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Signals from Δ ++ and f 0 in the AliRsn package

Signals from Δ ++ and f 0 in the AliRsn package. Sergey Kiselev, ITEP Moscow for the TOF group Introduction Motivation, Data, Estimations Experience with the AliRsn package Input, output info ϕ  K + K - , K * 0  K + π - Δ ++  p π + , Δ 0  p π - , f 0  π + π -

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Signals from Δ ++ and f 0 in the AliRsn package

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  1. Signals from Δ++ and f0 in the AliRsn package • Sergey Kiselev, ITEP Moscow for the TOF group • Introduction • Motivation, Data, Estimations • Experience with the AliRsn package • Input, output info • ϕ K+K- , K*0 K+π- • Δ++  pπ+ , Δ0  pπ- , f0  π+π- • ρ0, ω, K*0  π+π- • Conclusions and recommendations PWG2/ALICE, CERN S.Kiselev

  2. Introduction SQM’07:short-lived resonances, motivation + last results channel B.R.(%) c (fm)RHIC dataΔm (MeV)ALICE studies a1(1260) π  ~0.5 0.5 ρ0(770)π+ π-~100 1.3 p+p/d+A/Au+Au -70 p+p/Au+Au Δ++(1232)  p π+~100 1.6 p+p/d+Au -40 f0(980) π+ π- 66 2.6 p+p/Au+Au K*(892) πK ~100 4 p+p/d+Au/Au+Au -10 p+p/Au+Au Σ*(1385)  Λπ 88 5.5 p+p/d+Au/Au+A 0 Λ*(1520) p K45 12.6 p+p/d+Au/Au+Au 0p+p/Au+Au Ξ*(1530) Ξπ~100 21 p+p/d+Au/Au+Au 0 ω(782)  π+ π- π089 23 p+p/d+Au 0 ω(782) π0 9 23 p+p/d+Au/Au+Au 0 ω(782)  π+ π- 2 23 ω(782) e+e-7 10-223 p+p/d+Au/Au+Au in prog. Φ(1020) K+ K-49 44 p+p/d+Au/Au+Au 0 p+p/Au+Au Φ(1020) e+e-3 10-244 p+p/d+Au/Au+Au in prog. Life Time PWG2/ALICE, CERN S.Kiselev

  3. Introduction – Δ++ motivation P.Fachini SQM07 Δ++  Mass and Width PDG • Δ++ mass shift observed in both minimum bias p+p and d+Au at √sNN = 200 GeV • Width agrees with PDG for both systems within errors • possible explanations: π+π- rescattering in p+p collisions, P. Fachini et.al., J.Phys.G33:431-440,2007 PDG PWG2/ALICE, CERN S.Kiselev

  4. Introduction – f0 motivation A. Badalà- SQM07- Levoča – 24/06/-29/06/07 Nuclear Modification Ratios (RCP) for resonances RHIC results have shown as, in the intermediate pt region, nuclear modification factors depend on the constituent quarks rather than on particle mass. Recent suggestion by Maiani et al. (Phys. Lett. B645(2007)138) to use this observable to solve the problem of the real quark composition of some resonances as the fo(980)( or ?) PWG2/ALICE, CERN S.Kiselev

  5. RHIC data: Δ++/p, f0 /π-ratios nucl-ex/0403026 nucl-ex/0305034 • Δ++/p ~ 0.20 • f0/ π- ~ 0.05 ~107 min.bias pp events PWG2/ALICE, CERN S.Kiselev

  6. Estimations, SHAKER + data ratios (31.03.08 PWG2/ALICE week) PWG2/ALICE, CERN S.Kiselev

  7. AliRsn analysis: input info Two Alberto Pulvirenti’s macros: AliRsnAnalysis.C, AddRsnAnalysisTask.C for the PROOF analysis on CAF Main input values:  277500 Pythia6 min.bias pp @ 10 TeV events: /COMMON/COMMON/LHC08c11_10TeV_0.5T absolute value of the resonance code (e.g. 2224 for Δ++ and ant- Δ++, 10221 for f0). !!! Pythia6 code, mass, width, … could differ from PDG ones (e.g. 9010221 for f0). Look at the PYTHIA6 particle table in the file: AliRoot/PYTHIA6/AliDecayerPythia.cxx  The daughter pair of the resonance (p+pi+ for Δ++, p-pi- for anti-Δ++)  nMixedEvents = 5  other parameters for tracking, vertex, … PWG2/ALICE, CERN S.Kiselev

  8. AliRsn analysis: output info Main output: 3 types of the invariant mass distribution for particle pairs: 1. true event pairs, true signal, Strue, from Monte-Carlo (MC) - will be fitted by the Breit-Wigner (BW) with parameters M0 , Γ0 2. event pairs, signals+backgrount (S+B) 3. mixed event pairs, background (Bmix) - Bmix will be normalized to S+B in the region Minv.mass > Mb - the extracted signal: (S+B) - Bmix For each of the types:  reconstructed info  MC info PWG2/ALICE, CERN S.Kiselev

  9. AliRsn: ϕ K+K- Mb = 1.1 GeV Strue is in a good agreement with (S+B)-Bmix Higher statistics needed PWG2/ALICE, CERN S.Kiselev

  10. AliRsn: K*0 K+π- Mb = 1.2 GeV ! (S+B)-Bmix ,besides Strue, has probably input from other resonances. Recommendation: to list all other mothers of the pairs. ? Large χ2 /ndf Γ0 (fit)=Γ0 (PYTHIA6) PWG2/ALICE, CERN S.Kiselev

  11. AliRsn: Δ++ pπ+ • Mb = 1.4 GeV • ? Ntrue (Δ++ ) = Ntrue (ϕ) • Recommendation: to list primary multiplicities. • ?Γ0 (fit)=80 MeV < • Γ0 (PYTHIA6) =120 MeV •  add anti-Δ++ to increase statistics PWG2/ALICE, CERN S.Kiselev

  12. AliRsn: … +anti-Δ++ !The larger pt the larger discrepancy between (S+B)-Bmix and Strue Strue/Bmix (±2RMS) = 3, 8 and 12% for pt =1-2, 2-3 and 3-4 GeV/c respectively (~2 times lower than estimations with SHAKER) reconstructed  MC PWG2/ALICE, CERN S.Kiselev

  13. …with MC info Results with MC are very close to ones with reconstruction. All open questions still exist. PWG2/ALICE, CERN S.Kiselev

  14. AliRsn: Δ0 pπ-+ anti-Δ0 … ! discrepancy between (S+B)-Bmix and Strue larger than for Δ++ Input from other resonances? Additional source of “signals” in PYTHIA6: GEANT primaries can be decay products of resonances. PWG2/ALICE, CERN S.Kiselev

  15. AliRsn: f0  π+π- Only one true pair! PYTHIA6 multiplicity of f0 is too low !? PDG PYTHIA6 KF KC particle chg col anti mass width w-cut lifetime decay 10221 259 f_0 0 0 0 1.00000 0.00000 0.00000 0.00000E+00 1 IDC on/off ME Br.rat. decay products 1574 1 0 0.520000 pi+ pi- 1575 1 0 0.260000 pi0 pi0 1576 1 0 0.110000 K+ K- 1577 1 0 0.055000 K_L0 K_L0 1578 1 0 0.055000 K_S0 K_S0 PWG2/ALICE, CERN S.Kiselev

  16. AliRsn: ρ0 π+π- Mb = 1.2 CeV … ~2 times discrepancy between (S+B)-Bmix and Strue  Contributions of other resonances, ω, … PWG2/ALICE, CERN S.Kiselev

  17. AliRsn: ω π+π- True pairs not from one channel: ω π+π- (Br=2.2%) ω π+π-π0 (Br=89%) AliRsn controls the pair, not the channel AliRsn: K*0  π+π- There is no such channel in PYTHIA6 313 K*0 m= 0.896 width=0.050 Br.rat. decay products 0.665 K+ pi- 0.333 K0 pi0 0.002 K0 gamma It looks like we observe the π+π- pairs from the chain K*0  K0π0π+π-π0Experts study the problem PWG2/ALICE, CERN S.Kiselev

  18. Conclusions and recommendations • The AliRsn package works well. Takes ~10 min. on CAF for ~3 105 pp @ 10 TeV events. • Thanks a lot Alberto with colleagues. • 1. The signal extracted with mixed events, (S+B)-Bmix , is higher than the true signal Strue , exception ϕ K+K- • 2. Large χ2 of the BW fit. Γ0(fit)< Γ0(PYTHIA6), exceptionK*0 K+π- • 3. PYTHIA6 multiplicity of f0 is too low! Only ONE π+π-pair from f0 • Recommendations for AliRsn: • to test the package with a “cocktail” generator with random primary particles + resonances (PYTHIA6 primaries can be decay products of resonances) • to list all mothers of the pair studied • to list multiplicity of all primaries PWG2/ALICE, CERN S.Kiselev

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