European Centre for
Theoretical Studies in Nuclear Physics and Related Areas (ECT)
Villazzano July 3 - 8, 2006
"Observables in -interactions and their relevance to QCD"
11:00
– 11:45
“Precision
spectroscopy in the charmonium mass region using antiproton annihilation”
In contrast to systems at high momentum transfer where high accuracy
predictions based on QCD can be made, several essential phenomena are still
quantitatively unsetteled in strongly interacting systems with low momentum
transfer. These phenomena include quark confinement, existence of hadrons other
than mesons and baryons, and the generation of the mass of hadrons. Hadronic
states provide an intrinsically ideal system to address these issues. In
particular, the spectroscopy of states with charm quark content provide a
window of opportunity between the chiral and the heavy quark limits. Such
states can be produced in copious numbers in antiproton-proton annihilation at
the appropriate energy.
Beams of antiprotons with unsurpassed brilliance will be available with
momenta between 1,5 and 15 GeV/c at the new FAIR facility in Darmstadt,
Germany. The combination of stochastic and electron phase space cooling will
allow spectroscopy measurements with about 50 keV mass resolution and up to 1032
/cm2 luminosity. These studies will be performed with the PANDA
detector that is to be located inside the High Energy Storage Ring. This
general purpose detector is a magnetic spectrometer with nearly 4pi acceptance
for charged and neutral particles. An overview of the physics program and the
detector will be presented.
11:45
– 12:30
“Spin and dependent parton
distributions”
The momentum and the spin structure of the proton are rather well known
concerning the longitudinal degrees of freedom: a fast moving proton is
visualized as a bunch of collinear partons and the way they share the momentum
and the longitudinal spin (helicity) has been studied for many years.
Much less, or nothing, is known about the transverse distribution, both
of momenta (intrinsic motion, k_perp) and spin. The spin transversity
distribution is so far unmeasured; we know that subtle spin-k_perp correlations
induce many measured spin effects. A review is given, stressing the importance
of (polarized) antiproton to gain new
information.
14:00
– 14:45
“Some
Perspectives of Anti-proton and Antikaon Physics”
14:45
– 15:30
“Towards
the spectrum of Hadrons using LatticeQCD”
Progress
by the Lattice Hadron Physics Collaboration in determining the baryon and meson
resonance spectrum of QCD using Monte Carlo methods with space-time lattices is
described. The extraction of
excited-state energies necessitates the evaluation of correlation matrices of
sets of operators, and the importance of extended three-quark operators to
capture both the radial and orbital structures of baryons is emphasized. The use of both quark-field smearing
and link-field smearing in the operators is essential for reducing the
couplings of the operators to the high-frequency modes and for reducing
statistical noise in the correlators. The extraction of nine energy levels in a
given symmetry channel is demonstrated, and identifying the continuum spin
quantum numbers of the levels is discussed.
16:00
– 16:45
“Results
from Hermes in view of future Experiments”
The HERMES experiment started data taking in 1995 with the aim to solve the spin puzzle, i.e. to understand the violation of the Ellis-Jaffe sum rule. In the mean time HERMES has expanded its physics program significantly. This talk will report on new results on the spin structure of the nucleon, on nuclear effects in fragmentation processes and results and future prospects of the measurement of hard exclusive reactions that are related to generalized parton distributions. It will be shown that part of the program can be completed by the measurement of complementary reactions at the new antiproton facility FAIR.
16:45
– 17:30
“Hadrogenesis
and spectroscopy with PANDA”
In this
talk we motivate and discuss the hadrogenesis conjecture in the
context of the PANDA project at GSI.
17:30
– 18:15
“Polarization effects in interactions
with final state hyperons“
Studies of antihyperon -
hyperon production in antiproton - proton collisions may provide a mean to
investigate the underlying reaction mechanism in terms of a quark-pair
annihilation/creation process. The reaction was studied in some detail at the
CERN antiproton facility LEAR in the single strangeness sector. Special
emphasis was put on spin observables in the antilambda-lambda reaction since
the lambda self-analysing weak decay allows this degree of freedom to be
measured with high precision. The use of a polarised proton target made it, in
addition, possible to make a complete determination of the scattering matrix
for the reaction. These
results will be reviewed and the prospects to extend such studies to the
multiple strangeness sector and to charmed hyperons at the upcoming HESR
antiproton facility at FAIR will be discussed.
9:45
– 10:30
“Hadrons
in Matter: Theory and Observables”
11:00
– 11:45
“Quarks
and Gluons in Annihilations”
The basic theoretical ideas of the handbag mechanism for hard exclusive
reactions will be reviewed and compared with other factorization schemes. The
most important feature of the handbag mechanism is the factorization of the
process amplitudes into a partonic subprocess, e.g. in two-photon
annihilations, and in s dependent fom factors which represent moments of
two-hadron distribution amplitudes, time-like version of generalized parton
distributions. The handbag approach will be applied to various two-photon
annihilations into two hadrons as well as to
and g meson at large Mandelstam
variables s, t and u. Exclusive charmonium decays will also be discussed
briefly. Interesting topics like color-octet and higher-twist contributions
will be mentioned.
11:45
– 12:30
“Meson
and exotics decays in QCD inspired models”
Although our understanding of QCD spectroscopy and electroweak transitions between hadrons is reasonably well developed, and has benefited greatly from recent developments in lattice QCD, one very important aspect of the physics of hadrons, their open-flavor strong decays, is still treated using simple models that date from the 1970s. In this talk I will stress the importance of improving our understanding of these strong decays, and review some questions that we may be able to address both experimentally and theoretically, through expected developments in charmonium and related systems.
14:00
– 14:45
“Hadron
modifications seen with electromagnetic probes”
14:45
– 15:30
“Study
of hadron in-medium properties in antiproton-nucleus collisions“
The study of antiproton-nucleus collisions with the PANDA detector at
the future FAIR facility allows to extend the investigation of hadrons in the
nuclear medium from the light and strange quark sector to hadrons with open and
hidden charm. An important question to be addressed in antiproton-nucleus
collisions is the absorption cross
section in nuclear matter, since the suppression of the
yield in
relativistic nucleus-nucleus collisions has been proposed as a signature for
Quark-Gluon-Plasma formation. Observables related to the in-medium mass shift
of
mesons and charmonium states will also be discussed in the
talk.
Due to the distinct kinematics accessible in annihilation in
nuclear targets with its almost 2 GeV energy release, PANDA can also contribute
to the investigation of in-medium properties of
and
mesons, as well
as antibaryons like
and
, which can be created at rest or with very small momenta
inside the nuclear medium.
16:00
– 16:45
“Quarkonium
on the lattice”
Recent lattice
studies on quarkonium properties will be reviewed.
16:45
– 17:30
“In
medium properties of strange hadrons”
A brief discussion of the Kbar N interaction will be given, as well as
the many body techniques used to evaluate the K^- interaction with a nuclear
medium. Comparison with present data on K¯ atoms will be done and
predictions for deeply bound states will be shown, with states around 50 MeV
binding but widths twice as big that do not support claims for narrow deeply
bound states from peaks seen at KEK and FINUDA, for which recent alternative
conventional explanations have been made.
I will also show results on the eta selfenergy in nuclear matter and the
possibility to find nuclear bound eta states.
Regarding strange baryons in the medium results will be shown for the
Lambda(1520) which has a width
considerably increased in nuclei.
A discussion on methods to verify experimentally this property will be
made.
Finally, a brief discussion will be made of many body modes of
antiproton annihilation in nuclei and possible methods to test them.
17:30
– 18:15
“The
Sivers effect and -interactions”
The
Sivers effect is essentially an asymmetry in the parton distribution of quarks
and gluons inside a transversely polarized hadron. As such it can give rise to
observed single-spin phenomena. A remarkable property of the Sivers effect is,
that it is expected to have an opposite sign in Drell-Yan as compared to
semi-inclusive deep-inelastic scattering. Phenomenological studies show that
Drell-Yan measurements in -interactions would serve as a clean tool in order to check
the expected sign reversal. Such a study would check our present understanding
of single-spin asymmetries in the framework of QCD in an unprecedented way.
The talk
covers these issues of the Sivers function as well as related physics of the
so-called Boer-Mulders function. In general, the importance of a dedicated
Drell-Yan program for -interactions will be stressed.
9:45
– 10:30
“Testing
Novel Phenomena in QCD and AdS/CFT using Antiprotons”
I will
discuss a number of inclusive and exclusive measurements using antiproton beams
which can illuminate novel features of QCD, including measurements of timelike
generalized parton distributions, the production of charm at two different
thresholds, as well as the single-spin and double-spin asymmetries. The
interactions of antiprotons in nuclear targets will allow tests of exotic
nuclear phenomena such as color transparency, hidden color, reduced nuclear
amplitudes, and the non-universality of nuclear antishadowing. I will also
discuss predictions for antiproton physics based on the AdS/CFT correspondence.
11:00
– 11:45
Brodsky
continuation
11:45
– 12:30
“Drell-Yan
process in a parton model with offshellness“
We show that triple differential cross sections for Drell-Yan lepton
pair production cannot be properly described neither in leading nor in
next-to-leading order of perturbative QCD for the experimentally accessible
energies in p-p and p-pbar collisions. One has to include distributions of the
two kinematic parton variables which are neglected in the Bjorken limit, the
transverse momentum and the virtuality of the quarks. Using simple
distributions for these variables we show that the triple and the double
differential cross sections can be described without a need for an additional
K-factor. We show that the virtuality (offshellness) distribution is a higher
twist effect. We conclude that higher twist effects are important for lepton
pair production in the presently accessible energy regime.
9:45
– 10:30
“Single
spin asymmetries in scattering”
We study
time reversal odd distribution and fragmentation functions, that appear in
single spin asymmetries in high-energy scattering processes. Special emphasis
is given to the role of (small) intrinsic transverse momenta of partons.
Effects show up in transverse moments obtained in weighted azimuthal
asymmetries. While in electroweak processes specific functions (such as the
Sivers distribution function) appear with different signs multiplying the
elementary underlying electroweak cross sections at the parton level, one finds
in hadronic processes that the functions appear multiplied with (calculable)
gluonic pole cross sections.
11:00
– 11:45
“Physics with low
Enrgy Antiprotons“
11:45
– 12:30
“Hard
exclusive reactions in ppbar
interactions”
We study the scaling regime of proton-antiproton annihilation into a
lepton pair and a photon or meson in the forward direction. The leading twist
amplitude factorizes into an antiproton distribution amplitude, a
short-distance matrix element and a long-distance dominated transition
distribution amplitude (TDA) which describes the nucleon to meson or photon
transition. This TDA generalizes the concept of GPDs to three quark operators
non-forward matrix elements. The impact representation of this TDA maps out the
transverse locations of the small size core and the meson or photon cloud
inside the proton.
14:00
– 14:45
“Charmonium
Spectroscopy”
Ever
since its discovery the charmonium system has proven to be a powerful tool for
the understanding of the strong interaction. The high mass of the c quark makes it plausible
to attempt a description of the dynamical properties of the
system in terms
of non-relativistic potential models, in which the functional form of the
potential is chosen to reproduce the asymptotic properties of the strong interaction.
The free parameters in these models are to be determined from a comparison with
experimental data.
Today,
more the thirty years after the discovery of the J/y,
charmonium physics continues to be an exciting and interesting field of
research. The recent discoveries of new particles, the exploitation of the
B-factories as rich sources of charmonium states, the start of new projects and
facilities have given rise to renewed interest in heavy quarkonia and
stimulated a lot of experimental and theoretical activities.
In
this talk we will review the status of charmonium spectroscopy. After a general
introduction of the subject we will describe the experimental techniques used
for the study of charmonium. We will then review the present knowledge of the spectrum and
discuss recent developments and future opportunities.
14:45
– 15:30
“The
PAX Project“
16:00
– 16:45
“Polarization
of Antiprotons”
“Understanding
the Filtex Results“
The spin
filtering by a multiple passage of a stored beam through a polarized internal
gas target is a unique possibility of polarizing high luminosity beam of
antiprotons to a high degree of polarization. Apart from the polarization by
the spin-dependent transmission, a unique geometrical feature of spin filtering
in storage rings is a scattering of stored particles within the ring
\cite{Meyer}. A rotation of the spin in the scattering process affects the
polarization buildup. We report here a fully quantum-mechanical evolution
equation for the spin-density matrix of a stored beam which incorporates the
scattering within the ring. We show how dramatically the interplay of the
transmission and scattering within the ring changes from polarized electrons to
polarized protons in the atomic target. After discussions of the FILTEX results
on filtering of stored protons, we comment on the strategy of spin filtering of
antiprotons for the PAX experiment at GSI FAIR.
16:45
– 17:30
“An
alternative method for Polarizing Antiprotons”
We propose an effective method for polarising antiprotons in a storage
ring by means of a parallel moving polarised electron beam. If their relative
kinetic energy is adjusted to the order of 1keV the probability for spin
exchange is as large as ≈ 270barn. Using a 80% polarised
electron beam with a peak current of 1.2 A and an average of 32mA a
polarisation of the antiproton beam of 50% in 1.5 hours is achieved under
realistic conditions in a 1.8 Tm storage ring. The basis of this proposal are
new calculations of the spin transfer cross sections and a state of the art
source of polarised electrons. The examples of a specialised low energy
polariser ring and the polarisation in a high energy experimental storage ring
show that the method is realisable with a polarised electron source based on
todays technology.
If time permits a discussion of recent proposals with other methods is
given and some critical theoretical considerations are analysed.
17:30
– 18:15
“Hadron
Physics at RHIC”
The
Relativisticy Heavy Ion Collider is the first accelerator capable of colliding
high energetic deuterons and nuclei. It is also possible to collide beams of
highly polarized protons. With the resulting data samples it is possible to
probe nucleon structure at low x and to study the spin structure of the nucleon.
We will give a summary of present results and provide an outlook of the program
as it evolves to higher luminosities at RHIC II and electron-proton/nucleus
collisions at e-RHIC.
9:00
– 9:45
“Notes
on Spectroscopy and String Breaking“
In the
first part of this presentation, an update is given on charmonium and
bottomonium spectroscopy as viewed from the time-honoured one-gluon exchange plus
confinement potential approach. But rather than adding further phenomenological
pieces in order to fit data, we introduce the non-perturbative so-called
induced interaction (well known from atomic and nuclear physics) and study its
implications for the fine and hyperfine structure of charmonium. In the second
part, the coupling of excited charmonium states to the open-charm continuum and
connections with recent lattice QCD simulations of string breaking will be
discussed.
9:45
– 10:30
“Use
of EFT’s in the Charmonium system”
11:00
– 11:45
“Partial-wave
analysis of reactions:
(LEAR) and future (FAIR)”
11:45
– 12:30
“Hypernuclear
experiments at PANDA”