1. Low-energy anti-kaon nucleon and nuclei interactions
J. Marton
Stefan Meyer Institute
Austrian Academy of Sciences, Vienna
LEANNIS
19th IUPAP Conference on Few Body Problems

2. 19th IUPAP Conference on Few Body Problems
Scope
A kind of overview on open problems and current and future attempts to solve them (here I want to focus on dedicated experiments)
Topics which are in the scope of the LEANNIS network
of the EU project HadronPhysics2
Few Body problems involving strangeness: Specific talks on theoretical approaches and experiments (experiments: M. Iio, O. Vazques Doce, S. Okada, Y. Fujiwara) at this Conference T1 T2 T3 T4 T5 T6 T7 T8 T9
T10
T11
LEANNIS
19th IUPAP Conference on Few Body Problems

3. 19th IUPAP Conference on Few Body Problems
Content
Motivation for new (experimental) studies
Exotic (hadronic) atoms – threshold data
Kaonic hydrogen isotopes (strong interaction effect on 1s)
Kaonic helium isotopes (strong interaction on 2p)
Search for bound strange nuclear systems (K-pp, K-ppn …)
K- stopped
K- in-flight
pp collisions
New ideas
Status and Outlook
19th IUPAP Conference on Few Body Problems

4. Motivation for new studies
The low-energy kaon-nucleon interaction is neither simple nor well understood
Central importance for the physics of strong interaction has the dynamics driven by chiral symmetry breaking in low-energy QCD
Problems arise from the existence of hyperon resonances like the Λ(1405)
Problems arise also due to 2 nucleon K- absorption possibly imitating bound states
The development of reliable theories suffers from the lack of precision data on the observables at threshold (e.g. shift/width of kaonic atoms)
Interesting question:
Two-pole structure??
Λ(1405) & Λ(1420) and
their impact
19th IUPAP Conference on Few Body Problems

5. 19th IUPAP Conference on Few Body Problems
Sources of experimental information on the low energy (anti)kaon-nucleon interaction
Kaon-proton scattering data (old data with
large errors, above threshold  extrapolation)
πΣ mass spectrum
Threshold decay ratios
X-ray data of light kaonic atoms (K-p, K-d, K-He): see talks by S. Okada and Iio at this conference
Kaonic hydrogen  increase precision, threshold data important input for theory
Kaonic deuterium  first experimental studies, threshold data important input for theory
Kaonic helium-4  2p shift small (KEK 570), rules out „superstrong“ antikaon nuclear interaction
Kaonic helium-3  first experimental studies
Reliable theory has to cope these informations
19th IUPAP Conference on Few Body Problems

6. Kaonic hydrogen and deuterium
Strong interaction effects manifest in hadronic shift and width of the 1s state, i.e. deviation from the electromagnetic value of the 1s state and broadening due to absorption
which can be calculated with an accuracy of about 1eV by solving the Klein-Gordon (KG) equation and taking into account vacuum polarization (VP) and final size (FS) effect.
Strong interaction effect on 2p state is weak (meV) and experimentally undetermined, but has severe consequences for the x-ray yield
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X-ray yields
Strong interaction on 2p level 2p width Γ2p
Γ2p limits yield - but is poorly known
K-p
2p width
R.C. Barrett, A.Deloff
meV
PRC 60(1999)025201
T. Koike et al.
25 meV
PRC 53 (1996) 79
M.P. Faifmann
4±2 meV
Proc. DAFNE99
K-d
M. G. Raisi and S.Z. Kalantari,
PRA 79 (2009)
19th IUPAP Conference on Few Body Problems

8. Threshold data on kaonic hydrogen
solved the so-called "kaonic hydrogen puzzle"  interaction is repulsive
Precision limited (e.g. error bar of width > 50%)
Most precise values for shift and width from DEAR experiment (CCDs)
But still precision limited
shift vs. width (1 σ errors) see below
DEAR (2005)
1s = ± 37 (stat.) ± 6 (syst.) eV
1s = ± 111 (stat.) ± 30 (syst.) eV
aK-p = ( ± ± 0.015) +
i(0.302 ±0.135± 0.036) fm
KpX (1998)
1s = ± 63 (stat.) ± 11 (syst.) eV
1s = ± 208 (stat.) ± 100 (syst.) eV
aK-p = (-0.78 ± 0.15 ± 0.03) +
i(0.49 ±0.25± 0.12) fm
using Deser-Trueman (i.e. lowest order)
19th IUPAP Conference on Few Body Problems

9. Close interconnection between experiment and theory
Example
K-p: extraction of scattering lengths from experimenta data
Even more challenging is the case of kaonic deuterium
Lowest order: Deser-Trueman
NLO: Isospin breaking corrections
U.-G- Meißner, U. Raha and A. Rusetsky, Eur. Phys.J. C35 (2004) 349
19th IUPAP Conference on Few Body Problems

10. KN interaction at threshold
K-p: repulsive at threshold, attractive below threshold
threshold
real part
Imag. part
DEAR data
B. Borasoy, R. Nißler and W. Weise,
Phys. Rev. Lett. 94, (2005)
19th IUPAP Conference on Few Body Problems

11. New experiments -- new (x-ray) detectors
Silicon Drift Detectors with large active area
active area  100 mm2
Excellent energy resolution, timing
2 different types for exotic atom research
SDD with external FET
(commercial product, KETEK)
system studied:
K-4He (E570/KEK), K-3He (E17/J-PARC)
SDD with on chip integrated FET
 SIDDHARTA (JRA10/EU-FP6)
systems to be studied:K-p, K-d ….
19th IUPAP Conference on Few Body Problems

12. Kaonic nuclear clusters ?
Prototype system K-pp
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13. Recent developments in theory
Variational calculations
Faddeev calculations
See talk by N. Shevchenko at this Conference
Binding energy: 55 – 70 MeV
Decay width: 95 – 110 MeV
N. Shevchenko, et al. PRL 98 (2007)
N. Shevchenko et al. PRC (2007)
Y. Ikeda, T. Sato PRC 76 (2007)
Binding energy: MeV
Decay width: MeV
T. Yamazaki, Y. Akaishi PRC 76 (2007)
A. Dote, T. Hyodo, W. Weise NPA 804 (2008) 197
A. Dote, T.Hyodo, W. Weise PRC 79 (2009)
19th IUPAP Conference on Few Body Problems

14. K-pp: Comparison experiment-theory
VC … Variational calculations
AY02 … VC Akaishi and Yamazaki PL B535 (2002) 70
FC … Faddeev calculations
Not a clear picture VC
OBELIX,
NPA789 (2007)222
FINUDA
PRL94 (2005)
AY02
AY02 FC VC FC
OBELIX,
NPA789 (2007)222
FINUDA
PRL94 (2005)
DISTO, preliminary
Proc. EXA/LEAP09,
Hyp. Int. in print
DISTO, preliminary
Proc. EXA/LEAP09,
Hyp. Int. in print

15. Production of antikaon-mediated bound nuclear cluster (KNC)?
stopped K- reactions on light nuclei
in-flight K- reactions
protons on proton (or light nuclei)
heavy ion collisions
antiproton induced reactions
dedicated experiments
exclusive measurement
19th IUPAP Conference on Few Body Problems

16. Search for kaonic nuclear clusters with AMADEUS at LNF
See talk by O. Doce Vazquez
AMADEUS collaboration:
114 scientists from 13 Countries and 33 Institutes
Search for kaonic nuclear systems
with S-1 using
K- stopped in helium gas and
employing the modified KLOE
apparatus at DAΦNE/LNF
for exclusive experiments
lnf.infn.it/esperimenti/siddharta
and
LNF-07/24(IR) Report on lnf.infn.it web-page (Library)
19th IUPAP Conference on Few Body Problems

17. K-pp production in pp reaction with FOPI
p on hydrogen target at 3 GeV
Experimental search for the most simple KNC – the prototype system ppK- with
missing mass spectroscopy
invariant mass reconstruction
 Presently taking data at GSI
19th IUPAP Conference on Few Body Problems

18. Search for K-pp in flight (E15@J-PARC)
3He(K-,n) reaction, experiment in connection with E17
K-pp
cluster
neutron
3He (liquid)
reaction K-
Missing mass spectroscopy
by n detection
decay L p p-
Charged particles decay
Search for K-pp bound state with
Missing mass spectroscopy and
Invariant mass reconstruction
Invariant mass reconstruction
19th IUPAP Conference on Few Body Problems

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New ideas
Search for kaonic nuclear clusters S-2 (double strangeness)
Production via antiproton annihilation proposed, EB> 100 MeV
Proposed by P.Kienle (*), T.Yamazaki and W.Weise (**)
(*) Int. Jour. Mod. Phys. A 22 (2007)365
(**) arXiv:nucl-th/ v1 (2005)
Idea supported by Obelix data
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New experiments?
Requirements for pbar annihilation studies at rest:
(J. Zmeskal et al. Proc. EXA08, Hyp. Int. In print)
Low-energy pbar beam: AD/CERN, FLAIR/FAIR
Detector for exclusive annihilation studies
in nuclei
Start counter – scintillating fibers with
Geiger Mode - APD readout
PID – with a TPC - GEM
(similar as proposed for PANDA)
For neutral particle detection - a Calorimeter
with alternating scintillating fibres – lead layers (KLOE-type)
High statistics
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Status and Outlook
New experiments on threshold data (shift, width) of light kaonic atoms are running or in preparation
Threshold data are crucial prerequisites for the theoretical description (enhancement of the predictive power for sub-threshold)
Challenge: Nature of Λ(1405) – 2-pole structure? Can one investigate this question experimentally?
Theoretical studies on the question of kaonic nuclear clusters are ongoing (Faddeev, variational calculations)
Evidence for existence of kaonic nuclear clusters (FINUDA, OBELIX, DISTO, …)
New fully exclusive experiments with various reactions are indispensible and are in preparation
New idea: Kaonic nuclear cluster with double strangeness produced in antiproton annihilation
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22. 19th IUPAP Conference on Few Body Problems
Thank you
No phenomenon is a real phenomenon until it is an observed phenomenon. John Archibald Wheeler
If you haven't found something strange during the day, it hasn't been much of a day.
(A. Wheeler)
19th IUPAP Conference on Few Body Problems

23. 19th IUPAP Conference on Few Body Problems
Spare
19th IUPAP Conference on Few Body Problems

24. Interconnection experiment-theory cont‘d
Extrapolation of subthreshold behavior from experimental data
πΣ mass spectrum extrapolation from analysis of data above threshold
(B. Borasoy, R. Nissler and W. Weise, Eur.J. A25 (2005) 79)
Precision threshold data (SIDDHARTA) will increase the predictive power
K-p threshold
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25. 19th IUPAP Conference on Few Body Problems
Experiments
KN threshold studies by x-ray spectroscopy
see talks by S. Okada and Iio at this conference
Search for quasi-bound nuclear systems with S=-1 DISTO,
see talk by O. Doce Vazquez on AMADEUS at this Conference
Search for quasi-bound nuclear systems with S-2 (OBELIX, CERN AD, FLAIR)
19th IUPAP Conference on Few Body Problems

26. Comparison of chiral and phenomenological KN interaction
1405
1420
T. Hyodo and W. Weise, PR C77 (2008)
19th IUPAP Conference on Few Body Problems