A search for double anti-kaon production in antiproton- 3 He - PowerPoint PPT Presentation

A search for double anti-kaon production in antiproton- 3 He annihilation at J-PARC F. F.Saku kuma, , RIKEN Tum-Riken Kick-Off Meeting @ TUM, May 10-11, 2010. 1

This talk is based on the LoI submitted in June, 2009. 2

Contents  (brief) Introduction of “Kaonic Nuclear Cluster”  Possibility of “Double-Kaonic Nuclear Cluster” by Stopped-p bar Annihilation  Experimental Approach  Summary 3

Kaonic Nuclear Cluster (KNC) the existence of deeply-bound kaonic nuclear cluster is predicted from strongly attractive K bar N interaction the density of kaonic nuclei is predicted to be extreme high density Binding Width Central Kaonic Energy Nuclei [MeV] Density [MeV] K − p 3.5 ρ 0 27 40 3.1 ρ 0 K − pp 48 61 9.2 ρ 0 K − ppp 97 13 8.8 ρ 0 K − ppn 118 21 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 4

Theoretical Situation of KNC theoretical predictions for kaonic nuclei, e.g., K - pp Binding Energy Method Width (MeV) (MeV) Akaishi, Yamazaki ATMS 48 61 PLB533, 70 (2002). Shevchenko, Gal, Mares Faddeev 55-70 90-110 PRL98, 082301 (2007). Ikeda, Sato Faddeev 79 74 PRC76, 035203 (2007). Dote, Hyodo, Weise 40-70 ( πΣ N-decay) chiral SU(3) 19+/-3 NPA804,197(2008). • whether the binding energy is deep or shallow • how broad is the width ? Koike, Harada PLB652, 262 (2007). DWIA 3 He(K-,n) 5

Experimental Situation of KNC E549@KEK-PS E548@KEK-PS 4 He （ stopped K-,p) 12 C(K - ,n) K - pnn? 12 C(K - ,p) E549@KEK-PS 4 He （ stopped K-, Λ N) unknown strength between Q.F. & 2N abs. missing mass Prog.Theor.Phys.118:181-186,2007. - deep K-nucleus PLB 659:107,2008 potential of ~200MeV no “narrow” structure K - pp/ K - pn/ K - pnn? K - ppn? arXiv:0711.4943 6

Experimental Situation of KNC (Cont’d) peak structure  signature of kaonic nuclei ? K - pp? K - pp? K - pp? Λ -p invariant mass FI NUDA@DA Φ NE OBELI X@CERN-LEAR DI STO@SATUREN NP, A789, 222 (2007) PRL, 94, 212303 (2005) PRL,104,132502 (2010) We need conclusive evidence with observation of formation and decay ! 7

Experimental Principle of J-PARC E15 search for K-pp bound state using 3 He(K - ,n) reaction neutron 3 He K - pp K - Formation cluster Decay Mode to decay charged particles Λ p exclusive measurement by π - Missing mass spectroscopy and p I nvariant mass reconstruction 8

J-PARC E15 Setup Sweeping Beam Line Magnet Spectrometer Beam trajectory K1.8BR CDS & target E15 will provide the Beam Line Neutron Neutron ToF Wall Counter conclusive evidence of K - pp Beam Sweeping p Magnet n Cylindrical π − Detector p System 1GeV/c K- beam 9

What will happen to put one more kaon in the kaonic nuclear cluster? Possibility of “Double-Kaonic Nuclear Cluster” by Stopped-p bar Annihilation 10

Double-Kaonic Nuclear Cluster  The double-kaonic nuclear clusters have been predicted theoretically.  The double-kaonic clusters have much stronger binding energy and a much higher density than single ones. Width Central- B.E. [MeV] [MeV] Density K-K-pp -117 35 17 ρ 0 K-K-ppn -221 37 K-K-ppp -103 - 14 ρ 0 K-K-pppn -230 61 K-K-pppp -109 - PL,B587,167 (2004). & NP, A754, 391c (2005). How to produce the double-kaonic nuclear cluster?  heavy ion collision  (K - ,K + ) reaction  p bar A annihilation We use p bar A annihilation 11

Double-Strangeness Production with p bar The elementary p bar -p annihilation reaction with double-strangeness production: + → + + + − 98MeV p p K K K K This reaction is forbidden for stopped p bar , because of a negative Q-value of 98MeV However, if multi kaonic nuclear exists with deep bound energy, following p bar annihilation reactions will be possible ! theoretical + → + + + + − − + − 3 pn prediction p He K K K K pn B 106MeV KK B.E.=117MeV + → + + + − − + − 3 0 pp p He K K K K pp B 109MeV Γ =35MeV KK + + − − + → + + + − 4 pnn p He K K K K pnn B 126MeV KK B.E.=221MeV + − − + → + + + − 4 0 ppn p He K K K K ppn B 129MeV Γ =37MeV KK 12

Production Mechanism of K - K - pp with p bar + 3 He? For example, the possible K - K - pp production mechanisms are as follows: with stopped p bar ① direct K - K - pp production with 3N annihilation ② Λ * Λ * production with 3N annihilation followed by K - K - pp formation with in-flight p bar in addition above 2ways, ③ elementally p bar +p  KKKK production followed by K - K - pp formation  Some theorist’s comment: If the K - K - pp bound system can be exist, such system could be Λ * Λ * molecular system by analogy between Λ * K - p. Then the binding energy could be small of about from 30 to 60 MeV.  it has been observed that cross section of p bar +p->KKKK with around 1GeV/c p bar -beam is very small of less than 1 µ b, so it would be very difficult experimentally. It’s worthwhile to explore these exotic system with p bar , although the mechanism is NOT completely investigated! A theoretical problem: The K - K - interactions have been calculated in lattice QCD as strongly repulsive interaction. However, these K-K- interactions are neglected simply in the PLB587,167 calculation which only shows the K-K-pp bound system. 13

Double-Strangeness Production Yield by Stopped-p bar Annihilation From several stopped-p bar experiments, the inclusive production yields are: − → × 2 ( ) ~ 5 10 R pp KK → Λ Σ × − 3 0 2 R p He ( ( )) ~ 0.6 10 → Λ Σ × − 4 0 2 R p He ( ( )) ~ 1.1 10 Naively, the double-strangeness production yield would be considered as: → R pA ( KKKK ) − = → × γ 2 5 ( ) ~ 10 R pp KK γ : reduction factor ~ 10 -2 14

Past Experiments of Double-Strangeness Production in Stopped-p bar Annihilation Observations of the double-strangeness production in stopped p bar annihilation have been reported by only 2 groups , DIANA@ITEP and OBELIX@CERN/LEAR. yield (10 -4 ) experiment channel events K + K + X DIANA 4 0.31+/-0.16 [p bar +Xe] K + K 0 X 3 2.1+/-1.2 K + K + Σ - Σ - p s 34+/-8 0.17+/-0.04 K + K + Σ - Σ + n π - OBELIX 36+/-6 2.71+/-0.47 K + K + Σ - Λ n [p bar + 4 He] 16+/-4 1.21+/-0.29 K + K + K - Λ nn 4+/-2 0.28+/-0.14 Although observed statistics are very small, their results have indicated a high yield of ~10 -4 15

Past Experiments (Cont’d) DIANA [Phys.Lett., B464 , 323 (1999).]  p bar Xe annihilation  p=<1GeV/c p bar -beam @ ITEP 10GeV-PS  700-liter Xenon bubble chamber, w/o B-field  10 6 pictures  7.8x10 5 p bar Xe inelastic  2.8x10 5 p bar Xe @ 0-0.4GeV/c yield (10 -4 ) Channel events K + K + X 4 0.31+/-0.16 K + K 0 X 3 2.1+/-1.2 16

Past Experiments (Cont’d) OBELIX (’86~’96) [Nucl. Phys., A797 , 109 (2007).]  p bar4 He annihilation yield (10 -4 )  stopped p bar @ CERN/LEAR channel events K + K + Σ - Σ - p s  gas target ( 4 He@NTP, H 2 @3atm) 34+/-8 0.17+/-0.04  cylindrical spectrometer w/ B-field K + K + Σ - Σ + n π - 36+/-6 2.71+/-0.47  spiral projection chamber, K + K + Σ - Λ n 16+/-4 1.21+/-0.29 scintillator barrels, jet-drift chambers K + K + K - Λ nn 4+/-2 0.28+/-0.14  2.4x10 5 /4.7x10 4 events of 4/5-prong in 4 He  p min = 100/150/300MeV/c for π /K/p they discuss the possibility of formation and decay of K - K - nn and K - K - pnn bound system 17

The double-strangeness production yield of ~10 -4 makes it possible to explore the exotic systems. Experimental Approach 18

How to Measure? we focus the reaction: + − − + → + + 3 0 p He K K K K pp (although K - K - pp decay modes are not known at all,) we assume the most energetic favored decay mode: − − → Λ + Λ K K pp final state = K + K 0 ΛΛ We can measure the K - K - pp signal exclusively by detection of all particles, K + K 0 ΛΛ , using K 0  π + π - mode We need wide-acceptance detectors. 19

Expected Kinematics K + K 0 X momentum spectra assumptions:  widths of K - K - pp = 0 + → + + + − − 3 0 p He K K K K pp  isotropic decay S (th.+11MeV) B.E=120MeV B.E=150MeV B.E=200MeV ~70MeV/c Kaon ~150MeV/c Kaon ~200MeV/c Kaon In the K - K - pp production channel, the kaons have very small momentum of up to 300MeV/c, even if B.E.=200MeV. We have to construct low mass material detectors. ~200MeV/c π from K 0 S , ~800MeV/c Λ , ~700MeV/c p from Λ , ~150MeV/c π - from Λ 20

Procedure of the K - K - pp Measurement Key points of the experiment  high intensity p bar beam  wide-acceptance and low-material detector How to measure the K-K-pp signal S K + missing-mass w/ Λ -tag  (semi-inclusive) K 0  (inclusive) ΛΛ invariant mass S K + ΛΛ detection  (exclusive) K 0 * 1 because of the low-momentum kaon, it could be hard to detect all particles * 2 semi-inclusive and inclusive spectra could contain background from 2N annihilation and K - K - pp decays, respectively 21