Search for double anti-kaon nuclear bound states at J-PARC F.Sakuma, RIKEN 1 Strangeness ECT*, 15-19, Oct, 2012.

2 (brief) Introduction of “Kaonic Nuclear Cluster” “Double-Kaonic Nuclear Cluster” search using p bar + 3 He annihilation at rest using p+p reaction using anti-duetron beam? Summary Outline

we will open new door to the high density matter physics, like the inside of neutron stars Kaonic Nuclear Cluster (KNC) 3 T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004). Density [1/fm 3 ] high density some predictions show the density of the KNC is high density more than normal nuclear-density K bar N interaction strongly attractive K bar N interaction is clarified to be strongly attractive by Kaonic-atom experiments in 20 th. deeply-bound kaonic nuclear cluster (KNC) This leads the prediction of deeply-bound kaonic nuclear cluster (KNC), as many theorists pointed out.

4 Experimental Situation of KNC  NE We need more evidences in various channels! PRL, 94, (2005) PRL,104, (2010) stopped-K - + A  (  + p) + X 2.85GeV-p + p  (  + p) + K + B.E. = 115MeV  = 67MeV B.E. = 103MeV  = 118MeV Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS… K - pp   p?

5 J-PARC E15 Experiment 1GeV/c K- beam p  p n Neutron ToF Wall K1.8BR Beam Line neutron Beam trajectory CDS & target Sweeping Magnet Neutron Counter Beam Line Spectrometer search for the K - pp using 3 He( in-flight K -,n) reaction flight length = 15m Beam Sweeping Magnet Cylindrical Detector System K - pp Missing mass Spectroscopy via neutron Invariant mass reconstruction  The latest results will be given in M. Iwasaki’s talk

6 “Double-Kaonic Nuclear Cluster” What will happen to put one more kaon in the kaonic nuclear cluster?

7 Double-Kaonic Nuclear Cluster (DKNC) The double-kaonic nuclear clusters have been predicted theoretically. PL,B587,167 (2004). The double-kaonic clusters have much stronger binding energy much higher density than single ones. (AMD calc.) ppn ppnK - ppnK - K -

8 Two New Calculations M.Hassanvand, Y.Akaishi, T.Yamazaki N.Barnea, A.Gal, E.Z.Liverts PRC84(2011)015204, Proc.Jpn.Acad.Ser.B87(2011)362 arXiv: Deeply bound & Compact B=50~200MeV,  ~75MeV NOT Deeply bound & NOT Compact B~30MeV,  ~80MeV

Experimental Approaches to Search for DKNC 9 How to produce the double-kaonic nuclear cluster?  heavy ion collision  (K -,K + ) reaction  p bar A annihilation  p+p reaction …  d bar A annihilation We would like to perform exotic states search at J-PARC!  ① K1.8BR  ② primary  ③ K1.8BR

10 ① “Double-Kaonic Nuclear Cluster” search Using p bar + 3 He annihilation at rest

The elementary p bar -p annihilation reaction with double-strangeness production: This reaction is forbidden for stopped p bar, because of a negative Q-value of 98MeV the DKNC in p bar A annihilation? if multi kaonic nuclear exists with deep bound energy, following p bar annihilation reactions will be possible !?  98MeV 11 e.g. Then we can investigate the DKNC with exclusive or semi-inclusive measurement with exclusive or semi-inclusive measurement final state: the most energetic favored decay mode  p    p

12 Past Experiments of Double-Strangeness Production in Stopped-p bar Annihilation They did NOT observe any double-strangeness event in p bar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c) ReactionFrequency (90% C.L.) p bar A   0  0 X <4x10 -4 p bar A   0 K - X <5x10 -4 p bar A  K + K + X <5x10 -4 p bar A  HX<9x10 -5 [Phys.Lett., B144, 27 (1984).] several groups reported double-strangeness production in p bar +A annihilation hydrogen bubble-chamber BNL in association with the H-dibaryon search

13 Past Experiments of Double-Strangeness Production in Stopped-p bar Annihilation experimentChannel# of eventsyield (x10 -4 [p bar +Xe] PLB464, 323 (1999). K+K+XK+K+X40.31+/-0.16 K+K0XK+K0X32.1+/-1.2 [p bar + 4 He] NPA797, 109 (2007). K+K+--psK+K+--ps 34+/ /-0.04 K+K+-+n-K+K+-+n- 36+/ /-0.47 K+K+-nK+K+-n 16+/ /-0.29 K + K + K -  nn 4+/ /-0.14 Although observed statistics are small, their results have indicated a high yield of ~10 -4

Expected K - K - pp Cross-Section? the K - K - pp is assumed to be produced by  *  * collision --- double-strangeness production yield in p bar A: ~ free  * production yield: ~  x0.1 free  *  * production yield: ~  x0.01  *  * production yield in p bar A: ~ even if all  *  * become the K - K - pp state, K - K - pp production yield in p bar A: ~ small production yield is expected … moreover, Q-value of  *  * production in p bar3 He reaction is negative (Q = -55MeV)

15 Experimental Strategy I.investigation of “double-strangeness production” in p bar + 3 He annihilation at rest II.toward search for “double-kaonic nuclear cluster” in p bar + 3 He annihilation at rest present situation of the double-strangeness production in p bar +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!

K1.8BR Beam Line CDS & target Beam Line Spectrometer 16 Experimental Setup We will perform the experiment at J-PARC K1.8BR beam line stopped-p bar beam initial beam mom. : 0.7GeV/c w/ tungsten degrader (t=31mm) 30kW, Pt-target p-p- Engineering run (2012, Jun.)

17 Double-Strangeness Measurement K + K +  - channelK + K 0  channel K + detection 24%  detection 4.1% K + K +  detection 4.4%  K + detection 2.1% K + K +  - detection 2.8%  K + K 0 detection 0.29% K1.8BR evaluated using GEANT4 toolkit Many-body decay are considered to be isotropic decay. branching ratios of K 0  K 0 S /K 0 S      /   p   are included. acceptance is defined by CDC acceptances of K + K + and 

18 Double-Strangeness Measurement (Cont’d) duty factor of the accelerator and apparatus : 21h/24h DAQ and analysis eff. : 0.7 sensitivity  =S/sqrt(S+B) backgrounds are assumed to be, K - : S:B=9:1  K + K + : S:B=8:2  : S:B=7:3   : S:B=5:5 from engineering run, and the S/N ratio is NOT depend on the production ratio 30kW, 3weeks DIANA/OBELIX K + K + : 1100  : 200 p-p- Engineering run (2012, Jun.)

19 Experimental Strategy I.investigation of “double-strangeness production” in p bar + 3 He annihilation at rest II.toward search for “double-kaonic nuclear cluster” in p bar + 3 He annihilation at rest present situation of the double-strangeness production in p bar +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!

20 Procedure of the K - K - pp Search methods of the measuremt (semi-inclusive) K 0 K + missing-mass w/  -tag (inclusive)  invariant mass (exclusive) K 0 K +  measurement --- K 0 K + w/  -tag ---  --- K 0 K +  K - K - pp binding energy  evaluated using GEANT4 toolkit   (K - K - pp) = 100 MeV  isotropic decay  branching ratios of K 0  K 0 S /K 0 S      /   p   are included. acceptance

production yield: K - K - pp bound-state = ? (3N) K - K -  phase-space = 5x10 -5 (3N) K + K 0  0  0  0 phase-space = 5x10 -5 (2N) K + K 0 K 0  0 (n) phase-space = 3x Assumptions  total yield : upper limit of p bar A  KKX, 5x10 -4  3N : 20% of yield, and 3N:2N = 1:3  K - K - pp yield : parameter evaluate sensitivity to the K-K-pp observation using these assumptions  non-mesonic : mesonic = 1 : 1 branching ratio: BR(K - K - pp   ) = 0.25 BR(K - K - pp   0  0 = 0.25 BR(K - K - pp   0  0  0 ) = 0.5 assumptions

Expected K - K - pp production yield in p bar A: ~  We have less sensitivity to the K - K - pp with the assumptions 22 Sensitivity to the K - K - pp signal (Exclusive) in exclusive measurement --- B KK = 120 MeV --- B KK = 150 MeV --- B KK = 200 MeV 30kW, 6weeks 100kW, 6weeks 270kW, 6weeks 50kW, 6weeks number of proton on target  =S/sqrt(S+B) 3  significance of K - K - pp yield (/sopped-p bar )

Expected 50kW, 6weeks 23 assumptions: K - K - pp production yield = /stopped-p bar B.E. = 200 MeV  = 100 MeV 3 He(p bar,  /K + K 0 )X measurements give us some hints?

24 Related Topics in p bar A annihilation We can also search for H-dibaryon (H-resonance) by using  invariant mass / missing mass. PRC (R) (2007). The exclusive H search with stopped-p bar beam has never been done. Of course we can measure K - pp production with the dedicated detector, simultaneously. NP, A789, 222 (2007). EPJ, A40, 11 (2009). K - pp? H? Our experiment can check the OBELIX results of the K - pp with a dedicated spectrometer yield ~ 10 -4

25 ② “Double-Kaonic Nuclear Cluster” search using p+p reaction

the produced K - K - pp can be identified by both missing-mass spectrum  M(K + K + ) invariant-mass spectrum M(  ) 26 8GeV decay production Experimental Principle

The free  production CS in p+p collision is known to be   ~ x  total ~ 50  b The free  * production CS at 2.83GeV is known to be   * ~4.5  b ~ 0.1 x   The double-  production CS is expected to be   ~ x x  total ~ 50nb Thus, the double-  * production CS is expected to be   ~ 0.1 x 0.1 x   ~ 0.5nb The DISTO result indicates the K - pp production CS is as much as  * production CS, so we simply assume K - K - pp production CS to be  K-K-pp ~   ~ 0.5nb Of course, these are very rough estimations and depend on incident energy 27 T.Yamazaki, et al., Proc.Jpn.Acad.Ser.B87(2011)362 Expected Cross-Section

Prof. Noumi If yield of proton is assumed to be as same as that of pion, ~10 8 proton/spill(6s) is expected with p p ~8-10GeV 28 Proton Primary Beam Line Good momentum resolution:  p/p~0.1% High Intensity Secondary Beam ： 1.0 x 10 6 Hz (6 x 10 6 per spill, 6 sec spill 15GeV  Primary beam line ( proton/spill) will be used as high-resolution un-separated secondary beam line

CS :  K-K-pp ~ 0.5nb Beam : 8 GeV proton 10 8 / 6s x 1 month (30d) = 4x10 13 Target : LH 2 target 0.85 g/cm 2 (= SKS target, g/cm 3 12 cm) ~10 4 / month K - K - pp 29 Expected Production Yield

Kinematics  [momentum vs. cos(  lab )] p(K + 2 ) vs. p(K + 1 ) cos(  lab )(K + 2 ) vs. cos(  lab )(K + 1 ) cos(  lab )(  2 ) vs. cos(  lab )(  1 ) p(  2 ) vs. p(  1 ) production & decays are assumed to be isotropic 30 B.E = 200MeV K + [momentum vs. cos(  lab )]

for example … ee acceptance KK acceptance E16 spectrometer + hadron-spectrometer upgrade 31 Experimental Setup E16 experiment: investigation of vector meson modification in medium (p+A) precise di-lepton measurement with high statistics proton /spill with thin targets

detector acceptance  lab (degree)  lab (degree) K+K+ -- p generated events 32 B.E = 200MeV Detector Acceptance  

acceptance for the exclusive measurement is 0.0% double-K + accepted event double-  accepted event 33 acceptance = 16%  1600 / monthacceptance = 0.7%  30 / month K + [mom vs. cos(  lab )]  - from  [mom vs. cos(  lab )] p from  [mom vs. cos(  lab )] K + [mom vs. cos(  lab )]  - from  [mom vs. cos(  lab )] p from  [mom vs. cos(  lab )]  decay :100% pp  -  - decay: 40% Detector Acceptance (Cont’d) measurement of p(p, K + K + )X reaction could be feasible

34 ③ “Double-Kaonic Nuclear Cluster” search using d bar beam?

35 d bar +A annihilation? Anti-deuteron (d bar ) beam has never been realized. Using high-power proton accelerator (~270kW), we could use the world's first d bar beam at J-PARC! Why d bar +A annihilation? Nobody has done, and nobody knows. In baryonic number B=0 annihilation, four nucleon masses are released in small region, followed by creation of the highly energetic/excited blob. In B>0 annihilation, more exotic matter could be produced. Increase of strangeness production could be observed as same as QGP/hadronic-gas formation in A+A reaction. Such anomalous condition, exotic state such as H-dibaryon and K - K - pp could be generated. p - n - p n u - u - u - d - d - d - u u u d d d d bar +d annihilation (B=0) (B=0)

36 d bar J-PARC? d bar production in p+A reaction d bar J-PARC K1.8BR Mom. (GeV/c)# of events d bar /  - yield 4.541(3.0±1.5)x (3.9±0.8)x (2.4±1.0)x (6.0±3.0)x10 -8 At AGS, d bar production was studied in 30GeV p+Be reaction in 1960’s production angle: 4.5 degrees d bar /  - = (5.5±1.5)x10 5GeV/c after  - decay & d bar abs. correction  d bar /p bar ~ GeV p+Be, 4.5 AGS D.E.Dorfan, et al., PRL14(1965)1003  p bar intensity in 30GeV p+Pt reaction at 6 degrees is 7*10 3 /1kW/spill(6s) from the commissioning result in 2012 Feb.  2*10 5 p bar 30kW, Pt-target  Assumptions: d bar /p bar ~ decrease of d bar yield caused by absorption in 60mm Pt-target is twice of p bar yield d bar K1.8BR = 0.1 d bar 30kW, Pt-target d bar K1.8BR will be checked toward realizing d bar beam

37 Summary Single-Kaonic Nuclear Cluster Search (K - pp): Single-Kaonic Nuclear Cluster Search (K - pp): The E15 experiment will finally start physics run in this FY. Double-Kaonic Nuclear Cluster Search (K - K - pp): Double-Kaonic Nuclear Cluster Search (K - K - pp): p bar + 3 He annihilation at K1.8BR double-strangeness measurement will be conducted as a first step measurement of 3 He(p bar,  /K 0 K + )X reaction will be given us some hints of the K - K - pp 8 GeV/c p+p primary p(p, K + K + )X measurement using the E16 spectrometer could be feasible d bar K1.8BR expected yield: 0.1 d bar /spill(6s) with 30kW, Pt-target

Thank you! 38

39 Schedule Year (JFY)K1.8BR (p bar,d bar )high-pt (p) 2009beam-tune 2010beam-tune 2011recovery 2012E E15/shutdownconstruction? 2014E17/E31/here?construction? 2015…E16? 2016…E16?

Backup 40

41 p bar J-PARC K1.8BR p bar stopping-rate  50kW, 30GeV  6.0degrees  Ni-target p bar production yield with a p bar CS parameterization 250 stopped p bar 0.7GeV/c, l degrader  3cm Incident Beam momentum bite : +/-2.5% (flat) incident beam distribution : ideal Detectors Tungsten Degrader :  = 19.25g/cm 3 Plastic Scintillator : l=1cm,  =1.032g/cm 3 Liquid He3 target :  =7cm, l=12cm,  =0.080g/cm 3 p bar stopping-rate evaluation by GEANT4 6.5x GeV/c

42 Trigger Scheme p bar + 3 He charged particle multiplicity at rest CERN LEAR, streamer chamber exp. NPA518,683 (1990). NcBranch (%) / / / / / / expected stopped-p bar yield = 50kW All events with a scintillator hit can be accumulated expected K-K-pp event

43 Backgrounds (semi-inclusive) K 0 K + missing-mass w/  -tag  stopped-p bar + 3 He  K 0 + K + + K-K-pp  stopped-p bar + 3 He  K 0 + K + +  +   stopped-p bar + 3 He  K 0 + K + +  +  +  0 …  stopped-p bar + 3 He  K 0 + K + + K 0 +  0 + (n)  stopped-p bar + 3 He  K 0 + K + +  0 + (n) … 3N annihilation 2N annihilation signal *each spectrum is obtained with the same production yield K 0 K + missing-mass

44 Backgrounds (Cont’d) (inclusive)  invariant mass  stopped-p bar + 3 He  K 0 S + K + + K-K-pp   +   stopped-p bar + 3 He  K 0 S + K + + K-K-pp   0 +  0  stopped-p bar + 3 He  K 0 S + K + + K-K-pp   0 +  0 +  0 … missing 2  missing 2  +   B.E = 200 MeV  = 100 MeV signal *each spectrum is obtained with the same production yield  invariant mass

Kaon identification 45 n=1.02 K + [mom vs. cos(  lab )] however, proton contamination is … ???

KEK-PS E248 (AIDA) Past Experiment … 46 12GeV p+p  K + +K + +X

d bar beam J-PARC Proceeding of “Low Energy Antiproton Physics Conference (LEAP 98)”

1GeV/c d bar beam line ~ 30 d bar 50GeV (full power?)

49