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Search for exotics by emulsion

Search for exotics by emulsion. J.Kawada & U.Kose (Nagoya). Emulsion. 3-dimensional Sub-micron tracking detector. Possible to detect the short-lived particles. Direct observation of decay topology!!. First detection of …. X-particle in cosmic ray interaction(1971)

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Search for exotics by emulsion

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

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

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

  4. CHORUSExperiment Short Base-Line neutrino oscillation experiment @ CERN (1994～1997) • 5.06  1019 POTs (1994-1997) • <Enm> ~ 27 GeV • <L> ~ 0.6 km

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

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

  7. CHORUS Analysis Method

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

  9. Automatic Scanning track shifting track Found track summing

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

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

  12. CHORUSResults 1－　 νμ→ντOscillation－ Noντ observation 143,742(CC) + 24,184(NC) Events were analyzed No candidate

  13. CHORUSResults －　 charm associatingonly－ Accepted to Nucl. Phys. BPhys. Lett. B 614 (2005) 155 • Charmed Hyper Nuclei • D*+ production • D0 production • Antineutrino charm production • Fragmentation properties • QE charm production • Λc production • BR   • CC associate charm production • D0 production • Diffractive Ds* production 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

  14. B(D0 V4) B(D0 V2) CHORUSResults 2－　 Measurement of D0 production－ sample: 95450νμCC events Observed D0 events 2 prong (V2) 841 (background: 37) (D0)=0.4010.027 4 prong (V4) 230 (background:0.25) 6 prong (V6) 3 (background:0.19) (D0)/(CC)=0.0269 ± 0.0018 ± 0.0013 = 0.207 ± 0.016 ± 0.004 Phys. Lett. B. 613 (2005) 105

  15. CHORUSResults ３ －　 Anti neutrino charmproduction－ Sample: 2,704 νμ CC interactions

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

  17. Charmed Pentaquark Search

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

  19. Weak Weak Strong Strong Theoretical Overview Θ0c（uuddc)Mass prediction Ｉｆ Θc mass is bellow DN threshold (2807MeV) Θc can decay “Weakly” →lifetime ofΘccan be expected to be in the range of other charm hadrons.

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

  21. Possible decay Mode of Θ0c Θ0c　 →　 Ｄ＊－　Ｐ　 　　　　 →　 Ｄ＊0ｎ　 　　　　 →　 Ｄ－ Ｐ　　　　 　　 　 →　 Ｄ 0 ｎ　 Above threshold Strong Decay Θ0c→　 θ＋（Lepton)－ν 　　　　 →　 θ＋π－ 　　　　 →　 Ｐ π－Ｋｓ０ 　　 　 →　 Ｐ Ｋ＋π－π－( golden topology) 　　　　　　　　　　　： 　　　　　　　　　　　： Below threshold Ｗｅａｋ Decay

  22. Background of Θｃ Main background in emulsion are D0 , K0and Λ0 decay. And neutron , K0 and Λ0 interaction without any visible nuclear breakup at the interaction point.

  23. Proton ID is the key to distinguish Θ0c and D0!! How to Detect and Identify ? Proton Identification to eliminate D0 B.G. D0 →K －π+ (2-prongs) 　　　　 →　 K0π+π－(2-prongs) 　　　 　→　 K－π+π+π－(4-prongs) : : cτ=123μm Any way , no proton in daughters.

  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. π μ K P dE/dX VS Momentum(GeV/c) separatable region

  26. How to Detect and Identify ? Topological analysis to eliminate Λ0 B.G. Λ0 decay mode Λ0　→　Ｐ π－2-prongs （63.9％） 　→　ｎ π0all neutral （35.8％） cτ=7.89cm 2-prongs only ( also Ks0 ). 4-prongs decay is only for D0,Θ0c.

  27. summary of Identification  If 4-prongs decay have proton daughter, it could be Θ0c !!

  28. So far… We have already found 6 , 4-prongs decay , in 2,704 νμ int.

  29. estimation of lifetime D0 Momentum[GeV/c] P[GeV/c] = 1.5 × λｰ1 λ　＝　＜θdecay＞ D0 MC simulation θdecay measured in emulsion <θdecay> momentum → gamma factor → estimated “cτ”

  30. Estimated cτ for 4-prongs decay data MC About cτ, these 6 events are very D0 like. Estimated cτ[μm] cτ（D0）123μm

  31. How to Detect and Identify ? Θ0c search Long flight length decay search 3mm 1.5mm 3mm 1.5mm 6.4mm 10mm So far Θ0c may have long lifetime This range is never searched before!!

  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. P n n P n νμ created μ－and hadrons and charm hadron P P n P n n n μ－ n P n P P νμ hadron Charm hadron interacts with nuclei and Λ+ｃis absorbed Decay Roughly drawing of charmed hyper-nuclei production

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

  36. How to identify a “charmed” • 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 νμ interactions. No candidate ε（ＣＣ）/ε（ＨＦ）　＝　０．８７±０．１０ Upper limit of production rate by 27GeV νμ (90%CL) M.Miyanishi et al. CERN-PH-EP/2005-017 further search will be done…

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

  39. Backup

  40. Summary of Identification

  41. How to Detect and Identify ? Also 2-prongs… Kinematical analysis to eliminate Λ0B.G. θｙ θｙ daughter daughter parent parent θｘ θｘ neutral daughter daughter daughter no neutral escape Λ0 , Ks0 case ～１００％ neutral escape D0,Θ0c case 2-prongs decay is also possible. If proton ID is done.

  42. Flight Length of D0 F.L.(micron)

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