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HERA-B results

HERA-B results. Antonio Zo ccoli Università and INFN – Bologna For the HERA-B Collaboration. HERA-B history. The history of the experiment: - 1994 proposal - 1995 experiment approved - 1995-1999 R&D, production and installation - 2000 first detector commissioning

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HERA-B results

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  1. HERA-B results Antonio Zoccoli Università and INFN – Bologna For the HERA-B Collaboration 62nd PRC meeting - Zeuthen - 23/10/2006

  2. HERA-B history The history of the experiment: - 1994 proposal - 1995 experiment approved - 1995-1999 R&D, production and installation - 2000 first detector commissioning - 2001-2002 detector upgrade (HERA shut down) and update of the physics program - 2002 Nov.–2003 Feb. data taking Only 4 months for the physics data taking ! The original schedule was very tight. An unforeseen R&D phase was necessary due to aging problems  Delays on the schedule

  3. Si gas = high rates had to face LHC equivalent particle flux 10 years in advance. • exploring a new regime of radiation load, particle flux, event rates... detectors trigger system DAQ At forefront of technology 62nd PRC meeting - Zeuthen - 23/10/2006

  4. μ+μ- e+e- ~ 120000 J/ψ ~ 2200 ψ′ σJ/ψ ~ 64 MeV ~ 170000 J/ψ ~ 3000 ψ′ σJ/ψ ~ 44 MeV 104 104 J/ψ entries/(30 MeV/c2) entries/(25 MeV/c2) J/ψ 103 103 ψ′ ψ′ 2.5 3.0 3.5 4.0 2.8 3.2 3.6 4.0 m(e+e-)[GeV/c2] m(μ+μ-)[GeV/c2] • 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 Main data samples Three target materials: pC,pW and pTi collisions

  5. Physics topics • FCNC D0 μμ Br limit Phys. Lett. B596 (2004) 173. • Beauty production: • bb cross section (J/ det.) Phys. Rev. D73 (2006) 052005. • bb cross section (semilept.) Paper ready •  production Phys. Lett. B638 (2006) 13. • Charmonium studies: • J/ production Phys. Lett. B638 (2006) 407. • J/diff. distributions Note stage • J/A-dependence Analysis ongoing • (2s) production In press on Eur. Phys. J C. • c/J/ production ratio Note stage • Pentaquark production Phys. Rev. Lett. 93 (2004) 212003. • Λ polarization Phys. Lett. B638 (2006) 415. • K*/Φ production In press on Eur. Phys. J C. • Open charm production Note stage • Deuteron production Analysis ongoing • Hyperon production Note stage • Luminosity determination Paper Draft 62nd PRC meeting - Zeuthen - 23/10/2006

  6. Beauty production 62nd PRC meeting - Zeuthen - 23/10/2006

  7. pA bb X bJ/ψ Y e+e-/+- Y pA bb X b1Y b2Z ℓ+ J/ψ Δz p ℓ- b Y IW b σ(bb): inclusive b production B Meson has a long life time ( ~ 9 mm at HERA-B kinematics) ~ 0.5 mm dilepton vertex resolution. Two methods: 1) J/ from a B decay detached from primary interaction 2) two leptons from B semileptonic decays downstream upstream 1 Analysis cuts: - Impact parameter - [Decay length (Δz)] I2 Y b p Z I1 2 Normalizationon the inclusive prompt J/ cross section.  Systematic error minimization 62nd PRC meeting - Zeuthen - 23/10/2006

  8. Open b production 1) Detached J/ψ method • C,W,Ti targets • Full statistics • Unbinned likelihood fit 20% sys., main contribution: Br(bbJ/X) = 2.320.20% Lifetime:  = (1.39 ± 0.19)ps 62nd PRC meeting - Zeuthen - 23/10/2006

  9. 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) Open b cross section Phys. Rev. D73 (2006) 052005 • Theoretical uncertainties: • b quark mass 4.5 - 5 GeV • At NLO, scale (m) dependence • E789/E771 measurements do not agree with each other 2) Semileptonic B decay method: preliminary result. 62nd PRC meeting - Zeuthen - 23/10/2006

  10. Charmonium studies 62nd PRC meeting - Zeuthen - 23/10/2006

  11. HERA-B √s = 41.6 GeV W [GeV2/c2] Ti Au C <pT2> E672/706, E771, E789 √s = 38.8 GeV Si Be A 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) W Ti E771 (Si) HERA-B E672/E706 (Be) Increase of <pT2> with cms energy and with A.  Consistent with a linear dependence on the nuclear path length. C pT[GeV/c]  Kinematic range enlarged 62nd PRC meeting - Zeuthen - 23/10/2006

  12. 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 62nd PRC meeting - Zeuthen - 23/10/2006

  13. dN 1 N d(cosθ) cosθ J/y polarization Measured in different reference systems (CS, GJ, HCM) and wrt pT and xF dN/d(cosθ)  1 + λθcos2θ Preliminary HCM (arb. norm.) -CS frame shows the largest longitudinal polarization. -Kinematical dependence on pT. -Not in conflict with other experiments. BEAM (arb. norm.) CS HCM BEAM CS lθ Preliminary |lθ| > |lθ| > |lθ| <pT> [GeV/c] <xF> 62nd PRC meeting - Zeuthen - 23/10/2006

  14. J/yA-Dependence Test of charmonium production models in nuclear matter (NRQCD + initial/final state interactions in nucleus) -  < 1: charmonium suppression by nuclear effects - HERA-B: extract  from runs with two target wires simultaneously (carbon: A=12, tungsten: A=184) - Results from full m+m– sample. Only statistical uncertainties. Similar results from the e+e- sample. • PT broadening effect as seen by E866 experiment • Previous result of FNAL E866 extended to xF = –0.35 62nd PRC meeting - Zeuthen - 23/10/2006

  15. a 1.0 0.9 0.8 Models (with variants): • - R. Vogt, PRC 61 (2000) 035203, NP A700 (2002) 539 • K.G. Boreskov & A.B. Kaidalov, JETPL 77 (2003) 599 0.7 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 B&K 1.0 Vogt: final state absorption 0.9 HERA-B preliminary (di-muon channel, carbon+tungsten double-wire runs) errors statistical only E866 38.8 GeV Be/Fe/W E789 38.8 GeV Be/C/Cu/W E772 38.8 GeV H2/C/Ca/Fe/W NA50 29.1 GeV Be/Al/Cu/Ag/W NA3 22.9 GeV H2/Pt 0.8 xF 0.7 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 J/yA-Dependence 62nd PRC meeting - Zeuthen - 23/10/2006

  16. (2S) Production HERA-B c HERA-B ti HERA-B w Combined results (e+e- + μ+μ-): E444 NA38, NA50 & NA51 • (2S) cross section measurement relative to J/ reduction of systematic uncertainties • No dependence on cms energy and kinematics except for Na38/50/51. All results consistent within 4%. E705 NA38 E331 E789 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 62nd PRC meeting - Zeuthen - 23/10/2006

  17. E771 HERA-B NRQCD (p-p) NA50 E789 pT xF y(2S) differential distributions  (2S) and J/ states have very similar kinematics Fraction of J/ from (2S) : Constraint on the double ratio(test of lepton universality): current PDG avg.: 1.03 ± 0.12 62nd PRC meeting - Zeuthen - 23/10/2006

  18. preliminary 2002/2003 data (di-muon sample) background: mixed events after background subtraction entries/(10 MeV/c2) m(μ+μ-γ)-m(μ+μ-) [GeV/c2] ccProduction Selection: The measurement: • fraction of J/ψ’s from χc: • kinematic distributions • A-dependence from the 2000 data, with 370 ± 74 χc’s(μ+μ- + e+e-): R(c) = 0.32 ± 0.06 ± 0.04 [Phys. Lett. B 561, 61 (2003)] new data: 40bigger χcstatistics (the largest analyzed in a hadronic experiment) 62nd PRC meeting - Zeuthen - 23/10/2006

  19. E771 (p-Si) E369/ 610/ 673 (p-Be) π-A ISR (p-p) 2000 expected final precision 2002/3 prelim. E705 (p-Li) CDF (p-p) HERA-B R(cc) Preliminary evaluation (2002/2003 data): (21 ± 5)% of the produced J/ψ’s come from χc decays based on 1300 χc’s reconstructed in the di-muon channel (less than 10% of the total statistics) 62nd PRC meeting - Zeuthen - 23/10/2006

  20. ISR E705 E331 E444 UA6 E331 NA3 p-p p-A E595 E288 E672/706 E771 χc ψ′ b NA50 E789 NA3 J/ψ J/ψ J/ψ Indirect and direct J/ψ production Using partial/preliminary HERA-B results: (7.0±0.4)% (21 ± 5)% (0.065±0.011)% (to be improved!) extracted from MB data (72 ± 5)% of the J/ψ’s are produced directly Curve: NLO NRQCD fit of all data (Maltoni et al., hep-ph/0601203) 62nd PRC meeting - Zeuthen - 23/10/2006

  21. Other topics 62nd PRC meeting - Zeuthen - 23/10/2006

  22. First reported negative result based on high statistics. K-(us) or (uds) Searched pentaquark states: Θ+(1530, uudds) → pK0(or nK+) Ξ (ddssu) → Ξπ(or ΣK) → Λππ + (uudds) p K0 p Pentaquark Searches Phys. Rev. Lett.93:212003,2004 wire 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, -) 62nd PRC meeting - Zeuthen - 23/10/2006

  23.  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% 62nd PRC meeting - Zeuthen - 23/10/2006 Phys. Rev. Lett. 93 (2004) 212003

  24. Open charm production D0+D0 49 ± 10 D*± entries/(10 MeV/c2) entries/(10 MeV/c2) Kππ inv. mass [GeV/c2] Kπ inv. mass [GeV/c2] m(Kππ)-m(Kπ) [GeV/c2] D± 194 ± 20 92 ± 11 entries/(0.5 MeV/c2) Cross section measurements: 62nd PRC meeting - Zeuthen - 23/10/2006

  25. Open charm production: results HERA-B prel. D0+D0 W Ti curves: σpA = σpN·Aα C without E789: with E789: √ D±/D0 √ HERA-B prel. ud α(D0)= 0.92±0.08 α(D±)= 1.02±0.09 α(D*±)= 1.05±0.14 • - D0: unclear situation at high √s E789 result clearly disfavored • - energy dependence well described in each case by the function • - α consistent with NO suppression • - from isospin symmetry and feeddown BRs • σ(D+)/ σ(D0)=0.326±0.003 62nd PRC meeting - Zeuthen - 23/10/2006

  26. K*/Φ + (anti)deuteron production Exploited the very good PiD (RICH). K*0K+π- ΦK+K- Cronin effect Deuteron Anti-Deuteron Preliminary results Cross section measurements. 62nd PRC meeting - Zeuthen - 23/10/2006

  27. Summary • HERA-B was installed in 2000. Designed to face LHC equivalent particle flux and data rates 10 years in advance. • Very important experience for the people involved, but also for many other experiments • About 100 PhD theses finalized • The physics data taking was in 2002-2003 (4 months) • The physics program was limited by the statistics, but provided interesting results (e.g. QGP community) • About 20 physics papers are foreseen: • 11 paper published, • 6 in advanced stage, • few analyses still ongoing 62nd PRC meeting - Zeuthen - 23/10/2006

  28. Conclusions • HERA-B has been partly disappointing since our original ambitious goal could not be fulfilled. Nonetheless, valuable results have been achieved: detector and triggering/DAQ innovations, several published physics results, many successful former HERA-B students. • HERA-B analysis activities are drawing to an end. The last results are being prepared for publication. At that point we will have produced results on all topics (and more) outlined in our May 2001 report to the PRC. (the basis for the PRC's approval for running after the HERA upgrade shutdown) • We would like to thank the Directorate, the Laboratory, the PRC, the Referee’s for their strong support and their guidance over the last decade. THANK YOU! 62nd PRC meeting - Zeuthen - 23/10/2006

  29. Backup Slides 62nd PRC meeting - Zeuthen - 23/10/2006

  30. 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 62nd PRC meeting - Zeuthen - 23/10/2006

  31. 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 62nd PRC meeting - Zeuthen - 23/10/2006

  32. 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) Phys. Rev. Lett. 93 (2004) 191801 62nd PRC meeting - Zeuthen - 23/10/2006

  33. 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/CEM calculations (hep-ph/0311048) M(+-) (GeV/c2) 75 ± 14statee Craigie parametrization 62nd PRC meeting - Zeuthen - 23/10/2006 M(e+e-) (GeV/c2)

  34. direction of e+(μ+) as seen in the J/ψ rest frame θ polarization axis Decay angular distribution: polarization frames Il Nuovo Cimento Vol. XXXIII, N. 2 (1964) Phys. Rev. D16, 2219 (1977) Collins-Soper (“CS”) 1) Gottfried-Jackson (“GJ”) bisector between beam and (–)target directions in the J/ψ rest frame target direction in the J/ψ rest frame = (-)J/ψdirection in the lab frame E866, NA3, etc. reformulated as “BEAM” 2) 3) helicity “HCM” beam direction in the J/ψ rest frame J/ψ directionin the hadron (p-n) CM frame CDF, NA60, etc. E615, E672-706, E771, E537, etc. 62nd PRC meeting - Zeuthen - 23/10/2006

  35. E866 38.8 GeV p-Cu E444 20.6 GeV π±-C/Cu/W NA3 22.9 GeV p-H2 NA3 22.9 GeV p-Pt HB 41.6 GeV p-C/Ti/W experimental situation: CS frame J/ψ significantly polarized at low momentum (low pTand |xF|) lθ 62nd PRC meeting - Zeuthen - 23/10/2006

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