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Evidence for formation of K 0 S p resonance's in (Anti)Neutrino Interactions

Evidence for formation of K 0 S p resonance's in (Anti)Neutrino Interactions. Further (preliminary) results of re-analysis of data of the Big Bubble Chamber Neutrino Collaboration : BEBC(CERN)+ 15’BC(FNAL) by A. Asratyan, A. Dolgolenko and M. Kubantsev (ITEP, Moscow).

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Evidence for formation of K 0 S p resonance's in (Anti)Neutrino Interactions

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  1. Evidence for formation of K0Sp resonance's in (Anti)Neutrino Interactions Further (preliminary) results of re-analysis of data of the Big Bubble Chamber Neutrino Collaboration: BEBC(CERN)+ 15’BC(FNAL)by A. Asratyan, A. Dolgolenko and M. Kubantsev(ITEP, Moscow) HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  2. Paying tribute for future burial place of the 15’ Pentaquark Detector (Fermilab) The archeological site with one of the diggers. Another, the BEBC, is by the CERN Theory Division HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  3. published in hep-ex/0309042, Yad. Fiz. 67, 704 (2004) [Phys.At.Nucl.67,682(2004)] First result of the study: Observation Θ+ P+ K0S in (Anti)Neutrino Interactions HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  4. K0Sp resonances in neutrino interactions We consider data from series of neutrino experiments with two big bubble chambers: Fermilab 15’ and CERN BEBC. These were close to each other in geometry, fiducial volume and operation conditions. Data were collected and processed using very similar techniques and algorithms. It allowed us to merge these data in one big set. HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  5. K0Sp resonances in neutrino interactions Neutrino interactions were recorded in wide band neutrino beams of : Fermilab 400 GeV accelerator (E180) and 800 GeV Tevatron (E632) with Neon-Hydrogen fill of 15’ BC and CERN 450 GeV accelerator with Hydrogen (WA21), Deuterium (WA25) and Neon (WA59) fills of BEBC. HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  6. K0Sp resonances in neutrino interactions These experimental data compiled by A. Asratyan (ITEP) comprise some 120000 (Anti)neutrino charge current (CC) events*: νμ (νμ)+ A → μ- (μ+) +X. Neutral current events: νμ(νμ)+A→ νμ(νμ)+X are not included (not measured systematically). Even after several decades the bubble chamber neutrino data are still unrivaled in quality and completeness of physics information. *Unfortunately Fermilab E53 data are not included (61800 CC νμ Ne events) HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  7. K0Sp resonances in neutrino interactions We analysed CC events with the hadron system (X) containing protons (identified) + K0S →π+π -(fitted) +X’. νμ μ- Sketch of the neutrino event in the bubble chamber HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  8. K0Sp resonances in neutrino interactions 18746 26323 9753 882 5621 61325 13155 16314 15693 5927 1190 52279 Neutrino (D+Ne)42579,(Ne) 22810; Antineutrino (D+Ne)39124,(Ne) 16256 events HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  9. K0Sp resonances in neutrino interactions Hydrogen data(WA21) Published analysis: Identified protons emitted in momentum range of 300<P<900 MeV/c in association with K0Sin νμCC and νμCC collisions with Hydrogen, Deuterium, and Neon are used. Accepted Deuterium data(WA25) Neon data(WA59+E180+E632) HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  10. K0Sp resonances in neutrino interactions K0S p (identified) invariant mass for νμCC and νμCC events combined with the random star background: 26 events with ~8 events of the background; significance of 6.7 σ. The same distribution with bins shifted by 5Mev is fitted to get mass and width of the peak. Width of the peak is compatible with instrumental resolution. Neon plus Deuterium Mass=1533 ± 5 MeV/c2 Width <20MeV/c2 HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  11. K0Sp resonances in neutrino interactions We expand the proton sample for a new study: First step, use events with ALL identified protons (no 400<P<900 MeV/c requirement). However, we keep only events with any ADDITIONAL proton of momentum below 400 MeV/c to avoid events of hard nucleon re-scattering and break-up. Second step , use other positive particles and assign proton mass. HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  12. K0Sp resonances in neutrino interactions Identified protons only Light shaded events with additional K0S anddark-shaded ones are with additional Λ0 HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  13. K0Sp resonances in neutrino interactions Add possible protons: positive tracks with momentum > 1 GeV Distributions of K0p and K0π+ invariant masses (top and bottom). Shaded areas correspond to the K*+ (890) mass region of 840 < m(K0π+) < 940 MeV Further this region is excluded. Combinatory background is very high. HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  14. K0Sp resonances in neutrino interactions Combined sample of identified and assigned protons( no K*). The light- and dark-shaded histogamms are for selections pL < 5.0 and 2.5 GeV on logitudinal momentum of the K0Sp HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  15. K0Sp resonances in neutrino interactions Close look at the K0Sp system with pL < 2.5 GeV: Dotted histogram depicts the “random star” background. Light shaded events with additional K0S and dark-shaded ones are with additional Λ0. Associated Λ0 events suggest positive strangeness of observed K0Sp states. HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  16. K0Sp resonances in neutrino interactions νonly Yields of the three peaks (relative to all events) are close in neutrino and antineutrino beams. So far we do not consider masses above 1.7 GeV νonly HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  17. K0Sp resonances vs Λ0π Λ0π+ Λ0π - νonly Further probing negative strangeness states: Σ*+(1385) and Σ*+(1583) are seen in ν and Σ*-(1385) in ν. Note: branching of the Σ*+(1583) to K0Sp is about 40 times lower that to Λ0π+ νonly ν + ν HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  18. K0Sp resonances in neutrino interactions • We make following observations for K0Sp resonances: • no strangeness directly determined for K0S • excess of associated Λ0 in these events; • Known Σ* states in this region follow the charge of the current: in νbeam produced Σ*+ , in ν – Σ*-; Σ*+(1583) can not produce second peak in K0Sp • At the same time relative number of the peak K0Sp events is about to be proportional to number of all CC events in the ν and ν samples. • The Σ*+ hypothesis for these three observed states is not supported HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  19. K0Sp resonances in neutrino interactions Preliminary HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  20. K0Sp resonances in neutrino interactions PRELIMINARY: In the expanded sample of (anti)neutrino events with identified and assigned protons three baryon resonance’s with masses of 1531 ± 2, 1577± 3 and 1659 ± 5 MeV are observed in invariant mass K0S p system formed in (anti)neutrino interactions with Neon and Deuterium. Width of 1531 and 1577 Mev resonance’s is less than 17 MeV(experimental resolution). 1659 Mev state may have intrinsic width of 20-30 MeV. The Σ*+ hypothesis for these three observed states is disfavored. Estimated signal significance (S/sqrt(B)) of 9.3, 7.0 and 5.0 σ . These states are tentatively interpreted as the known pentaquark Θ+ (1530) and (yet unknown) spin/isospin partners thereof. HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  21. Summary and Outlook • Exotic baryon resonance Θ+(1540) is observed in several (>13) experiments with very narrow width (< 9 MeV/c2), re-analysis of kaon experiments gives width ~1 MeV. • The state has pentaquark structure (UUDDS) and is a possible member of an anti-decuplet • Isospin 0 is supported experimentally. Other numbers are unknown (some theorists like parity and spin +1/2) • Possible other members of the anti-decuplet Ξ– – and Ξ0 are observed by NA49 experiment but no other experiment yet confirmed it! HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  22. Summary and Outlook(cont.) • New anti-charmed pentaquark state is reported by H1. • Strong experimental confirmation by at least one single very high statistics experiment is still required (several experiments do not see the signal) • Several dedicated experiments are in progress now! • Search for other new members of the pentaquark exotic family is on (see following presentation) HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

  23. Authors are specially thankful to I. Strakovski and Ya. Azimov for fruitful discussions HSQCD-2004,St.Petersburg, Repino,Russia, May21 2004

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