Jets at the Tevatron - PowerPoint PPT Presentation

Jets at the tevatron l.jpg
Download
1 / 26

  • 277 Views
  • Uploaded on
  • Presentation posted in: Pets / Animals

Jets at the Tevatron. B. Paul Padley Dept of Physics and Astronomy Rice University. Exciting Time. Obviously we have entered an era of new energy and luminosity. Clearly the is a great potential to do new and exciting things And the old stuff even looks new and exciting.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Jets at the Tevatron

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Jets at the tevatron l.jpg

Jets at the Tevatron

B. Paul Padley

Dept of Physics and Astronomy

Rice University


Exciting time l.jpg

Exciting Time

  • Obviously we have entered an era of new energy and luminosity.

  • Clearly the is a great potential to do new and exciting things

  • And the old stuff even looks new and exciting.

  • Probing ~10-19 m scale


Highest mass di jet event so far l.jpg

Highest mass di-jet event so far

Highest mass di-jet event so far

(corrected mass = 1364 GeV/c2):

r-fview

ET = 666 GeV

h= 0.43

ET = 633 GeV

h= -0.19


D0 highest dijet mass event l.jpg

D0 Highest Dijet Mass Event

1206 GeV/c2 dijet mass event


Clusters l.jpg

Clusters

  • Use Run II cone algorithm

  • Combine particles in a R=0.7 cone

  • Use the four vector of every tower as a seed

  • Rerun using the midpoints between pairs of jets as seeds

  • Overlapping jets merged if the overlap area contains more than 50% of lower Pt jet, otherwise particles assigned to nearest jet.

Cf. Blazey et al. Hep-ex/0005012v2


Slide6 l.jpg

Jets

Both groups are using E-scheme recombination

Cf. Blazey et al. Hep-ex/0005012v2


Inclusive jet cross section l.jpg

Inclusive Jet Cross Section

Extending Run 1 reach by ~150 GeV

Run II Data shown taken between Feb 2002 and summer 2003

(They are planning on new results using Kt algorithm in May)


Inclusive jet cross section8 l.jpg

Inclusive Jet Cross Section

  • Excitement about Run 1 high ET excess

  • SM explanation: gluon PDF not well constrained at high x

Use EKS pQCD

http://zebu.uoregon.edu/~soper/EKSJets/jet.html


Inclusive jet cross section ratio l.jpg

Inclusive Jet Cross Section Ratio

Both plots the same with extra point on the lower


Inclusive jet cross section10 l.jpg

Inclusive Jet Cross Section

Notice forward jets


Inclusive jet cross section11 l.jpg

Inclusive Jet Cross Section


Inclusive jet cross section12 l.jpg

Inclusive Jet Cross Section

JES uncertainty <7% dominant contributor to systematic uncertainties


Dijet cross section l.jpg

Dijet Cross Section


Dijet cross section14 l.jpg

Dijet Cross Section


Dijet df decorrelations l.jpg

Dijet Df Decorrelations

Jet 1

In leading order pQCD dijets are back to back

Df=p

Jet 2


Dijet df decorrelations16 l.jpg

Dijet Df Decorrelations

Three jet events in leading order pQCD

As Kt goes to 0, Df goes to p

If Kt is large Df<<p

Jet 1

Jet 3

Df<p

Kt

Jet 2

Df distribution is directly sensitive to QCD higher order radiation without explicitly measuring the third jet


Dijet df decorrelations17 l.jpg

Dijet Df Decorrelations


Df decorrelations compare to lo l.jpg

Df Decorrelations, Compare to LO


Df decorrelations compare to lo19 l.jpg

Df Decorrelations, Compare to LO

Poor fit to data at low Pt.

At higher Pt’s it gets better, especially in the 2.3 to 2.8 regime

Same plots as previous page, just spread out for print visibility


Dijet df decorrelations20 l.jpg

Dijet Df Decorrelations


Dijet df decorrelations21 l.jpg

Dijet Df Decorrelations

Pythia Tune A reproduces the data best.


Underlying event studies l.jpg

Underlying Event Studies

Transverse regions are sensitive to underlying event

“Back-to-Back”

(Df12>150o,ETj2/ETj1>0.8)


Underlying event studies23 l.jpg

Underlying Event Studies

Run 2

Min-Bias

0.25 per unit h-f

  • Direction of leading jet to define 3 fregions


Underlying event studies 2 l.jpg

Underlying Event Studies (2)

Run 2 data:

Current MC with default parameters fail to reproduce data.

In Run 1 PYTHIA 6.206 tuned adding multi-parton interactions.

  • Shows the average charged particle density, dN/dhdf, in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events compared with PYTHIA Tune A and HERWIG after CDFSIM.


Underlying event studies 3 l.jpg

Underlying Event Studies (3)

PYTHIA tuned (on Run 1 data) reproduces Run 2 data well

HERWIG (with no multi-parton interaction) works only at high ETj1.

  • Average charged PTsum density, dPT/dhdf, in the “transverse” region

    (pT > 0.5 GeV/c, |h| < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events compared with PYTHIA Tune A and HERWIG after CDFSIM.


Conclusions l.jpg

Conclusions

  • First results have been shown – no surprises

  • Highest mass DY events have been observed

  • Jet Energy Scale is dominant error in inclusive cross sections

  • Pythia Tune A (by Rick Field) on the Run 1 data is reproducing soft data well.


  • Login