Double antikaonic nuclear clusters in antiproton-3He annihilation at J-PARC F.Sakuma, RIKEN C. CURCEANU (INFN Frascati, Italy), M. IWASAKI (RIKEN, Japan), P. KIENLE (TUM, Germany), H. OHNISHI (RIKEN, Japan), M. TOKUDA (TITECH, Japan), K. TSUKADA (Tohoku-U, Japan), E. WIDMANN (SMI, Austria), T. YAMAZAKI (RIKEN/U-Tokyo, Japan), J. ZMESKAL (SMI, Austria) LEAP2011 @ TRIUMF, April 27 - May 1, 2011.

Outline (brief) Introduction of “Kaonic Nuclear Cluster” Possibility of “Double-Kaonic Nuclear Cluster” in pbar+A annihilation at rest Experimental Approach Summary

Kaonic Nuclear Cluster (KNC) KbarN interaction is clarified to be strongly attractive by Kaonic-atom experiments in 20th. This leads the prediction of deeply-bound kaonic nuclear cluster (KNC), as many theorists pointed out. the density of the KNC is predicted to be high density more than normal nuclear-density (r0) Density [1/fm3] T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004). we will open new door to the high density matter physics, like the inside of neutron stars

Experimental Situation of KNC B.E. = 103MeV G = 118MeV B.E. = 115MeV G = 67MeV K-ppLp? K-ppLp? FINUDA@DAFNE DISTO@SATUREN PRL, 94, 212303 (2005) PRL,104,132502 (2010) stopped-K- + A  (L + p) + X 2.85GeV-p + p  (L + p) + K+ We need more evidences in various channels! Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS…

search for the K-pp using 3He(in-flight K-,n) reaction J-PARC E15 Experiment search for the K-pp using 3He(in-flight K-,n) reaction K1.8BR Beam Line neutron Beam trajectory CDS & target Sweeping Magnet Neutron Counter Spectrometer Neutron ToF Wall flight length = 15m Cylindrical Detector System Missing mass Spectroscopy via neutron p Beam Sweeping Magnet n K-pp L Invariant mass reconstruction p- will start next year p 1GeV/c K- beam

Possibility of “Double-Kaonic Nuclear Cluster” What will happen to put one more kaon in the kaonic nuclear cluster? Possibility of “Double-Kaonic Nuclear Cluster” in pbar+A annihilation at rest Why at rest? probability of multi-nucleon annihilation (exotic B>0 annihilation) should be larger than in-flight reactions

Double-Kaonic Nuclear Cluster (DKNC) The double-kaonic nuclear clusters have been predicted theoretically. ppn The double-kaonic clusters have much stronger binding energy and a much higher density than single ones. (AMD calc.) ppnK- PL,B587,167 (2004). How to produce the double-kaonic nuclear cluster? heavy ion collision (K-,K+) reaction pbarA annihilation ppnK-K- We use pbarA annihilation

the DKNC in pbarA annihilation? The elementary pbar-p annihilation reaction with double-strangeness production: -98MeV This reaction is forbidden for stopped pbar, because of a negative Q-value of 98MeV if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will be possible! e.g. the most energetic favored decay mode final state: p- p p+ We can investigate the DKNC with exclusive or semi-inclusive measurement

Related Topics We can also search for H-dibaryon (H-resonance) by using LL invariant mass / missing mass. Of course we can measure K-pp production with the dedicated detector, simultaneously. E522@KEK-PS H? OBELIX@CERN-LEAR K-pp? PRC75 022201(R) (2007). NP, A789, 222 (2007). EPJ, A40, 11 (2009). The exclusive H search with stopped-pbar beam has never been done. Our experiment can check the OBELIX results of the K-pp with a dedicated spectrometer

Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation There are NO results of the DKNC search, but several groups reported double-strangeness production in pbar+A annihilation hydrogen bubble-chamber experiment @ BNL in association with the H-dibaryon search They did NOT observe any double-strangeness event in pbar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c) [Phys.Lett., B144, 27 (1984).] Reaction Frequency (90% C.L.) pbarAL0L0X <4x10-4 pbarAL0K-X <5x10-4 pbarAK+K+X pbarAHX <9x10-5

Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation Channel # of events yield (x10-4) DIANA@ITEP [pbar+Xe] PLB464, 323 (1999). K+K+X 4 0.31+/-0.16 K+K0X 3 2.1+/-1.2 OBELIX @CERN/LEAR [pbar+4He] NPA797, 109 (2007). K+K+S-S-ps 34+/-8 0.17+/-0.04 K+K+S-S+np- 36+/-6 2.71+/-0.47 K+K+S-Ln 16+/-4 1.21+/-0.29 K+K+K-Lnn 4+/-2 0.28+/-0.14 Although observed statistics are very small, their results have indicated a high yield of ~10-4

Experimental Approach The double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems. Experimental Approach

Experimental Strategy Current situation of the double-strangeness production in pbar+A (A>2) annihilation at rest: NO results using a dedicated spectrometer except for bubble chamber experiments. NO results with high-statistics measurement. investigation of “double-strangeness production” in pbar+3He annihilation at rest, with high statistics data search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

Setup K1.8BR key points Beam Line preliminary We will perform the proposed experiment at J-PARC K1.8BR beam line K1.8BR Beam Line CDS & target Spectrometer key points high intensity pbar beam low mass material detector wide acceptance detector ~2800 L smass =3.5+/-0.1MeV/c2 preliminary 0.9GeV-K- + A  L + X reconstructed pp- inv. mass in commissioning run (2010, Oct.)

pbar stopping-rate evaluation pbar Beam @ J-PARC K1.8BR Incident Beam momentum bite : +/-2.5% (flat) incident beam distribution : ideal Detectors Tungsten Degrader : r=19.25g/cm3 Plastic Scintillator : l=1cm, r=1.032g/cm3 Liquid He3 target : f=7cm, l=12cm, r=0.080g/cm3 pbar stopping-rate evaluation by GEANT4 50kW, 30GeV 6.0degrees Ni-target 6.5x103/spill/3.5s @ 0.7GeV/c pbar production yield with a pbar CS parameterization 250 stopped pbar/spill @ 0.7GeV/c, ldegrader~3cm pbar stopping-rate

Trigger Scheme All events with a scintillator hit can be accumulated expected stopped-pbar yield = 250/spill @ 50kW All events with a scintillator hit can be accumulated pbar+3He charged particle multiplicity at rest CERN LEAR, streamer chamber exp. NPA518,683 (1990). Nc Branch (%) 1 5.14 +/- 0.04 3 39.38 +/- 0.88 5 48.22 +/- 0.91 7 7.06 +/- 0.46 9 0.19 +/- 0.08 <Nc> 4.16 +/- 0.06 expected K-K-pp event

Experimental Strategy present situation of the double-strangeness production in pbar+A (A>2) annihilation at rest: NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments. high-statistics measurement is NOT performed! investigation of “double-strangeness production” in pbar+3He annihilation at rest search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

Double-Strangeness Measurement acceptances of K+K+ and LL evaluated using GEANT4 toolkit Many-body decay are considered to be isotropic decay. branching ratios of K0K0S/K0Sp+p-/Lpp- are included. acceptance is defined by CDC K+K+LS- channel K+K0LL channel K+K+ detection 2.4 x 10-1 LL 4.1 x 10-2 K+K+L 4.4 x 10-2 LLK+ 2.1 x 10-2 K+K+Lp- 2.8 x 10-2 LLK+K0 2.9 x 10-3 CDS @ K1.8BR

Double-Strangeness Measurement (Cont’d) 30kW, 1week sensitivity 30kW, 2weeks sensitivity to 100 double-strangeness events (~10s) detection is evaluated by the MC. 30kW, 6weeks OBELIX/ DIANA 50kW, 6weeks 1.E-04 production-yield (/stopped-pbar) * The following are included duty factor of the accelerator and apparatus : 21h/24h DAQ and analysis eff. : 0.7 100kW, 6weeks number of proton on target if we assume the double-strangeness production-yield to be 10-4 / stopped-pbar as reported by the OBELIX and DIANA groups: expected yield 30kW, for 2weeks K+K+ event 750 LL event 130

Experimental Strategy present situation of the double-strangeness production in pbar+A (A>2) annihilation at rest: NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments. high-statistics measurement is NOT performed! investigation of “double-strangeness production” in pbar+3He annihilation at rest search for “double-kaonic nuclear cluster” in pbar+3He annihilation at rest

Procedure of the K-K-pp Search methods of the measuremt (semi-inclusive) K0K+ missing-mass w/ L-tag (inclusive) LL invariant mass (exclusive) K0K+LL measurement --- K0K+ w/ L-tag --- LL --- K0K+LL K-K-pp binding energy acceptance evaluated using GEANT4 toolkit G(K-K-pp) = 100 MeV isotropic decay branching ratios of K0K0S/K0Sp+p-/Lpp- are included.

Backgrounds (semi-inclusive) K0K+ missing-mass w/ L-tag signal stopped-pbar + 3He  K0 + K+ + K-K-pp stopped-pbar + 3He  K0 + K+ + L + L stopped-pbar + 3He  K0 + K+ + L + L + p0 … stopped-pbar + 3He  K0 + K+ + K0 + S0 + (n) stopped-pbar + 3He  K0 + K+ + X0 + (n) … 3N annihilation 2N annihilation K0K+ missing-mass *each spectrum is obtained with the same production yield

Backgrounds (Cont’d) (inclusive) LL invariant mass signal stopped-pbar + 3He  K0S + K+ + K-K-pp L + L  S0 + S0  S0 + S0 + p0 … missing 2g missing 2g+p0 LL invariant mass B.E = 200 MeV G = 100 MeV *each spectrum is obtained with the same production yield

Sensitivity to the K-K-pp observation is estimated using the MC Expected Yield Sensitivity to the K-K-pp observation is estimated using the MC assumptions production yield: K-K-pp bound-state = ? (3N) K-K-LL phase-space = 5x10-5 (3N) K+K0S0S0p0 phase-space = 5x10-5 (2N) K+K0K0S0(n) phase-space = 3x10-4 total yield : upper limit of pbarAKKX, 5x10-4 3N : 20% of yield, and 3N:2N = 1:3 K-K-pp yield : parameter branching ratio: BR(K-K-ppLL) = 0.25 BR(K-K-ppS0S0 = 0.25 BR(K-K-pp S0S0 p0) = 0.5 non-mesonic : mesonic = 1 : 1

Sensitivity to the K-K-pp signal (Exclusive) significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra 50kW, 6weeks --- BKK = 120 MeV --- BKK = 150 MeV --- BKK = 200 MeV 100kW, 6weeks K-K-pp production yield 3s significance of (/stopped-pbar) 270kW, 6weeks 30kW, 6weeks number of proton on target

Expected Spectra @ 50kW, 6weeks # of K-K-pp = 32 K+K0 missing mass (2K2L) assumption in the figures: K-K-pp production yield = 10-4/stopped-pbar B.E. = 200 MeV G = 100 MeV The signal can be discriminated from the other backgrounds in the exclusive K+K0 missing mass spectrum. # of K-K-pp LL = 357 LL invariant mass K+K0 missing mass # of K-K-pp = 208 LL invariant mass # of K-K-pp LL = 15

Summary We will search for Double-Kaonic Nuclear Cluster (DKNC) by pbar + 3He annihilation at rest, using the pbar + 3He  K+ + K0 + X (X = K-K-pp) channel @ J-PARC K1.8BR beam line. In preparation for the DKNC search, double-strangeness production measurement will be conducted as a first step. We are now improving this experimental idea toward the proposal submission to J-PARC.

The proposed experiment will start in around JFY2015??? Schedule Year (JFY) K1.8BR 2009 beam-tune 2010 2011 recovery 2012 E17/E15 2013 E15/E31 2014 2015 here? The proposed experiment will start in around JFY2015???