872 research outputs found
The running coupling method with next-to-leading order accuracy and pion, kaon elm form factors
The pion and kaon electromagnetic form factors are calculated at
the leading order of pQCD using the running coupling constant method. In
calculations the leading and next-to-leading order terms in
expansion in terms of are taken into
account. The resummed expression for is found. Results of numerical
calculations for the pion (asymptotic distribution amplitude) are presented.Comment: 9 pages, 1 figur
Exclusive high- electroproduction: light-cone wave functions and electromagnetic form factors of mesons,
We apply the light-cone technique to electroproduction reaction long considered as a means of measuring the electromagnetic form
factor of the pion. We show that the interpretation of the long-standing puzzle
of large transverse cross section () in terms of the transition on the mesons in the light-cone proton is possible, but
requires quite a slow decrease of the F_{\rho\pi}(\q2) form factor. This
interpretation can be tested in the related reaction.
Corrections which are due to the final-state meson-baryon interactions (FSI)
are evaluated and are shown to amount to a effect at moderately large
\q2. Vanishing FSI with increasing - the color transparency phenomenon
- is shown to be very strong
SNAP satellite focal plane development
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics
Pion Form Factor in the NLC QCD SR approach
We present results of a calculation of the electromagnetic pion form factor
within a framework of QCD Sum Rules with nonlocal condensates and using a
perturbative spectral density which includes \mathcal{O}(\alpha_s)
contributions.Comment: 9 pages, 2 figures (embedded). Talk presented by the second author at
the Workshop on Physics of Fundamental Interactions, Institute of High Energy
Physics, Protvino, Russia, 22--25 December 200
Pseudovector components of the pion, pi^0 -> gamma gamma, and F_pi(q^2)
As a consequence of dynamical chiral symmetry breaking the pion
Bethe-Salpeter amplitude necessarily contains terms proportional to gamma_5
gamma.P and gamma_5 gamma.k, where k is the relative and P the total momentum
of the constituents. These terms are essential for the preservation of low
energy theorems, such as the Gell-Mann--Oakes-Renner relation and those
describing anomalous decays of the pion, and to obtaining an electromagnetic
pion form factor that falls as 1/q^2 for large q^2, up to calculable
ln(q^2)-corrections. In a simple model, which correlates low- and high-energy
pion observables, we find q^2 F_pi(q^2) ~ 0.12 - 0.19 GeV^2 for q^2 >~10 GeV^2.Comment: 15 pages, 2 figures, REVTE
Active cooling control of the CLEO detector using a hydrocarbon coolant farm
We describe a novel approach to particle-detector cooling in which a modular
farm of active coolant-control platforms provides independent and regulated
heat removal from four recently upgraded subsystems of the CLEO detector: the
ring-imaging Cherenkov detector, the drift chamber, the silicon vertex
detector, and the beryllium beam pipe. We report on several aspects of the
system: the suitability of using the aliphatic-hydrocarbon solvent PF(TM)-200IG
as a heat-transfer fluid, the sensor elements and the mechanical design of the
farm platforms, a control system that is founded upon a commercial programmable
logic controller employed in industrial process-control applications, and a
diagnostic system based on virtual instrumentation. We summarize the system's
performance and point out the potential application of the design to future
high-energy physics apparatus.Comment: 21 pages, LaTeX, 5 PostScript figures; version accepted for
publication in Nuclear Instruments and Methods in Physics Research
Person localization using sensor information fusion
Nowadays the incredible grow of mobile devices market led
to the need for location-aware applications. However, sometimes person
location is di cult to obtain, since most of these devices only have a GPS
(Global Positioning System) chip to retrieve location. In order to sup-
press this limitation and to provide location everywhere (even where a
structured environment doesn't exist) a wearable inertial navigation sys-
tem is proposed, which is a convenient way to track people in situations
where other localization systems fail. The system combines pedestrian
dead reckoning with GPS, using widely available, low-cost and low-power
hardware components. The system innovation is the information fusion
and the use of probabilistic methods to learn persons gait behavior to
correct, in real-time, the drift errors given by the sensors.This work is part-funded by ERDF - European Regional Development Fund through
the COMPETE Programme (operational programme for competitiveness) and by
National Funds through the FCT Fundao para a Cincia e a Tecnologia (Portuguese
Foundation for Science and Technology) within project FCOMP-01-0124-FEDER-
028980 (PTDC/EEI-SII/1386/2012). Ricardo also acknowledge FCT for the support
of his work through the PhD grant (SFRH/DB/70248/2010)
Light-cone QCD Sum Rules for the Baryon Electromagnetic Form Factors and its magnetic moment
We present the light-cone QCD sum rules up to twist 6 for the electromagnetic
form factors of the baryon. To estimate the magnetic moment of the
baryon, the magnetic form factor is fitted by the dipole formula. The numerical
value of our estimation is , which is in
accordance with the experimental data and the existing theoretical results. We
find that it is twist 4 but not the leading twist distribution amplitudes that
dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.
Does fix the Electromagnetic Form Factor at ?
We show that the decay is a reliable
source of information for the electromagnetic form factor of the pion at
by using general arguments to estimate, or
rather, put upper bounds on, the background processes that could spoil this
extraction. We briefly comment on the significance of the resulting
.Comment: 10 pages revtex manuscript, one figure--not included, U. of MD PP
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