A Closer Look at the
The “underlying event” consists of
hard initial & final-state radiation
plus the “beam-beam remnants” and
possible multiple parton interactions.
Underlying Event in Run 2 at CDF
CERN MC4LHC Workshop
July 2003
During the workshop the theorists, ATLAS/CMS
Proton
experimenters, and I constructed a “wish
list” ofmore
data new
Much
Run 2
Underlying Event
from CDF relating to “min-bias” and the
results
I can show here!
“underlying event” and I promised
to do thethan
analysis
and have the data available by the Itime
of make the plots
will
the Santa Barbara workshop in February 2004.
Outgoing Parton
New CDF Run 2 results!






available in the CDF
“blessed plots” area soon!
Outgoing Parton
PT(hard)
Initial-State Radiation
AntiProton
Underlying Event
Final-State
Radiation
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”.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 1
The “Transverse” Regions
as defined by the Leading Jet
Jet #1 Direction
“Transverse” region is
very sensitive to the
“underlying event”!
Charged Particle Df Correlations
2p
pT > 0.5 GeV/c |h| < 1
Away Region
“Toward-Side” Jet
Df
Look at the charged
particle density in the
“transverse” region!
Jet #1 Direction
Transverse
Region 1
Df
“Toward”
“Toward”
“Transverse”
“Transverse”
“Away”
“Trans 1”
f
Leading
Jet
“Trans 2”
Toward Region
Transverse
Region 2
“Away”
“Away-Side” Jet
Away Region
0
-1
h
+1
 Look at charged particle correlations in the azimuthal angle Dfrelative to the leading

calorimeter jet (JetClu R = 0.7, |h| < 2).
o
o
o
o
o
Define |Df| < 60 as “Toward”, 60 < -Df < 120 and 60 < Df < 120 as “Transverse 1” and
o
“Transverse 2”, and |Df| > 120 as “Away”. Each of the two “transverse” regions have
o
area DhDf = 2x60 = 4p/6. The overall “transverse” region is the sum of the two
o
transverse regions (DhDf = 2x120 = 4p/3).
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 2
Particle Densities
DhDf = 4p = 12.6
2p
f
31 charged
charged particles
particle
Charged Particles
pT > 0.5 GeV/c |h| < 1
CDF Run 2 “Min-Bias”
CDF Run 2 “Min-Bias”
Observable
Average
Nchg
Number of Charged Particles
(pT > 0.5 GeV/c, |h| < 1)
3.17 +/- 0.31
0.252 +/- 0.025
PTsum
(GeV/c)
Scalar pT sum of Charged Particles
(pT > 0.5 GeV/c, |h| < 1)
2.97 +/- 0.23
0.236 +/- 0.018
Average Density
per unit h-f
chg/dhdf = 1/4p
3/4p = 0.08
0.24
dNchg
13 GeV/c PTsum
0
-1
h
+1
Divide by 4p
dPTsum/dhdf = 1/4p
3/4p GeV/c = 0.08
0.24 GeV/c
 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 3
“Transverse”
Particle Densities
Charged Particles
pT > 0.5 GeV/c |h| < 1
2p
Away Region
Jet #1 Direction
Df
Transverse
Region 1
f
Leading
Jet
AVE “transverse”
(Trans 1 + Trans 2)/2
Area = 4p/6
“Toward”
“Trans 1”
“Trans 2”
Toward Region
Transverse
Region 2
“Away”
1 charged particle in the
“transverse 2” region
Away Region
0
-1
h
+1
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”.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 4
Charged Particle Density
Df Dependence
Charged Particle Density: dN/dhdf
Log Scale!
Jet #1 Direction
10.0
30 < ET(jet#1) < 70 GeV
Df
“Toward”
“Transverse”
“Transverse”
Jet #3
“Away”
Charged Particle Density
CDF Preliminary
“Toward-Side” Jet
data uncorrected
"Transverse"
Region
1.0
Jet#1
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
“Away-Side”
“Away-Side”
Jet Jet
0.1
0
30
60
90
Min-Bias
0.25 per unit h-f
120
150
180
210
Df (degrees)
240
270
300
Leading Jet
330
360
 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 5
Refer to this as a
“Leading Jet” event
Charged Particle Density
Df Dependence
Jet #1 Direction
Df
Particle Density:
Density: dN/dhdf
dN/dhdf
Charged Particle
“Toward”
“Transverse”
CDF Preliminary
“Transverse”
“Away”
Refer to this as a
“Back-to-Back” event
Jet #1 Direction
Df
“Toward”
“Transverse”
Density
Charged Particle Density
Subset
10.0
10.0
data uncorrected
30 << ET(jet#1)
ET(jet#1)<<70
70GeV
GeV
30
Back-to-Back
Leading Jet
Min-Bias
"Transverse"
"Transverse"
Region
Region
1.0
1.0
Jet#1
Jet#1
Charged Particles
Charged
(|h|<1.0, PT>0.5 GeV/c)
(|h|<1.0,
“Transverse”
0.1
0.1
“Away”
00
30
60
90
120
150
180
180
210
210
240
240
270
270
300
300
330
330 360
360
Df (degrees)
(degrees)
Jet #2 Direction
 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).
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 6
Charged Particle Density
Df Dependence
“Leading Jet”
Jet #1 Direction
Charged Particle Density: dN/dhdf
Df
272
CDF Preliminary
“Toward”
252
256
260
264 268
276 280
284
288
292
248
296
244
data uncorrected
30 < ET(jet#1) < 70 GeV
300
240
304
236
308
232
“Transverse”
312
228
“Transverse”
316
224
320
220
324
Jet#1
216
328
212
“Away”
332
208
336
204
340
200
“Back-to-Back”
344
196
348
192
Jet #1 Direction
352
188
Df
"Transverse"
Region
184
180
356
"Transverse"
Region
360
4
176
“Toward”
8
172
12
0.5
168
16
164
“Transverse”
“Transverse”
20
160
24
1.0
156
28
Leading Jet
152
“Away”
Back-to-Back
36
148
1.5
144
140
40
44
136
48
132
Jet #2 Direction
52
2.0
128
Polar Plot
32
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
124
56
60
120
64
116
68
112
108
104
100
96
88
84
80
76
72
92
 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 7
“Transverse” PTsum Density
versus ET(jet#1)
Jet #1 Direction
Df
“Toward”
“Transverse”
“Transverse”
“Away”
“Back-to-Back”
Jet #1 Direction
Df
“Toward”
“Transverse”
"AVE Transverse" PTsum Density: dPT/dhdf
1.4
“Transverse”
"Transverse" PTsum Density (GeV/c)
“Leading Jet”
uncorrected
datadata
uncorrected
theory + CDFSIM
PY Tune A
1.0
0.8
0.6
0.4
Back-to-Back
HW
0.2
1.96 TeV
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
“Away”
Jet #2 Direction
Leading Jet
2 Preliminary
CDF Run
Preliminary
1.2
100
150
200
250
ET(jet#1) (GeV)
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 12
“Transverse” PTsum Density
versus ET(jet#1)
Jet #1 Direction
Df
Charged PTsum Density: dPT/dhdf
100.0
“Transverse”
“Transverse”
“Away”
"AVE Transverse" PTsum Density: dPT/dhdf
Leading Jet
CDF Run 2 Preliminary
1.2
data uncorrected
1.0
CDF Preliminary
95 < ET(jet#1) < 130 GeV
30 < ET(jet#1) < 70 GeV
data uncorrected
Leading Jet
Min-Bias
10.0
"Transverse"
Region
1.0
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
Jet#1
0.1
0
0.8
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
0.6
30-70 GeV
0.4
Charged PTsum Density: dPT/dhdf
95-130 GeV
Back-to-Back
0.2
1.96 TeV
50
100
ET(jet#1) (GeV)
Jet #1 Direction
Df
“Toward”
“Transverse”
95 < ET(jet#1) < 130 GeV
Very little dependence on
ET(jet#1) in the “transverse”
200
250
region150
for “back-to-back”
events!10.0
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
100.0
Charged PTsum Density (GeV/c)
"Transverse" PTsum Density (GeV/c)
1.4
Charged PTsum Density (GeV/c)
“Toward”
“Transverse”
Back-to-Back
30 < ET(jet#1) < 70 GeV
Min-Bias
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
1.0
CDF Preliminary
Jet#1
data uncorrected
"Transverse" Region
0.1
“Away”
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
Jet #2 Direction
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 13
“TransDIF” PTsum Density
versus ET(jet#1)
“Leading Jet”
Jet #1 Direction
"MAX-MIN Transverse" PTsum Density: dPT/dhdf
Df
“Toward”
“TransMAX”
"Transverse" PTsum Density (GeV/c)
2.0
CDF Run 2 Preliminary
CDF Run 2 PreliminaryPY Tune A
Jet #1 Direction
data uncorrected
“TransMIN”
“Away”
data uncorrected
theory + CDFSIM
theory + CDFSIM
Df
1.5
LeadingJet
“Toward”
1.0
“Back-to-Back”
Jet #1 Direction
Df
“Toward”
“TransMAX”
0.5
“TransMIN”
Back-to-Back
“Away”
1.96 TeV
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
“TransMAX”
“TransMIN”
“Away”
Jet #2 Direction
0
50
“MAX-MIN” is very sensitive to
the “hard scattering” component
of the “underlying event”!
100
150
200
250
ET(jet#1) (GeV)
 Use the leading jet to define the MAX and MIN “transverse” regions on an event-byevent 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 14
“TransMIN” PTsum Density
versus ET(jet#1)
“Leading Jet”
Jet #1 Direction
Df
"MIN Transverse" PTsum Density: dPT/dhdf
“Toward”
“TransMAX”
"Transverse" PTsum Density (GeV/c)
0.6
CDF Run 2 Preliminary
Jet #1 Direction
“TransMIN”
“Away”
1.96 TeV
data uncorrected
theory + CDFSIM
Df
Leading Jet
Jet
Leading
PY Tune A
0.4
“Toward”
“Back-to-Back”
Jet #1 Direction
Df
“Toward”
“TransMAX”
“TransMIN”
“Away”
Jet #2 Direction
“TransMAX”
0.2
“TransMIN”
Min-Bias
“Away”
Back-to-Back
Back-to-Back
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
“transMIN” is very sensitive to the
“beam-beam remnant” component
of the “underlying event”!
100
150
200
250
ET(jet#1) (GeV)
 Use the leading jet to define the MAX and MIN “transverse” regions on an event-byevent 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 15
“Transverse” PTsum Density
PYTHIA Tune A vs HERWIG
“Leading Jet”
Jet #1 Direction
Df
"AVE Transverse" PTsum Density: dPT/dhdf
“Toward”
“Transverse”
“Transverse”
“Away”
“Back-to-Back”
Jet #1 Direction
Df
“Toward”
“Transverse”
“Transverse”
"Transverse" PTsum Density (GeV/c)
1.4
Leading Jet
CDF Preliminary
1.2
data uncorrected
theory + CDFSIM
PY Tune A
1.0
0.8
0.6
0.4
Back-to-Back
HW
0.2
1.96 TeV
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
ET(jet#1) (GeV)
“Away”
Jet #2 Direction
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 19
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!
Charged PTsum Density: dPT/dhdf
Charged PTsum Density: dPT/dhdf
100.0
Charged Particles
30 < ET(jet#1) < 70 GeV
(|h|<1.0, PT>0.5 GeV/c)
Back-to-Back
PY Tune A
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
100.0
10.0
1.0
CDF Preliminary
Jet#1
"Transverse"
Region
data uncorrected
theory + CDFSIM
Charged Particles
30 < ET(jet#1) < 70 GeV
(|h|<1.0, PT>0.5 GeV/c)
Back-to-Back
HERWIG
10.0
"Transverse"
Region
1.0
CDF Preliminary
0.1
0.1
0
30
60
90
120
150
180
210
240
270
300
330
360
0
30
60
90
120
Df (degrees)
150
180
210
240
270
300
330
360
330
360
Df (degrees)
Data - Theory: Charged PTsum Density dPT/dhdf
Data - Theory: Charged PTsum Density dPT/dhdf
2
2
data uncorrected
theory + CDFSIM
1
Back-to-Back
30 < ET(jet#1) < 70 GeV
PYTHIA Tune A
CDF Preliminary
Data - Theory (GeV/c)
CDF Preliminary
Data - Theory (GeV/c)
Jet#1
data uncorrected
theory + CDFSIM
0
-1
"Transverse"
Region
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
data uncorrected
theory + CDFSIM
1
30 < ET(jet#1) < 70 GeV
Back-to-Back
HERWIG
0
-1
"Transverse"
Region
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
Jet#1
Jet#1
-2
-2
0
30
60
90
120
150
180
210
240
270
300
330
360
0
30
90
120
150
180
210
240
270
300
Df (degrees)
Df (degrees)
KITP Collider Workshop
February 17, 2004
60
Rick Field - Florida/CDF
Page 20
Charged PTsum Density
PYTHIA Tune A vs HERWIG
Data - Theory: Charged PTsum Density dPT/dhdf
Data - Theory: Charged PTsum Density dPT/dhdf
2
2
data uncorrected
theory + CDFSIM
1
Back-to-Back
30 < ET(jet#1) < 70 GeV
PYTHIA Tune A
CDF Preliminary
Data - Theory (GeV/c)
Data - Theory (GeV/c)
CDF Preliminary
0
-1
"Transverse"
Region
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
data uncorrected
theory + CDFSIM
1
30 < ET(jet#1) < 70 GeV
Back-to-Back
HERWIG
0
-1
"Transverse"
Region
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
Jet#1
Jet#1
-2
-2
0
30
60
90
120
150
180
210
240
270
300
330
0
360
30
60
90
120
210
240
270
300
330
360
330
360
Data - Theory: Charged PTsum Density dPT/dhdf
dPT/dhdf + 0.2 GeV/c
2
scalar PTsum density, dPTsum/dhdf.
 This corresponds to 0.2 x 4p = 2.5 GeV/c
in the entire range pT > 0.5 GeV/c, |h| < 1.
Data - Theory (GeV/c)
CDF Preliminary
 Add 0.2 GeV/c per unit h-f to HERWIG
KITP Collider Workshop
February 17, 2004
180
Df (degrees)
Df (degrees)
308 MeV in
R = 0.7 cone!
150
data uncorrected
theory + CDFSIM
1
30 < ET(jet#1) < 70 GeV
Back-to-Back
HERWIG + 0.2 GeV/c
0
-1
"Transverse"
Region
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
Jet#1
-2
0
30
Rick Field - Florida/CDF
60
90
120
150
180
210
240
270
300
Df (degrees)
Page 21
“Transverse” <pT> versus
“Transverse” Nchg
“Leading Jet”
Jet #1 Direction
"Transverse" Average PT versus Nchg
Df
2.0
2.0
CDF Run 2 Preliminary
“Toward”
CDF Run 2 Preliminary
Jet #1 Direction
data uncorrected
“Transverse”
“Away”
“Back-to-Back”
Jet #1 Direction
Df
“Toward”
“Transverse”
“Transverse”
Average PT (GeV/c)
data uncorrected
“Transverse”
Df
LeadingJet
Jet
Leading
ET(jet#1)< <7070GeV
GeV
3030< <ET(jet#1)
theory + CDFSIM
1.96
TeV
1.5
1.5
Back-to-Back
Back-to-Back
30
30<<ET(jet#1)
ET(jet#1)<<70
70GeV
GeV
“Toward”
1.0
1.0
“Transverse”
“Transverse”
PYTHIA Tune A 1.96 TeV
Min-Bias
Min-Bias
“Away”
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.5
0.5
00
22
44
6
8
10
12
14
16
18
20
22
Number of Charged Particles
“Away”
Min-Bias
Jet #2 Direction
 Look at the <pT> of particles in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus
the number of particles in the “transverse” region: <pT> vs Nchg.
 Shows <pT> versus Nchg in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) for “Leading
Jet” and “Back-to-Back” events with 30 < ET(jet#1) < 70 GeV compared with “minbias” collisions.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 26
“Transverse” PTmax
versus ET(jet#1)
Jet #1 Direction
“Leading Jet”
Df
“TransMIN”
Highest“TransMAX”
pT particle
in the
“transverse” region!
“Back-to-Back”
“Away”
Jet #1 Direction
Df
“Toward”
“TransMAX”
PTmaxT
PTmaxT
“TransMIN”
“Away”
"Transverse" PTmax (GeV/c)
Jet #1 Direction
“Toward”
PTmaxT
"Transverse" Charged PTmax
3.0
CDF Run 2 Preliminary
1.96 TeV
Df
2.5
data uncorrected
Leading Jet
2.0
“Toward”
1.5
“TransMAX”
1.0
“TransMIN”
0.5“Away”
Min-Bias
Back-to-Back
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
ET(jet#1) (GeV)
Jet #2 Direction
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).
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 27
Min-Bias “Associated”
Highest pT
charged particle!
Charged Particle Density
“Associated” densities do
not include PTmax!
Charged Particle Density: dN/dhdf
PTmax Direction
0.5
PTmax
Direction
Df
Correlations in f
Charged Particle Density
CDF Preliminary
Associated Density
PTmax not included
data uncorrected
0.4
Df
Charge Density
0.3
0.2
0.1
Min-Bias
Correlations
in f
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
PTmax
0.0
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
 Use the maximum pT charged particle in the event, PTmax, to define a direction and

is “associated”
more probable
to finddN
a chg
particle
look at the It
the
density,
/dhdf, in “min-bias” collisions (pT > 0.5
PTmax than it is to
GeV/c, |h| <accompanying
1).
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 28
Min-Bias “Associated”
Rapid rise in the particle
density in the “transverse”
region as PTmax increases!
Charged Particle Density
Associated Particle Density: dN/dhdf
PTmaxDirection
Direction
PTmax
Df
“Toward”
“Transverse”
“Transverse”
Correlations in f
“Away”
Associated Particle Density
Jet #1
Df
PTmax > 2.0 GeV/c
1.0
PTmax > 2.0 GeV/c
PTmax > 1.0 GeV/c
0.8
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
CDF Preliminary
data uncorrected
PTmax > 0.5 GeV/c
Transverse
Region
0.6
Transverse
Region
0.4
0.2
Jet #2
PTmax
PTmax not included
Min-Bias
0.0
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
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!).
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 29
Back-to-Back “Associated”
Charged Particle Densities
Maximum pT particle in
the “transverse” region!
Jet #1 Direction
PTmaxT
Direction
“Associated” densities do
not include PTmaxT!
Df
Df
“Toward”
“TransMAX”
PTmaxT
“TransMIN”
Df
PTmaxT
Direction
Jet#1
Region
Jet#2
Region
Jet#1
Region
Jet#2
Region
“Away”
Jet #2 Direction
 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).
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 34
Back-to-Back “Associated”
Charged Particle Density
“Associated” densities do
not include PTmaxT!
PTmaxT
Direction
Jet #1
Jet#1
Region
Associated Particle Density
Df
Jet #2
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
CDF Preliminary
Jet #3
Jet#2
Region
Associated Particle Density: dN/dhdf
10.0
data uncorrected
Back-to-Back
30 < ET(jet#1) < 70 GeV
PTmaxT not included
1.0
Jet#2
Region
PTmaxT > 2.0 GeV/c
PTmaxT > 1.0 GeV/c
Jet #4??
"Jet#1"
Region
PTmaxT
PTmaxT > 0.5 GeV/c
0.1
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
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).
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 35
Back-to-Back “Associated”
Charged Particle Densities
“Back-to-Back”
charge density
Jet #1 Direction
Df
Charged Particle Density: dN/dhdf
10.0
“Toward”
“Transverse”
“Away”
“Back-to-Back”
“associated” density
Df
Jet #2 Direction
Jet#1
Region
Charged Particle Density
“Transverse”
CDF Preliminary
data uncorrected
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
"Transverse"
Region
1.0
Associated Density
PTmaxT not included
PTmaxT
Back-to-Back
PTmaxT > 0.5 GeV/c
PTmaxT
Direction
30 < ET(jet#1) < 70 GeV
Jet#1
0.1
Jet#2
Region
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
 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
It is
more probable
to find
a
GeV/c, for “back-to-back”
events with 30
< ET(jet#1) < 70 GeV.
particle accompanying
PTmaxT
than itof
is the
to find
a particle
in the
Shows Df dependence
charged
particle
density, dNchg/dhdf for charged particles
“transverse”
region!
(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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 37
Back-to-Back “Associated”
Charged Particle Densities
“Back-to-Back”
charge density
Charged Particle Density: dN/dhdf
Jet #1 Direction
Df
2
CDF Preliminary
346
350
354
358
6
10
14
18
342
22
338
26
334
data uncorrected
“Toward”
30 < ET(jet#1) < 70 GeV
Back-to-Back
30
330
34
326
38
322
42
318
46
314
“Transverse”
“Transverse”
50
310
54
Jet#1
306
58
302
62
298
“Away”
66
294
70
290
“Back-to-Back”
“associated” density
74
286
78
"Transverse"
Region
282
Jet #2 Direction
278
274
82
PTmaxT
270
86
"Transverse"
Region
90
94
266
Df
Jet#1
Region
98
262
102
0.5
258
106
254
110
250
PTmaxT
Direction
114
1.0
246
118
242
122
238
Jet#2
Region
126
234
130
1.5
230
134
226
138
222
142
2.0
218
Polar Plot
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
214
154
206
158
202
162
198
194
190
186
Associated Density
PTmaxT not included
146
150
210
178
174
170
166
182
 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 38
Back-to-Back “Associated”
Charged Particle Densities
“Back-to-Back”
charge density
Charged Particle Density: dN/dhdf
Jet #1 Direction
Df
2
CDF Preliminary
346
350
354
6
358
10
14
18
22
342
26
338
data uncorrected
“Toward”
30 < ET(jet#1) < 70 GeV
Back-to-Back
30
334
34
330
38
326
42
322
46
318
50
314
“Transverse”
“Transverse”
54
310
Jet#1
306
58
62
302
“Away”
66
298
70
294
74
290
“Back-to-Back”
“associated” density
78
286
Jet #2 Direction
"Transverse"
Region
282
278
82
274
PTmaxT
270
86
"Transverse"
Region
90
94
98
266
Df
Jet#1
Region
102
262
0.5
258
106
110
254
PTmaxT
Direction
114
250
1.0
246
118
122
242
126
238
Jet#2
Region
1.5
234
230
130
134
138
226
2.0
218
Polar Plot
Associated Density
PTmaxT > 2 GeV/c
(not included)
142
222
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
214
146
150
154
210
158
206
162
202
198
194
190
178
186
174
170
166
182
 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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 39
Jet Topologies
QCDThree
Four
Jet
QCD
Jet Topology
Topology Charged Particle Density: dN/dhdf
QCD
2-to-4
Scattering
Multiple Parton Interactions
2
Preliminary
CDF
Final-State
Jet #1
data uncorrected
Radiation
Outgoing Parton
346
10
14
30 < ET(jet#1) < 70 GeV
Outgoing Parton
Outgoing PartonBack-to-Back
18
30
34
38
326
42
322
46
318
Jet #1
PT(hard)
50
54
Jet#1
306
58
PT(hard)
302
298
PTmaxT
Proton
Direction
Proton
6
358
26
330
310
Jet #3Df
354
22
334
314
Jet#1
Region
350
342
338
62
66
70
294
Jet #4
74
290
78
286
Jet #4
AntiProton
AntiProton
"Transverse"
Jet #3
Region
282
278
274
Jet#2
Region
Underlying Event
Underlying Event
PTmaxT
270
86
90
94
98
266
Underlying Event
102
262
Jet #2
0.5
258
Underlying Event
106
254
110
Jet #2
250
114
1.0
246
118
126
238
1.5
234
230
130
134
138
226
Particles
ChargedFinal-State
GeV/c)
(|h|<1.0, PT>0.5
Radiation
Associated Density
PTmaxT > 2 GeV/c
(not included)
142
222
2.0
218
214
146
150
154
210
Polar Plot
Initial-State
Radiation
122
242

82
"Transverse"
Region
158
206
162
202
198
194
190
178
186
174
170
166
182
Parton
Outgoing
Outgoing
Shows the Df dependence
ofParton
the “associated” charged particleOutgoing
density,Parton
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 40
Back-to-Back “Associated”
Charged Particle Density
Associated Particle Density: dN/dhdf
PTmaxT
Direction
10.0
Df
Jet#2
Region
Jet#1
Region
Associated Particle Density
CDF Preliminary
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
data uncorrected
Back-to-Back
1.0
Jet#2
Region
95 < ET(jet#1) < 130 GeV
30 < ET(jet#1) < 70 GeV
"Jet#1"
Region
PTmaxT
PTmaxT > 2.0 GeV/c (not included)
0.1
Log Scale!
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
 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!
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 41
Back-to-Back “Associated”
Charged PTsum Density
Associated PTsum Density: dPT/dhdf
PTmaxT
Direction
Df
Jet#2
Region
Jet#1
Region
Associated PTsum Density (GeV/c)
100.0
CDF Preliminary
Back-to-Back
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
data uncorrected
10.0
Jet#2
Region
1.0
95 < ET(jet#1) < 130 GeV
PTmaxT
30 < ET(jet#1) < 70 GeV
"Jet#1"
Region
PTmaxT > 2.0 GeV/c (not included)
0.1
0
30
60
90
Log Scale!
120
150
180
210
240
270
300
330
360
Df (degrees)
 Look at the Df dependence of the “associated” charged PTsum density, dPTsum/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!
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 42
“Back-to-Back”
“Associated” Density
“Back-to-Back” vs “Min-Bias”
“Birth” ofCharge
jet#3 in the
“Associated”
Density
“transverse” region!
PTmaxT
Direction
Associated Particle Density: dN/dhdf
Df
“Min-Bias”
“Associated” Density
Associated Particle Density
Jet#2
Region
10.0
Jet#1
Region
PTmax Direction
Df
PTmaxT > 2.0 GeV/c
PTmax > 2.0 GeV/c
Charged Particles
Particles
Charged
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
(|h|<1.0,
3030< <ET(jet#1)
ET(jet#1)< <7070GeV
GeV
1.0
Min-Bias x 1.65
PTmaxT
PTmaxT
PTmax
PTmax
Min-Bias
PTmaxT,
PTmaxT,PTmax
PTmaxnot
notincluded
included
CDFPreliminary
Preliminary
CDF
data
uncorrected
data
uncorrected
0.1
Correlations in f
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
Log Scale!
“Birth” of jet#1 in
 Shows the Df dependence of the “associated” charged particle density,“min-bias”
dNchg/dhdf
for
collisions!
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 43
“Back-to-Back”
“Associated” Density
“Back-to-Back” vs “Min-Bias”
“Birth” ofPTsum
jet#3 in the
“Associated”
Density
“transverse” region!
PTmaxT
Direction
Associated PTsum Density: dPT/dhdf
Jet#2
Region
“Min-Bias”
“Associated” Density
Associated PTsum Density (GeV/c)
Df
Jet#1
Region
PTmax Direction
Df
10.0
30 < ET(jet#1) < 70 GeV
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
1.0
Min-Bias
Min-Bias x 1.65
PTmaxT > 2.0 GeV/c
PTmax > 2.0 GeV/c
PTmaxT
PTmax
CDF Preliminary
data uncorrected
PTmaxT, PTmax not included
0.1
Correlations in f
0
30
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
Log Scale!
“Birth” of jet#1 in
 Shows the Df dependence of the “associated” charged particle density,“min-bias”
dNchg/dhdf
for
collisions!
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.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 44
“Associated” PTsum Density
PYTHIA Tune A vs HERWIG
HERWIG (without multiple parton
interactions) does not produce
enough “associated” PTsum in the
direction of PTmaxT!
Associated PTsum Density: dPT/dhdf
PTmaxT > 0.5 GeV/cAssociated PTsum Density: dPT/dhdf
10.0
Associated PTsum Density (GeV/c)
Associated PTsum Density (GeV/c)
10.0
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
PTmaxT not included
1.0
PTmaxT > 0.5 GeV/c
Back-to-Back
30 < ET(jet#1) < 70 GeV
PY Tune A
CDF Preliminary
PTmaxT
data uncorrected
theory + CDFSIM
"Jet#1"
Region
0.1
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
PTmaxT not included
1.0
PTmaxT > 0.5 GeV/c
HERWIG
CDF Preliminary
30
60
90
120
150
180
210
240
270
300
330
360
0
30
60
90
120
Df (degrees)
"Jet#1"
Region
2
CDF Preliminary
And HERWIG (without multiple
parton interactions) does not 2
Charged Particles
produceBack-to-Back
enough PTsum in the
(|h|<1.0, PT>0.5 GeV/c) 30 < ET(jet#1) < 70 GeV
direction
opposite of PTmaxT!1
PTmaxT not included
PYTHIA Tune A
Data - Theory (GeV/c)
data uncorrected
theory + CDFSIM
150
180
210
240
270
300
330
360
Df (degrees)
Data - Theory: Associated PTsum Density dPT/dhdf
Data - Theory: Associated PTsum Density dPT/dhdf
Data - Theory (GeV/c)
PTmaxT
data uncorrected
theory + CDFSIM
0.1
0
1
Back-to-Back
30 < ET(jet#1) < 70 GeV
0
-1
PTmaxT
CDF Preliminary
data uncorrected
theory + CDFSIM
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
Back-to-Back
30 < ET(jet#1) < 70 GeV
PTmaxT not included
0
-1
PTmaxT
HERWIG
"Jet#1"
Region
"Jet#1"
Region
-2
-2
0
30
60
90
120
150
180
210
240
270
300
330
360
0
30
90
120
150
180
210
240
270
300
330
360
Df (degrees)
Df (degrees)
KITP Collider Workshop
February 17, 2004
60
Rick Field - Florida/CDF
Page 46
“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 Associated PTsum Density: dPT/dhdf
Associated PTsum Density: dPT/dhdf
10.0
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
PTmaxT not included
Associated PTsum Density (GeV/c)
Associated PTsum Density (GeV/c)
10.0
1.0
PTmaxT > 2.0 GeV/c
Back-to-Back
30 < ET(jet#1) < 70 GeV
PY Tune A
CDF Preliminary
PTmaxT
data uncorrected
theory + CDFSIM
"Jet#1"
Region
0.1
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
PTmaxT not included
1.0
PTmaxT > 2.0 GeV/c
CDF Preliminary
PTmaxT
data uncorrected
theory + CDFSIM
"Jet#1"
Region
0.1
0
30
60
90
120
150
180
210
240
270
300
330
360
0
30
60
90
120
Df (degrees)
CDF Preliminary
240
270
300
330
360
Data - Theory
PTmaxT
0
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
"Jet#1"
Region
PTmaxT > 2.0 GeV/c (not included)
Back-to-Back
30 < ET(jet#1) < 70 GeV
HERWIG
data uncorrected
theory + CDFSIM
-1
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
210
Data - Theory: Associated Particle Density dN/dhdf
1
0.0
-1.0
180
2
PYTHIA Tune A
theory + CDFSIM
1.0
150
Df (degrees)
But HERWIG (without multiple
Data - Theory: Associated
Particleinteractions)
Density dN/dhdf
parton
produces
too few particles
in the
Back-to-Back
CDF Preliminary
direction
opposite
of
PTmaxT!
30
<
ET(jet#1)
<
70 GeV
data uncorrected
2.0
Data - Theory
Back-to-Back
30 < ET(jet#1) < 70 GeV
HERWIG
PTmaxT
"Jet#1"
Region
PTmaxT > 2.0 GeV/c (not included)
-2.0
-2
0
30
60
90
120
150
180
210
240
270
300
330
360
0
30
Df (degrees)
KITP Collider Workshop
February 17, 2004
60
90
120
150
180
210
240
270
300
330
360
Df (degrees)
Rick Field - Florida/CDF
Page 48
“Transverse 1” Region vs
“Transverse 2” Region
Jet #1 Direction
Df
Jet #1 Direction
“Toward”
“Trans 1”
“Trans 2”
“Away”
“Back-to-Back”
Jet #1 Direction
Df
“Toward”
“Trans 1”
"Transverse 1" vs "Transverse 2"
3.5
1.8
“Trans 2”
"Transverse
"Transverse
2" <PT>
2" Nchg
(GeV/c)
“Leading Jet”
CDF
CDFRun
Run22Preliminary
Preliminary 3030< <ET(jet#1)
ET(jet#1)< <7070GeV
GeV
Df
3.0
1.6
data
datauncorrected
uncorrected
2.5
1.4
Leading Jet
Leading Jet
1.96 TeV
“Toward”
2.0
1.2
“Trans1.51”
“Trans 2”
1.96 TeV
1.0
1.0
Back-to-Back
Back-to-Back
Charged
ChargedParticles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
“Away”
0.5
0.8
0
2
4
6
8
10
12
14
"Transverse 1" Nchg
“Away”
Jet #2 Direction
 Use the leading jet to define two “transverse” regions and look at the correlations
between “transverse 1” and “transverse 2”.
 Shows the average
of charged
particles
the “transverse
2” region
average number
pT of charged
particles
in thein“transverse
2” region
versusversus
the the
number of charged particles in the “transverse 1” region for pTT > 0.5 GeV/c and |h| < 1
for “Leading Jet” and “Back-to-Back” events.
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 49
“Transverse 1” Region vs
“Transverse 2” Region
"Transverse 1" vs "Transverse 2"
"Transverse 1" vs "Transverse 2"
3.5
3.0
"Transverse 2" Nchg
3.0
data uncorrected
theory + CDFSIM
Leading Jet
30 < ET(jet#1) < 70 GeV
CDF Run 2 Preliminary
"Transverse 2" Nchg
CDF Run 2 Preliminary
PY Tune A
2.5
1.96 TeV
2.0
HW
1.5
data uncorrected
theory + CDFSIM
2.5
PY Tune A
2.0
1.5
HW
1.0
1.0
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.5
0.5
0
2
4
6
8
10
12
14
0
2
4
"Transverse 1" Nchg
6
8
10
12
"Transverse 1" Nchg
"Transverse 1" vs "Transverse 2"
"Transverse 1" vs "Transverse 2"
1.8
1.50
CDF Run 2 Preliminary
data uncorrected
theory + CDFSIM
1.6
PY Tune A
1.96 TeV
1.4
Leading Jet
30 < ET(jet#1) < 70 GeV
"Transverse 2" <PT> (GeV/c)
"Transverse 2" <PT> (GeV/c)
Back-to-Back
30 < ET(jet#1) < 70 GeV
1.2
HW
1.0
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
CDF Run 2 Preliminary
data uncorrected
theory + CDFSIM
1.25
Back-to-Back
30 < ET(jet#1) < 70 GeV
1.00
PY Tune A
0.75
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.8
0.50
0
2
4
6
8
10
12
14
0
"Transverse 1" Nchg
KITP Collider Workshop
February 17, 2004
2
4
6
8
10
12
"Transverse 1" Nchg
Rick Field - Florida/CDF
Page 50
Summary
Jet #1 Direction
“Leading Jet”
Df
Jet #1 Direction
“Back-to-Back”
“Toward”
“Toward”
“Trans 1”
Df
“Trans 1”
“Trans 2”
“Trans 2”
“Away”
“Away”
Jet #2 Direction
 There are some interesting correlations between the “transverse 1” and
“transverse 2” regions both for “Leading-Jet” and “Back-to-Back” events!
 PYTHIA Tune A (with multiple parton scattering) does a much better job in
describing these correlations than does HERWIG (without multiple parton
scattering).
Question: Is this a probe of
multiple parton interactions?
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 51
Summary
“Leading Jet”
Jet #1 Direction
Jet #1 Direction
Df
“Back-to-Back”
Df
“Toward”
“Toward”
“Transverse”
“Transverse”
“Transverse”
“Transverse”
“Away”
“Away”
Jet #2 Direction
 “Back-to-Back” events have less “hard scattering” (initial and final state
radiation) component in the “transverse” region which allows for a closer look at
the “beam-beam remnant” and multiple parton scattering component of the
“underlying” event.
 PYTHIA Tune A (with multiple parton scattering) does a much better job in
describing the “back-to-back” events than does HERWIG (without multiple
parton scattering).
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 52
Summary
Max pT in the
“transverse” region!
“Associated” densities do
not include PTmaxT!
Jet #1 Direction
Df
PTmaxT
Direction
PTmax Direction
Df
“Toward”
“TransMAX”
“TransMIN”
Jet#2
Region
Df
Jet#1
Region
Next Step
Correlations in f
Look at the jet topologies
Jet #2 Direction
(2 jet vs 3 jet vs 4 jet etc).
 The “associated” densities
strong
correlations
Seeshow
if there
is an
excess of(i.e. jet structure) in the
“transverse” region both for “Leading Jet” and “Back-to-Back” events.
4 jet events due to multiple
interactions!
 The “birth” of the 1st jet inparton
“min-bias”
collisions looks very similar to the
PTmaxT
“Away”
“birth” of the 3rd jet in the “transverse” region of hard scattering “Back-toBack” events.
Question: Is the topology
3 jet or 4 jet?
KITP Collider Workshop
February 17, 2004
Rick Field - Florida/CDF
Page 53