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Physics I+Computing

Physics I+Computing. John Huth. Transition from cosmic rays to collider physics. Cosmic ray reconstructed in both the muon spectrometer and inner detector. Use expertise in muon spectrometer to investigate early physics: W/Z production Z pt, distributions Lay groundwork for

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Physics I+Computing

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  1. Physics I+Computing John Huth

  2. Transition from cosmic rays to collider physics Cosmic ray reconstructed in both the muon spectrometer and inner detector Use expertise in muon spectrometer to investigate early physics: W/Z production Z pt, distributions Lay groundwork for higher energy+lum. discovery physics John Huth DOE Site Visit

  3. John Huth DOE Site Visit

  4. Z’s in early data (Kashif, Black, Huth) Calibration of spectrometer, inner detector Early physics – Pt distribution helps understand PDF’s σ*Br*eff=150 pb at 7 TeV Inv. Mass distribution with bckg. sim. from bbar Pt distribution, with unfolding John Huth DOE Site Visit

  5. W-/W+ Ratio (Martinez, Belloni, Guimaraes) Sensitive to PDF’s Main backgrounds: W→τν Top Z →μμ Can be done with low energy + modest Lum. →Extension of cosmic ray asym →Can be done with a few days at 1029 John Huth DOE Site Visit

  6. W-/W+ Ratio in Rapidity John Huth DOE Site Visit

  7. Z+jets (Kagan, Black, Huth, Moed) QCD tests Sensitive to new physics (technicolor, Higgs) Calibration of jet energy scales (from recoil system) Predictions for Z+N jet cross sections for varying CM energies At low luminosities, examine energy flow In recoil system Gain experience in jet systematics John Huth DOE Site Visit

  8. Δφ Z-Jet (Kagan, Black, Huth, Moed) Z Δφ Jet John Huth DOE Site Visit

  9. ΔφZ-Jet (Kagan, Black, Huth, Moed) Back-to-back deviation from QCD radiation effects Relatively insensitive to jet energy scales = early measurement Derive hadronic energy scale 10TeV@100 pb-1 John Huth DOE Site Visit

  10. Investigation of associated Higgs production (Kagan, Black, Huth, +Gallichio, Schwartz) ZH final state had long been neglected at LHC Backgrounds dominate Recent studies have revived interest in this mode Jet recombination Boosted Higgs From Butterworth et al arXiv:0810.0409v1 : John Huth DOE Site Visit

  11. Fuller treatment Studies by Butterworth et al. had neglected b-quark showering and decay New variables found show s/b rejection bckg Higgs John Huth DOE Site Visit

  12. Heavy flavor in VB Production (Martinez, Guimaraes) B-jet merging in W/Z+bbar Matrix element generation of Wbbar required to get full kinematic distribution ΔR John Huth DOE Site Visit

  13. B-jet corrections (Moed) Improving resolution of b-bar dijets → Correct for energy loss and neutrinos in semi-leptonic decays Electrons more difficult (inside jets) John Huth DOE Site Visit

  14. Technirho decays into Z+γ(Black) Cleaner signature than Z+2 jets, smaller branching fraction – viable with a few fb-1of data Red=background from contiuum Blue=signal John Huth DOE Site Visit

  15. Involvement in analysis groups • Early work in muon combined performance working group • Capitalize on experience with cosmic ray analysis • Reconstruction efficiency • Work with SM Z/W (+jets) groups • Z pt distribution, cross section • Introduction of MadGraph to ATLAS • W+/W- asymmetry • Top group (see also MF’s talk next) • b quark energy corrections • Jet merging • Heavy flavor studies • Lepton+X convenor (K. Black) • Luminosity group (L. Kashif) • US ATLAS Analysis Forum Chair (K. Black) John Huth DOE Site Visit

  16. Physics I Summary • Early physics – concentrate on SM measurements • Z cross section (Kashif) • W+/W- ratio (Martinez) • Z+jets (Kagan) • Preparation for higher energy/luminosity • Understand b-jet response, jet merging John Huth DOE Site Visit

  17. Computing • Relevant sites: • CERN • Tier 0 – work on reconstruction • LxPlus – main development site • Local cluster shared with U. Michigan in Bldg. 188 • BNL • Tier 1 site, development, main data repository for US • Harvard • Tier 2 – Odyssey cluster major engine for US ATLAS Production • Tier 3 – Odyssey cluster – main data repositories for Harvard group John Huth DOE Site Visit

  18. Networking in Boston 300 Bent St. MIT Harvard Harvard 1 Summer St. BU NoX metro ring: 128 fibers (only a few fibers are in use) -> NYC -> BNL -> CERN John Huth DOE Site Visit

  19. Northeast Tier 2 Center Harvard: 500-700 dedicated cores for ATLAS prod. 6568 cores, 21.0 MSpecInt2K 750 TB SAN 2 x Cisco 6509 + 10 Gbps dedicated fiber to NoX Lustre parallel file system + NFS Shared access to FAS FACILITY BU: 700 cores, 2.1 MSpecInt2K 500 TB SAN Cisco 6509 + 10 Gbps dedicated fiber to NoX ATLAS DEDICATED John Huth DOE Site Visit

  20. ATLAS Computing@Harvard 1 FTE sys. admin from Harvard supports T2/T3 300-500 cores available for individual analyses Disk space had been main bottleneck – usage approx. 20 TB 30 TB donated from M.Seltzer (SEAS) Production jobs on HU_T2 John Huth DOE Site Visit

  21. ATLAS work done on the Harvard Odyssey cluster Apr-15-2009 through Jul-15-2009 20.1 Terabytes Odyssey NET2 storage 500T GPFS Boston University 9.1 Terabytes 500 cores 2.33 Ghz Intel Harpertown 79635 simulation 12191 pile-up 5680 validation 3573 event generation 1546 merge 1420 reconstruction 941 test 4 digitization 104,990 successful PANDA jobs 28,000 cpu-days delivered Tier 1 John Huth DOE Site Visit

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