Upload
curry
View
37
Download
0
Embed Size (px)
DESCRIPTION
Plans for the first Jet Paper. PWG04 August 24 th 2009. Christian Klein- Bösing for the PWG04 Task Force. A Short , Early P aper on Charged J et R econstruction in p+p ?. Want a maximum of statistics Statistical precision Systematic studies - PowerPoint PPT Presentation
Citation preview
Plans for the first Jet Paper
PWG04 August 24th 2009
Christian Klein-Bösing for the PWG04 Task Force
A Short, Early Paper on Charged Jet Reconstruction in p+p?
• Want a maximum of statistics– Statistical precision– Systematic studies
• Depend on understanding of high pT tracking – High pT spectra needed first
• But even if the paper will be not “short” or “early” the following should give you an idea of the key points
PWG04 08.2009 Christian Klein-Bösing 2
Not in the timescale of a few weeks
Title
PWG04 08.2009 Christian Klein-Bösing 3
Inclusive Jet Production and Jet Fragmentation in p+p collisions at 7 TeV/10 TeV
Measured with Charged particles in the ALICE Experiment
Beam Energy/Luminosity
PWG04 08.2009 4
7 TeV p+p 10 TeV p+p
Here only MB events, luminosity more relevant when triggering, (But pileup effects depend on luminosity and bunch pattern).109 ≈ 20 d × 60% × 1 kHz
Christian Klein-Bösing
PYTHIA8 simulation + fastjet (R = 0.7)
Rough Abstract
PWG04 08.2009 Christian Klein-Bösing 5
Figures and Tables
• Fig. 1: Response matrix– MC all vs. MC charged– MC charged vs. rec
• Fig. 2:– Fragmentation function (for charged jet)– Comparison to MC and MLLA
• Fig. 3:– Jet spectrum, corrected up to charged jet energy– Unfolded to total jet energy (for different cuts in z of
the leading jet)PWG04 08.2009 Christian Klein-Bösing 6
Fig. 1
• Response Matrix– Emphasize the two levels of
corrections to reconstructed jets
– Charged track jet → charged particle jet → all particle jet
PWG04 08.2009 Christian Klein-Bösing 7
MC
(all
R =
0.4)
MC
(ch.
R =
0.4
)
MC (ch. R = 0.4)
Rec (R = 0.4)
Fig. 2
• Bias of the charged jet reconstruction– Reduced when using dijets
(TODO)
• Compare to different fragmentation models– PYTHIA (string)– HERWIG (cluster)– Also differ in UE– TODO
• At low ξ comparable to calculations (e.g. MLLA) without corrections?– Influence of UE– TODO
• pT,jet > 40 GeV most relevant for comparison with Pb+PbPWG04 08.2009 Christian Klein-Bösing 8
Leading jet fragmentation for R = 0.4 (LHC09a1-3)
Fig. 3
PWG04 08.2009 Christian Klein-Bösing 9
• Raw spectrum corrected for detector effects (charged jet spectrum)
• Fully corrected total jet spectrum
• Different subsamples of jets corrected to full– Different leading
particle z (TODO)
Tables
• Table 1:– Examples for reconstructed momentum shift and
smear due to:• Limited Cone radius• Charged to neutral• MC to reconstruction
• Table 2:– Systematic uncertainties
PWG04 08.2009 Christian Klein-Bösing 10
TODO
Rough Layout
PWG04 08.2009 Christian Klein-Bösing 11
What Needs to Be Done
– Systematic uncertainties • Jet Momentum scale checks• Flavour dependence, biases (cuts on jet shapes)
– Corrections• Revisit unfolding procedure: variable bin size, regularization• Underlying event in multiple collisions
– High pT QA• cannot rely on jet spectrum if single particle spectra are not understood
– Connection to MB data → coordinate QA– Sharpen focus on fragmentation
• Comparison to generators (i.e. PYTHIA: Lund Fragmentation, HERWIG cluster fragmentation) and theory
– Analysis note
PWG04 08.2009 12Christian Klein-Bösing
Momentum Scale
• Induced by JF– Cone radius/R-parameter
• Bias
– Algorithms– Can be studied with data
alone• Correlations• Average energy in certain
“trigger-bin” compared to mean momentum
• Should be symmetric in η-φ: otherwise acceptance effects
– 2D correlation TODO
• Also handle on UE contribution
• Induced by reconstruction– QA, high pT spectra
PWG04 08.2009 Christian Klein-Bösing 13
Charged particles correlated with leading jet axis
High pT QA: Cuts
PWG04 08.2009 Christian Klein-Bösing 14
Improved cut on1/pT uncertainty (relative)
loose cuts
loose cuts +rel pT
error
B. Bathen
People from the PWG4 Task Force
• Jet Spectrum– Unfolding: CKB, Ydalia Delgado
• Jet Finders– FastJet: S. Jangal, M. Estienne, J. Thäder, O. Busch– Deterministic Annealing: D. Perrino
• Di-jets: D. Perrino• Fragmentation function: B. Bathen, V. Roman• Jet shape/topology: S. Pochybova. L. Molnar• Underlying event: A. Abrahantas, E. Lopez, S. Valero, A. Agosc• High pT QA: G. Barros (M. Munhoz), M. Verweij (M. van
Leeuwen), B. Bathen
PWG04 08.2009 15Christian Klein-Bösing