Shedding new Light on Kaon-Nucleon/Nuclei Interaction and its Astrophysical Implications with the AMADEUS experiment at DAFNE Alessandro Scordo HADRON 2015 18/09/2015

Before starting…. The aim of this talk is to let you into the wonderful possibilities of the DAFNE accelerator together with the AMADEUS exp. No time for all the analysis details (and not so much astrophysics…) All the presented MC simulations have been performed thanks to the very important collaboration of prof. Wycech (Warsaw)

The DANE accelerator e+ e- at 510 MeV ->  at-rest resonance decays at 49.2 % in K+ K- back to back pair Monochromatic beam of low momentum K- (pk = 127 MeV/c) Currents of 2 A (e-) and 1 A (e+) KLOE detector

What was done at DANE Past experiments Low-energy Kaon-nuclei processes Kaonic atoms Hypernuclei SIDDHARTA FINUDA FINUDA AMADEUS – step 0

What Next @ DANE Low-energy Kaonic atoms Kaon-Nuclei Hypernuclei Hyperon-Nuclei Kaonic atoms Hypernuclei SIDDHARTA-2 AMADEUS? AMADEUS Kaon mass

AMADEUS AMADEUS collaboration 116 scientists from 14 Countries and 34 Institutes lnf.infn.it/esperimenti/siddharta and 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) 6

The scientific goal of AMADEUS 1) K-N potential → how deep can an antikaon be bound in a nucleus? - UKN strongly affects the position of the L(1405) state → we investigate it through (S-p)0 decay --- Y p CORRELATION - if UKN is strongly attractive then possible K- multi-N bound states → we investigate through (L/S-N) decay --- Y N CORRELATION Y-N potential → extremely poor experimental information from scattering data - UYN determines the strength of the final state YN (elastic & inelastic) → could be tested by Y N CORRELATION K-N → L/S p cross section below 100 MeV/c (analysis still to be started) Hypernuclei?

Essential impact on the case of NEUTRON STARS

Low-energy K- hadronic interactions studies with KLOE 2002-2005 data MC simulations show that : ~ 0.1 of K- stopped in the DC gas (90% He, 10% C4H10) ~ 2% of K- stopped in the DC wall (750 mm c. f. , 150 mm Al foil). Possibility to use KLOE materials as an active target Advantage: unprecedent resolution : p/p ~ 0.4 MeV/c 4-geometry with ~ 96% acceptance Calorimeter optimized for  : m ~ 7 MeV/c2 Vertex position resolution ~ 1 mm (in DC) Disadvantage: Non dedicated target → different nuclei contamination → complex interpretation .. but → new features .. K- in flight absorption. K- K+

Pure Carbon target inside KLOE (2012) AMADEUS step-0: Pure Carbon target inside KLOE (2012) Dedicated run in november/december 2012 with a Carbon target 4/6 mm thickness Advantages: gain in statistics (~90 pb-1; analyzed 37 pb-1, x1.5 statistics) K- absorptions occur in Carbon at-rest.

PART 1 Y p CORRELATION resonant VS non-resonant production study

The 2 poles picture of (1405) two poles: (z1 = 1424+7-23– i 26+3-14 ; z2 = 1381+18-6– i 81+19-8 ) MeV mainly coupled to KN mainly coupled to  → line-shape depends on production mechanism Line-shape also depends on the decay channel : Pure I=0 (free from (1385) background)

The golden S0 p0 channel L(1405) signal searched by K- interaction with a bound proton in Carbon K- p → S0p0 detected via: (Lg)(gg) Mass limit on 12C at rest 2004-2005 data 2012 data Only at rest events (cut at mass limit)

The S+ p- channel DC gas DC wall Total H IF 4He AR 4He DC gas DC wall Total IF H IF 12C AR 12C Removing the H component is fundamental since it behaves like a high mass pole!!!

non-resonant / resonant absorption ratio: - at rest ~ 2.3 The Non-Resonant L p- channel Preliminary non-resonant / resonant absorption ratio: - at rest ~ 2.3 - in flight ~ 4.1 c2/ (ndf – np) = 1.5 non-resonant / resonant absorption ratio: - at rest ~ 2.3 - in flight ~ 4.1 c2/ (ndf – np) = 1.5 counts/(10MeV/c) Counts/(0.04) +++ Data ----- Global fit cosqp (MeV/c) pp (MeV/c) Absorptions in 12C (from Carbon wall data) Σ/Λ nuclear conversion K-N→Σ π counts/(3MeV/c2) ΣN→ΛN Non-Resonant (in-flight) (at-rest) Resonant S* (in-flight) (at-rest) mp (MeV/c)

PART 2 Single & multi – nucleon K- absorption kaonic nuclear clusters investigation through Lp,t / S0p correlation

Λp correlation study Preliminary without 3NA Fit 3D (PΛ, Pp, θΛp) ----- K-N → Σπ + Σp/Λp conversion in 4He ----- K-H → Σπ + Σp/Λp conversion in 12C - No fragmentation (higher mass) - Residual fragmented (lower mass) ----- K-NN → Λπp (higher mass) ----- K-NN → Σπp (lower mass) ----- K-NN → Σp + Σp/Λp conversion in 4He ----- K-NN → Λp (higher mass) ----- K-NN → Σ0p (lower mass) ----- Uncorrelated background Preliminary without 3NA +++ Data ---- Global fit MΛp (MeV/c2)

We need to fix the yield of Λp correlation study Fit 3D (PΛ, Pp, θΛp) with 3NA We need to fix the yield of 2NA/3NA absorption!!! never measured before

Λt correlation studies in 4He 150 events in gas of the DC (He + C4H10 ) red line - back to back events (cosΘΛt ) < -0.95 4NA process : - highest part of invariant mass - back-to-back topology Clear back-to-back enhancement of Λt events

Λt correlation studies in 4He: preliminary mass and angle simulataneous fit data Highest statistics ever in the Λt channel --- carbon data from DC wall --- 4NA K- 4He → Λt in flight MC --- 4NA K- 4He → Λt at rest MC --- 4NA K- 4He → Σ0t , Σ0 → Λγ MC BR(K-4He(4NA) → Λt) < 1.1 x 10-4 /Kstop σ(100 MeV/c) (K-4He(4NA)→Λt) = (0.41 ± 0.13 (stat ) +0.01 -0.02 (sys)) mb paper in preparation

S0p correlation study Final fit 2NA-QF clearly separated From other processes From the contributions to the fit, the yields are extracted for K- stop

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.E. : 15-75 MeV/c2 (15 MeV/c2 steps) Width: 30-70 MeV/c2 (20 MeV/c2 steps)

S0p correlation study Significance: 1 s Fit with ppK- Best solution: (best c2 and higher yield) - B.E. = 45 MeV/c2 - Width = 30 MeV/c2 Significance: 1 s

PART 3 Exploring the possibility to study Hypernuclei

L hypernuclei with K- at rest on Carbon Pion momentum (MeV/c): 272.72 NMWD: Proton momentum (MeV/c): (273550) MeV/c Looking for a monochromatic pion and a proton in coincidence

π- momentum 273 MeV/c (corresponding to the ground state, with B =10.8 MeV)

Conclusions The DAFNE accelerator, together with the AMADEUS experiment, represents a unique possibility to perform complete studies in the low-energy strangeness sector SIDDHARTA & AMADEUS experiments already obtained excellent results SIDDHARTA could take new data in 2017 AMADEUS is still not an approved experiment, it is using old existing KLOE data, yet….. 1) Already shown impressive capabilities to investigate several processes 2) Many channels have been studied and papers are in preparation 3) Even more channels still have to be opened….there’s room for everyone! The final goal is to have the possibility to have a DEDICATED experiment in order to really investigate the KN, YN, L(1405), hypernuclei physics with no contaminations If you are interested in such a possibility….join the cause! We are looking for other institutes/universities/groups to become members of the AMADEUS collaboration