565 research outputs found
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
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
Molecular evidence of incipient speciation within Anopheles gambiae s.s. in West Africa
We karyotyped and identified by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis Anopheles gambiae s.s. samples collected in several African countries. The data show the existence of two non-panmictic molecular forms, named S and M, whose distribution extended from forest to savannahs, Mosquitoes of the S and M forms are homosequential standard for chromosome-2 inversions in forest areas. In dry savannahs, S is characterized mainly by inversion polymorphisms typical of Savanna and Bamako chromosomal forms, while M shows chromosome-2 arrangements typical of Mopti and/or Savanna and/or Bissau, depending on its geographical origin. Chromosome-2 inversions therefore seem to be involved in ecotypic adaptation rather than in mate-recognition systems. Strong support for the reproductive isolation of S and M in Ivory Coast comes from the observation that the kdr allele is found at high frequencies in S specimens and not at all in chromosomal identical M specimens. However, the kdr allele does not segregate with molecular forms in Benin
Theta dependence of the vacuum energy in the SU(3) gauge theory from the lattice
We report on a precise computation of the topological charge distribution in
the SU(3) Yang--Mills theory. It is carried out on the lattice with high
statistics Monte Carlo simulations by employing the definition of the
topological charge suggested by Neuberger's fermions. We observe significant
deviations from a Gaussian distribution. Our results disfavour the theta
behaviour of the vacuum energy predicted by instanton models, while they are
compatible with the expectation from the large Nc expansion.Comment: Plain latex, 4 pages, 2 figure
Age limit in bronchiolitis diagnosis: 6 or 12 months?
Aim: The most frequent cause of lower respiratory tract infection in infants is bronchiolitis. Up to now there is no agreement on the upper limit age of bronchiolitis. Our aim was to identify if there are clinical differences in infants hospitalized for bronchiolitis between 0–6 months and 6–12 months of age. A secondary aim was to establish whether there was differences in terms of recurrent wheezing at 12, 24, and 36 months of follow-up. Methods: We retrospectively analyzed clinical and virological records of 824 infants hospitalized for bronchiolitis during 11 consecutive epidemic seasons. From each infant at admission to the hospital nasopharyngeal washing was collected, clinical severity was assessed and clinical data were extracted from a structured questionnaire. At 12–24–36 months after discharge, parents were interviewed seeking information on recurrent wheezing. Results: A total of 773 infants (Group1) were ≤6 months of age, while 51 were >6 months (Group 2). No differences between family history for atopy and passive smoking exposure were observed between the two groups. Respiratory syncyzial virus was detected more frequently in Group 1 and human bocavirus in Group 2. The clinical severity score (p = 0.011) and the use of intravenous fluids (p = 0.0001) were higher in Group 1 with respect to Group 2 infants. At 36 months follow-up 163/106 (39.4%) Group 1 and 9/9 Group 2 infants experienced recurrent wheezing (p = 0.149). Conclusion: We demonstrated that 0-6 months old infants bronchiolitis differs from > 6 months bronchiolitis
Non perturbative renormalization in coordinate space
We present an exploratory study of a gauge-invariant non-perturbative
renormalization technique. The renormalization conditions are imposed on
correlation functions of composite operators in coordinate space on the
lattice. Numerical results for bilinears obtained with overlap and
O(a)-improved Wilson fermions are presented. The measurement of the quark
condensate is also discussed.Comment: Lattice2003(improve), 3 page
Non-Perturbative Renormalisation of Composite Operators
It is shown that the renormalisation constants of two quark operators can be
accurately determined (to a precision of a few per-cent using 18 gluon
configurations) using Chiral Ward identities. A method for computing
renormalisation constants of generic composite operators without the use of
lattice perturbation theory is proposed.Comment: 3 pages, uuencoded compressed postscript file, to appear in the
Proceedings of the International Symposium on Lattice Field Theory, Dallas,
Texas, 12-17 October 1993, Southampton Preprint 93/94-0
ROBOT-MEDIATED AND CLINICAL SCALES EVALUATION AFTER UPPER LIMB BOTULINUM TOXIN TYPE A INJECTION IN CHILDREN WITH HEMIPLEGIA
Objective: The aim of this pilot study was to examine changes in different aspects of impairment, including spasticity in the upper limbs, of hemiplegic children following botulinum toxin type A intervention. Progress was assessed using standard clinical measurements and a robotic device. Design: Pre-post multiple baseline. Subjects: Six children with hemiplegia. Methods: Botulinium toxin type A injections were administered into the affected upper limb muscles. Outcomes were evaluated before and one month after the injection. Outcome assessments included: Melbourne Scale, Modified Ashworth Scale (MAS) and Passive Range of Motion. Furthermore, a robotic device was employed as an evaluation tool. Results: Patients treated with botulinum toxin type A had significantly greater reduction in spasticity (MAS, p < 0.01), which explains an improvement in upper limb function and quality movement measured with the Melbourne Scale (p < 0.01). These improvements are consistent with robot-based evaluation results that showed statistically significant changes (p < 0.01) following botulinum toxin type A injections. Conclusion: The upper limb performs a wide variety of movements. The multi-joint nature of the task during the robotmediated evaluation required active control of joint interaction forces. There was good correlation between clinical scales and robotic evaluation. Hence the robot-mediated assessment may be used as an additional tool to quantify the degree of motor improvement after botulinum toxin type A injections
Intense terahertz pulses from SPARC-LAB coherent radiation source
The linac-based Terahertz source at the SPARC_LAB test facility is able to gene
rate highly intense Terahertz broadband
pulses
via
coherent transition radiation (CTR) from high brightness electron beams. The THz pulse duration is typically
down to 100 fs RMS and can be tuned through the electron bunch duration and shaping. The measured stored energy in a
single THz pulse has reached 40
ÎĽ
J, which corresponds to a peak
electric field of 1.6 MV/cm at the THz focus. Here we
present the main features, in particular spatial and sp
ectral distributions and energy
characterizations of the
SPARC_LAB THz source, which is very competitive for investigations in Condensed Matter, as well as a valid tool for
electron beam longitudinal diagnostics
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