1 / 36

Scalar mesons in VES experiment

Scalar mesons in VES experiment. Outlook. Introductory remarks VES Experiment Scalars at VES – various topics Conclusions. Why to study scalars. NOTE ON SCALAR MESONS by C. Amsler , T. Gutsche , S . Spanier and N.A.T¨ornqvist (in RPP 2011):

hume
Download Presentation

Scalar mesons in VES experiment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Scalar mesons in VES experiment Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  2. Outlook • Introductory remarks • VES Experiment • Scalars at VES – various topics • Conclusions Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  3. Why to study scalars NOTE ON SCALAR MESONS by C. Amsler, T. Gutsche, S. Spanierand N.A.T¨ornqvist (in RPP 2011): • quantum numbers of the vacuum (JPC = 0++) • can condense into the vacuum and break a symmetry such as a global chiralU(Nf )L× U(Nf)R • How they break ? Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  4. Experimental approaches and evidences • Numerous and various • OPE scattering π/K N  N π/K π, N K/π K • Diffractive π N  NPPP • p p̅  PPP(at rest & in flight) • γ γ PP • D(*)/ B PPPDalitz plot • J/ψ K* K π • τ K π ν • φ [a0(980) + f0(980)] γ • ….. • In general: mostly PP – S wave Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  5. VES setup • secondary (mostly π-) beam of U-70, p ~ 25 – 45 ГэВ/с • magnetic spectrometer pt = 0.5 - 0.7 GeV/с • EM – calorimetry • K/π – identification (4-18 GeV/с) • Fast DAQ (104/spill) • Minimum bias trigger 1 - target; 2 - veto counters; 3 - multiplicity discriminator; 4 -magnet ; 5 - Čh detector; 6 –Sci–hodoscope; 7 - Ecal Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  6. Experimental studies of scalars with VES • Form-factor of the decay ηʹ → ηππ • The (ωφ) in Charge Exchange Reaction • ISB decay f1(1285)  3 π • Search for ISB decay π(1800)  ηππ Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  7. Form-factors in the decaysηʹ → ηππ • The width and spectral shape of the ηʹ → ηππ are of interest for various aspects • General tool: ChPT (expansion in p2, mu,d,s, 1/Nc in Nc  approach) • + FSI (heavy ηʹ) • intermediate Resonances in play • encoded in LEC (@low s) • introduced “by hands” or dynamically • Mainly with JPC = 0++ (coupling to 1- suppressed in I=0 P  PPP due to G-parity) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  8. ηʹ → ηπ+π- DP with VES • Measured in • diffractive associative production ηʹ π- • Charge exchange reaction • largest sample at the moment (~23 k ev) • more general DP parameterization: |M|2 1 + a  Y + b  Y 2 + c  X + d  X2 + … (1) Compared w. “linear” one ( complex) |M|2 |1 +   Y| 2 + c  X + d  X2 (2) (1) & (2) equivalent ONLY for b > a2/4  0 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  9. VES Dalitz plot Y – dependence of Dalitz plot distribution for 8 slices on X. Data (points) and fitting function (line) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  10. ηʹ → ηπ+π- DP with VES (cont’d) • The parameter сcompatible with zero as expected from C – symmetry • The b NEGATIVE  the “linear” parameterization not adequate • The large and NEGATIVE d impacts models Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  11. ηʹ → ηππ DP: Experiment vs. Theory • PL B651 22 (2007) (VES) [26] B.Borasoy and R.Nissler, EPJ A26, 383 (2005) • PAN 72 231 (2009) (GAMS) (neutral mode; may differ) • PR D 83, 012003 (2011) (BESIII) - New (~44 k ev) JHEP 1105:094,2011 RafelEscribano, PereMasjuan, Juan Jose Sanz-Cillero Large-NcChPT vs. RChT Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  12. Scalars in ηʹ → ηππ DP • a0(980) contribution dominant •  is essential • But … heavier tensor states are not negligible • Accounting for other states required to study scalers Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  13. Scalar in (ωφ) system in charge-exchange (OPE compatible) reaction Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  14. X(1812): Earlier observation in J/ψ(γωφ) By BESII Collab. ( Ablikim et al.), Phys. Rev.Lett.96:162002,2006 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  15. PWA of (ωφ) system (Hadron-2009, Proceedings of XIII International Conference) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  16. PWA of (ωω) system Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  17. N(ωφ)/N(ωω) ratiofor JP=0+ Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  18. OZI rule in 0+ & 2+ N0+() /N0+ () = 0.65  0.10 (1.82 GeV < M < 2.0 GeV) • The violation of the OZI rule in decays of scalar resonances is expected in many models “On the origin of the OZI rule in QCD”, Nathan Isgur , H.B. Thacker Phys.Rev. D64 094507, 2001 ……. Compare with 2+ N2+() /N2+ () = 0.045  0.010 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  19. ISB Decay f1(1285)π+π-π0 • IGJPC = 0+1++ M = 1282 MeV,  = 24 MeV • Dominant channels : KKπ, ηππ(incl. a0(980)π),4π • Decay to 3π violates Isospin Symmetry Possible mechanisms - f1(1285)  a1(1260) mixing(a la ω ρ, η π, Δ  N, Σ  Λ) - «contact» f1 3π - Intermediate scalars mixing: f1π a0  π f0 3π (possibly) enhanced through KK- loops (Achasov, Devyanin, Shestakov PL B88, 1979) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  20. Experimental findings • 1-st report @Meson-2008 (Cracow) • Final publication EPJ A (2011) 47: 68 • Associative f1π- production • π- A  A f1π- M(ηπ+π-) in η3π f1(1285) Effect of angular weighting 1+ (0+ 0- ) P on M(π+π- ) M(π+π- ) for M(3 π) within f1(1285) mass region Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  21. Experimental result Estimates within “Achasov’ model” varying a0/f0 parameters BR(f1π+π-π0) / BR(f1ηπ+π- ) ~ 0.05 – 0.5 % VES result exceeds maximal (with extreme f0(980)-KK coupling) More: accounting for lower 2-mass tail Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  22. Comparison w. BES-III VES BES-III arxiv/1012.1377v1.pdf Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  23. Possible (another) mechanism? • FSI (re - scattering) expected -- small @ BES as a0(f0) and  well separated -- large @ VES as all products “confined” • An example: Triangle Singularity (TS) ISB (1405/1475) f0arXiv:1108.3772v1 Jia-Jun Wu et al. TS a0 f0 mixing f1(1285) f1(1285) • JP = 1+ vs. 0- other TS character • f1(1285) light  loop particles off-shell Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  24. Search for ISB π(1800)  ηππ • Assuming a0 (980)  f0 (980) mixing • major JP=0-π(1800)  f0(980) π a0 π ηππ • Rich source: diffractive π- N → N π-(1800) with π-(1800) → (ηπ0) π- • 3-particles final state compared w. f1π case • but: broad (>120 MeV) π(1800) compared w. narrow (~25 MeV) f1(1285) • Specific feature (PWA needed): 0-(1800)→ 0+(ηπ) π M(0+)~0.98 ГэВ neutral only Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  25. Experimental observations π- N → N ηπ0 π- with  → +-0 for π(1800) region 1.72 < M(ηπ0 π- )< 1.92 GeV M(ηπ0) - left M(ηπ-) - right Signal compatible w. a0(980): N(a00 ) 600 60 N(a0- ) 130 60 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  26. PWA of (+-0)0- •  → +-0 with final experimental width • Very large (combinatorial) background • 5–particles PWA (includes ω(782) → +-0 and bckg.) • Many isobars ρ(770), a2(1320), a1(1260), b1(1235), a0(980) • 24 waves (JPC=0--, 0-+,1+-,1--,1++,2-+,2++,…) • Different production mechanisms (exchanges) (OPE, ω, diffraction) → t - dependencies • Separate waves w. (not symmetric) a00 and a0- • Model dependent a0 (980)  f0 (980) “mixing” signal • JP = 0- for π(1800)  “a00” - Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  27. Some (large) waves (preliminary) 2++ωρ 0- →“a00” - 0-+ a1ρ Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  28. Preliminary result @ 90% CL N.B.: π(1800)  K*K => no TS – like enhancement • Analyses π- N → N π-(1800) → (ηπ0) π- → () () π- desired • much less bckg lower noise; less states; (relatively) larger signal • pilot VES run (2010) with 1-track final state: promising • full run planned for November 2011 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  29. Conclusions • Specific shape of Dalitz plot for ηʹ → ηπ+π- adopted with RChT; scalarsAND tensors contribute • Scalar near threshold in ω(782) (1020) compatible w. X(1812) by BESII strongly violates OZI rule • ISB–decay f1(1285)π+π-π0 incompatible with “KK-loop mixing” of a0 (980)  f0 (980) alone: too intensive and structured • An indication to ISB–decay π(1800)  ηππ through “a0 (980)” needs more analyses Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  30. Backup slidesηʹ → ηπ+π- by VES in BES interpretation Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  31. Backup slidesRChT vs. large-NcChPT Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  32. Backup slides waves for PWA of (ωω) • 1 - (0++)0- JLS=000 11 - (0-+)0+ JLS=011 • 2 - (2++)0- JLS=202 12 - (2-+)0+ JLS=211 • 3 - (2++)0- JLS=220 13 - (1++)0+ JLS=122 • 4 - (2++)0- JLS=222 14 - (3++)0- JLS=322 • 5 - (2++)1- JLS=202 15 - (2++)1+ JLS=202 • 6 - (4++)0- JLS=422 16 - (4++)1+ JLS=422 • 7 - (4++)0- JLS=440 17 - FLAT • 8 - (4++)0- JLS=442 • 9 - (4++)0- JLS=422 • 10 - (6++)0- JLS=642 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  33. Backup slides K*K* rescattering vs. () resonance arXiv:1107.0781v1 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  34. Backup slides X(1812) search @ BELLE • X(1812) search @ BELLE in B+  K+ (ω) - no signal (arXiv:0902.4757v2) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  35. Backup slides(1405) f0(980)0 @BESIII Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

  36. Backup slidesM(π+π- ) in (1440) →  w. TS Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.2011

More Related