Transcript Introduction

ATLAS Physics Workshop
26-28 Oct, CERN
(Exotics, top-physics)
Arshak Tonoyan
Exotics
http://agenda.cern.ch/fullAgenda.php?ida=a056744#2005-10-27
Titles of talks
• W’ and Z’ with 10 fb-1 of data
K. Benslama, K. Black, S. Willocq
• WZ scattering
P.-A. Delsart, J. Idarraga, G. Azuelos (University of
Montreal)
• A Search for Lepton Flavor
Violation (LFV) in Decay of Z
boson to μτ.
V. Bansal, V. Savinov (University of Pittsburgh)
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
3
Titles of talks
• Heavy Majorana Neutrinos NR , WR
and Z‘ from LRSM with Full
Simulation AODs
V. Savinov (University of Pittsburgh)
• Vector Resonance from Strong
EWSB in pp → WWtt, tttt
M. Gintner, I. Melo, B. Trpisova (University of Zilina)
• Preface to the search for new stable
heavy leptons and quarks at LHC
Belotsky K.M. (MEPhI, Moscow)
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
4
W’ and Z’ with 10 fb-1 of data
• W’ Z’ – extra gauge bosons
• Limits of Tevatron MW’ > 842 GeV, MZ’ > 845
GeV
• Full private simulation, Z’→μμ, mass range
1 - 4 TeV & W’→μν with mass 1 TeV (less
investigated), backgrounds and how to
suppress them were considered
• Conclusion: they are observable with 10 fb-1
data (except 4 TeV)
• Plans: to optimize cuts, look at e & τ
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
5
WZ scattering
• WZ resonance in the Chiral Lagrangian Model
• 5000 events were fully simulated by
modifying PYTHIA code (WZ →jjll, WZ→lνjj)
• Conclusions: They have good set of cuts
leading to good efficiencies & promising for
signal discovery with 100 fb-1 data.
• Plans: W+jets, Z+jets background and pile-up
are not considered yet,
New physics model (Extra-dimensional
“Higgsless” model) is in simulation process
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
6
A Search for LFV in decay of Z
boson to μτ
• Z →μτ – LFV at low energy scale (provided by
SUSY)
• LEP’s Upper Limit: BR(Z →μτ) < 1.2x10-5
• Fast simulation (ATLFAST), Z→W+ jets,
Z→ττ, Z→ttbar backgrounds were considered
and just 3 variables to suppress background
• Conclusion: Upper Limit with 30 fb-1 data is
2.4x10-5 (higher than at LEP!)
• Plans: to do something about W+jets
background
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
7
Top-physics
http://agenda.cern.ch/fullAgenda.php?ida=a056967#2005-10-28
Top ongoing analyses
•
Jet Calibration and Top mass reconstruction
– D. Pallin, E. Cogneras, S. Binet (Clermont)
– Jiansen Lu, D.M. Gingrich, H Ahmed Hossain (Alberta)
•
Top mass reconstruction
– J. P. Meyer, A.I. Etienvre, J. Schwindling (DAPNIA)
•
Commissioning with tt and single top events
– M. Barisonzi, Z. van Kesteren, S. I, van Vulpen, W. Verkerke, S Bentvelsen (NIKHEF)
•
Single top (s-channel and t-channel)
– A. Lucotte (Grenoble)
•
Single top trigger studies
– G. Comune (MSU)
•
Single top (Wt channel) and tt cross section
– M. Cobal (Udine), M.P. Giordani (Udine), S. Rolli (Tufts), C. Roda (Pisa)
•
Top spin polarization and W polarization
– F. Hubaut, E. Monnier, P. Pralavorio, B. Resende (CPPM)
– V. Simak, K. Smolek (Prague)
•
FCNC in top decays (tt and single top), Asymmetries
– J. Caravalho, A. Onofre, F. Veloso (LIP)
– T.L. Cheng (RHUL)
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
9
Top mass measurement:
reconstruction and W+4 jets
background contribution
• Analysis has been done for different levels (AOD,
CBNT) and for different generators (TopRex,
MC@NLO) using “Rome sample” ~ 0.47 fb-1
• Generated mass(MC@NLO) 175 GeV, reconstructed
176.1 ± 0.6GeV (AOD), 175.5 ± 0.6 GeV (CBNT)
• Important note: S/B for W+jets background is 30
(not 65 as in TDR!)
• Conclusions: results, obtained by different ways
are compatible, W+jets contribution is negligible
• Plans: Would be useful to have DC3 samples with
several generated mass values and more W+jets
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
10
Studies on Electroweak
Single Top Production
• Allows direct measurement of Vtb in CKM, forwardbackward asymmetries, probe for new physics
• Analysis has been done at AOD level using “Rome
sample” in general.
• Top mass reconstruction in t-channel, varying
selection cuts
cross section measurement for s-channel
• Conclusions: TDR cuts need to be optimized,
charge-dependent selection is available, for schannel W can be replaced by H+ (same final state)
• Plans: High statistics W+jets samples needed
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
11
Polarization studies in tt events
with full simulation
• Test SM, search for anomalous couplings
• The most complete analysis. TopRex and MC@NLO
were compared in fast and full simulation.
• Conclusions: It was shown that ATLAS can measure
precisely W polarization ~1-2% and top spin
correlation ~5% after 10fb-1
• This precision requires a deep understanding of all
objects (Electrons, Muons, Jets)
• Plans: systematics update with full simulation light/b-jet miscalibration, b-tagging efficiency...
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
12
My impressions
• In Exotics a lot of work can/need
be done
• In Top-physics they already have
good tools at least for reported
tasks
A.Tonoyan
ATLAS-JINR Physics Workshop
25 Nov 2005
13