6,656 research outputs found
Spin Physics in the Resonance Region
Recent results from Jefferson Lab on measurement of inclusive double
polarization asymmetries in the nucleon resonance region are discussed.
Preliminary results on the first moment of the structure function g_1(x,Q^2)
for protons, and on the generalized Gerasimov-Drell-Hearn integral for neutrons
are presented as well. The first moment for protons shows a strong Q^2
dependence below Q^2 = 1 GeV^2, and changes sign near Q^2 = 0.3 GeV^2. Strong
double polarization asymmetries are observed in exclusive electroproduction of
pions from polarized protons.Comment: 9 pages, 6 figures, Talk presented at the 3rd International
Conference on Perspectives in Hadronic Physics, Trieste May 7-11, 200
Strangeness Physics with CLAS at JLab
A brief overview of strangeness physics with the CLAS detector at JLab is
given, mainly covering the domain of nucleon resonances. Several excited states
predicted by the symmetric constituent quark model may have significant
couplings to the K-Lambda or K-Sigma channels. I will discuss data that are
relevant in the search for such states in the strangeness channel, and give an
outlook on the future prospects of the N* program at JLab with electromagnetic
probes.Comment: 9 pages, 7 figures, Conference on Strangeness in Nuclei, SENDAI 200
Evidence of new nucleon resonances from electromagnetic meson production
The study of nucleon resonances in electromagnetic meson production with the
CLAS detector is discussed. The electromagnetic interaction is complementary to
pion scattering in the exploration of the nucleon excitation spectrum. Higher
mass states often decouple from the channel and are not seen in . Photoproduction of mesons, such as , and
may be more sensitive to many of these states. The CLAS
detector, combined with the use of energy-tagged polarized photons and
polarized electrons, as well as polarized targets and the measurement of recoil
polarization, are the tools needed for a comprehensive nucleon resonance
program. Some of the recently published high statistics data sets had
significant impact on further clarifying the nucleon excitation spectrum.Comment: 6 pages, 4 figures, presented at MESON 2012, Krako
The Nucleon Structure in the Resonance Region
Recent results on inclusive and exclusive electroproduction experiments at
Jefferson Lab are discussed. They include measurements of the spin responses
for protons and neutrons in and above the resonance region, exclusive single
and double pion production to measure resonance transition multipoles, and
searches for predicted yet unobserved quark model states. A brief outlook into
the new domain of generalized parton distribution is given as well.Comment: 13 pages, 11 figures, Talk at the International Conference on Mesons
and Light Nuclei, Prague July 2 - 6, 200
Study of excited nucleons and their structure
Recent advances in the study of excited nucleons are discussed. Much of the
progress has been achieved due to the availability of high precision meson
production data in the photoproduction and electroproduction sectors, the
development of multi-channel partial wave analysis techniques, and advances in
Lattice QCD with predictions of the full excitation spectrum.Comment: 6 pages, 4 figures, Invited talk at NSTAR 201
Excitation of Nucleon Resonances
I discuss developments in the area of nucleon resonance excitations that are
necessary to bring our understanding of nucleon structure in the regime of
strong QCD to a qualitatively new level. They involve the collection of high
quality data in various channels, a more rigorous approach in the search for
"missing" quark model states, an effort to compute some critical quantities in
nucleon resonance excitations from first principles, i.e. QCD, and a proposal
aimed at obtaining an understanding of a fundamental quantity in nucleon
structure.Comment: 9 pages, 2 figure
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