J-PARC E27 Experiment. Tomofumi NAGAE (Kyoto University)

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1 J-PARC E7 Experiment Tomumi NAGAE (Kyoto University)

2 Linac J-PARC Facility (KEK/JAEA) South to North Neutrino Beams (to Kamioka) 3 GeV Synchrotron 3 GeV Synchrotron Materials and Life Experimental Facility CY7 Beams JFY8 Beams JFY9 Beams Photo in July 9 Hadron Exp. Facility

3 Hadron Experimental Hall World highest intensity Kaon beams! First beam in Feb. 9 6m x 56m Production target (T1) K1.8BR SKS K1.8 KL K1.1 High p (under constr.) 3 GeV Primary Beam K1.1BR

4 World Facilities in 1st Century For Strangeness Nuclear Physics HI, π, anti-p GSI/FAIR Mainz (e,e K+) DA&NE (K-,π-) J-PARC (K-,K+), (K-,π-) JLab (e,e K+)

5 Hadron Program History 1: Oct.-Nov. E19: Penta-quark search in π - p K - X at 1.9 GeV/c First physics data taking in Hadron Hall 1: Feb., after Earthquake E19: π - p K - X at GeV/c 1: June E7: d(π +,K + ) for K - pp, a pilot run 5 kw / 7 kw

6 Hadron Program History 1: Dec. 1 kw E1: (π -,K + ) 6 ΛH 13: March - May kw E15: 3 He(K -,n) for K - pp Radiation Accident E13: Hypernuclear γ-ray spectroscopy; 4 ΛHe, 19 ΛF

7 Beams at K1.8: π ± K π x1^6 E1 K- x1^6 SX Power (kw) E E

8 E7 : Search for K - pp in d(π +,K + ) Spokesperson : T. Nagae (Kyoto) Y. Ichikawa et al., PTEP (14) 11D3. Y. Ichikawa et al., PTEP (15) 1D1.

9 J-PARC E7 Collaboration Yudai Ichikawa 1,, Tomumi Nagae 1, Hyoungchan Bhang 3, Stefania Bufalino 4, Hiroyuki Ekawa 1,, Petr Evtoukhovitch 5, Alessandro Feliciello 4, Hiroyuki Fujioka 1, Shoichi Hasegawa, Shuhei Hayakawa 6, Ryotaro Honda 7, Kenji Hosomi, Kenichi Imai, Shigeru Ishimoto 8, Changwoo Joo 3, Shunsuke Kanatsuki 1, Ryuta Kiuchi, Takeshi Koike 7, Harphool Kumawat 9, Yuki Matsumoto 7, Koji Miwa 7, Manabu Moritsu 1, Megumi Naruki 1, Masayuki Niiyama 1, Yuki Nozawa 1,RyotaOta 6, Atsushi Sakaguchi 6, Hiroyuki Sako, Valentin Samoilov 5, Susumu Sato, Kotaro Shirotori 1, Hitoshi Sugimura, Shoji Suzuki 8, Toshiyuki Takahashi 8, Tomonori Takahashi 11, Hirokazu Tamura 7, Toshiyuki Tanaka 6, Kiyoshi Tanida 3, Atsushi Tokiyasu 1, Zviadi Tsamalaidze 5, Bidyut Roy 9, Mifuyu Ukai 7, Takeshi Yamamoto 7 and Seongbae Yang 3 1 Department Physics, Kyoto University, Kyoto 66-85, Japan ASRC, Japan Atomic Energy Agency, Ibaraki , Japan 3 Department Physics and Astronomy, Seoul National University, Seoul , Korea 4 INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Torino, I-115 Torino, Italy 5 Joint Institute for Nuclear Research, Dubna, Moscow Region 14198, Russia 6 Department Physics, Osaka University, Toyonaka 56-43, Japan 7 Department Physics, Tohoku University, Sendai , Japan 8 High Energy Accelerator Research Organization (KEK), Tsukuba, 35-81, Japan 9 Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, India 1 Research Center for Nuclear Physics, Osaka , Japan 11 RIKEN, Saitama , Japan

10 New type Strange matter Strange Mesons (K, K - ) in nuclei Excitation Energy (MeV) 5 4 A-1 Ξ [Z] A-1 Ξ - [Z+1] _ A K [Z] - A K [Z+1] ( K -,K + ) ( K -, π + ), π -,K + ( K -, π - ), π +,K + ( K -,N) ( ) ( ) 3 1 A- ΛΛ [Z] Σ + A-1 [Z-1] A-1 Σ [Z] - A-1 Σ [Z+1] A-1 Λ [Z] π - A [Z+1] S =- Nuclei S =-1 Nuclei A [Z] S = Nuclei A [Z+1] A [Z+]

11 K - pp KN : attraction in Isospin= Kaonic hydrogen X-ray ; SIDDHARTA, M.Bazzi et al., NPA 881 (1) Low-energy scattering measurements (145) below K - p threshold K - pp : Y=1, I=1/, J π = -

12 tted in opposite direction, ignoring a final state raction inside nucleus. The angular correlation ween a! and a proton from same point in target g. (b)] clearly indicates existence this kind ction. Even for heavy nuclei such as 7 Al and 51 V ilar correlations were observed, which might suggest absorption would take place at surface a nucleus. n following analysis, we use!-p pairs emitted he opposite direction ( cos!lab <!:8) only from t nuclear targets (6 Li, 7 Li, and 1 C). ince back-to-back angular correlation between a! a proton is so clear, it is naturally expected that two icles are emitted from a K! pp intermediate system. angular correlation is smeared out due to Fermi ions two protons at surface a nucleus by ch K! is absorbed after cascading down atomic its by emitting x rays. If reaction process were ply a two-nucleon absorption process, mass em should be close to sum a kaon and two proton ss, namely, :37 GeV=c. The initial motion two tons does not affect invariant-mass distribution. The invariant-mass distribution!-p pairs is wn in Fig. 3. A significant mass decrease pp system with respect to its expected mass is obved. It can be interpreted as a bound state composed kaon and two protons, hereafter abbreviated as K! pp. n inset Fig. 3, acceptance corrected invariantss distribution for events with two well-defined longk protons is shown. Since trigger and detection eptance are monotonically increasing functions invariant mass in this mass region, peak furshifts to a lower mass side. The binding energy "6 "3! pp # 115!5 $stat%!4 $syst% MeV and width # # "14 $stat%" $syst% MeV are obtained from fitting!11!3 h a Lorentzian function (folded with a Gaussian with : :33 GeV=c. Here, systematic errors were estimated by changing event selections in! invariant mass and!-p opening angle cut as well as by taking account detector acceptance change due to possible systematic deviations in absolute momentum scale, reaction vertex distributions, etc. Although we still have ambiguities on absolute normalization, a rough estimate on yield K! pp!! " p is order.1% per stopped K!. Consistency Monte Carlo simulation used for estimations acceptance and resolutions was examined by producing K! pp events according to Agnello et al., (5) 133 obtained M. mass and width. The PRL94, same simulation conditions were applied to se events; momentum dis6 7 1 tributions! s and protons,!-p opening angle Experiments on - K pp First evidence K pp with Li+ Li+ C by FINUDA - -BK-pp [MeV] arbitrary unit counts/(1mev/c ) p-λ invariant mass [GeV/c ].45.5 FIG. 3. Invariant mass a! and a proton in back-to-back correlation ( cos!lab <!:8) from light targets before acceptance - correction.+the inset shows result after acceptance correction for events which have two protons with well-defined good tracks. Only bins between. and :33 GeV=c are used for fitting. DISTO data: p+p K pp + K at.85 GeV M=67±3±5 MeV/c Γ= 118±8± MeV T. Yamazaki et al., PRL 14 (1) 135. P. Kienle et al., Eur. Phys. J. A 48 (1) 183. PHYSICAL REV PRL 14, 135 (1) B (K pp) [MeV].5 1 (a) large-angle proton: high-p T(p) M = 67 () M(K+p+p) = Γ = 118 (8) M(Λ*+p) = M(Σ+π+p) = 67.1 Deviation UNC/SIM (arb. scale) B=115+6/-5+3/-4 MeV Γ= 67+14/-11+/-3 MeV Missing Mass M(K) [MeV/c ] (b) small-angle proton: low-p (p) 45

13 Theoretical work on K - pp K - pp does exist!!...but maybe broad (consistent with EXPs) (MeV) ATMS Yamazaki & Akaishi, PLB535 () 7. Faddeev Shevchenko, Gal, Mares, PRL98 (7) 831. Faddeev Ikeda & Sato, PRC79 (9) 351. Variational Wycech & Green, PRC79 (9) 141. Faddeev, Maeda, Akaishi, Yamazaki, Proc. Jpn. Acad., B, 89 (13) 418. Variational Dote, Hyodo, Weise, PRC79 (9) 143. Faddeev Ikeda, Kamano, Sato, PTP14 (1) 533. Faddeev Barnea, Gal, Liverts, PLB 71 (1) 13. B Γ FSI effects? ; V.K. Magas et al., PRC 74 (6) 56. Λ*N bound state? ; T. Uchino et al., NPA (11) 53.

14 E7: d(π +,K + ) reaction 1.69 GeV/c Yamazaki & Akaishi, Phys. Rev. C76 (7) 451.

15 Experimental setup [ d(π +, K + ) reaction at p π = 1.69 GeV/c ] K1.8 beam line spectrometer 1.69 GeV/c π + beam Δp/p ~ 1-3 K + J- PARC K1.8 beam line π + SKS spectrometer GeV/c for K + Δp/p ~ 1-3 ΔΩ ~ 1 msr Target Liquid deuterium 15

16 d(π +,K + ) inclusive spectrum; in simulation dσσ /dω /dm o -16 o (Lab) dσ /dω o -16 o (Lab) [µ b/sr/mev] QFΛ Λ Σ + QFΣ K-pp QFY*+πYN Σ Σ* Λ* Missing Mass[GeV/c ]

17 Range Counter System for E7 5 layers (1+++5+cm) plastic scinti deg. (L+R) 5 cm TOF

18 One-proton tagging Quasifree Y productions Decays from K-pp

19 Particle Identification in Range Counter

20 Spectrometer performance (Calibration) p(π +, K + )Σ + at 1.58 GeV/c K + momentum is almost same as d(π +, K + )K - pp reaction. Missing mass resolution Σ + Σ + ΔM =.8±.1 MeV/c (FWHM) Missing mass resolution d(π +, K + )K - pp reaction ΔM =.7±.1 MeV/c (FWHM)

21 p(π +,K + )1.69 GeV/c Σ + Counts / 1MeV Σ* + p(π +,K + )Σ GeV/c d /d Lab [µb/sr] Σ + production ΔM = 3.MeV(FWHM) Mass = MeV Σ + (1385) production Yπ production present data old data Scattering Angle Lab [deg] )] /d /dm o -16 o (Lab) [µb/sr/(4mev/c d 7 data Missing Mass[GeV/c ] total + + p (1385) + + p K + + p K + K Missing Mass [GeV/c ]

22 d(π +, K + GeV/c (a) (b) ΣN-ΛN GeV Mass shift for Y* by ~3 MeV K-pp

23 at Library Research Reactor Institute, Ky ΣN ΛN cusp Peak at 13.5±.4±.9 MeV Width = /-1.+.6/-.3 MeV (b) aded from

24 Cusp (Tan) 4

25 θ πk dependence ( data, sim) Y* peak positions are shifted to low mass side for all scattering angles. < Peak position > data simulation 5

26 Coincidence study Inclusive Proton Coincidence proton =p>5 MeV/c

27 Proton Coincidence Rate ΣN-ΛN GeV K-pp -like structure.4%

28 Decay modes classification with two protons d(π +,K + pp)x ppx = pp-π - for Λp mode, pp-π - γ for Σ p mode, pp-ππ for Yπp mode (a) (b) (c)

29 proton coincidence. The spectrum was fitted with a relativistic Breit Wigner (/π )MMd m $(q) f (MMd ) = (m MMd ) + (m $(q)). (/π )MMd m $(q). () f (MMd ) = + $(q) (/π)mm dm (m MM ) (m $(q)) d. () f (MMd ) = The mass-dependent width was $(q) = $ (q/q ), in which q (q (m MM ) + (m $(q)) d " and proton in " p rest frame at mass MMd (m ). The ob +17), in which +1 q (q ) is momentum t width was $(q) Mass : = $75 (stat.) (syst.) MeV/c and 16 (q/q (stat.) 78 (syst.) p rest frame at mass MM (m ). The obtained mass and +18 ppwidth he "was are dth $(q) = $ (q/q ), in which q (q ) is momentum system 95 responds to binding energy K d 17 (sta and (stat.) +66 (syst.) MeV, respectively. pp -like structure (syst.) MeV/c Thisare cor-decaying to " production cross section K " p rest Width frame at: mass MM (m ). The obtained mass and width 78 45d pp system 95 (stat.) (syst.) MeV se valu ding energy K (syst.) µb/sr. systematic errors ±.3 (stat.) st.) MeV/c and (stat.) (syst.) Thisand cor 17 MeV, respectively. 1 The PTEP 15, 1D1 Y. Ichikawa et al.missin pp -like fitting +18 into +3 account uncertainties ranges, binning ction K structure decaying " p dσ/d& = system : (stat.) 1 (syst.) MeV and p energy Binding K pp K pp " Energy tion efficiency se twotoprotons indσ/d& estimated RCA, andtaking Breit Wigner shape (syst.) The systematic errors values into µb/sr. K pp -like structure decaying " p were = K pp " p folded missing-mass resolution. The differential cr s inµb/sr. fitting ranges,function errors binning with values missing-mass spectrum, into detect.) The systematic se were estimated taking p mode like structure #p decay mode (i) waslorentzian also estimated from th Σ o protons in RCA, and Breit Wigner shape by changing fitting ranges, binning missing-mass spectrum, detec pp -lik. Thus, a branching fraction K distribution MM d htons in missing-mass resolution. The differential cross section K pp RCA, and Breit Wigner shape by changing Lorentzian / $ =.9 (stat.) (syst.). This ratio was discussed $ #p also" estimated p #p decay mode (i) was from fitting same.14.4assuming pp missing-mass resolution. The differential cross section K view andpredicted be 1. using chiral. Thus, a branching fraction K topp -like structure was unitary obtainedmodel as in Ref. [7 decay mode (i) was also estimated from fitting assuming (Fig. same Next, we try to understand ratio histogram (c)) with obta (stat.) (syst.). This ratio was discussed from a oretical point.14.4 fraction K pp -like structure was obtained as us, a branching pp -like structu ). By using mass distribution for K f (M M d o be using chiral unitary model in Ref. [7]. dσ + + (stat.).4 (syst.). This ratio was discussed from a oretical point K mass ) process cross(fig. section inclusive d&d M Md (M Md )inclu distribution erstand ratio histogram (c)) with obtained(πk, pp 1. using chiral unitary model in Ref. [7]. g mass distribution for K pp -like structure and double-differential K pp -like structure

30 E7 Summary d(π +,K + ) missing mass spectrum at 1.69 GeV/c threshold cusp at.13 GeV/c mass shift ~3 MeV in Y* region proton coincidence an enhancement K - pp -like structure GeV/c