud and aerosol interaction mission (CLAIM-3D) combining measurements of aerosol characteristics in the vicinity of clouds and profiles of cloud microphysical characteristics. Such a set of collocated measurements will allow new insights in the complex field of cloud-aerosol interactions affecting directly the development of clouds and precipitation, especially in convection. The cloud scanner measures radiance reflected or emitted by cloud sides at several wavelengths to derive a profile of cloud particle size and thermodynamic phase. For the retrieval of effective size a Bayesian approach was adopted and introduced in a preceding paper. In this paper the potential of the approach, which has to account for the complex three-dimensional nature of cloud geometry and radiative transfer, is tested in realistic cloud observing situations. In a fully simulated environment realistic cloud resolving modelling provides complex 3-D structures of ice, water, and mixed phase clouds, from the early stage of convective development to mature deep convection. A three-dimensional Monte Carlo radiative transfer is used to realistically simulate the aspired observations. A large number of cloud data sets and related simulated observations provide the database for an experimental Bayesian retrieval. An independent simulation of an additional cloud field serves as a synthetic test bed for the demonstration of the capabilities of the developed retrieval techniques
Double Type-II Seesaw, Baryon Asymmetry and Dark Matter for Cosmic e^\pm Excesses
We construct a new realization of type-II seesaw for neutrino masses and
baryon asymmetry by extending the standard model with one light and two heavy
singlet scalars besides one Higgs triplet. The heavy singlets pick up small
vacuum expectation values to give a suppressed trilinear coupling between the
triplet and doublet Higgs bosons after the light singlet drives the spontaneous
breaking of lepton number. The Higgs triplet can thus remain light and be
accessible at the LHC. The lepton number conserving decays of the heavy
singlets can generate a lepton asymmetry stored in the Higgs triplet to account
for the matter-antimatter asymmetry in the Universe. We further introduce
stable gauge bosons from a hidden sector, which obtain masses and annihilate
into the Higgs triplet after spontaneous breaking of the associated non-Abelian
gauge symmetry. With Breit-Wigner enhancement, the stable gauge bosons can
simultaneously explain the relic density of dark matter and the cosmic
positron/electron excesses.Comment: 9 pages, 4 figures, minor rewording, final PRD version (in Press
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