95 research outputs found
Unified Chew-Mandelstam SAID analysis of pion photoproduction data
A unified description of single-pion photoproduction data, together with
pion- and eta-hadroproduction data, has been achieved in a Chew-Mandelstam
parametrization which is consistent with unitarity at the two-body level.
Energy-dependent and single-energy partial wave analyses of pion
photoproduction data have been performed and compared to previous SAID fits and
multipoles from the Mainz and Bonn-Gatchina groups.Comment: 11 pages, 9 figures, and 2 table
Physics Opportunities with Meson Beams
Over the past two decades, meson photo- and electro-production data of
unprecedented quality and quantity have been measured at electromagnetic
facilities worldwide. By contrast, the meson-beam data for the same hadronic
final states are mostly outdated and largely of poor quality, or even
nonexistent, and thus provide inadequate input to help interpret, analyze, and
exploit the full potential of the new electromagnetic data. To reap the full
benefit of the high-precision electromagnetic data, new high-statistics data
from measurements with meson beams, with good angle and energy coverage for a
wide range of reactions, are critically needed to advance our knowledge in
baryon and meson spectroscopy and other related areas of hadron physics. To
address this situation, a state of-the-art meson-beam facility needs to be
constructed. The present paper summarizes unresolved issues in hadron physics
and outlines the vast opportunities and advances that only become possible with
such a facility.Comment: 46 pages, 10 figures, 4 table
Experimental Tests of QCD Scaling Laws at Large Momentum Transfer in Exclusive Light-Meson Photoproduction
We evaluated CLAS Collaboration measurements for the 90◦ meson photoproduction off the nucleon using a tagged photon beam spanning the energy interval s = 3–11 GeV2. The results are compared with the “quark counting rules” predictions
Mjerenja u JLab s realnim fotonima pomoću fotonskog označivača u dvorani B
Data on real-photon induced reactions have been taken using the Tagged Photon Facility (TPF) and the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility (JLab) during the first year of running in Hall B. These data have been taken for the purpose of investigating the electromagnetic structure of mesons, nucleons, and nuclei. This report summarizes the status of these experiments.Tijekom prve godine rada sustava s označavanjem fotona u dvorani B pri ubrzivaču s neprekidnim elektronskim snopom (CEBAF) u Thomas Jeffersonovom nationalnom akceleratorskom pogonu (JLab) postigli su se podaci o raznim fotonima izazvanim reakcijama. Tim se podacima istražuju elektromagnetske strukture mezona, nukleona i atomskih jezgri. Ovaj je rad sažetak tih mjerenja
Extended SAID Partial-Wave Analysis of Pion Photoproduction
A unified Chew-Mandelstam description of single-pion photoproduction data,
together with pion- and eta-hadroproduction data, has been extended to include
measurements carried out over the last decade. We consider photo-decay
amplitudes evaluated at the pole with particular emphasis on ng couplings and
the influence of weighting on our fits. Both energy-dependent and single-energy
analysis (energy-binned data) are considered.Comment: 30 pages, 18 figures, and 14 table
Is the LHCb plausible in the GlueX total cross sections ?
New high-statistics total cross section data for from
the GLUonic EXcitation (GlueX) experiment are fitted in a search for the exotic
state observed by the Large Hadron Collider beauty (LHCb)
collaboration. The integrated luminosity of this GlueX experiment was about
. The fits show that destructive interference involving
an -wave resonance and associated non-resonance background produces a sharp
dip structure about below the LHCb mass, in the same location
as a similar structure is seen in the data. Limitations of the employed model
and the need for improved statistics are discussed.Comment: 4 pages, 3 figures, 2 table
Radiative Decay Width of Neutral non-Strange Baryons from PWA
An overview of the GW SAID and ITEP groups effort to analyze pion
photoproduction on the neutron-target will be given. The disentanglement the
isoscalar and isovector EM couplings of N* and Delta* resonances does require
compatible data on both proton and neutron targets. The final-state interaction
plays a critical role in the state-of-the-art analysis in extraction of the
gamma n --> pi N data from the deuteron target experiments. It is important
component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH programsComment: 7 pages, 7 figures, 1 table; Proceedings of International Conference
Dark Matter, Hadron Physics and Fusion Physics, Messina, Italy, Sept. 2014;
will be published in EPJ Web of Conference
Pseudoscalar and Scalar Meson Photoproduction Interpreted by Regge Phenomenology
We have evaluated pseudoscalar and scalar neutral pion photoproduction in
and above the resonance
region and within Regge phenomenology. Our fit, including GlueX
pseudoscalar photoproduction data, shows that previous SLAC
measurements for above
are at variance with SLAC data with more recent measurements made by GlueX in
vicinity of . The Regge model predicts that the beam
polarization asymmetry of the scalar meson is opposite to that of
pseudoscalar meson photoproduction, however, the cross sections are similar.
While the vector natural parity meson exchange is dominant in both cases, the
contribution of the pseudovector unnatural parity meson exchange is very small.
Using Regge phenomenology, we predicted high energy behavior for double
polarized observables , , , and
for the reactions and .Comment: 8 pages, 5 figures, several small glitches were fixe
Conceptual Design of Beryllium Target for the KLF Project
The Kaon Production Target (KPT) is an important component of the proposed
K-Long facility which will be operated in JLab Hall~D, targeting strange baryon
and meson spectroscopy. In this note we present a conceptual design for the
Be-target assembly for the planned K-Long beam line, which will be used along
with the GlueX spectrometer in its standard configuration for the proposed
experiments. The high quality 12-GeV CEBAF electron beam enables production of
a K flux at the GlueX target on the order of , which
exceeds the K flux previously attained at SLAC by three orders of
magnitude. An intense K beam would open a new window of opportunity not
only to locate "missing resonances" in the strange hadron spectrum, but also to
establish their properties by studying different decay channels systematically.
The most important and radiation damaging background in K production is due
to neutrons. The Monte Carlo simulations for the proposed conceptual design of
KPT show that the resulting neutron and gamma flux lead to a prompt radiation
dose rate for the KLF experiment that is below the JLab Radiation Control
Department radiation dose rate limits in the experimental hall and at the site
boundary, and will not substantially affect the performance of the
spectrometer.Comment: 9 pages, 9 figure
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