Monday, March 11, 2002 - DPG-Tagungen

Nuclear Physics Monday
Sessions
– Invited and Contributed Lectures, Posters –
HK1 Plenary Session
Time: Monday 13:45–15:45 Room: Plenarsaal
Plenary Talk HK 1.1 Mon 13:45 Plenarsaal
Instantons and Confinement in QCD — •Gerard ’t Hooft —
Utrecht University and Spinoza Institute
Quantum Chromodynamics, a theory that describes in great detail
the dynamics of the strong forces among the subatomic particles, is a
non-Abelian gauge theory, and it has a delicate topological structure.
The nature of the forces that keep the quarks permanently confined into
pairs or triplets can be understood in terms of this topology: we find
that Bose-Einstein condensation takes place in the colour-magnetic sector.
The theory allows for a very special kind of transitions, or events,
called ”instantons”. It turns out that these explain the special way in
which the chiral symmetry of the system is manifested, such as the entirely
different mixing angles between the vector particles on the one
hand and the isoscalars on the other.
Plenary Talk HK 1.2 Mon 14:30 Plenarsaal
A Perspective on Nuclear Structure Physics in the Context of
the U.S. Long Range Planning Process — •Richard F. Casten
— Wright Nuclear Structure Laboratory, Yale University, New Haven,
CT 06520-8124, U.S.A.
Nuclear physics in the USis entering a crucial phase in which two major
facilities – CEBAF at Jefferson Laboratory and RHIC at Brookhaven
National Laboratory – are now running and obtaining significant new
results, and in which a third facility, the exotic beam laboratory Rare
Isotope Accelerator (RIA), is being recommended as the highest priority
for major new construction in the current Long Range Planning Pro-
HK2 Theory I
cess. These initiatives reflect the three major pillars on which nuclear
physics research stands, namely, the interactions of quarks and gluons,
the quark-gluon structure of hadronic matter, and of the structure of
nuclei themselves. Each of these has wider ramifications, especially in
regard to astrophysics and the Standard Model. This talk will focus on
the recent Long Range planning effort in the US– both the nature of
the process itself and on the Recommendations resulting from it. It will
then go on to discuss in more specificity the major accomplishments in
nuclear structure in recent years and the exciting prospects for future
discoveries in this field. Especially important in this regard is the discovery
potential inherent in the RIA facility. This work was supported
by U.S. DOE under Grant No. DE-FG02-91ER-40609.
Plenary Talk HK 1.3 Mon 15:15 Plenarsaal
Heavy Ion Physics in the RHIC Era — •Thomas Peitzmann —
Universität Münster, 48149 Münster, Germany
The first year of running of the Relativistic Heavy Ion Collider in
Brookhaven at a beam energy of √ sNN = 130 GeV has brought the study
of strongly interacting matter into a new era and has already provided
a large number of exciting results by the four heavy ion experiments.
Highlights of these early results will be presented and discussed in comparison
with previous results from lower energy heavy ion experiments
and from measurements in pp (p¯p) collisions and with theoretical expectations.
The status of the measurements at the full RHIC energy of
√ sNN = 200 GeV in 2001 and the future prospects will also be discussed.
Time: Monday 16:15–19:00 Room: A
Group Report HK 2.1 Mon 16:15 A
New soft pion theorems for hard reactions — •M.V. Polyakov 1,2 ,
P.V. Pobylitsa 1,2 ,andM.I. Strikman 1,3 — 1 Petersburg Nuclear
Physics Institute, 188350 Gatchina, Russia — 2 Institute for Theoretical
Physics II, Ruhr University Bochum, 44780 Bochum, Germany —
3 Pennsylvania State University, University Park, PA16802,USA
We prove a new soft pion theorem for the near threshold pion production
by a hard electromagnetic probe. This theorem relates various
near threshold pion production amplitudes to the nucleon form factors
at large momentum transfer. The new soft pion theorem exploits the
kinematic domain Q 2 ≫ Λ 3 /mπ (Λ ∼ 1 GeV is a typical hadronic scale,
Q 2 is a virtuality of the incident photon).
The new soft pion theorem is in a good agreement with the SLAC
data for the structure function F p
2 (W, Q 2 ) for W 2 ≤ 1.4 GeV 2 and
9 ≤ Q 2 ≤ 30.7 GeV 2 .
Group Report HK 2.2 Mon 16:45 A
Relativistic chiral SU(3) symmetry, large Nc sum rules and
meson-baryon scattering — •Matthias F.M. Lutz 1 and Evgeni
E. Kolomeitsev 2 — 1 GSI, Planck Str. 1, D-64291 Darmstadt and Institut
für Kernphysik, TU Darmstadt, D-64289 Darmstadt — 2 ECT*,
Villa Tambosi, I-38050 Villazzano (Trento)
The relativistic chiral SU(3) Lagrangian is used to describe kaonnucleon
scattering imposing constraints from the pion-nucleon sector and
the axial-vector coupling constants of the baryon octet states. We solve
the covariant coupled-channel Bethe-Salpeter equation with the interaction
kernel truncated at chiral order Q 3 where we include only those
terms which are leading in the large Nc limit of QCD. The baryon decuplet
states are an important explicit ingredient in our scheme, because
together with the baryon octet states they form the large Nc baryon
ground states of QCD. Part of our technical developments is a minimal
chiral subtraction scheme within dimensional regularization, which leads
to a manifest realization of the covariant chiral counting rules. All SU(3)
symmetry-breaking effects are well controlled by the combined chiral and
large Nc expansion, but still found to play a crucial role in understanding
the empirical data. We achieve an excellent description of the data set
typically up to laboratory momenta of plab � 500 MeV.
Group Report HK 2.3 Mon 17:15 A
Determination of vector meson properties by matching resonance
saturation to a constituent quark model — •Stefan Leupold
— Institut für Theoretische Physik, Universität Giessen, Germany
We calculate the low-energy coefficients of chiral perturbation theory
in two different ways, namely (i) by assuming resonance saturation and
(ii) within a constituent quark model derived as the low energy effective
theory of the instanton model. By matching the expressions of the two
models we determine mass and coupling constants for vector and axialvector
mesons. We recover in this way the KSFR relation as well as
the universality of the vector meson coupling. The latter is found to be
g =2π. For the ρ-meson mass we get mρ = √ 8 πFπ ≈ 826 MeV where
Fπ denotes the pion decay constant.
HK 2.4 Mon 17:45 A
Electromagnetic transition form factors and dilepton decay
rates of nucleon resonances — •Mikhail Krivoruchenko, Christian
Fuchs, Boris Martemyanov, andAmand Faessler —Institut
fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle
14, D-72076 Tuebingen, Germany
Relativistic, kinematically complete phenomenological expressions for
the dilepton decay rates of nucleon resonances with arbitrary spin and
parity are derived in terms of the magnetic, electric, and Coulomb tran-