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Updated results for Λ (1405)  Σ 0 π 0 with HADES

Updated results for Λ (1405)  Σ 0 π 0 with HADES. Introduction Analysis of Λ(1405)  Σ 0 π 0 Analysis of Σ (1385 ) 0  Λ π 0 Outlook. Nature of the Λ (1405). N-K or Σ-π. (q 4 q). (uds). m ≈ 1406 MeV/c 2 Г ≈ 50 MeV/c 2. q 3 baryon ?. Pentaquark ?. Molecular state ?.

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Updated results for Λ (1405)  Σ 0 π 0 with HADES

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  1. Updated results for Λ(1405)Σ0π0 with HADES • Introduction • Analysis of Λ(1405) Σ0 π0 • Analysis of Σ(1385)0 Λ π0 • Outlook

  2. Nature of the Λ(1405) N-K or Σ-π (q4q) (uds) m ≈ 1406 MeV/c2 Г ≈ 50 MeV/c2 q3 baryon ? Pentaquark ? Molecular state ? Λ(1405) oscillates mainly between a (K-,p) - and a (Σ,π) – bound state. → Information about the kaon-nucleon interaction. But not known is the contribution of the two states to the Λ(1405). With this (K-,p)- intermediate - bound state, the Λ(1405) could be a doorway for the simplest kaonic cluster the ppK-

  3. The Λ(1405) Resonance What tells the PDG ? S = -1

  4. The Λ(1405) Resonance What tells the PDG ? S = -1 PDG uses theory to fit the mass of the Resonance and not one of the several experiments

  5. The Λ(1405) Resonance What tells the PDG ? S = -1 PDG uses theory to fit the mass of the Resonance and not one of the several experiments ~30 MeV below KN threshold only discovered decays Σ⁺π⁻/ Σ⁻π⁺/ Σ0π0

  6. Experiments with K-/π- induced reactions First measurement by Alston et al. in 1961 by K- p → Λ(1405) + π- + π+ • Several experiments with K beam • most of them • long ago • poor statistics Only 3 experiments have measured the Λ (1405) in π induced reactions

  7. Properties of different production mechanisms V. K. Magas et al. Phys. Rev. Lett. 95, 052301 (2005) S. Prakhov et al. Phys. Rev. C 70 (2004) 034605 A.W. Thomas et al., Nucl. Phys. B56 15 (1973) Feature of the resonance Pole mass seems to be different when the Λ(1405) is produced in different production mechanisms. Could be explained by different coupling strength of the production to the two poles of the resonance KN-Amplitude dominant pS-Amplitude dominant

  8. HADES at GSI 85° High Acceptance Di-electron Spectrometer 15° • High acceptance for dilepton pairs • Momentum resolution ≈ 1 % - 5 % • Particle identification via dE/dx & Tof • 1.2 · 109 Events in p+p at Ebeam= 3.5 GeV 3

  9. Decay channels of / BR: 0 BR: 33.3 BR: 1.3 BR: 87 Г≈ 50 MeV/c2 Г≈ 36 MeV/c2

  10. Decay channels of / BR: 0 BR: 33.3 BR: 1.3 BR: 87 Г≈ 50 MeV/c2 Г≈ 36 MeV/c2

  11. Decay channels of / BR: 0 BR: 33.3 BR: 1.3 BR: 87 Г≈ 50 MeV/c2 Г≈ 36 MeV/c2

  12. Decay channels of / BR: 0 BR: 33.3 BR: 1.3 BR: 87 Г≈ 50 MeV/c2 Г≈ 36 MeV/c2

  13. Λ(1405) Σ0π0

  14. Hades and the Forward Wall 85° 15° 7° FW

  15. Hades and the Forward Wall 85° 15° 7° FW • On that sample the analysis will proceed • cuts on the K+ mass • cuts on Λ(1116) [mass and track cut] • cuts on missing mass of all charged particles [ > π0]

  16. Hades and the Forward Wall 85° 15° 7° FW • On that sample the analysis will proceed • cuts on the K+ mass • cuts on Λ(1116) [mass and track cut] • cuts on missing mass of all charged particles [ > π0]

  17. The analysis of the Λ(1405) HADES + FW DATA Λ(1116)

  18. The analysis of the Λ(1405) HADES + FW DATA Λ(1116) MeV/c2 MeV/c2

  19. The analysis of the Λ(1405) HADES + FW DATA Sideband on K+ mass When a π is miss identified as a K+ Λ(1116) Λ(1116) When a p is miss identified as a K+

  20. The analysis of the Λ(1405) HADES + FW DATA Sideband on K+ mass When a π is miss identified as a K+ Λ(1116) When a p is miss identified as a K+

  21. Understanding the data Λ Σ0 Σ(1385)0 Λ(1405) Λ(1520)  Work in Progress • Try to describe experimental data: • Describe misidentification background with sideband • analysis. • Simulate all physical channels containing a real K+. • Determine the strengths of all contributions via a • multi-parameter fit to the experimental data.

  22. Understanding the data Λ Σ0 Σ(1385)0 Λ(1405) Λ(1520)  Work in Progress • Try to describe experimental data: • Describe misidentification background with sideband • analysis. • Simulate all physical channels containing a real K+. • Determine the strengths of all contributions via a • multi-parameter fit to the experimental data.

  23. Start of multi parameter fit Input Constraints 1 2 Strategy Output 3 4 Contributing channels + K+ misidentification

  24. Start of multi parameter fit Input Constraints 1 2 > > > Strategy Output 3 4 Contributing channels + K+ misidentification

  25. Start of multi parameter fit Input Constraints 1 2 > > > > > Strategy Output 3 4 Contributing channels + K+ misidentification

  26. Start of multi parameter fit Input Constraints 1 2 > > > > > Strategy Output 3 4 Contributing channels • Observable to Fit : • Don’t fit one Histogram but 6 • Choose 6 mass areas for • for these 6 mass areas look at • Fit all Ingredients simultaneously in these 6 mass bins + K+ misidentification

  27. Start of multi parameter fit Input Constraints 1 2 Λ Σ0 Σ(1385)0 Λ(1405) > > > > > Strategy Output 3 4 Contributing channels • Observable to Fit : • Don’t fit one Histogram but 6 • Choose 6 mass areas for • for these 6 mass areas look at • Fit all Ingredients simultaneously in these 6 mass bins + K+ misidentification

  28. Start of multi parameter fit Input Constraints 1 2 Λ Σ0 Σ(1385)0 Λ(1405) > > > > > Strategy Output 3 4 Contributing channels • Observable to Fit : • Don’t fit one Histogram but 6 • Choose 6 mass areas for • for these 6 mass areas look at • Fit all Ingredients simultaneously in these 6 mass bins • One scaling factor for • each channel • Shape stays the same + K+ misidentification

  29. multi parameter fit  Work in Progress Contributing channels + K+ misidentification

  30. multi parameter fit  Work in Progress Contributing channels + K+ misidentification

  31. multi parameter fit  Work in Progress Contributing channels + K+ misidentification

  32. multi parameter fit  Work in Progress Contributing channels + K+ misidentification

  33. multi parameter fit  Work in Progress Contributing channels + K+ misidentification

  34. multi parameter fit Sum of contributions from fit Exp Data  Work in Progress  Work in Progress Contributing channels + K+ misidentification

  35. multi parameter fit Sum of contributions from fit Exp Data  Work in Progress Contributing channels + K+ misidentification

  36. Understanding the data Contributing channels Wall • Exp • Sim  Work in Progress + K+ misidentification

  37. Final Λ(1405) selection The L(1405) and S(1385) can be distinguished by investigating the missing mass of all particles:  Work in Progress Sum of contributions from fit Exp Data

  38. Final Λ(1405) selection The L(1405) and S(1385) can be distinguished by investigating the missing mass of all particles:  Work in Progress π0 CUT: 170 – 290 MeV/c2

  39. Final Λ(1405) selection  Work in Progress Spectrum still contains other contributions: Wall

  40. Final Λ(1405) selection  Work in Progress • Spectrum still contains other contributions: • Subtract misidentification background • (obtained from sideband analysis) • Subtract all other contributing channels • (obtained from simulations). Wall  Work in Progress

  41. Final Λ(1405) selection  Work in Progress • Spectrum still contains other contributions: • Subtract misidentification background • (obtained from sideband analysis) • Subtract all other contributing channels • (obtained from simulations). Wall  Work in Progress  Work in Progress  Work in Progress

  42. Σ(1385)0

  43. Final Σ(1385) selection The L(1405) and S(1385) can be distinguished by investigating the missing mass of all particles: Wall  Work in Progress π0 CUT: 65 – 230 MeV/c2

  44. Final Σ(1385) selection  Work in Progress • Spectrum still contains other contributions: • Subtract misidentification background • (obtained from sideband analysis) • Subtract all other contributing channels • (obtained from simulations). Wall

  45. Final Σ(1385) selection  Work in Progress • Spectrum still contains other contributions: • Subtract misidentification background • (obtained from sideband analysis) • Subtract all other contributing channels • (obtained from simulations). Wall  Work in Progress

  46. Final Σ(1385) selection  Work in Progress • Spectrum still contains other contributions: • Subtract misidentification background • (obtained from sideband analysis) • Subtract all other contributing channels • (obtained from simulations). Wall  Work in Progress  Work in Progress

  47. Summary • Reconstruction of the Λ(1405) in the neutral decay channel was shown. • The intermediate Λ(1116) can be reconstructed • A sideband Analysis on K+ mass describes the combinatorial • background under the Λ(1116) • Background contribution can be extracted from a multi parameter fit • A Λ(1405) and a Σ(1385) signal could be extracted after subtracting • all the background contributions

  48. Outlook Improve the quality of the multi parameter fit Extract cross section for Λ(1405) and Σ(1385)0 production The final aim is to compare the Λ(1405) line shapes of all three decay channels to compare with various theories Search for Kaonic Bound states in the HADES data

  49. HADES Collaboration G. Agakishiev8, C. Agodi1, A. Balanda3,e, G. Bellia1,a, D. Belver15, A. Belyaev6, A. Blanco2, M. Böhmer11, J. L. Boyard13, P. Braun-Munzinger4, P. Cabanelas15, E. Castro15, S. Chernenko6, T. Christ11, M. Destefanis8, J. Díaz16, F. Dohrmann5, A. Dybczak3, T. Eberl11, E. Epple11, L. Fabbietti11, O. Fateev6, P. Finocchiaro1, P. Fonte2,b, J. Friese11, I. Fröhlich7, T. Galatyuk4, J. A. Garzón15, R. Gernhäuser11, C. Gilardi8, M. Golubeva10, D. González-Díaz4, E. Grosse5,c, F. Guber10, M. Heilmann7, T. Hennino13, R. Holzmann4, A. Ierusalimov6, I. Iori9,d, A. Ivashkin10, M. Jurkovic11, B. Kämpfer5, K. Kanaki5, T. Karavicheva10, D. Kirschner8, I. Koenig4, W. Koenig4, B. W. Kolb4, R. Kotte5, A. Kozuch3,e, F. Krizek14, R. Krücken11, W. Kühn8, A. Kugler14, A. Kurepin10, J. Lamas-Valverde15, S. Lang4, J. S. Lange8,K. Lapidus10, L. Lopes2, M. Lorenz4, L. Maier11, A. Mangiarotti2, J. Marín15, J. Markert7, V. Metag8, B. Michalska3, D. Mishra8, E. Morinière13, J. Mousa12, C. Müntz7, L. Naumann5, R. Novotny8, J. Otwinowski3, Y. C. Pachmayer7, M. Palka4, Y. Parpottas12, V. Pechenov8, O. Pechenova8, T. Pérez Cavalcanti8, J. Pietraszko4, W. Przygoda3,e, B. Ramstein13, A. Reshetin10, M. Roy-Stephan13, A. Rustamov4, A. Sadovsky10, B. Sailer11, P. Salabura3, A. Schmah4, J. Siebenson11, R. Simon4, S. Spataro8, B. Spruck8, H. Ströbele7, J. Stroth7,4, C. Sturm7, M. Sudol4, A. Tarantola7, K. Teilab7, P. Tlusty14, M. Traxler4, R. Trebacz3, H. Tsertos12, I. Veretenkin10, V. Wagner14, H. Wen8, M. Wisniowski3, T. Wojcik3, J. Wüstenfeld5, S. Yurevich4, Y. Zanevsky6, P. Zumbruch4

  50. Introduction

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