1. Search for exotics by emulsion J.Kawada & U.Kose (Nagoya)

2. Emulsion 3-dimensional Sub-micron tracking detector π ‐ K production Recorded in ballon experiment ～ 100 microns Possible to detect the short-lived particles. Direct observation of decay topology!! X-particle in cosmic ray interaction(1971) Tau-neutrino at Fermi Lab E872 exp.(2000) First detection of …......

3. What will we search … ? In CHORUS experiment, a ｂｏｕｔ 150,000 ν μ and ν μ events have been located in emulsion and fully reconstructed. - 93,807 ν μ analyzed event by event and 2,013 ν μ induced charm events, -2,704 ν μ analyzed 40 charm have been found CHORUS experiment has a very large number of charm events, it may also produce anticharmed Pentaquarks and charmed hyper nuclei.

4. CHORUS Experiment Short Base-Line neutrino oscillation experiment @ CERN (1994 ～ 1997) 5.06  10 19 POTs (1994-1997) ~ 27 GeV ~ 0.6 km Ratio （ GeV) νμ νμ 93.9 ％ 26.9 νμ νμ 5.3 ％ 21.7 νe νe 0.007 ％ 47.9 νe νe 0.002 ％ 35.3 ντ ντ negligible －

5. 770 kg emulsion target and scintillating fibre tracker Calorimeter Air core spectrometer and emulsion tracker Air core spectrometer and emulsion tracker Veto plane Muon spectrometer Muon spectrometer  - -  - - h-h- h-h- Nucl. Instr. Meth A 401 (1997) 7 CHORUS detector

6. CHORUS Emulsion 71cm 36cm 36plates Charged particle 350μ ｍ 90μ ｍ

7. CHORUS Analysis Method

8. CCD and XYZ stage Host CPU Network data storage Automatic microscopes Ultra Track Selector(UTS)

9. Found track track shifting summing track Automatic Scanning

10. Calorimeter Air-core magnet beam Muon spectrometer  Emulsion target Interaction vertex Electronic detector prediction Scan-Back Method

11. All track segments in fiducial volume After a low momentum tracks rejection (P > 100 MeV) and number of segments  2 After rejection of passing-through tracks Tracks confirmed by electronic detectors NET SCAN Decay! νint Vtx point

12. CHORUS Results 1 － ν μ →ν τ Oscillation － No ν τ observation 143,742(CC) + 24,184(NC) Events were analyzed No candidate

13. CHORUS Results － charm associating only － Phys. Lett. B. 613 (2005) 105 Phys. Lett. B. 604 (2004) 11 Phys. Lett. B. 604 (2004) 145 Phys. Lett. B. 575 (2003) 198 Phys. Lett. B. 555 (2003) 156 Phys. Lett. B. 549 (2002) 48 Phys. Lett. B. 539 (2002) 188 Phys. Lett. B. 527 (2002) 173 Phys. Lett. B. 435 (1998) 458 Charmed Hyper Nuclei D *+ production D 0 production Antineutrino charm production Fragmentation properties QE charm production Λ c production BR   CC associate charm production D 0 production Diffractive D s * production Accepted to Nucl. Phys. B Phys. Lett. B 614 (2005) 155

14. CHORUS Results 2 － Measurement of D 0 production － Phys. Lett. B. 613 (2005) 105 2 prong (V2) 841 (background: 37) 4 prong (V4) 230 (background:0.25) Observed D 0 events sample: 95450 ν μ CC events 6 prong (V6) 3 (background:0.19)  (D 0 )=0.401  0.027  (D 0 )/  (CC)=0.0269 ± 0.0018 ± 0.0013 = 0.207 ± 0.016 ± 0.004 B(D 0  V4) B(D 0  V2)

15. CHORUS Results ３ － Anti neutrino charm production － Decay topology Candidate events Background 2-prongs161.4±0.3 4-prongs60.13±0.06 1-prongs40.8±0.2 3-prongs40.3±0.2 5-prongs20.02±0.01 Total322.7±0.4 Sample: 2,704 ν μ CC interactions

16. What will we do next … ? １． Charmed Pentaquark ２． Charmed Hyper Nuclei

17. Charmed Pentaquark Search

18. Θc Production from ν u u d u u d d d d c ν （ Lepton) + proton ΘｃΘｃ W－W－

19. Theoretical Overview Θ 0 c （ uuddc) Mass prediction Θ 0 c Mass Model Ｔｈｅｏｒｉｓ ｔ 2710 ＭｅＶ diquark-diquark- antiquark Ｊａｆｆｅ，Ｗ ｉｌｃｚｅｋ 2704 ＭｅＶ skyrme model Ｗｕ, Ma 3445 ＭｅＶ lattice QCD Sasaki 2985 ＭｅＶ diquark-triquark Ｋａｒｌｉｎｅ ｒ，Ｌｉｐｋｉ ｎ Ｉｆ Θc mass is bellow DN threshold (2807MeV) Θc can decay “ Weakly ” Weak Strong → lifetime of Θc can be expected to be in the range of other charm hadrons.

20. Experimental Evidence at H1 hep-ex/0403017 Only one evidence by H1 Collaboration: m=3099 MeV can be considered as pD* stateOnly one evidence by H1 Collaboration: m=3099 MeV can be considered as pD* state Θ c (3099) can be considered as an excited state (chiral partner) of the predicted ground pentaquark state Θ c (2710) M. Nowak et al, hep-ph/0403184Θ c (3099) can be considered as an excited state (chiral partner) of the predicted ground pentaquark state Θ c (2710) M. Nowak et al, hep-ph/0403184

21. Possible decay Mode of Θ 0 c Strong Decay Θ 0 c → Ｄ ＊－ Ｐ → Ｄ ＊ 0 ｎ → Ｄ － Ｐ → Ｄ 0 ｎ Ｗｅａｋ Decay Θ 0 c → θ ＋ （ Lepton) － ν → θ ＋ π － → Ｐ π － Ｋｓ ０ → Ｐ Ｋ ＋ π － π － ( golden topology) ： Above threshold Below threshold

22. Background of Θ ｃ Main background in emulsion are D 0, K 0 and Λ 0 decay. And neutron, K 0 and Λ 0 interaction without any visible nuclear breakup at the interaction point.

23. How to Detect and Identify ? Proton Identification to eliminate D 0 B.G. D 0 → K － π + (2-prongs) → K 0 π + π － (2-prongs) → K － π + π + π － (4-prongs) : Any way, no proton in daughters. cτ=123μm Proton ID is the key to distinguish Θ 0 c and D 0 !!

24. Proton ID by dE/dX and P.H...….. 1.2GeV/cπ 1.2Gev/c P Test experiment@KEK T.Toshito et al. N.I.M A516(2004)436-439

25. dE/dX VS Momentum(GeV/c) PK π μ separatable region

26. How to Detect and Identify ? Topological analysis to eliminate Λ 0 B.G. Λ 0 decay mode Λ 0 → Ｐ π － 2-prongs （ 63.9 ％） → ｎ π 0 all neutral （ 35.8 ％） cτ=7.89cm 2-prongs only ( also Ks 0 ). 4-prongs decay is only for D 0,Θ 0 c.

27. summary of Identification 4-prongs decay mode proton daughter Θ0cΘ0c Yes D0D0 No Λ0Λ0 Yes Ks 0 No  If 4-prongs decay have proton daughter, it could be Θ 0 c !!

28. So far … Decay topology Candidate events Background 2-prongs161.4±0.3 4-prongs60.13±0.06 1-prongs40.8±0.2 3-prongs40.3±0.2 5-prongs20.02±0.01 Total322.7±0.4 We have already found 6, 4-prongs decay, in 2,704 ν μ int.

29. estimation of lifetime P[GeV/c] = 1.5 × λ ｰ 1 λ ＝ ＜ θ decay ＞ θ decay momentum → gamma factor → estimated “ cτ ” D0D0 measured in emulsion D 0 Momentum[GeV/c] MC simulation

30. Estimated cτ for 4-prongs decay cτ （ D 0 ） 123μm Estimated cτ[μm] About cτ, these 6 events are very D 0 like. dataMC

31. How to Detect and Identify ? Long flight length decay search So far 6.4mm 10mm 1.5mm 3mm 1.5mm 3mm Θ 0 c may have long lifetime This range is never searched before!! Θ 0 c search

32. Near Future plan…  Long Flight Length decay search (Now just started)  Proton ID Research & Development A little bit far Future plan … ?  New experiments to search Pentaquark

33. Charmed Hyper Nuclei Search

34. Roughly drawing of charmed hyper-nuclei production νμνμ P n P P P P P P n n n n n n n P n Charm hadron interacts with nuclei and Λ + ｃ is absorbed μ－μ－ hadron ν μ created μ － and hadrons and charm hadron Decay

35. How does it look? s=1 hyper fragment decay observed in CHORUS emulsion Decay point F.L. is a few microns M.Miyanishi et al. CERN-PH-EP/2005-017

36. How to identify a “ charmed ” 1.Energy release is bigger than “ stranged ”. → Stranged Hyper-Nuclei can ’ t exceed 200 MeV. 2. Charmed Hyper-Nuclei can have s=1 particle as a daughter. → K/π/P separation by dE/dX

37. So far … Searched in 22,200 ν μ interactions. No candidate Upper limit of production rate by 27GeV ν μ M.Miyanishi et al. CERN-PH-EP/2005-017 further search will be done … (90%CL) ε （ＣＣ） /ε （ＨＦ） ＝ ０．８７ ± ０．１０

38. Summary Emulsion can give the “ first direct observation ” of pentaquark, and charmed hyper nuclei. We have already had several thousands of ν μ interactions, and analysis is going on. For charmed hyper nuclei, 22,200 ν μ interactions have been analyzed and no candidate have been found. Further search will be done …

39. Backup

40. Summary of Identification proton4-prongs 2-prong with neutral Θ0cΘ0c  D0D0 no  Λ0Λ0  Ks 0 no

41. How to Detect and Identify ? Also 2-prongs … Kinematical analysis to eliminate Λ 0 B.G. 2-prongs decay is also possible. If proton ID is done. no neutral escape Λ 0, Ks 0 case ～１００％ θｙθｙ θｘθｘ parent daughter neutral escape D 0,Θ 0 c case θｙθｙ θｘθｘ parent daughter neutral daughter

42. Flight Length of D 0 F.L.(micron)