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

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

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

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

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

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 19th IUPAP Conference on Few Body Problems

19th IUPAP Conference on Few Body Problems 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 0.014 - 46 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) 012510 19th IUPAP Conference on Few Body Problems

Threshold data on kaonic hydrogen KpX@KEK 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 = - 193 ± 37 (stat.) ± 6 (syst.) eV 1s = 249 ± 111 (stat.) ± 30 (syst.) eV aK-p = (-0.468 ± 0.090 ± 0.015) + i(0.302 ±0.135± 0.036) fm KpX (1998) 1s = - 323 ± 63 (stat.) ± 11 (syst.) eV 1s = 407 ± 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

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

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, 213401 (2005) 19th IUPAP Conference on Few Body Problems

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

Kaonic nuclear clusters ? Prototype system K-pp 19th IUPAP Conference on Few Body Problems

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) 082301 N. Shevchenko et al. PRC (2007) 044004 Y. Ikeda, T. Sato PRC 76 (2007) 035203 Binding energy: 20 - 50 MeV Decay width: 40 - 100 MeV T. Yamazaki, Y. Akaishi PRC 76 (2007) 045201 A. Dote, T. Hyodo, W. Weise NPA 804 (2008) 197 A. Dote, T.Hyodo, W. Weise PRC 79 (2009) 014003 19th IUPAP Conference on Few Body Problems

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) 212303 AY02 AY02 FC VC FC OBELIX, NPA789 (2007)222 FINUDA PRL94 (2005) 212303 DISTO, preliminary Proc. EXA/LEAP09, Hyp. Int. in print DISTO, preliminary Proc. EXA/LEAP09, Hyp. Int. in print

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

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

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

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

19th IUPAP Conference on Few Body Problems 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/0507058 v1 (2005) Idea supported by Obelix data 19th IUPAP Conference on Few Body Problems

19th IUPAP Conference on Few Body Problems 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 19th IUPAP Conference on Few Body Problems

19th IUPAP Conference on Few Body Problems Status and Outlook New experiments on threshold data (shift, width) of light kaonic atoms are running (SIDDHARTA@LNF) or in preparation (E17@J-PARC) 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 19th IUPAP Conference on Few Body Problems

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

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

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 19th IUPAP Conference on Few Body Problems

19th IUPAP Conference on Few Body Problems Experiments KN threshold studies by x-ray spectroscopy (SIDDHARTA@LNF, E17@J-PARC) see talks by S. Okada and Iio at this conference Search for quasi-bound nuclear systems with S=-1 (E549@KEK, DISTO, FOPI@GSI, E15@J-PARC, AMADEUS@LNF) 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

Comparison of chiral and phenomenological KN interaction 1405 1420 T. Hyodo and W. Weise, PR C77 (2008) 035204 19th IUPAP Conference on Few Body Problems