1. XXXIV International Meeting on Fundamental Physics
From HERA and the TEVATRON
to the LHC
Physics at the Tevatron
Rick Field
University of Florida
(for the CDF & D0 Collaborations)
Real Colegio Maria Cristina, El Escorial, Spain
4th Lecture
Detailed Study of the “Underlying Event”
at the Tevatron
CDF Run 2
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

2. The “Underlying Event” in Run 2 (CDF)
The “underlying event” consists of hard initial & final-state radiation plus the “beam-beam remnants” and possible multiple parton interactions.
Studying the “Underlying Event”
Two Classes of Events: “Leading Jet” and “Back-to-Back”.
Two “Transverse” regions: “transMAX”, “transMIN”, “transDIF”.
PTmax and PTmaxT distributions and averages.
Df Distributions: “Density” and “Associated Density”.
<pT> versus charged multiplicity: “min-bias” and the “transverse” region.
Correlations between the two “transverse” regions: “trans1” vs “trans2”.
Studying the “Underlying Event” in Drell-Yan Production.
Extrapolations to the LHC.
Florida-Perugia
CMS at the LHC
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

3. The “Transverse” Regions as defined by the Leading Jet
Charged Particle Df Correlations pT > 0.5 GeV/c |h| < 1
Look at the charged particle density in the “transverse” region!
“Transverse” region is very sensitive to the “underlying event”!
Look at charged particle correlations in the azimuthal angle Df relative to the leading calorimeter jet (JetClu R = 0.7, |h| < 2).
Define |Df| < 60o as “Toward”, 60o < -Df < 120o and 60o < Df < 120o as “Transverse 1” and “Transverse 2”, and |Df| > 120o as “Away”. Each of the two “transverse” regions have area DhDf = 2x60o = 4p/6. The overall “transverse” region is the sum of the two transverse regions (DhDf = 2x120o = 4p/3).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

4. Particle Densities Charged Particles pT > 0.5 GeV/c |h| < 1
DhDf = 4p = 12.6
CDF Run 2 “Min-Bias”
CDF Run 2 “Min-Bias”
Observable
Average
Average Density
per unit h-f
Nchg
Number of Charged Particles
(pT > 0.5 GeV/c, |h| < 1)
3.17 +/- 0.31 /
PTsum (GeV/c)
Scalar pT sum of Charged Particles
2.97 +/- 0.23 /
1 charged particle
dNchg/dhdf = 1/4p = 0.08
dNchg/dhdf = 3/4p = 0.24
3 charged particles
1 GeV/c PTsum
dPTsum/dhdf = 1/4p GeV/c = 0.08 GeV/c
dPTsum/dhdf = 3/4p GeV/c = 0.24 GeV/c
3 GeV/c PTsum
Divide by 4p
Study the charged particles (pT > 0.5 GeV/c, |h| < 1) and form the charged particle density, dNchg/dhdf, and the charged scalar pT sum density, dPTsum/dhdf.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

5. “Transverse” Particle Densities
Charged Particles
pT > 0.5 GeV/c |h| < 1
Area = 4p/6
AVE “transverse”
(Trans 1 + Trans 2)/2
1 charged particle in the
“transverse 2” region
dNchg/dhdf = 1/(4p/6) = 0.48
Study the charged particles (pT > 0.5 GeV/c, |h| < 1) in the “Transverse 1” and “Transverse 2” and form the charged particle density, dNchg/dhdf, and the charged scalar pT sum density, dPTsum/dhdf.
The average “transverse” density is the average of “transverse 1” and “transverse 2”.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

6. Charged Particle Density Df Dependence
Log Scale!
Leading Jet
Min-Bias
0.25 per unit h-f
Shows the Df dependence of the charged particle density, dNchg/dhdf, for charged particles in the range pT > 0.5 GeV/c and |h| < 1 relative to jet#1 (rotated to 270o) for “leading jet” events 30 < ET(jet#1) < 70 GeV.
Also shows charged particle density, dNchg/dhdf, for charged particles in the range pT > 0.5 GeV/c and |h| < 1 for “min-bias” collisions.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

7. Charged Particle Density Df Dependence
Refer to this as a “Leading Jet” event
Subset
Refer to this as a
“Back-to-Back” event
Look at the “transverse” region as defined by the leading jet (JetClu R = 0.7, |h| < 2) or by the leading two jets (JetClu R = 0.7, |h| < 2). “Back-to-Back” events are selected to have at least two jets with Jet#1 and Jet#2 nearly “back-to-back” (Df12 > 150o) with almost equal transverse energies (ET(jet#2)/ET(jet#1) > 0.8) and with ET(jet#3) < 15 GeV.
Shows the Df dependence of the charged particle density, dNchg/dhdf, for charged particles in the range pT > 0.5 GeV/c and |h| < 1 relative to jet#1 (rotated to 270o) for 30 < ET(jet#1) < 70 GeV for “Leading Jet” and “Back-to-Back” events.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

8. Charged Particle Density Df Dependence
“Leading Jet”
“Back-to-Back”
0.5
1.0
1.5
2.0
Polar Plot
Shows the Df dependence of the charged particle density, dNchg/dhdf, for charged particles in the range pT > 0.5 GeV/c and |h| < 1 relative to jet#1 (rotated to 270o) for 30 < ET(jet#1) < 70 GeV for “Leading Jet” and “Back-to-Back” events.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

9. “Transverse” PTsum Density versus ET(jet#1)
“Leading Jet”
Hard Radiation!
“Back-to-Back”
Min-Bias
0.24 GeV/c per unit h-f
Shows the average charged PTsum density, dPTsum/dhdf, in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.
Compares the (uncorrected) data with PYTHIA Tune A and HERWIG after CDFSIM.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

10. “Transverse” PTsum Density versus ET(jet#1)
30-70 GeV
GeV
Very little dependence on ET(jet#1) in the “transverse” region for “back-to-back” events!
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

11. “TransDIF” PTsum Density versus ET(jet#1)
“Leading Jet”
Hard Radiation!
“Back-to-Back”
“MAX-MIN” is very sensitive to the “hard scattering” component of the “underlying event”!
Use the leading jet to define the MAX and MIN “transverse” regions on an event-by-event basis with MAX (MIN) having the largest (smallest) charged PTsum density.
Shows the “transDIF” = MAX-MIN charge PTsum density, dPTsum/dhdf, for pT > 0.5 GeV/c, |h| < 1 versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

12. “TransMIN” PTsum Density versus ET(jet#1)
“Leading Jet”
“Back-to-Back”
“transMIN” is very sensitive to the “beam-beam remnant” component of the “underlying event”!
Use the leading jet to define the MAX and MIN “transverse” regions on an event-by-event basis with MAX (MIN) having the largest (smallest) charged particle density.
Shows the “transMIN” charge particle density, dNchg/dhdf, for pT > 0.5 GeV/c, |h| < 1 versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

13. “Transverse” PTsum Density PYTHIA Tune A vs HERWIG
“Leading Jet”
“Back-to-Back”
Now look in detail at “back-to-back” events in the region 30 < ET(jet#1) < 70 GeV!
Shows the average charged PTsum density, dPTsum/dhdf, in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.
Compares the (uncorrected) data with PYTHIA Tune A and HERWIG after CDFSIM.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

14. Charged PTsum Density PYTHIA Tune A vs HERWIG
HERWIG (without multiple parton interactions) does not produces enough PTsum in the “transverse” region for 30 < ET(jet#1) < 70 GeV!
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

15. Min-Bias “Associated” Charged Particle Density
Highest pT charged particle!
“Associated” densities do not include PTmax!
Use the maximum pT charged particle in the event, PTmax, to define a direction and look at the the “associated” density, dNchg/dhdf, in “min-bias” collisions (pT > 0.5 GeV/c, |h| < 1).
It is more probable to find a particle accompanying PTmax than it is to find a particle in the central region!
Shows the data on the Df dependence of the “associated” charged particle density, dNchg/dhdf, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events. Also shown is the average charged particle density, dNchg/dhdf, for “min-bias” events.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

16. Min-Bias “Associated” Charged Particle Density
Rapid rise in the particle density in the “transverse” region as PTmax increases!
PTmax > 2.0 GeV/c
Transverse Region
Transverse Region
Ave Min-Bias
0.25 per unit h-f
PTmax > 0.5 GeV/c
Shows the data on the Df dependence of the “associated” charged particle density, dNchg/dhdf, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 0.5, 1.0, and 2.0 GeV/c.
Shows “jet structure” in “min-bias” collisions (i.e. the “birth” of the leading two jets!).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

17. “Transverse” PTmax versus ET(jet#1)
“Leading Jet”
Highest pT particle in the “transverse” region!
“Back-to-Back”
Min-Bias
Use the leading jet to define the “transverse” region and look at the maximum pT charged particle in the “transverse” region, PTmaxT.
Shows the average PTmaxT, 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 the average maximum pT particle, PTmax, in “min-bias” collisions (pT > 0.5 GeV/c, |h| < 1).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

18. Back-to-Back “Associated” Charged Particle Densities
Maximum pT particle in the “transverse” region!
“Associated” densities do not include PTmaxT!
Use the leading jet in “back-to-back” events to define the “transverse” region and look at the maximum pT charged particle in the “transverse” region, PTmaxT.
Look at the Df dependence of the “associated” charged particle and PTsum densities, dNchg/dhdf and dPTsum/dhdf for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmaxT) relative to PTmaxT.
Rotate so that PTmaxT is at the center of the plot (i.e. 180o).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

19. Back-to-Back “Associated” Charged Particle Densities
“Associated” densities do not include PTmaxT!
Jet#2 Region ??
Log Scale!
Look at the Df dependence of the “associated” charged particle density, dNchg/dhdf for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 0.5 GeV/c, PTmaxT > 1.0 GeV/c and PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV.
Shows “jet structure” in the “transverse” region (i.e. the “birth” of the 3rd & 4th jet).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

20. Back-to-Back “Associated” Charged Particle Densities
charge density
“Back-to-Back”
“associated” density
Shows the Df dependence of the “associated” charged particle density, dNchg/dhdf for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 0.5 GeV/c, PTmaxT > 1.0 GeV/c and PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV.
It is more probable to find a particle accompanying PTmaxT than it is to find a particle in the “transverse” region!
Shows Df dependence of the charged particle density, dNchg/dhdf for charged particles (pT > 0.5 GeV/c, |h| < 1) relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

21. Back-to-Back “Associated” Charged Particle Densities
charge density
“Back-to-Back”
“associated” density
0.5
1.0
1.5
2.0
Polar Plot
Shows the Df dependence of the “associated” charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) and the charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1 relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

22. Back-to-Back “Associated” Charged Particle Densities
charge density
“Back-to-Back”
“associated” density
0.5
1.0
1.5
2.0
Polar Plot
Shows the Df dependence of the “associated” charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1, PTmaxT > 2.0 GeV/c (not including PTmaxT) relative to PTmaxT (rotated to 180o) and the charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1, relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

23. Rick Field – Florida/CDF/CMS
Jet Topologies
QCD Four Jet Topology
QCD Three Jet Topology
0.5
1.0
1.5
2.0
Polar Plot
Shows the Df dependence of the “associated” charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1, PTmaxT > 2.0 GeV/c (not including PTmaxT) relative to PTmaxT (rotated to 180o) and the charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1, relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

24. Back-to-Back “Associated” Charged Particle Density
Jet#2 Region
Log Scale!
Look at the Df dependence of the “associated” charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 2.0 GeV/c for “back-to-back” events with 30 < ET(jet#1) < 70 GeV and 95 < ET(jet#1) < 130 GeV.
Very little dependence on ET(jet#1) in the “transverse” region for “back-to-back” events!
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

25. “Back-to-Back” vs “Min-Bias” “Associated” Charge Density
“Birth” of jet#3 in the “transverse” region!
“Back-to-Back”
“Associated” Density
“Min-Bias”
“Associated” Density
Log Scale!
“Birth” of jet#1 in “min-bias” collisions!
Shows the Df dependence of the “associated” charged particle density, dNchg/dhdf for pT > 0.5 GeV/c, |h| < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV.
Shows the data on the Df dependence of the “associated” charged particle density, dNchg/dhdf, pT > 0.5 GeV/c, |h| < 1 (not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 2.0 GeV/c.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

26. “Associated” PTsum Density PYTHIA Tune A vs HERWIG
HERWIG (without multiple parton interactions) does not produce enough “associated” PTsum in the direction of PTmaxT!
PTmaxT > 0.5 GeV/c
And HERWIG (without multiple parton interactions) does not produce enough PTsum in the direction opposite of PTmaxT!
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

27. “Associated” PTsum Density PYTHIA Tune A vs HERWIG
For PTmaxT > 2.0 GeV both PYTHIA and HERWIG produce slightly too much “associated” PTsum in the direction of PTmaxT!
PTmaxT > 2 GeV/c
But HERWIG (without multiple parton interactions) produces too few particles in the direction opposite of PTmaxT!
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

28. Jet Multiplicity
Max pT in the “transverse” region!
HERWIG (without multiple parton interactions) does not have equal amounts of 3 and 4 jet topologies!
Data have about equal amounts of 3 and 4 jet topologies!
Shows the data on the number of jets (JetClu, R = 0.7, |h| < 2, ET(jet) > 3 GeV) for “back-to-back” events with 30 < ET(jet#1) < 70 GeV and PTmaxT > 2.0 GeV/c.
Compares the (uncorrected) data with HERWIG after CDFSIM.
Compares the (uncorrected) data with PYTHIA Tune A after CDFSIM.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

29. The “Central” Region in Drell-Yan Production
Look at the charged particle density and the PTsum density in the “central” region!
Charged Particles (pT > 0.5 GeV/c, |h| < 1)
After removing the lepton-pair everything else is the “underlying event”!
Look at the “central” region after removing the lepton-pair.
Study the charged particles (pT > 0.5 GeV/c, |h| < 1) and form the charged particle density, dNchg/dhdf, and the charged scalar pT sum density, dPTsum/dhdf, by dividing by the area in h-f space.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

30. Rick Field – Florida/CDF/CMS
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune A25
Tune A50
MSTP(81) 1
MSTP(82) 4
PARP(82)
2.0 GeV
PARP(83)
0.5
PARP(84)
0.4
PARP(85)
0.9
PARP(86)
0.95
PARP(89)
1.8 TeV
PARP(90)
0.25
PARP(67)
4.0
MSTP(91)
PARP(91)
1.0
2.5
5.0
PARP(93)
15.0
25.0
UE Parameters
ISR Parameter
Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), Tune A25 (<pT(Z)> = 10.1 GeV/c), and Tune A50 (<pT(Z)> = 11.2 GeV/c).
Intrensic KT
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

31. CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune AW
MSTP(81) 1
MSTP(82) 4
PARP(82)
2.0 GeV
PARP(83)
0.5
PARP(84)
0.4
PARP(85)
0.9
PARP(86)
0.95
PARP(89)
1.8 TeV
PARP(90)
0.25
PARP(62)
1.0
1.25
PARP(64)
0.2
PARP(67)
4.0
MSTP(91)
PARP(91)
2.1
PARP(93)
5.0
15.0
UE Parameters
ISR Parameters
Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune AW (<pT(Z)> = 11.7 GeV/c).
Effective Q cut-off, below which space-like showers are not evolved.
The Q2 = kT2 in as for space-like showers is scaled by PARP(64)!
Intrensic KT
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

32. Drell-Yan Production at the Tevatron
Lepton-Pair Transverse Momentum
<PT(pair)> versus M(pair) Z Z
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and PYTHIA Tune A.
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

33. Drell-Yan Production at the LHC
Lepton-Pair Transverse Momentum
<PT(pair)> versus M(pair)
The lepton-pair <PT> much larger at the LHC! Z Z
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG.
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG.
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

34. The “Underlying Event” in Drell-Yan Production (Tevatron)
Charged particle density versus M(pair)
The “Underlying Event”
HERWIG (without MPI) is much less active than PY Tune AW (with MPI)! Z Z
Shows the charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and PYTHIA Tune A.
Shows the charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (with no MPI).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

35. The “Underlying Event” in Drell-Yan Production (LHC)
Charged particle density versus M(pair)
The “Underlying Event”
HERWIG (without MPI) is much less active than PY Tune AW (with MPI)!
“Underlying event” much more active at the LHC! Z Z
Charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (without MPI).
Charged particle density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG (without MPI).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

36. The “Underlying Event” in High PT Jet Production (LHC)
Charged particle density versus PT(jet#1)
The “Underlying Event”
“Underlying event” much more active at the LHC!
Charged particle density in the “Transverse” region versus PT(jet#1) at 1.96 TeV for PY Tune AW and HERWIG (without MPI).
Charged particle density in the “Transverse” region versus PT(jet#1) at 14 TeV for PY Tune AW and HERWIG (without MPI).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

37. UE&MB@CMS UE&MB@CMS UE&MB@CMS
Rick Field (Florida)
Darin Acosta (Florida)
Paolo Bartalini (Florida)
Albert De Roeck (CERN)
Livio Fano' (INFN/Perugia at CERN)
Filippo Ambroglini (INFN/Perugia at CERN)
Khristian Kotov (UF Student, Acosta)
Me at CMS!
Measure Min-Bias and the “Underlying Event” at CMS
The plan involves two phases.
Phase 1 would be to measure min-bias and the “underlying event” as soon as possible (when the luminosity is low), perhaps during commissioning. We would then tune the QCD Monte-Carlo models for all the other CMS analyses. Phase 1 would be a service to the rest of the collaboration. As the measurements become more reliable we would re-tune the QCD Monte-Carlo models if necessary and begin Phase 2.
Phase 2 is “physics” and would include comparing the min-bias and “underlying event” measurements at the LHC with the measurements we have done (and am doing now) at CDF and then writing a physics publication.
Darin
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS

38.
Study charged particles
and muons using the CMS detector
at the LHC (during the pilot run)!
Min-Bias Studies: Charged particle distributions and correlations. Construct “charged particle jets” and look at “mini-jet” structure and the onset of the “underlying event”. (requires only charged tracks)
“Underlying Event” Studies: The “transverse region” in “leading Jet” and “back-to-back” charged particle jet production and the “central region” in Drell-Yan production. (requires charged tracks and muons for Drell-Yan)
Drell-Yan Studies: Transverse momentum distribution of the lepton-pair versus the mass of the lepton-pair, <pT(pair)>, <pT2(pair)>, ds/dpT(pair) (only requires muons). Event structure for large lepton-pair pT (i.e. mm +jets, requires muons).
IMFP Day April 6, 2006
Rick Field – Florida/CDF/CMS