QNP Workshop Abstracts
Quark Nuclear Physics Workshop Abstracts
Meson production in nucleon-nucleon collisions
Please guess from the title !
Spin Structure Physics at RHIC
In the next few years RHIC will come on line with the ability to
provide high luminosity polarized proton - polarized proton
collisions at unprecidented energies. Detectors such as STAR
will be able to investigate the spin of the glue, delta G,
at low x via direct photon-jet and jet-jet channels. The
polarization of sea quarks can be investigated in Drell-Yan
and W,Z production. The measurment program, detector capabilities,
and time scales will be discussed in relationship to other
experiments planned at other facilities.
Exchange currents in radiative hyperon decays
The radiative decay widths of decuplet hyperons are evaluated in a chiral
constituent quark model including electromagnetic exchange currents
between quarks. Exchange currents contribute significantly to the E2
transition amplitude, while they largely cancel for the M1 transition
amplitude. Strangeness suppression of the radiative hyperon decays is
found to be weakened by exchange currents. Differences and similarities
between our results and other recent model predictions are discussed.
Interface of quark and hadronic degrees of freedom and color transparency
Relying on the quark-hadron duality one can
take advantage of each of the two approaches to
(virtual) photoproduction of vector mesons
off nuclei. QCD gauge invariance in quark
representation dictates a strong cancellation
between diagonal and off-diagonal amplitudes
in hadronic basis (color transparency). The
latter is, however, more effective describing
quantum interference phenomena important at
low and intermediate energies.
Near-Threshold Phi Production in pp Collisions and the Strangeness
Content of the Nucleon
The production of light vector mesons (phi,omega) in pp reactions has
been measured in a kinematically complete experiment using the DISTO spectromet
er at SATURNE. The extracted phi/omega production ratio is compared to estimates
based on the OZI rule and possible implications for the strange quark content o
f the nucleon are discussed. The relation to proton/antiproton annihilation and
nucleon spin structure experiments is briefly reviewed.
Structure of Bound Nucleon and QCD Sum Rules
Relativistic analysis of a bounded nucleon
is presented from point of view of nuclear physics.
A connexion with some models for nucleon structure
is shown. The QCD sume rules are rewritten for a
bounded nucleon. A possibilty of the QCD sume rules
extraction from light nuclei data is dicussed.
LISS Physics: ("All the Questions for which We Always Wanted to Know the
Answers") -- Parts I, II?
!!! THIS IS NOT AN ABSTRACT !!!:
Rather than giving a LISS Physics "overview" (which the guess is
that most people have heard or at least have heard about), one
would try to present current understanding of a few selected
Phsics topics at LISS (e.g., near-threshold charm production,
polarization observables in Color Transparency, etc. ... the
exact topics to be decided), in one or two short talks with the
aim of getting some feedback. Locally there was some discussion
that it might be useful to have such a talk (or talks) earlier
rather than later in the workshop. I am planning on coming for
the beginning and will stay most of the second week. Les Bland
and Steve Vigdor will be coming the second week as that is IU
spring break. Les (I believe) would also be prepared to discuss
aspects of LISS Physics -- but I will let him speak for himself.
THIS NON-ABSTRACT PROVIDED FOR DISCUSSION/ITERATION!
The experimental program at COSY
The cooler synchrotron COSY-Juelich provides phase space cooled
proton beams in the momentum range from 0.27 GeV/c up to 3.5 GeV/c.
A particle beam of high quality is very favourable for precision
experiments and essential e.g. for meson threshold production
as the first time impressively demonstrated by the pion
production data from Bloomington, IUCF.
The high resolution studies in the
u- and d-quark systems performed at IUCF and CELSIUS are extended
to the strangeness sector at COSY.
All COSY experiments are designed for kinematically complete
measurements with full soid angle coverage. Such measurements
allow detailed analysis of multiparticle reactions in different
channels.
The physics program at COSY will be presented including first
results as well as future plans.
The experimental status of the spin structure functions,g1 and g2,
on the neutron and proton
A review will be given on the latest measurements on the Spin Structure
Functions of the Nucleon. This will include new information from the
recently completed E155 measurements At Slac, which measured very
high precision measurements on both the proton and neuton from very low
momentum tgransfer to 38 GeV2. The neuton target for E155 was
purified LI(6)D which reached pplarizations of nearly 30 % with
very hish radiation resistance. It is expected at the
time of the conference the results will be available for the asymmetry
for the deuteron from this material and it will be compared to
the results form E143 and the SMC experiments. The
status of the origin of the nucleon spin from this data
and the accuracy of the extraction of the quark helicity
decomposition will be presented.
Heavy Quarks in Polarized Structure Functions
Please guess from the title !
Quark Asymmetries in the Proton
Asymmetries in the proton's sea quark distributions,
such as those between u-bar & d-bar, s & s-bar and
c & c-bar, are reviewed. In addition, the mechanisms
for the breaking of SU(2)_spin x SU(2)_flavour symmetry
in the valence quark sector are examined in view of
recent analyses of proton and deuteron structure
function data at large x.
Pion Nucleon Scattering and the Structure of the first Excited States of
the Nucleon
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Heavy-quark expansion and the strangeness content of the proton
We show that there is a rigorous sum rule for the
Ellis-Jaffe moment if heavy-quarks are neglected.
There is a simple rule for the correction due to
each heavy quark.
Inside Mesons: Coupling Constants and Form Factors
Recent investigations of meson coupling constants
such as rho-pi-pi and gamma-pi-rho from non-perturbative
QCD modeling will be reported. The approach employs
dressed quark propagators that incorporate the main
features from recent work on Dyson-Schwinger equation studies
and model field theories. Form factors will also be
considered and initial explorations at finite temperature
will be will described.
Quark Deconfinement and Chiral Restoration at Finite Chemical Potential
Please guess from the title !
Recent progress in the study of off-forward parton distributions
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Confinement Physics in QCD
The confinement mechanism in QCD is studied in
terms of the dual Higgs picture using the lattice
QCD in the maximally abelian gauge.
The gluon propagator which leads to confinement
is extracted from the direct calculation of
the lattice QCD simulation.
We study also the close relation between monopoles
and instantons, and their correlation can be
understood in terms of the gluon configuration.
Dual Higgs Theory for Confinement Phenomena
Based on the dual superconductor picture,
we study confiement, monopoles and the gluon
configuration in the maximally abelian (MA) gauge.
Abelian dominance for the confinement can be
analytically proved by regarding the off-diagonal
angle variable as a random variable in the lattice
formaism.
Using the lattice QCD simulation, the monopole is
found to accompany with a large gluon fluctuation
in the MA gauge, and this large fluctuation
leads to the area law of the Wilson loop.
We derive the direct relation between the string
tension (confinement force) and the monopole
density in the analytical way.
Isospin violation in the pion-nucleon system
Please guess from the title !
Exchange terms in the constituent quark-meson coupling model
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Baryon excitations in the deformed oscillator quark model
We study excited baryons in a deformed
oscillator quark model.
Observed spectrum of excited nucleons appear
to form rotational bands,
which imply spatially deformed intrinsic states.
We show that this is also the case for SU(3)
baryons, suggesting that it reflects flavor-independent
gluon dominant dynamics.
In order to see further the property of deformation,
we study electromagnetic decays of excited baryons.
We find that the deformation is important particularly
for the Roper resonance.
Dual Ginzburg-Landau theory and Quark Nuclear Physics
We have been studying non-perturbative phenomena of QCD in terms of
the dual Ginzburg-Landau (DGL) theory. The DGL theory use the
concept of the dual Higgs mechanism for color confinement.
The recent lattice QCD studies support the essential aspect of this
mechanism as the appearence of color monopole and the abelian dominance
in the long range phenomena.
We apply the DGL theory on Quark Nuclear Physics, where hadrons
and nuclei are described in terms of quarks and gluons.
We shall discuss the derivation of linear potential, chiral symmetry
breaking, meson spectrum and the behavior of the QCD vacuum at finite
temperature.
A Polarized e-p Facility for LISS
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Novel QCD Phenomena and the Abelian Correspondence Principle
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Shadowing in neutrino deep inelastic scattering and the determination
of the strange quark distribution
Please guess from the title !
Topology in the zero modes enhancement (ZME) model of the QCD vacuum.
Please guess from the title !
Recent Progress in the Quark Meson Coupling Model
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Public Lecture "Some Recent Advances in Radio-diagnostics and Radio-therapy"
Technological innovation continues to impact greatly
medical diagnosis and care . Many of the advances are derived from
physics principles and techniques . Two recent example discussed are
the development of digital detectors for X-ray diagnosis and the
application of high energy charged particles in radiation therapy .
The replacement of X-ray film by digital readout detectors will have
a dramatic effect on dagnosis both through the improved contrast and
also by the ability to immediately have the information in a form
suitable for telemedicine .
About 120,000 people still die each year in the USA alone due to lack
of local tumor control in the absence of distant metastases .
One way of improving local control is to replace high energy X-ray
beams with charged particles which have a much better depth - dose
profile . Many facilities are being developed around the world to do
this including one at Indiana University which will be described .
Lattice Calculation of the Strangeness Magnetic Moment of the Nucleon
I report on a recent lattice QCD calculation
of the strangeness magnetic moment of the nucleon.
Our result is G_M^s(0)= -0.36\pm 0.20 . The
sea contributions from the u and d quarks are
about 80% larger. However, they cancel to a large
extent due to their electric charges, resulting
in a smaller net sea contribution of
-0.097\pm 0.037 mu_N to the nucleon magnetic
moment. As far as the neutron to proton magnetic
moment ratio is concerned, this sea contribution
tends to cancel out the cloud-quark effect from
the Z-graphs and results in a ratio of -0.68
\pm 0.04 which is close to the SU(6) relation
and the experiment. The strangeness Sachs
electric mean-square radius is found to be
small and negative.
Chiral symmetry restoration and parity mixing
Please guess from the title !
Direct Quark Processes in the Weak YN Interaction
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Is SU(3) Chiral Perturbation Theory an Effective Field Theory?
I will argue that the use of
dimensional regularization in such calculations leads to spurious
convergence problems which can be ameliorated if one keeps only the
model-independent long-distance loop pieces. This makes things look more
like the quark model!!
Experiments at LISS (charm and/or strangeness)
I would be happy to talk about specific ideas for
experiments at a facility such as LISS. I believe
that Will Jacobs might be presenting some of these
ideas during the first week of the workshop.
Depending on the interest of the participants, I
can elaborate on the possibilities of studying
the following at LISS: open-charm production in
pp collisions, strangeness content of the proton
via p --> p+phi fragmentation, or other topics.
Ideally, Jacobs' talk will generate some
suggestions for measurements from the other
workshop participants which I might be able to
assess while in Adelaide (assuming good computer
links to the US), and subsequently report on at
the workshop.
Heavy Hybrids
Gluonic excitations are studied in the adiabatic
approximation using QCD Coulomb gauge motivatied
Hamiltonian.
Baryons in a covariant diquark-quark model
Baryons in a covariant diquark-quark model
Abstract: In a model where constituent quarks and diquarks
interact through quark exchange the Bethe-Salpeter
equation in ladder approximation for the nucleon
and delta is solved. Quark and diquark confinement
is effectively parametrized by
choosing appropriately modified propagators. The
coupling to external currents is implemented
via nontrivial vertex functions for quarks and
diquarks to ensure gauge invariance at the
constituent level. Nucleon matrix elements
are evaluated in a generalized impulse
approximation, and electromagnetic, pionic
and axial form factors are calculated.(*)
(*) G.Hellstern, R. Alkofer, M. Oettel,
H. Reinhardt, Nucl. Phys. A, in press
Not Strange But Bizarre Physics from the SAMPLE Experiment
The first measurement of the neutral weak magnetism of the proton was
recently performed by the SAMPLE collaboration at the Bates Linear
Accelerator Center. The experimental method involves the detection of
the parity violation in the elastic scattering of longitudinally
polarized electrons. Its measurement is recognized as a "formidable
experimental challenge."
The value of the strangeness magnetic form factor of the proton G_M^s
determined in the SAMPLE experiment is +0.23 +/- 0.37 +/- 0.24 nuclear
magnetons (n.m.) at Q^2 = 0.1 GeV^2. Here the first error is
statistical and the second is the estimated systematic error. This
result suggests a sign for the strangeness magnetic moment opposite to
that of most theoretical expectations which are typically -0.3 n.m.
The SAMPLE result has lead some to argue that the strangeness moment
of the proton is indeed positive and now models are appearing that can
achieve this result.
Through the use of equalities based on the QCD path integral, I will
illustrate the bizarre physics associated with a positive strangeness
moment for the proton. I will also motivate why future experimental
estimates of the strange quark form factor are likely to move toward
negative values perhaps as large as -0.75 n.m.
Flavor Symmetry and Charge Symmetry for Parton Distributions
Please guess from the title !