4,058 research outputs found
Signature of Sub GeV Dark Matter particles at LHC and TEVATRON
In this letter, we investigate the production of light dark matter particles
at LHC in light of the model (N = 2 SUSY inspired) proposed in Ref. [1] and
demonstrate that they will be copiously produced if the colored messengers Fq
are lighter than 1 TeV. We expect up to a million events if the Fq mass is
about 500 GeV, assuming a ~1 inverse fb luminosity. In addition, we show that,
even if the Fq mass is above a few TeV, searches for Fq production at LHC are
promising because a kinematical signature can be used to separate the signal
from background. This signature is similar to that expected in supersymmetric
scenarios. Hence, our study shows that most of the Fq mass range could be
constrained using LHC data. This should encourage further studies since they
could infirm/confirm the MeV DM scenario.Comment: 4 page
Measuring the SUSY Breaking Scale at the LHC in the Slepton NLSP Scenario of GMSB Models
We report a study on the measurement of the SUSY breaking scale sqrt(F) in
the framework of gauge-mediated supersymmetry breaking (GMSB) models at the
LHC. The work is focused on the GMSB scenario where a stau is the
next-to-lightest SUSY particle (NLSP) and decays into a gravitino with lifetime
c*tau_NLSP in the range 0.5 m to 1 km. We study the identification of
long-lived sleptons using the momentum and time of flight measurements in the
muon chambers of the ATLAS experiment. A realistic evaluation of the
statistical and systematic uncertainties on the measurement of the slepton mass
and lifetime is performed, based on a detailed simulation of the detector
response. Accessible range and precision on sqrt(F) achievable with a counting
method are assessed. Many features of our analysis can be extended to the study
of different theoretical frameworks with similar signatures at the LHC.Comment: 28 pages, 12 figures (18 eps files). Revised version v2(published in
JHEP): Some important corrections and additions to v
The full detector simulation for the Atlas experiment: status and outlook
The simulation of the ATLAS detector is a major challenge, given the
complexity of the detector and the demanding environment of the LHC. The
apparatus, one of the biggest and most complex ever designed, requires a
detailed, flexible and, if possible, fast simulation which is needed already
today to deal with questions related to design optimization, to issues raised
by staging scenarios, and of course to enable detailed physics studies to lay
the basis for the first physics discoveries. Scalability and robustness stand
out as the most critical issues that are to be faced in the implementation of
such a simulation. In this paper we present the status of the present
simulation and the adopted solutions in terms of speed optimization,
centralization of services, framework facilities and persistency solutions.
Emphasis is put on the global performance when the different detector
components are collected together in a full and detailed simulation. The
reference tool adopted is Geant4.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 6 pages. PSN TUMT00
Aspects of GMSB Phenomenology at TeV Colliders
The status of two on-going studies concerning important aspects of the
phenomenology of gauge-mediated supersymmetry breaking (GMSB) models at TeV
colliders is reported. The first study deals with the characteristics of the
light Higgs boson spectrum allowed by the (minimal and non-minimal) GMSB
framework. Today's most accurate GMSB model generation and two-loop
Feynman-diagrammatic calculation of m_h have been combined. The Higgs masses
are shown in dependence of various model parameters at the messenger and
electroweak scales. In the minimal model, an upper limit on m_h of about 124
GeV is found for m_t = 175 GeV. The second study is focused on the measurement
of the fundamental SUSY breaking scale sqrt(F) at the LHC in the GMSB scenario
where a stau is the next-to-lightest SUSY particle (NLSP) and decays into a
gravitino with c*tau_NLSP in the range 0.5 m to 1 km. This implies the
measurement of mass and lifetime of long lived sleptons. The identification is
performed by determining the time of flight in the ATLAS muon chambers.
Accessible range and precision on sqrt(F) achievable with a counting method are
assessed.Comment: 22 pages, 9 figures (12 eps files). Report of the GMSB SUSY Working
Group, Workshop "Physics at TeV Colliders", Les Houches, 7-18 June 1999.
Revised version v3: A few typos correcte
Behaviour of a Geogrid Reinforced Embankment over Waste Material
The paper deals with the monitoring of a geogrid reinforced embankment, 5.0 m high and 600 m long, built to contain additional waste material in the municipal landfill in Modena (Northern Italy). The embankment was founded directly over the waste already placed in the landfill, consisting of\u27 compressible and dishomogeneus material, varying from solid urban waste to muddy industrial material. The geotechnical parameters assumed to characterize the fill soil and the waste material of the foundation soil are described. The settlements of the embankment and the forces and strains in the geogrids were monitored from the beginning of the construction until some months later. The instrumentation used in order to perform this control is described. The actual results are compared with those obtained from the design model and with other field tests concerning geogrid reinforced structures
Heterogeneity of resting and hyperemic myocardial blood flow in healthy humans
Objective: Absolute myocardial blood flow (MBF) is not well-defined in large normal populations, and appears to be heterogeneous in both humans and animals. These factors contribute to the difficulties in defining resting MBF to hibernating myocardium. We therefore assessed absolute baseline and hyperemic MBF in a large population of normal humans. Methods: MBF was quantified by positron emission tomography with oxygen-15-labeled water at baseline and during hyperemia induced by either adenosine or dipyridamole in 131 men and 38 women, aged 21-86 (mean 46±12) years. MBF was corrected for workload using the rate-pressure product (RPP). Results: Uncorrected baseline MBF ranged from 0.590 to 2.050 (mean 0.985±0.230) ml/min/g (coefficient of variation=27%), and corrected MBF from 0.736 to 2.428 (mean 1.330±0.316) ml/min/g (coefficient of variation=24%). MBF in the inferior region was significantly (P<0.0001) lower than either the anterior or lateral regions. Baseline MBF in females was significantly (P<0.001) higher than in males. Conclusions: These results confirm the heterogeneity of MBF in normals and highlight the difficulty in establishing the lower limit of normal MB
Fast shower simulation in the ATLAS calorimeter
The time to simulate pp collisions in the ATLAS detector is largely dominated by the showering of electromagnetic particles in the heavy parts of the detector, especially the electromagnetic barrel and endcap calorimeters. Two procedures have been developed to accelerate the processing time of electromagnetic particles in these regions: (1) a fast shower parameterisation and (2) a frozen shower library. Both work by generating the response of the calorimeter to electrons and positrons with Geant 4, and then reintroduce the response into the simulation at runtime.
In the fast shower parameterisation technique, a parameterisation is tuned to single electrons and used later by simulation. In the frozen shower technique, actual showers from low-energy particles are used in the simulation. Full Geant 4 simulation is used to develop showers down to ~1 GeV, at which point the shower is terminated by substituting a frozen shower. Judicious use of both techniques over the entire electromagnetic portion of the ATLAS calorimeter produces an important improvement of CPU time. We discuss the algorithms and their performance in this paper
The ATLAS Simulation: an LHC Challenge
The simulation program for the ATLAS experiment at CERN is currently in a full operational mode and integrated into the ATLAS common analysis framework, Athena. The OO approach, based on GEANT4, and in use during the DC2 data challenge has been interfaced within Athena and to GEANT4 using the LCG dictionaries and Python scripting. The robustness of the application was proved during the DC2 data challenge. The Python interface has added the flexibility, modularity and interactivity that the simulation tool requires in order to be able to provide a common implementation of different full ATLAS simulation setups, test beams and cosmic ray applications. Generation, simulation and digitization steps were exercised for performance and robustness tests. The comparison with real data has been possible in the context of the ATLAS Combined Test Beam (2004) and ongoing cosmic ray studies
La enseñanza de la psicolgĂa en los estados unidos de norte amĂ©rica
DescripciĂłn del entrenamiento de los psicĂłlogos en Estados Unidos. Sobre los tĂtulos universitarios, la investigaciĂłn y las caracterĂsticas de los Departamentos de PsicologĂa en Estados Unidos - Muestra de los cursos impartidos en la Universidad, divididos por tem
- …