physics i+computing

Physics I+Computing

John Huth

21-Aug-09 John Huth DOE Site Visit 2

Transition from cosmic rays to collider physics

Cosmic ray reconstructed in both themuon spectrometer and inner detectorUse expertise in

muon spectrometer toinvestigate early physics:

W/Z productionZ pt, distributions

Lay groundwork for higher energy+lum.discovery physics


Z’s in early data (Kashif, Black, Huth)

Calibration of spectrometer, inner detectorEarly physics –

Pt distribution helps understand PDF’sσ*Br*eff=150 pb at 7 TeV

Inv. Mass distribution withbckg. sim. from bbar

Pt distribution, withunfolding


W-/W+ Ratio (Martinez, Belloni, Guimaraes)

Sensitive to PDF’sMain backgrounds:

W→τνTopZ →μμ

Can be done with low energy + modest Lum.→Extension of cosmic ray asym

→Can be done with a few days at 1029


W-/W+ Ratio in Rapidity


Z+jets (Kagan, Black, Huth, Moed)

QCD testsSensitive to new physics (technicolor, Higgs)Calibration of jet energy scales (from recoil system)

Predictions for Z+N jetcross sections for varying CM energies

At low luminosities,examine energy flowIn recoil system

Gain experience in jet systematics


Δφ Z-Jet (Kagan, Black, Huth, Moed)

Z

Jet

Δφ

TeVs 10


Back-to-back deviation from QCDradiation effects

Relatively insensitiveto jet energy scales= early measurement

Derive hadronicenergy scale

10TeV@100 pb-1

Δφ Z-Jet (Kagan, Black, Huth, Moed)


Investigation of associated Higgs production (Kagan, Black, Huth,

+Gallichio, Schwartz)

From Butterworth et al arXiv:0810.0409v1 :

ZH final state had longbeen neglected at LHC

Backgrounds dominate

Recent studies have revived interest in thismode

Jet recombinationBoosted Higgs

http://arxiv.org/abs/0810.0409v1


bckg

Higgs

Fuller treatment

Studies by Butterworth etal. had neglected b-quarkshowering and decay

New variables found show s/b rejection


ΔR

Heavy flavor in VB Production (Martinez, Guimaraes)

B-jet merging in W/Z+bbar

Matrix element generation ofWbbar required to get fullkinematic distribution


B-jet corrections (Moed)

Improving resolution of b-bar dijets→ Correct for energy loss andneutrinos in semi-leptonic decaysElectrons more difficult (insidejets)


Technirho decays into Z+γ(Black)

Cleaner signature thanZ+2 jets, smaller branching fraction – viable with a few fb-1of data

Red=background from contiuumBlue=signal

TeVs 10 15 fb


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)


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


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


MITHarvard

Networking in Boston

Harvard

BU

-> NYC -> BNL -> CERN

NoX metro ring: 128 fibers(only a few fibers are in use)

300 Bent St.

1 Summer St.


Northeast Tier 2 Center

700 cores, 2.1 MSpecInt2K500 TB SANCisco 6509 + 10 Gbps dedicated fiber to NoXATLAS DEDICATED

6568 cores, 21.0 MSpecInt2K750 TB SAN2 x Cisco 6509 + 10 Gbps dedicated fiber to NoXLustre parallel file system + NFSShared access to FAS FACILITY

BU:

Harvard:500-700 dedicated

cores for ATLAS prod.


ATLAS Computing@Harvard

1 FTE sys. admin from Harvard supports T2/T3

300-500 cores availablefor individual analyses

Disk space had been main bottleneck – usageapprox. 20 TB

30 TB donated from M.Seltzer(SEAS)

Production jobs on HU_T2


79635 simulation12191 pile-up 5680 validation 3573 event generation 1546 merge 1420 reconstruction 941 test 4 digitization

Odyssey

Tier 1

20.1 Terabytes

9.1 Terabytes

104,990 successful PANDA jobs

500 cores 2.33 Ghz Intel Harpertown

NET2 storage500T GPFSBoston University

ATLAS work done on the Harvard Odyssey cluster Apr-15-2009 through Jul-15-2009

28,000 cpu-days delivered

physics i+computing

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