chris quigg symposium
DESCRIPTION
Chris Quigg Symposium. Predicting MB & UE at the LHC. Rick Field University of Florida. Outline of Talk. The inelastic non-diffractive cross section. The “underlying event” in a hard scattering process. The QCD Monte-Carlo model tunes. CDF Run 2. - PowerPoint PPT PresentationTRANSCRIPT
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 1
Chris Quigg SymposiumChris Quigg SymposiumPredicting MB & UE at the LHC
Rick FieldUniversity of Florida
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
CMS at the LHC
CDF Run 2
UE&MB@CMSUE&MB@CMS
Outline of Talk
The inelastic non-diffractive cross section.
The “underlying event” in a hard scattering process.
The QCD Monte-Carlo model tunes.
Relationship between the “underlying event” in a hard scattering process and “min-bias” collisions.
“Min-Bias” and the “underlying event” at the LHC.
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 2
J.D.J. StudentsJ.D.J. Students
J.D.JBob
Cahn
Chris Quiggme Gordy
Kane J.D.J
Jimmie & Rick
“Older than Dirt” hat!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 3
Proton-Proton CollisionsProton-Proton Collisions Elastic Scattering Single Diffraction
M
tot = ELSD DD HC
Double Diffraction
M1 M2
Proton Proton
“Soft” Hard Core (no hard scattering)
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
“Hard” Hard Core (hard scattering)
Hard Core The “hard core” component
contains both “hard” and “soft” collisions.
“Inelastic Non-Diffractive Component”
ND
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 4
Inelastic Non-Diffractive Cross-SectionInelastic Non-Diffractive Cross-Section
The inelastic non-diffractive cross section versus center-of-mass energy from PYTHIA (×1.2).
Inelastic Non-Diffractive Cross-Section: HC
0
10
20
30
40
50
60
70
0 2 4 6 8 10 12 14
Center-of-Mass Energy (TeV)
Cro
ss-S
ecti
on
(m
b)
RDF Preliminarypy Tune DW generator level
K-Factor = 1.2
Inelastic Non-Diffractive Cross-Section: HC
0
10
20
30
40
50
60
70
0.1 1.0 10.0 100.0
Center-of-Mass Energy (TeV)
Cro
ss-S
ecti
on
(m
b)
RDF Preliminarypy Tune DW generator level
K-Factor = 1.2
tot = ELSD DD ND
Linear scale! Log scale!
HC varies slowly. Only a 13% increase between 7 TeV (≈ 58 mb) and 14 teV (≈ 66 mb). Linear on a log scale!
My guess!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 5
QCD Monte-Carlo Models:QCD Monte-Carlo Models:High Transverse Momentum JetsHigh Transverse Momentum Jets
Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and final-state gluon radiation (in the leading log approximation or modified leading log approximation).
Hard Scattering
PT(hard)
Outgoing Parton
Outgoing Parton
Initial-State Radiation
Final-State Radiation
Hard Scattering
PT(hard)
Outgoing Parton
Outgoing Parton
Initial-State Radiation
Final-State Radiation
Proton Proton
Underlying Event Underlying Event
Proton Proton
Underlying Event Underlying Event
“Hard Scattering” Component
“Jet”
“Jet”
“Underlying Event”
The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or semi-soft multiple parton interactions (MPI).
Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event” observables receive contributions from initial and final-state radiation.
“Jet”
The “underlying event” is an unavoidable background to most collider observables and having good understand of it leads to
more precise collider measurements!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 6
MPI, Pile-Up, and OverlapMPI, Pile-Up, and Overlap MPI: Additional 2-to-2 parton-parton
scatterings within a single hadron-hadron collision.
Pile-Up
Primary
MPI: Multiple Parton Interactions
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
Pile-Up Proton
Interaction Region z
Proton ProtonProton
Pile-Up: More than one hadron-hadron collision in the beam crossing.
Overlap Overlap: An experimental timing issue where a hadron-hadron collision from the next beam crossing gets included in the hadron-hadron collision from the current beam crossing because the next crossing happened before the event could be read out.
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 7
Charged Jet #1Direction
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
Look at charged particle correlations in the azimuthal angle relative to the leading charged particle jet.
Define || < 60o as “Toward”, 60o < || < 120o as “Transverse”, and || > 120o as “Away”.All three regions have the same size in - space, x = 2x120o = 4/3.
Charged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
-1 +1
2
0
Leading Jet
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
Charged Particle Correlations PT > 0.5 GeV/c || < 1
Look at the charged particle density in the “transverse” region!
“Transverse” region very sensitive to the “underlying event”!
CDF Run 1 Analysis
CDF Run 1: Evolution of Charged JetsCDF Run 1: Evolution of Charged Jets“Underlying Event”“Underlying Event”
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 8
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)"T
ran
sver
se"
Ch
arg
ed D
ensi
ty
CTEQ3L CTEQ4L CTEQ5L CDF Min-Bias CDF JET20
1.8 TeV ||<1.0 PT>0.5 GeV
Pythia 6.206 (default)MSTP(82)=1
PARP(81) = 1.9 GeV/c
CDF Datadata uncorrectedtheory corrected
Default parameters give very poor description of the “underlying event”!
Note ChangePARP(67) = 4.0 (< 6.138)PARP(67) = 1.0 (> 6.138)
Parameter 6.115 6.125 6.158 6.206
MSTP(81) 1 1 1 1
MSTP(82) 1 1 1 1
PARP(81) 1.4 1.9 1.9 1.9
PARP(82) 1.55 2.1 2.1 1.9
PARP(89) 1,000 1,000 1,000
PARP(90) 0.16 0.16 0.16
PARP(67) 4.0 4.0 1.0 1.0
Plot shows the “Transverse” charged particle density versus PT(chgjet#1) compared to the QCD hard scattering predictions of PYTHIA 6.206 (PT(hard) > 0) using the default parameters for multiple parton interactions and CTEQ3L, CTEQ4L, and CTEQ5L.
PYTHIA default parameters
PYTHIA 6.206 DefaultsPYTHIA 6.206 DefaultsMPI constant
probabilityscattering
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 9
Parameter Default
Description
PARP(83) 0.5 Double-Gaussian: Fraction of total hadronic matter within PARP(84)
PARP(84) 0.2 Double-Gaussian: Fraction of the overall hadron radius containing the fraction PARP(83) of the total hadronic matter.
PARP(85) 0.33 Probability that the MPI produces two gluons with color connections to the “nearest neighbors.
PARP(86) 0.66 Probability that the MPI produces two gluons either as described by PARP(85) or as a closed gluon loop. The remaining fraction consists of quark-antiquark pairs.
PARP(89) 1 TeV Determines the reference energy E0.
PARP(82) 1.9 GeV/c
The cut-off PT0 that regulates the 2-to-2 scattering divergence 1/PT4→1/(PT2+PT0
2)2
PARP(90) 0.16 Determines the energy dependence of the cut-off
PT0 as follows PT0(Ecm) = PT0(Ecm/E0) with = PARP(90)
PARP(67) 1.0 A scale factor that determines the maximum parton virtuality for space-like showers. The larger the value of PARP(67) the more initial-state radiation.
Hard Core
Multiple Parton Interaction
Color String
Color String
Multiple Parton Interaction
Color String
Hard-Scattering Cut-Off PT0
1
2
3
4
5
100 1,000 10,000 100,000
CM Energy W (GeV)P
T0
(G
eV
/c)
PYTHIA 6.206
= 0.16 (default)
= 0.25 (Set A))
Take E0 = 1.8 TeV
Reference pointat 1.8 TeV
Determine by comparingwith 630 GeV data!
Affects the amount ofinitial-state radiation!
Tuning PYTHIA:Tuning PYTHIA:Multiple Parton Interaction ParametersMultiple Parton Interaction Parameters
Determines the energy dependence of the MPI!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 10
Old PYTHIA default(more initial-state radiation)New PYTHIA default
(less initial-state radiation)
Parameter Tune B Tune A
MSTP(81) 1 1
MSTP(82) 4 4
PARP(82) 1.9 GeV 2.0 GeV
PARP(83) 0.5 0.5
PARP(84) 0.4 0.4
PARP(85) 1.0 0.9
PARP(86) 1.0 0.95
PARP(89) 1.8 TeV 1.8 TeV
PARP(90) 0.25 0.25
PARP(67) 1.0 4.0
Old PYTHIA default(more initial-state radiation)New PYTHIA default
(less initial-state radiation)
Plot shows the “transverse” charged particle density versus PT(chgjet#1) compared to the QCD hard scattering predictions of two tuned versions of PYTHIA 6.206 (CTEQ5L, Set B (PARP(67)=1) and Set A (PARP(67)=4)).
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity
1.8 TeV ||<1.0 PT>0.5 GeV
CDF Preliminarydata uncorrectedtheory corrected
CTEQ5L
PYTHIA 6.206 (Set A)PARP(67)=4
PYTHIA 6.206 (Set B)PARP(67)=1
Run 1 Analysis
Run 1 PYTHIA Tune ARun 1 PYTHIA Tune APYTHIA 6.206 CTEQ5L
CDF Default!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 11
Use the maximum pT charged particle in the event, PTmax, to define a direction and look at the the “associated” density, dNchg/dd, in “min-bias” collisions (pT > 0.5 GeV/c, || < 1).
PTmax Direction
Correlations in
Charged Particle Density: dN/dd
0.0
0.1
0.2
0.3
0.4
0.5
0 30 60 90 120 150 180 210 240 270 300 330 360
(degrees)
Ch
arg
ed
Pa
rtic
le D
en
sit
y
PTmax
Associated DensityPTmax not included
CDF Preliminarydata uncorrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
Charge Density
Min-Bias
“Associated” densities do not include PTmax!
Highest pT charged particle!
PTmax Direction
Correlations in
Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events. Also shown is the average charged particle density, dNchg/dd, for “min-bias” events.
It is more probable to find a particle accompanying PTmax than it is to
find a particle in the central region!
CDF Run 1 Min-Bias “Associated”CDF Run 1 Min-Bias “Associated”Charged Particle DensityCharged Particle Density
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 12
Associated Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 30 60 90 120 150 180 210 240 270 300 330 360
(degrees)
As
so
cia
ted
Pa
rtic
le D
en
sit
y
PTmax > 2.0 GeV/c
PTmax > 1.0 GeV/c
PTmax > 0.5 GeV/c
CDF Preliminarydata uncorrected
PTmaxPTmax not included
Charged Particles (||<1.0, PT>0.5 GeV/c)
Min-Bias
PTmax Direction
Correlations in
Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 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.
Transverse Region
Transverse Region
Jet #1
Shows “jet structure” in “min-bias” collisions (i.e. the “birth” of the leading two jets!).
Jet #2
Ave Min-Bias0.25 per unit -
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PTmax > 0.5 GeV/c
PTmax > 2.0 GeV/c
CDF Run 1 Min-Bias “Associated”CDF Run 1 Min-Bias “Associated”Charged Particle DensityCharged Particle Density Rapid rise in the particle
density in the “transverse” region as PTmax increases!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 13
Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “toward”, “away” and “transverse” regions as a function of PTmax for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) for “min-bias” events at 1.96 TeV from PYTHIA Tune A (generator level).
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
Associated Charged Particle Density: dN/dd
0.0
0.1
1.0
10.0
0 30 60 90 120 150 180 210 240 270 300 330 360
(degrees)
Ch
arg
ed
Par
ticl
e D
en
sit
y
RDF Preliminarypy Tune A generator level
Charged Particles (||<1.0, PT>0.5 GeV/c)
Min-Bias1.96 TeV
PTmax > 0.5 GeV/cPTmax > 1.0 GeV/c
PTmax > 2.0 GeV/cPTmax > 5.0 GeV/c
PTmax > 10.0 GeV/c
Associated Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
1.6
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
Ch
arg
ed P
arti
cle
Den
sity
RDF Preliminarypy Tune A generator level
Min-Bias1.96 TeV
Charged Particles (||<1.0, PT>0.5 GeV/c)
"Toward"
"Transverse"
"Away"
Shows the dependence of the “associated” charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events at 1.96 TeV with PTmax > 0.5, 1.0, 2.0, 5.0, and 10.0 GeV/c from PYTHIA Tune A (generator level).
Associated Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 5 10 15 20 25
PTmax (GeV/c)
Ch
arg
ed
Par
ticl
e D
en
sit
y
Charged Particles (||<1.0, PT>0.5 GeV/c)
Min-Bias14 TeV
"Toward"
"Transverse"
"Away"
RDF Preliminarypy Tune A generator level
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty
RDF Preliminarypy Tune A generator level
Min-Bias
Charged Particles (||<1.0, PT>0.5 GeV/c)
14 TeV
1.96 TeV
“Toward” Region
“Transverse” “Transverse”
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
~ factor of 2!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 14
Charged Multiplicity Distribution
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30 35 40 45 50 55
Number of Charged Particles
Pro
ba
bil
ity
CDF Run 2 <Nchg>=4.5
py64 Tune A <Nchg> = 4.1
pyAnoMPI <Nchg> = 2.6
Charged Particles (||<1.0, PT>0.4 GeV/c)
CDF Run 2 Preliminary
HC 1.96 TeV
Normalized to 1
Charged Multiplicity Distribution
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30 35 40 45 50 55
Number of Charged Particles
Pro
ba
bil
ity
CDF Run 2 <Nchg>=4.5
Normalized to 1
CDF Run 2 Preliminary
Min-Bias 1.96 TeV
Charged Particles (||<1.0, PT>0.4 GeV/c)
Charged Particle MultiplicityCharged Particle Multiplicity
Data at 1.96 TeV on the charged particle multiplicity (pT > 0.4 GeV/c, || < 1) for “min-bias” collisions at CDF Run 2.
Proton AntiProton
“Minumum Bias” Collisions
The data are compared with PYTHIA Tune A and Tune A without multiple parton interactions (pyAnoMPI).
No MPI! Tune A!7 decades!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 15
The “Underlying Event”The “Underlying Event”
Proton Proton
Select inelastic non-diffractive events that contain a hard scattering
Proton Proton
Proton Proton +
Proton Proton
+ + …
“Semi-hard” parton-parton collision(pT < ≈2 GeV/c)
Hard parton-parton collisions is hard(pT > ≈2 GeV/c) The “underlying-event” (UE)!
Multiple-parton interactions (MPI)!
Given that you have one hard scattering it is more probable to have MPI! Hence, the UE has more activity than “min-bias”.
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 16
The Inelastic Non-Diffractive The Inelastic Non-Diffractive Cross-SectionCross-Section
Proton Proton
Proton Proton +
Proton Proton
Proton Proton
+
Proton Proton +
+ …
“Semi-hard” parton-parton collision(pT < ≈2 GeV/c)
Occasionally one of the parton-parton collisions is hard(pT > ≈2 GeV/c)
Majority of “min-bias” events!
Multiple-parton interactions (MPI)!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 17
The “Underlying Event”The “Underlying Event”
Proton Proton
Select inelastic non-diffractive events that contain a hard scattering
Proton Proton
Proton Proton +
Proton Proton
+ + …
“Semi-hard” parton-parton collision(pT < ≈2 GeV/c)
Hard parton-parton collisions is hard(pT > ≈2 GeV/c) The “underlying-event” (UE)!
Multiple-parton interactions (MPI)!
Given that you have one hard scattering it is more probable to have MPI! Hence, the UE has more activity than “min-bias”.
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 18
Min-Bias CorrelationsMin-Bias Correlations
Data at 1.96 TeV on the average pT of charged particles versus the number of charged particles (pT > 0.4 GeV/c, || < 1) for “min-bias” collisions at CDF Run 2. The data are corrected to the particle level and are compared with PYTHIA Tune A at the particle level (i.e. generator level).
Proton AntiProton
“Minumum Bias” Collisions
Average PT versus Nchg
0.6
0.8
1.0
1.2
1.4
0 10 20 30 40 50
Number of Charged Particles
Ave
rag
e P
T (
GeV
/c)
CDF Run 2 Preliminarydata corrected
generator level theory
Charged Particles (||<1.0, PT>0.4 GeV/c)
Min-Bias1.96 TeV
ATLAS
pyA
pyDW
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 19
Min-Bias: Average PT versus NchgMin-Bias: Average PT versus Nchg
Proton AntiProton
“Soft” Hard Core (no hard scattering)
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
“Hard” Hard Core (hard scattering)
CDF “Min-Bias”
= +
Average PT versus Nchg
0.6
0.8
1.0
1.2
1.4
0 5 10 15 20 25 30 35 40
Number of Charged Particles
Ave
rag
e P
T (
GeV
/c)
CDF Run 2 Preliminarydata corrected
generator level theory
Charged Particles (||<1.0, PT>0.4 GeV/c)
Min-Bias1.96 TeV
pyAnoMPI
ATLAS
pyA
Proton AntiProton
Multiple-Parton Interactions
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
+
Beam-beam remnants (i.e. soft hard core) produces low multiplicity and small <pT> with <pT> independent of the multiplicity.
Hard scattering (with no MPI) produces large multiplicity and large <pT>.
Hard scattering (with MPI) produces large multiplicity and medium <pT>.
The CDF “min-bias” trigger picks up most of the “hard
core” component!
This observable is sensitive to the MPI tuning!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 20
Charged Particle MultiplicityCharged Particle Multiplicity
Data at 1.96 TeV on the charged particle multiplicity (pT > 0.4 GeV/c, || < 1) for “min-bias” collisions at CDF Run 2.
Proton AntiProton
“Minumum Bias” Collisions
The data are compared with PYTHIA Tune A and Tune A without multiple parton interactions (pyAnoMPI).
Charged Multiplicity Distribution
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30 35 40 45 50 55
Number of Charged Particles
Pro
bab
ility
CDF Run 2 <Nchg>=4.5
py Tune A <Nchg> = 4.3
pyAnoMPI <Nchg> = 2.6
Charged Particles (||<1.0, PT>0.4 GeV/c)
CDF Run 2 Preliminary
Min-Bias 1.96 Normalized to 1
No MPI!
Tune A!
Charged Multiplicity Distribution
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30 35 40 45 50 55
Number of Charged Particles
Pro
ba
bil
ity
CDF Run 2 <Nchg>=4.5
py Tune A <Nchg> = 4.3
pyA 900 GeV <Nchg> = 3.3
Charged Particles (||<1.0, PT>0.4 GeV/c)
CDF Run 2 Preliminary
Min-BiasNormalized to 1
Proton Proton
“Minumum Bias” Collisions
Prediction from PYTHIA Tune A for proton-proton collisions at 900 GeV.
Tune A prediction at 900 GeV!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 21
Peter’s Pythia Tunes WEBsitePeter’s Pythia Tunes WEBsite
http://home.fnal.gov/~skands/leshouches-plots/
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 22
Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “transverse” regions as a function of PTmax for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) for “min-bias” events at 0.2 TeV and 14 TeV from PYTHIA Tune DW and Tune DWT at the particle level (i.e. generator level). The STAR data from RHIC favors Tune DW!
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dd
0.0
0.1
0.2
0.3
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
ns
ve
rse
" C
ha
rge
d D
en
sit
y
Min-Bias0.2 TeV
RDF Preliminarygenerator level
Charged Particles (||<1.0, PT>0.5 GeV/c)
PY Tune DWT
PY Tune DW
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
1.6
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
ns
ve
rse
" C
ha
rge
d D
en
sit
y RDF Preliminarygenerator level
Min-Bias14 TeV Charged Particles (||<1.0, PT>0.5 GeV/c)
PY Tune DW
PY Tune DWT
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
RHIC LHC
0.2 TeV → 14 TeV (~factor of 70 increase)
~1.35
~1.35
35% more at RHIC means 26% less at the LHC!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 23
Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 1.96 TeV and 14 TeV predicted by PYTHIA Tune DW at the particle level (i.e. generator level).
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
RHIC Tevatron
0.2 TeV → 1.96 TeV (UE increase ~2.7 times)
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
ns
ve
rse
" C
ha
rge
d D
en
sit
y
Charged Particles (||<1.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
Min-Bias 14 TeV
1.96 TeV
0.2 TeV
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC
1.96 TeV → 14 TeV (UE increase ~1.9 times)
~2.7
~1.9
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 24
The “Underlying Event” at STARThe “Underlying Event” at STAR
At STAR they have measured the “underlying event at W = 200 GeV (|| < 1, pT > 0.2 GeV) and compared their uncorrected data with PYTHIA Tune A + STAR-SIM.
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 25
LHC Predictions: 900 GeVLHC Predictions: 900 GeV
Proton Proton
“Minumum Bias” Collisions
Compares the 900 GeV data with my favorite PYTHIA Tunes (Tune DW and Tune S320 Perugia 0). Tune DW uses the old Q2-ordered parton shower and the old MPI model. Tune S320 uses the new pT-ordered parton shower and the new MPI model. The numbers in parentheses are the average value of dN/d for the region || < 0.6.
Proton Proton
“Minumum Bias” Collisions
Charged Particle Density: dN/d
0
1
2
3
4
5
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
en
sit
y
ALICE INEL
UA5 INEL
pyDW INEL (2.67)
pyS320 INEL (2.70)
RDF Preliminary
INEL = HC+DD+SD 900 GeV
Charged Particles (all pT)
Charged Particle Density: dN/d
0
1
2
3
4
5
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
en
sit
y
UA5
ALICE
pyDW_10mm (3.04)
pyS320_10mm (3.09)
NSD = HC+DD 900 GeV
RDF Preliminary
(SD + DD)/INEL = 28±8%DD/NSD = 12±4%
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 26
LHC Predictions: 900 GeVLHC Predictions: 900 GeV
Proton Proton
“Minumum Bias” Collisions
Shows the individual HC, DD, and SD predictions of PYTHIA Tune DW and Tune S320 Perugia 0. The numbers in parentheses are the average value of dN/d for the region || < 0.6. I do not trust PYTHIA to model correctly the DD and SD contributions! I would like to know how well these tunes model the HC component. We need to look at observables where only HC contributes!
Proton Proton
“Minumum Bias” Collisions
Charged Particle Density: dN/d
0
1
2
3
4
5
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
en
sit
y
ALICE INELUA5 INELpyDW times 1.11 (2.97)pyS320 times 1.11 (3.00)
RDF Preliminary
INEL = HC+DD+SD 900 GeV
times 1.11
Charged Particles (all pT)
Charged Particle Density: dN/d
0
1
2
3
4
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
en
sit
y
pyDW HC (3.30)
pyS320 HC (3.36)
pyDW SD (0.61)
pyS320 SD (0.53)
pyDW DD (0.59)
pyS320 DD (0.53)
900 GeV
RDF Preliminary Only HC
Only DD
Charged Particles (all pT)
Only SD
Charged Particle Density: dN/d
0
1
2
3
4
5
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
en
sit
y
ALICE INEL
UA5 INEL
pyDW INEL NPT1>0 (4.24)
pyS320 INEL NPT1>0 (4.48)
pyDW INEL (2.67)
pyS320 INEL (2.70)
RDF Preliminary
INEL = HC+DD+SD 900 GeV
Charged Particles (all pT)
Off by 11%!
(SD + DD)/INEL = 28±8%
Require at least one charged particle to have pT > 1 GeV/c. This is > 99% HC only!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 27
Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 0.9 TeV, 1.96 TeV, 7 TeV, 10 TeV, 14 TeV predicted by PYTHIA Tune DW at the particle level (i.e. generator level).
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
RHIC Tevatron
0.2 TeV → 1.96 TeV (UE increase ~2.7 times)
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC
1.96 TeV → 14 TeV (UE increase ~1.9 times)
Linear scale!
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
en
sity
Charged Particles (||<1.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
Min-Bias 14 TeV
1.96 TeV
0.2 TeV
7 TeV
0.9 TeV
10 TeV
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 2 4 6 8 10 12 14
Center-of-Mass Energy (TeV)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty RDF Preliminarypy Tune DW generator level
Charged Particles (||<1.0, PT>0.5 GeV/c)
PTmax = 5.25 GeV/c
RHIC
Tevatron900 GeV
LHC7
LHC14
LHC10
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 28
Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 0.9 TeV, 1.96 TeV, 7 TeV, 10 TeV, 14 TeV predicted by PYTHIA Tune DW at the particle level (i.e. generator level).
Log scale!
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
en
sity
Charged Particles (||<1.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
Min-Bias 14 TeV
1.96 TeV
0.2 TeV
7 TeV
0.9 TeV
10 TeV
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0.1 1.0 10.0 100.0
Center-of-Mass Energy (TeV)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty RDF Preliminarypy Tune DW generator level
Charged Particles (||<1.0, PT>0.5 GeV/c)
PTmax = 5.25 GeV/c
RHIC
Tevatron
900 GeV
LHC7
LHC14LHC10
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC7 LHC14
7 TeV → 14 TeV (UE increase ~20%)
Linear on a log plot!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 29
““Transverse” Charge DensityTransverse” Charge Density
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC 900 GeV
LHC7 TeV
900 GeV → 7 TeV (UE increase ~ factor of 2.1)
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
ns
ve
rse
" C
ha
rge
d D
en
sit
y
Charged Particles (||<2.0, PT>0.5 GeV/c) HC 900 GeV
RDF Preliminarygenerator level
pyS320
pyDW
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
ers
e"
Ch
arg
ed
De
ns
ity
Charged Particles (||<2.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
900 GeV
7 TeV
Shows the charged particle density in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) at 900 GeV as defined by PTmax from PYTHIA Tune DW and Tune S320 at the particle level (i.e. generator level).
factor of 2!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 30
Charged Multiplicity Distribution
0.00
0.02
0.04
0.06
0.08
0 5 10 15 20 25 30 35 40
Number of Charged Particles
Pro
bab
ilit
y
pyA 900 GeV <Nchg> = 14.2
pyDW 900 GeV <Nchg> = 14.4
pyS320 900 GeV <Nchg> = 14.2
pyP329 900 GeV <Nchg> = 14.7
HC 900 GeV
Normalized to 1 Charged Particles (||<2.0, all pT)
RDF Preliminary
Important 900 GeV Measurements
Proton Proton
“Minumum Bias” Collisions
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
The amount of activity in “min-bias” collisions (multiplicity distribution, pT distribution, PTsum distribution, dNchg/d).
The amount of activity in the “underlying event” in hard scattering events (“transverse” Nchg distribution, “transverse” pT distribution, “transverse” PTsum distribution for events with PTmax > 5 GeV/c).
We should map out the energy dependence of the “underlying event” in a hard scattering process from 900 GeV to 14 TeV!
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity
Charged Particles (||<2.0, PT>0.5 GeV/c) HC 900 GeV
RDF Preliminarygenerator level
pyS320
pyDW
Charged Multiplicity Distribution
0.00
0.04
0.08
0.12
0.16
0 2 4 6 8 10 12 14 16
Number of Charged Particles
Pro
ba
bil
ity
pyA <Nchg> = 5.0 STdev = 4.5
pyDW 900 GeV <Nchg> = 5.3
pyS320 900 GeV <Nchg> = 5.2
pyP329 900 GeV <Nchg> = 5.3
RDF Preliminary
HC 900 GeV
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
"Transverse" Charged Particle Multiplicity
0.00
0.06
0.12
0.18
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Number of Charged Particles
Pro
bab
ilit
y
py64DW <Nchg> = 3.5 <NchgDen> = 0.42
pyS320 <Nchg> = 3.4 <NchgDen> = 0.41
RDF Preliminarygenerator level
HC 900 GeV PTmax > 5 GeV/c
Charged Particles (||<2.0, PT>0.5 GeV/c)
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0.1 1.0 10.0 100.0
Center-of-Mass Energy (TeV)
"Tra
nsv
erse
" C
har
ged
Den
sity RDF Preliminary
py Tune DW generator level
Charged Particles (||<1.0, PT>0.5 GeV/c)
PTmax = 5.25 GeV/c
For every 1,000 events here
We get 3 events here!
It is very important to measureBOTH “min-bias” and the and the
“underlying event” at 900 GeV!To do this we need to collect
about 5,000,000 CMS min-bias triggers!
Chris Quigg Symposiun Fermilab December 14, 2009
Rick Field – Florida/CDF/CMS Page 31
The “Underlying Event” at 900 GeV The “Underlying Event” at 900 GeV
Show how well we could measure the “transverse” charged particle density versus PTmax with 10 M, 1 M, and 0.5 M “min-bias” (MB) events collected by CMS. Assumes that for all the events that the tracker is working well! The goal is to see how well the data (red squares) agree with the QCD MC prediction (black curve).
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
PTmax (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty
Charged Particles (||<2.0, PT>0.5 GeV/c)
RDF PreliminarypyDW generator level
900 GeV10 Million MB Collisions
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
PTmax (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty
Charged Particles (||<2.0, PT>0.5 GeV/c)
RDF PreliminarypyDW generator level
900 GeV1 Million MB Collisions
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
PTmax (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty
Charged Particles (||<2.0, PT>0.5 GeV/c)
RDF PreliminarypyDW generator level
900 GeV0.5 Million MB Collisions
Unfortunately, looks like this is all we will get!