636 research outputs found
-potential: a numerical study
We report the results of recent lattice simulations aimed at computing the
and potential energies in the singlet and the octet (adjoint)
representation.Comment: 7 pages, 4 figures, poster presented at the 31st International
Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013,
Mainz, German
Resonant plasma excitation by single-cycle THz pulses
In this paper, an alternative perspective for the generation of millimetric high-gradient resonant plasma waves is discussed. This method is based on the plasma-wave excitation by energetic single-cycle
THz pulses whose temporal length is comparable to the plasma wavelength. The excitation regime discussed in this paper is the quasi-nonlinear regime that can be achieved when the normalized vector potential of the driving THz pulse is on the order of unity. To investigate this regime and determine the strength of the excited electric elds, a Particle-In-Cell (PIC) code has been used. It has been found that by exploiting THz pulses with characteristics currently available in laboratory, longitudinal electron plasma waves with electric gradients up to hundreds MV/m can be obtained. The mm-size nature of
the resonant plasma wave can be of great utility for an acceleration scheme in which high-brightness electron bunches are injected into the wave to undergo a strong acceleration. The long-size nature of the acceleration bucket with respect to the short length of the electron bunches can be handled in a more robust manner in comparison with the case when micrometric waves are employed
On the color structure of Yang-Mills theory with static sources in a periodic box
We present an exploratory numerical study on the lattice of the color
structure of the wave functionals of the SU(3) Yang-Mills theory in the
presence of a static pair. In a spatial box with periodic boundary
conditions we discuss the fact that all states contributing to the Feynman
propagation kernel are global color singlets. We confirm this numerically by
computing the correlations of gauge-fixed Polyakov lines with color-twisted
boundary conditions in the time direction. The values of the lowest energies in
the color singlet and octet external source sectors agree within statistical
errors, confirming that both channels contribute to the lowest (global singlet)
state of the Feynman kernel. We then study the case of homogeneous boundary
conditions in the time direction for which the gauge-fixing is not needed. In
this case the lowest energies extracted in the singlet external source sector
agree with those determined with periodic boundary conditions, while in the
octet sector the correlator is compatible with being null within our
statistical errors. Therefore consistently only the singlet external source
contribution has a non-vanishing overlap with the null-field wave functional.Comment: 9 pages, 3 figure
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
Hardware development for the surface tension driven convection experiment aboard the USML-1 spacelab mission
The Surface Tension Driven Convection Experiment is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for March 1992. Hardware is under development to establish the experimental conditions and perform the specified measurements, for both ground based research and the flight experiment in a Spacelab single rack. Major development areas include an infrared thermal imaging system for surface temperature measurement, a CO2 laser and control system for surface heating, and for flow visualization, a He-Ne laser and optical system in conjunction with an intensified video camera. For ground based work the components of each system were purchased or designed, and tested individually. The three systems will be interfaced with the balance of the experimental hardware and will constitute a working engineering model. A description of the three systems and examples of the component performance is given along with the plans for the development of flight hardware
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
Reduction of computer usage costs in predicting unsteady aerodynamic loadings caused by control surface motions: Computer program description
A digital computer program was developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge and trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges were extracted analytically as a preliminary step to solving the integral equation of collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accomodated
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
Child Outcomes of Having a Parent with an AUD
Alcohol Use Disorder (AUD) affects not only the diagnosed individuals, but also those around them. This review explores how an AUD can affect parenting styles and, in turn, children’s development in four main areas of development (physical health, academic abilities, social development, and mental health). Generally, parents with an AUD negatively impact the child’s development (weight issues, poor academic skills, and aggressiveness). Existing limitations of the literature and future research directions are discussed, such as the use of cross-sectional studies and need for more clinical and longitudinal studies. Also, research on this topic extensively covers the situations of children within their nuclear families, but less is known about alternate family structures. Lastly, real-world implications of the findings are discussed
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