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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.20111
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Introductory remarks VES Experiment Scalars at VES – various topics Conclusions Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.20112
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NOTE ON SCALAR MESONS by C. Amsler, T. Gutsche, S. Spanier and N.A.T¨ornqvist (in RPP 2011): quantum numbers of the vacuum ( J PC = 0 ++ ) can condense into the vacuum and break a symmetry such as a global chiral U(N f ) L × U(N f ) R How they break ? Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.20113
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Numerous and various OPE scattering π /K N N π /K π, N K/ π K Diffractive π N N PPP p p ̅ PPP (at rest & in flight) γ γ PP D ( * ) / B PPP Dalitz 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, 19.09.20114
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5 1 - target; 2 - veto counters; 3 - multiplicity discriminator; 4 -magnet ; 5 - Čh detector; 6 –Sci – hodoscope; 7 - Ecal secondary (mostly π - ) beam of U-70, p ~ 25 – 45 ГэВ / с magnetic spectrometer p t = 0.5 - 0.7 GeV/ с EM – calorimetry K/ π – identification (4-18 GeV/ с ) Fast DAQ (10 4 /spill) Minimum bias trigger
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Form-factor of the decay η ʹ → η π π The ( ωφ ) in Charge Exchange Reaction ISB decay f 1 (1285) 3 π Search for ISB decay π (1800) η π π Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.20116
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The width and spectral shape of the ηʹ → η π π are of interest for various aspects General tool: ChPT (expansion in p 2, m u,d,s, 1/N c in N c approach) + FSI (heavy ηʹ) intermediate Resonances in play - encoded in LEC (@low s) - introduced “by hands” or dynamically Mainly with J PC = 0 ++ (coupling to 1 - suppressed in I=0 P PPP due to G-parity) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.20117
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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 X 2 + … (1) Compared w. “linear” one ( complex) |M| 2 |1 + Y| 2 + c X + d X 2 (2) (1) & (2) equivalent ONLY for b > a 2 /4 0 Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.20118
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9 Y – dependence of Dalitz plot distribution for 8 slices on X. Data (points) and fitting function (line)
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The parameter с compatible 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, 19.09.201110
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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) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201111 JHEP 1105:094,2011 Rafel Escribano, Pere Masjuan, Juan Jose Sanz-Cillero Large-Nc ChPT vs. RChT
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201112 a 0 (980) contribution dominant is essential But … heavier tensor states are not negligible Accounting for other states required to study scalers
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201113 in charge-exchange ( OPE compatible ) reaction
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201114 By BESII Collab. ( Ablikim et al.), Phys. Rev.Lett.96:162002,2006
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201115 (Hadron-2009, Proceedings of XIII International Conference)
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201116
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201117
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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 ……. Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201118 (1.82 GeV < M < 2.0 GeV) N 2+ ( ) /N 2+ ( ) = 0.045 0.010 N 0+ ( ) /N 0+ ( ) = 0.65 0.10 Compare with 2+
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I G J PC = 0 + 1 ++ M = 1282 MeV, = 24 MeV Dominant channels : KK π, ηππ (incl. a 0 (980) π ), 4 π Decay to 3 π violates Isospin Symmetry Possible mechanisms - f 1 (1285) a 1 (1260) mixing ( a la ω ρ, η π, Δ N, Σ Λ ) - «contact» f 1 3 π - Intermediate scalars mixing: f 1 π a 0 π f 0 3 π (possibly) enhanced through KK- loops (Achasov, Devyanin, Shestakov PL B88, 1979) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201119
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201120 1-st report @Meson-2008 (Cracow) Final publication EPJ A (2011) 47: 68 Associative f 1 π - production π - A A f 1 π - M( π + π - ) for M(3 π) within f 1 (1285) mass region Effect of angular weighting 1 + (0 + 0 - ) P on M( π + π - ) M( ηπ + π - ) in η 3 π f 1 (1285)
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201121 More: accounting for lower 2 -mass tail Estimates within “Achasov’ model” varying a 0 /f 0 parameters BR(f 1 π + π - π 0 ) / BR(f 1 ηπ + π - ) ~ 0.05 – 0.5 % VES result exceeds maximal ( with extreme f 0 (980)-KK coupling)
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201122 BES-III VES arxiv/1012.1377v1.pdf
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FSI (re - scattering) expected -- small @ BES as a 0 (f 0 ) and well separated -- large @ VES as all products “confined” An example: Triangle Singularity (TS) ISB (1405/1475) f 0 arXiv:1108.3772v1 Jia-Jun Wu et al. Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201123 a)TS b)a 0 f 0 mixing f 1 (1285) J P = 1 + vs. 0 - other TS character f 1 (1285) light loop particles off-shell
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Assuming a 0 (980) f 0 (980) mixing major J P =0 - π (1800) f 0 (980) π a 0 π η π π Rich source: diffractive π - N → N π - (1800) with π - (1800) → ( ηπ 0 ) π - 3-particles final state compared w. f 1 π case but: broad (>120 MeV) π (1800) compared w. narrow (~25 MeV) f 1 (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, 19.09.201124
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201125 for π (1800) region 1.72 < M( η π 0 π - )< 1.92 GeV M( η π 0 ) - left M( η π - ) - right Signal compatible w. a 0 (980): N(a 0 0 ) 600 60 N(a 0 - ) 130 60 π - N → N η π 0 π - with → + - 0
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→ + - 0 with final experimental width Very large (combinatorial) background 5–particles PWA (includes ω (782) → + - 0 and bckg.) Many isobars ρ (770), a 2 (1320), a 1 (1260), b 1 (1235), a 0 (980) 24 waves (J PC =0 --, 0 -+,1 +-,1 --,1 ++,2 -+,2 ++,…) Different production mechanisms (exchanges) (OPE, ω, diffraction) → t - dependencies Separate waves w. (not symmetric) a 0 0 and a 0 - Model dependent a 0 (980) f 0 (980) “mixing” signal J P = 0 - for π (1800) “a 0 0 ” - Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201126
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201127 2 ++ ωρ 0 -+ a 1 ρ 0 - →“a 0 0 ” -
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201128 @ 90% CL N.B.: π (1800) K*K => no TS – like enhancement Analyses π - N → N π - (1800) → ( ηπ 0 ) 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
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Specific shape of Dalitz plot for ηʹ → η π + π - adopted with RChT; scalars AND tensors contribute Scalar near threshold in ω (782) (1020) compatible w. X(1812) by BESII strongly violates OZI rule ISB–decay f 1 (1285) π + π - π 0 incompatible with “KK-loop mixing” of a 0 (980) f 0 (980) alone: too intensive and structured An indication to ISB–decay π (1800) η π π through “a 0 (980)” needs more analyses Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201129
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201130
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201131
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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, 19.09.201132
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201133 arXiv:1107.0781v1
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X(1812) search @ BELLE in B+ K+ ( ω ) - no signal (arXiv:0902.4757v2) Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201134
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201135
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Yu.Khokhlov (IHEP Protvino) for VES PhiPsi11 Novosibirsk, 19.09.201136
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