1. Investigation of the low-energy kaons hadronic interactions in light nuclei by AMADEUS Alessandro Scordo (on behalf of the AMADEUS COLLABORATION) MESON 2016, Krakow, 06/06/2016 1 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

2. KN interaction studies at low energy Single and Multi Nucleon absorption processes Status of K - pp bound state search AMADEUS @ DA  NE KLOE 2005 data analysis: K - absorption on 2 nucleons and ppK - bound state search in the  0 p final state 4 NA in K - 4 He -->  t channel Resonant/Non-resonant contributions in K - N->(  /  )  channels  (1405) in  0  0 and  +  - channels K - p->  0  0 cross section @ 100 MeV/c Future of AMADEUS A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 2 Content

3. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 3 KN interaction at low energy K - - nucleus potential is attractive Predicted by theory Confirmed by kaonic atoms M. Bazzi et al.. 2011. (SIDDHARTA Coll.), Phys. Lett. B704, 113 D. Cabrera, et al., PRC90 (2014) 055207 Talk of Hideyuki Tatsuno Today 10:30 (Plenary) Possible influence in nature of neutron stars?

4. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 4 KN interactions Recent measurements constrain the neutron star EOS to be stiff More experimental data are needed (KN(s) interactions, bound states,…) “most EOS curves involving exotic matter, such as kaon condensates or hyperons, tend to predict maximum masses well below 2.0M 0 and are therefore ruled out. Including the effect of neutron star rotation increases the maximum possible mass for each EOS. For a 3.15-ms spin period, this is a =2% correction and does not significantly alter our conclusions” P.B. Demorest et al, Nature 467 (2010) 1081-1083 Gazda D., Mares J., Nucl.Phys. A881 (2012)

5. measured acc. corr A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 5 K - pp bound state Prof. Nagae, HYP2015, Sep. 10, 2015 Theoretical predictions First evidence of K - pp with 6 Li+ 7 Li+ 12 C by FINUDA M. Agnello et al., PRL94, (2005) 212303 B=115+6/-5+3/-4 MeV Γ= 67+14/-11+2/-3 MeV DISTO data: p+p->K - pp (pΛ)+ K + at 2.85 GeV B=103±3±5 MeV Γ= 118±8±10 MeV T. Yamazaki et al., PRL 104 (2010) 132502 OBELIX: anti(p)+ 4 He -> K - pp (pΛ) B=160.9 ± 4.9 MeV  < 24.4 ± 8.0 MeV G. Bendiscioli et al, Nuclear Physics A 789 (2007) 222–242

6. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 6 A.O. Tokiyasu et al., Phys. Lett. B 728 (2014) 616-621 LEPS/SPring-8: d(γ,K +  - ) reaction (E γ =1.5-2.4 GeV) HADES: p+p -> K + p  @3.5 GeV Bonn-Gatchina Partial Wave Analysis well reproduces the data Extraction of upper limit G. Agakishiev et al., Phys. Lett. B 742 (2015) 242-248 J-PARC E15 : 3 He(K -,n) reaction @ 1 GeV/c T. Hashimoto et al., PTEP (2015) 061D01 B =95 +18 −17 (stat.) +30 −21 (syst.) MeV  = 162 +87 −45 (stat.) +66 −78 (syst.) MeV J-PARC E27: d(π +, K + ) reaction @ 1.69 GeV/c Y. Ichikawa et al., PTEP 2015, 021D01 Talk of Prof. Iwasaki Tuesday, 7 June 09:30 (Plenary) K - pp bound state Extraction of upper limit

7. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 7 Multi Nucleon absorption A K- produced in nuclear matter can undergo absorption on one or more nucleons Important role in kaonic atoms Competing process to the experimental search of di/tri-kaonic bound states 1N and 2N components of the Ikeda-Hyodo-Weise kaonic atom potential in Ni A. Gal, Nucl.Phys. A914 (2013) 270-279 First attempts to measure multinucleonic absorption C. Van Der Velde-Wilquet et al., Il Nuovo Cimento Vol. 39 A, N. 4 21 Giugno 1977 Determination of the Branching Fractions for K- Multi Nucleon Absorptions at Rest in C

8. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 8 KEK-PS: E549 Selection of the different mechanisms only on the base of the ΛN missing mass. A: associated to 2N absorption T. Suzuki et al., Mod. Phys. Lett. A23 (2008) 2520 Multi Nucleon absorption FINUDA:  - p emission rates in K - absorptions at rest on 6 Li, 7 Li, 9 Be, 13 C, and 16 O Missing mass of the K − + 6 Li → nπ − pA’ reaction: (B) events from K − 6 Li →  - p 4 He two-body QF (D) events compatible with the K - 6 Li →  - pπ 0 A M. Agnello et al., Phys. Rev. C 92 (2015)

9. AMADEUS AMADEUS collaboration 116 scientists from 14 Countries and 34 Institutes lnf.infn.it/esperimenti/siddhartaand LNF-07/24(IR) Report on lnf.infn.it web-page (Library) AMADEUS started in 2005 and was presented and discussed in all the LNF Scientific Committees Antikaon Matter At DA  NE: Experiments with Unraveling Spectroscopy EU Fundings FP7 – I3HP2 and HP3: Network WP9 – LEANNIS; WP24 (SiPM JRA); WP28 (GEM JRA) 9 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

10. 10 Experimental program of AMADEUS A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW AMADEUS aims to perform high precision studies of the low-energy K - interactions in solid and gaseous targets (H, 12 C, 4 He, 9 Be) in order to obtain unique quality information about: Interaction of K- with one or more nucleons Possible existence of kaonic nuclear clusters Nature of the controversial  (1405) resonance Low-energy K - p cross sections for p < 100 MeV/c (still missing) Many other processes of interest in the low-energy QCD in the strangeness sector

11. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 11 Future of AMADEUS 127 MeV/c K - from  --> K + K -

12. Low-energy K - hadronic interactions studies with KLOE 2005 data MC simulations show that : ~ 0.1% of K - stopped in the DC gas (90% He, 10% C 4 H 10 ) ~ 1% of K - stopped in the DC wall (750 mm c. f., 150 mm Al foil). K+K+ K-K- Possibility to use KLOE materials as an active target Advantages: Very good resolution :  p /p ~ 0.4 4  -geometry with ~ 96% acceptance Calorimeter optimized for  :  m   ~ 18 MeV/c 2 Vertex position resolution ~ 1 mm (in DC) Disadvantages: Non dedicated target → different nuclei contamination → complex interpretation.. but → new features.. K - in flight absorption. 12 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

13. AMADEUS step-0: Pure Carbon target inside KLOE (2012) Advantages: gain in statistics ( ~ 90 pb -1 ; analyzed 37 pb -1, x1.5 statistics) K - absorptions occur in 12 C at-rest. Dedicated run in 2012 with a 4/6 mm thick 12 C target 13 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

14. 14 K- Absorption Pin down the contribution of the process: (  0 -->  ) with respect to processes as: Kaonic Bound States Search for the formation of the ppK - and its decay in: Yield Extraction and Significance Goal of the analysis: Free from  N -->  N background K - + 12 C ->  0 p +A In DC wall ( 12 C+ 27 Al)

15. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 15 K - + 12 C ->  0 p +A Analysis steps: 1)  (1116) identification 2)Primary proton identification  identification(from Σ 0 →   ) in the EMC M p   (MeV/c 2 ) σ = 0. 5 MeV Λ π p p  selection Calorimeter Cluster   p common vertex (contamination of  d,  t below 2%)

16. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 16 K - + 12 C ->  0 p +A 4) Background evaluation and extraction of the  0 signal Prefit of the  invariant Mass -Obtained from sideband analysis Machine background (spurius hits in the EMC) -From  p  0 experimental sample with one or two  ’s detected Cut around  mass (1150-1235 MeV/c 2 ): -keep  0 p signal +  p  0 background (2  in the fit) -subtract machine background  p    Background

17. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 17 K - + 12 C ->  0 p +A 5) Interpretation of the  0 p signal 2NA 3NA 4NA  p  0  0 background Uncorrelated background (low mom. Protons from fragmentation) data simulations Residual nucleus unfragmented/fragmented ( 10 Be, 4 He+ 4 He+2n, 4 He+2p+4n,4p+6n) FSI of  0 and p with the residual nucleus Ingredients: Nucleons momenta according to Fermi Distribution in 12 C Energy and momentum conservation Difference of mass between the initial and residual K- in-flight (p ~ 120 MeV/c) and at-rest 50%-50% Final state interaction of  0 or p with other nucleons (1 or 2 collisions for  0 and p with 50% probability) For 2NA different fragmentation scenarios for the rest-nucleus A’ have been considered (modification only in  0 p invariant mass)

18. Final fit From the contributions to the fit, the yields are extracted for K - stop 18 2NA-QF clearly separated From other processes A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW K - + 12 C ->  0 p +A

19. 19 Absorption results...is there room for the signal of a ppK - bound state? Repeat the fit with the inclusion of a simulated bound state in a grid with different values for the Binding Energy and Width: B : 15-75 MeV/c 2 (15 MeV/c 2 steps)  : 30-70 MeV/c 2 (20 MeV/c 2 steps) K - + 12 C ->  0 p +A A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 1.74 fb -1 2004-2005 KLOE data

20. Best solution: (best  2 and higher yield) - B = 45 MeV/c 2 -  = 30 MeV/c 2 Fit with ppK - 20 K - + 12 C ->  0 p +A A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

21. F-test to evaluate the addition of an extra parameter to the fit: Evaluation of the significance of the ppK - signal 21 K - + 12 C ->  0 p +A Significance of “signal” hypothesis w.r.t “Null-Hypothesis” (no bound state) A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW MINOS 1  MINOS 2  MINOS 3  P-value = 0.25 --> 1  significance A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

22. The  0 p analysis has been completed for events in the DC wall 12 C + 27 Al -Obtention of the 2NA-QF yield -2NA-QF yield is very small w.r.t. all 3 body processes (3NA, FSI) -Bound state ppK - yield for B.E. 45 MeV/c 2 and Width 30 MeV/c 2 -the significance of the ppK - signal is of 1  according to F-test 22 K - + 12 C ->  0 p +A A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW Recently published in Phys. Lett. B758 (2016) 134-139

23. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 23 K - 4 He → Λt 4NA process Rare process of a K - absorbed on 4 nucleons (4NA) The Branching Ratio (BR) for non- pionic hyperon production (from K - multi-nucleon absorption in 4 He) was measured in [P. A. Katz et al., Phys.Rev. D1 (1970) 1267], 2/3/4 – NA were not distinguished Available data: ● in Helium : bubble chamber experiment [M.Roosen et al, Il Nuovo Cimento 66, (1981), 101] K - stopped in liquid helium, Λ dn/t search. 3 events compatible with the Λ t kinematics were found BR(K -4 He → Λt) = (3 ± 2) × 10 -4 /K stop global, no 4NA ● Solid targets FINUDA [Phys.Lett. B669 (2008) 229] (40 events in different solid targets)

24. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 24 K - 4 He → Λt 4NA process extra proton events (not possible in pure 4 He) 4NA process in 4 He : -highest part of invariant mass spectrum - back-to-back topology Clear back-to-back enhancement of Λt events K - + 4N   + t p +  - Detected by TOF Best  t statistics ever (150 events) M  t (MeV/c 2 ) In KLOE DC ( 4 He + 12 C + H) 90% 10% Cos  (  t) I. Tucakovic, Ph.D Thesis, 2015 PRELIMINARY

25. The nature of  (1405) two poles: (z1=1424+7-23– i 26+3-14; z2=1381+18-6– i 81+19-8) MeV (Y. Ikeda et al., Nucl.Phys. A881 (2012) -114) mainly coupled to KN mainly coupled to  → line-shape depends on production mechanism Line-shape also depends on the decay channel : 25 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW Only at rest events (cut at mass limit) Fitted data: B. Riley, Phys. Rev. D 11 (1975) 3065 J. Esmaili et al., Phys.Lett. B686 (2010) 23-28

26. Total (2005) H IF 4 He AR 4 He In-flight and at-rest interactions in 4 He can be kinematically separated, as well as the ones in H The nature of  (1405) K - N → (Y* ?) → Y  how much comes from resonance ? A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 26 M(  +  - ) (MeV/c 2 ) Without Carbon Target (2005) With Carbon Target (2012) (  M ~ 20 MeV/c 2 ) K - p   +  - p +  0  PRELIMINARY

27. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 27   (I=1); Res (  * - ) vs Non Res K - n →  - single nucleon absorption processes in 4 He for: non-resonant / resonant (I=1) at-rest / in-flight the goal is to measure |f N-R  (I=1)| to get information on |f N-R  (I=0)| doi:10.1016/j.nuclphysa.2016.05.007 Non Resonant At-rest Resonant At-rest Non Resonant In-flight Resonant In-flight

28. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 28  K - p->  0  0 ) @ 100 MeV/c ­Cross sections measurements at or below 100 MeV/c missing Existing data at (120,..) MeV/c with big relative errors (about 50% ) Calculations in according with latest kaonic hydrogen measurements M. Bazzi, et al., SIDDHARTA Collaboration, Phys. Lett. B 704 (2011) 113; M. Bazzi, et al., SIDDHARTA Collaboration, Nucl. Phys. A 881 (2012) 88. Y. Ikeda et al. / Nuclear Physics A 881 (2012) 98–114 Possible AMADEUS contribution

29. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 29  K - p->  0  0 ) @ 100 MeV/c p  (MeV/c) Strategy: Fit of the measured  0 -  0 distributions (from K- captures in gas) including: -K- 4 He capture at-rest + in-flight (bkg) -K- 12 C capture at-rest + in-flight (bkg) K- H interaction considered non-resonant (T = 1440 MeV far above the  (1405)) -K - H capture at-rest + in-flight (signal)

30. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 30 Conclusions Interaction of strange mesons and hyperons with nuclei is not yet fully understood Many questions are still open and need to be answered Accurate and high statistics data are needed in order to disentangle between the wide range of available theoretical models The AMADEUS experiment has the possibility to deliver high quality and high statistics data in this direction AMADEUS capability have been already anticipated by the very good results obtained analysing the KLOE data 2005 Multi Nucleon absorption in  0 p channel (exp) and K - p->  - (theo) published Other interesting analyses are ongoing (  -p/d/t,  0  0,  +  - ) Other interesting analysis will start soon (  0 -d/t,  0  -,  -  + ) DA  NE + AMADEUS represents a unique possibility to perform high quality experiments with low momentum kaons and should not be missed

31. A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 31 Spares

32. 32 Systematics errors, variation of: Minimum momentum for proton track (10 MeV/c around 170 MeV/c) Time window for MB and signal selection MB Yields  0 mass selection For simulations only: Minimum momentum for nucleons to exit the nucleus (170-220 MeV/c ± 15%) Probability of having more than 1 collision for FSI simulation (40/60, 60/40) A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW Systematic errors

33. 33 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW At-Rest & In-flight ratio K - 4 He -->  - (best resolution channel) E k (  - ) (MeV/c 2 )

34. 34 NO 3NA component:  2 red : 0.85  1.05  0 and p momentum distribution not well fitted Other kinematic distributions are less sensitive NO 2NA+FSI:  2 red : 0.85  1.18 Cos  (  0 p) and M(  0 p) distribution not well fitted Other kinematic distributions are less sensitive A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW 3NA vs 2NA+FSI

35. 35 A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW F-Test & p-value SSE 1 = Quadratic sum of residuals for model 1 ndf 1 = Number of degrees of freedom for model 1 SSE 2 = Quadratic sum of residuals for model 2 ndf 2 = Number of degrees of freedom for model 2 P-value for the F distribution is then calculated

36. Broader transition line due to strong interaction Kaonic atom formation K-K-K-K- e-e-e-e- Auger Electron NN 2) Cascade 1) Initial capture 3) Strong interaction stopped in a target medium 4) Absorption K-K-K-K- X-ray Shift and Width of last orbit e.g. 1s for K-p, K-d 2p for K-He highly-excited state deexcite n ~ sqrt(M*/m e ) n’ ~ 25 (for K-p) ( M* : K-p reduced mass) K-K-K-K- Kaonic Hydrogen A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW

37. 37 SIDDHARTA A. SCORDO (ON BEHALF OF AMADEUS COLLABORATION), MESON 2016, 06-06-2016, KRAKOW EM value K-p K α Kaonic hydrogen KαKα KβKβ higher Phys.Lett. B704 (2011) 113-117 K-4He (3d-2p) K-3He (3d-2p) Phys.Lett. B681 (2009) 310-314 Phys.Lett. B697 (2011) 199-202 Fundamental measurements for understanding KN interaction Talk of Hideyuki Tatsuno Today 10:30 (Plenary) KN interaction at low energy