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HERA-B results

HERA-B results. Università and INFN – Bologna From the HERA-B Collaboration. 13 Nations 30 Institutes. 150 physicists. HERA-B:. IHEP, Beijing U. Tsinghua. Norway. China. U. Oslo. LIP, U. Coimbra LIP, U. Lisbon. Portugal. Denmark. NBI, Copenhagen. ITEP, Moscow JINR, Dubna.

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HERA-B results

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  1. HERA-B results Università and INFN – Bologna From the HERA-B Collaboration HERA-B results

  2. 13 Nations 30 Institutes 150 physicists HERA-B: IHEP, Beijing U. Tsinghua Norway China U. Oslo LIP, U. Coimbra LIP, U. Lisbon Portugal Denmark NBI, Copenhagen ITEP, Moscow JINR, Dubna Russia U. Humboldt, Berlin U. Dortmund DESY MPI Heidelberg U. Heidelberg U. Mannheim MPI Munich U. Rostock U. Siegen DESY Zeuthen Slovenia J.F. Inst, Ljubljani Germany Spain U. Barcelona U. Zurich Switzerland INR, Kiev Ukraine U. Texas, Austin U. Cincinnati Wayne State U. U. Houston U. Calif, Los Angeles INFN, U. Bologna Italy U. Utrecht NIKHEF USA Netherlands HERA-B results

  3. Inner / Outer Tracker7 layers of GEM-MSGCs (inner) and honeycomb drift chambers (outer) Wire Target 2 stations, 4 wires each (C, Ti, W) Silicon Vertex Detector8 double-layers of double-sided Si-microstrips RICHC4F10 radiator, multianode PMT focal plane ECALW/Pb-scintillator sampling shashlik calorimeter, cluster pretrigger The HERA-B Detector Muon Detector4 layers of gas pixel chambers (inner) and MWPC with cathode pad readout (outer), pad-coincidence pretrigger Top View 920 GeV/c Protons e+/e- beam Magnet 20 m 10 m 0 m HERA-B results

  4. Si gas = high rates had to face LHC equivalent particle flux 10 ears in advance. • exploring a new regime of radiation load, particle flux, event rates... detectors trigger system DAQ At forefront of technology HERA-B results

  5. S=41.6 GeV 184W p-beam 12C 48Ti z [cm] The HERA-B detector • p-Nucleus interactions at 920 GeV • BX crossing rate: 10 MHz  Up to 4•107 interactions/s (~5ev/bx) • Very sophisticated and challenging detector. • Large central acceptance ( 5 > lab > 2 ) • Capability to reconstruct the full event • Very good particle ID for (e, , , K, p) • High resolution vertexing • Target: 8 wires in the p-beam halo 5 materials: C, Ti, Al, Pd, W • Double wire configuration for A-Dependence Measurements: C+W • Online event reconstruction • Very selective multilevel trigger (hardware + software) J/  μμ/ee  Suitable for P-Nucleus interaction studies HERA-B results

  6. Electromagnetic Calorimeter (ECAL) INFN contribution (Bologna) • Main Italian responsibilities: • readout and pretrigger electronics • Second Level Trigger and reconstruction codes • Detector calibration and maintenance HERA-B results

  7. Trigger & DAQ System Multilevel trigger scheme based on Kalman filter. 5 (10) MHz Pretrigger/Level 1 (rejection ~250) (<12 ms) Level 2 (rejection. ~200) 20 KHz (5-10 ms) Full online reconstruction and logging to tape 100 Hz (~1s) Two PC-Linux farms used in L2 and for the offline reconstruction. HERA-B results

  8. Electrons ~ 108,000 J/ σ= 64 MeV/c2 /  ~ 1600 (2S) Data taking finished in 2003. Main data samples • 150 M di-lepton trigger events (e+e-/μ+μ- triggers) • 300 000 J/ψ(>1000 per hour) • 15 000 c1+ c2 • 5 000 ψ(2S) • 210 M minimum bias events • 1000 ev/s >1TB/day • 35 M hard photon events • 60 M “glueball” trigger events

  9. Low-mass region: High-mass region: Approx. 3,500 eventsMass: 3674 MeV/c2Width: 53 MeV/c2 r/w (2S/3S) f (1S) y(2s) Dilepton spectrum: Muon Channel J/y Approx. 177,000 eventsMass: 3095 MeV/c2Width: 44 MeV/c2 HERA-B results

  10. Physics topics • Main physics topics addressed: • FCNC D0 μμ Br limit • bb cross section •  production • J/ production J/:pT distribution J/:xF distribution J/:A-dependence • (2s) production • c/J/ production ratio • Open charm production • Pentaquark production J/ Di-lepton trigger e+ e- + - (2s) C D0 bb (1-3s) MB data D0 K() HERA-B results

  11. W+ μ+ c 18 events 3 evt 6 events νμ d,s,b μ- u W- New Limit on BR(D0+) BR from SM: ~10-19 • Search for flavor-changing neutral current decay D0+(branching fraction enhanced in some MSSM models ~10-7) • 3 events in signal region: Phys.Lett.B596:173-183,2004 BR(D0+) < 2.010-6(90% CL) • Current limits by : • CDF: BR(D0+) < 2.510-6 (90% CL) Phys. Rev. D68 (2003) 091101 • BaBar: BR(D0+) < 1.310-6 (90% CL) hep-ex/0408023 HERA-B results

  12. pA bb X bJ/ψ Y e+e-/+- Y ℓ+ J/ψ Δz p ℓ- b Y IW σ(bb): inclusive b production B Meson has a long life time ( ~ 9 mm at HERA-B kinematics) ~ 0.5 mm dilepton vertex resolution J/ from a B decay will be detached from primary interaction downstream upstream Analysis cuts: - Decay lenght (Δz) - Impact parameter Normalizationon the inclusive prompt J/ cross section.  Systematic error minimization HERA-B results

  13. open b production • C,W,Ti targets • Full statistics • Unbinned likelihood fit 20% sys. error under investigation, main contribution: Br(bbJ/X) = 2.320.20% Lifetime:  = (1.41 ± 0.16)ps HERA-B results

  14. N. Kidonakis et al. 102 HERA-B E789 E771 σ(bb) (nb/nucleon) 10 Previous HERA-B result of year 2000 (~ 10 ev) [Eur. Phys. J. C26, 345 (2003)]: 1 R. Bonciani et al. 1000 900 400 500 600 700 800 Proton energy (GeV) Cross section Cross section obtained by using the fit based on NRQCD of J/ψ cross sections . Phys. Rev. D73 (2006) 052005 • Theoretical uncertainties: • b quark mass 4.5 - 5 GeV • At NLO, scale (m) dependence • Previous measurements do not agree between each other • Agreement with the previous HERA-B result (1.5 σ) HERA-B results

  15. Upsilon production E605 E605 E772 E771 R-108 CERN CCOR HERA-B NA3 FNAL FNAL FNAL FNAL pN + X, +-,e+e- 30.87.4stat Drell-Yan Comb. BG NLO calculation inside CEM (hep-ph/0311048) M(+-) (GeV/c2) 7514statee Craigie parametrization HERA-B results M(e+e-) (GeV/c2)

  16. p-p PHENIX HERA-B W p-A Ti σ(pAJ/ψ) [μb] σpA = σpN ·A0.96 C μ+μ- mass [GeV/c2] IHEP experimental data sometimes inconsistent A WA39 CERN-PS preliminary J/ψ production cross section inclusivemeasurement μ+μ- 100 ± 12 used MB data to minimize trigger systematics for each target material (A = 12 [C], 48 [Ti], 184 [W]) Good agreement with the fit of J/ψ + ψ′ cross sections and ψ′/ψ production ratios (29 results in all) in the context of NLO NRQCD (F. Maltoni) HERA-B results

  17. <pT> grows logarithmically with A: <pT>[GeV/c] Au Si C W Ti Be J/ψ Differential Distribution:pT Electron channel: compared with p-A results (√s=38.8 GeV) agreement with muon channel in all distributions. [GeV-2/c2] A 197 184 48 28 12 9 E789 (Au) HERA-B (W) HERA-B (Ti) E771 (Si) E672/E706 (Be) HERA-B (C) pT[GeV/c] HERA-B results

  18. E789 (Au) E672/E706 (Be) E789 (Be, Cu) E771 (Si) HERA-B (C-W) J/y Differential distribution:xF Electron channel: compared with p-A results (√s=38.8 GeV) agreement with muon channel in all distributions. Fitting curves: with C Ti W first data produced at negative xF HERA-B results

  19. J/y polarization Measured in different reference systems (CS, GJ, HCM) and wrt pT and xF Preliminary: [-0.3,0.0] ±0.1 GJ Same range as previous experiments xF pT  angle perpendicular to  Hint for  > 0 No experimental results important to study also  Also studied by CDF but at larger pT HERA-B results

  20. J/yA-Dependence • Test of charmonium production models in nuclear matter (nonrelativistic QCD + initial/final state interactions in nucleus) • Previous result of FNAL E866 extended to xF = –0.35 • Result from full m+m– sample, statistical uncertainties only, similar results for e+e- HERA-B results

  21. (2S) Production (1.63 ± 0.07)% C = (1.99 ± 0.24)% Ti (1.62 ± 0.10)% W E444 NA38, NA50 & NA51 E789 • Measure (2S) cross section relative to J/reduce systematic uncertainties • No dependence wrt A and cms energy • Competitive measurements E705 NA38 HERA-B c E331 HERA-B ti HERA-B w p-A E288 E771 B′σ(ψ′)/Bσ(J/ψ) (%) 12 184 197 9 6 27 2 9 64 28 12 1 108 184 184 12 238 12 HERA-B results

  22. y(2S) differential distributions Fraction of J/ψ from ψ′: Constraint on the double ratio(test of lepton universality) current PDG avg.: 1.03 ± 0.12 E771 HERA-B NRQCD (p-p) NA50 E789 pT xF HERA-B measurements extend the range of the previous results with comparable or better precision HERA-B results

  23. background: mixed events Muon channel R(c) Entries (10 MeV/c2) CSM Average NRQCD ECMS ccProduction • Test of charmonium production models: fraction R(c) of J/ from radiative decays c J/  μ+ μ–  HERA-B results M(J/ ) – M(J/)

  24. wire K-(us) or (uds) + (uudds) p K0 p Pentaquark Searches Phys. Rev. Lett.93:212003,2004 First negative result based on high statistics and performed on two different states. Searched pentaquark states: Θ+(1530, uudds) → pK0(or nK+) Ξ (ddssu) → Ξπ(or ΣK) → Λππ and charge c. • MB data sample (~210M evts, 3 nuclear targets C, Ti, W) used to: • search for the reported pentaquark signals • provide upper limits on particle yield ratios (vs Λ(1520) and Ξ0(1530)) • possibly determine physical quantities (width, spin, parity, charge) of pentaquarks for different final states (p-K0, -) HERA-B results

  25.  mass pK0s mass NA49 HERA-B UL(95%) -- UL(95%) mass GeV/c2 1.4 1.475 1.55 1.625 1.7 +,-- signals Counts Counts B d/dy b/C B d/dy b/C UL(95%)Bd/dy|y=0 = 4-16 b/N @ 1521-1555 MeV/c2 + / (1520) < 3 – 12 % UL(95%)Bd/dy|y=0 = 2.5 b/N @ 1862 MeV/c2 -- / -< 3/B% -- / (1530)0< 4/B% HERA-B results Phys. Rev. Lett. 93 (2004) 212003

  26. Open charm production: signals D0+D0 entries/(10 MeV/c2) entries/(10 MeV/c2) Kππ inv. mass [GeV/c2] Kπ inv. mass [GeV/c2] 49 ± 10 D± D*± 194 ± 20 92 ± 11 entries/(0.5 MeV/c2) m(Kππ)-m(Kπ) [GeV/c2] D0 D+ cτ= 125 ± 21 μm cτ= 292 ± 38 μm dN/dz [a.u.] agreement with PDG values preliminary HERA-B results proper decay length [μm] proper decay length [μm]

  27. Open charm production: cross section √ √ For Isospin symmetry and feeddown BRs, expected violated by about a factor 2 D*±/D0 D±/D0 Important test for QCD HERA-B prel. HERA-B prel. ud ud HERA-B results

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