LHC First Data
-
Upload
hedda-gardner -
Category
Documents
-
view
24 -
download
0
description
Transcript of LHC First Data
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 1
LHC First DataLHC First Data
Rick FieldUniversity of Florida
Outline of Talk How well did we do at predicting the behavior of the
“underlying event” at 900 GeV and 7 TeV? A careful look.
How well did we do at predicting the behavior of “min-bias” collisions at 900 GeV and 7 TeV? A careful look.
PYTHIA 6.4 Tune Z1: New CMS 6.4 tune (pT-ordered parton showers and new MPI).
Monte-Carlo Models Facing Real Data
CMS
ATLAS
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
Proton Proton
“Minimum Bias” Collisions
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 2
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 AntiProton
Underlying Event Underlying Event
Proton AntiProton
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!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 3
Traditional ApproachTraditional Approach
Look at charged particle correlations in the azimuthal angle relative to a leading object (i.e. CaloJet#1, ChgJet#1, PTmax, Z-boson). For CDF PTmin = 0.5 GeV/c cut = 1.
Charged Particle Correlations PT > PTmin || < cut
Leading Object Direction
“Toward”
“Transverse” “Transverse”
“Away”
Define || < 60o as “Toward”, 60o < || < 120o as “Transverse”, and || > 120o as “Away”.
Leading Calorimeter Jet or Leading Charged Particle Jet or
Leading Charged Particle orZ-Boson
-cut +cut
2
0
Leading Object
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
All three regions have the same area in - space, × = 2cut×120o = 2cut×2/3. Construct densities by dividing by the area in - space.
Charged Jet #1Direction
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
“Transverse” region very sensitive to the “underlying event”!
CDF Run 1 Analysis
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 4
““Transverse” Charged Particle DensityTransverse” Charged Particle Density
Fake data (from MC) at 900 GeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i.e. generator level) assuming 0.5 M min-bias events at 900 GeV (361,595 events in the plot).
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty
900 GeV
Charged Particles (||<2.0, PT>0.5 GeV/c)
RDF PreliminaryFake Data
pyDW generator levelChgJet#1
PTmax
Rick FieldMB&UE@CMS WorkshopCERN, November 6, 2009
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
Leading Charged Particle Jet, chgjet#1.
Leading Charged Particle, PTmax.
Prediction!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 5
““Transverse” Charged Particle DensityTransverse” Charged Particle Density
Fake data (from MC) at 900 GeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i.e. generator level) assuming 0.5 M min-bias events at 900 GeV (361,595 events in the plot).
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
ns
vers
e"
Ch
arg
ed D
ensi
ty
900 GeV
Charged Particles (||<2.0, PT>0.5 GeV/c)
RDF PreliminaryFake Data
pyDW generator levelChgJet#1
PTmax
CMS preliminary data at 900 GeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation (216,215 events in the plot).
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity CMS Preliminary
data uncorrectedpyDW + SIM
900 GeV
ChgJet#1
PTmax
Charged Particles (||<2.0, PT>0.5 GeV/c) Real Data!Monte-Carlo!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 6
““Transverse” Charged PTsum DensityTransverse” Charged PTsum Density
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
PT
su
m D
en
sity
(G
eV
/c)
900 GeV
Charged Particles (||<2.0, PT>0.5 GeV/c)
ChgJet#1
PTmax
RDF PreliminaryFake Data
pyDW generator level
Fake data (from MC) at 900 GeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i.e. generator level) assuming 0.5 M min-bias events at 900 GeV (361,595 events in the plot).
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
PT
sum
Den
sity
(G
eV/c
)
CMS Preliminarydata uncorrected
pyDW + SIM
900 GeV
Charged Particles (||<2.0, PT>0.5 GeV/c)
ChgJet#1
PTmax
CMS preliminary data at 900 GeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation (216,215 events in the plot).
Real Data!Monte-Carlo!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 7
PYTHIA Tune DWPYTHIA Tune DW
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 8
PYTHIA Tune DWPYTHIA Tune DW"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
erse
" C
har
ged
Den
sity RDF Preliminary
ATLAS corrected dataTune DW generator level
900 GeV
7 TeV
Charged Particles (||<2.5, PT>0.5 GeV/c)
ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
ATLAS Note: ATLAS-CONF-2010-029May 29, 2010
I read the points off with a ruler!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 9
PYTHIA Tune DWPYTHIA Tune DW
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
"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
erse
" C
har
ged
Den
sity RDF Preliminary
ATLAS corrected dataTune DW generator level
900 GeV
7 TeV
Charged Particles (||<2.5, PT>0.5 GeV/c)
ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
CMS ATLAS
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 10
PYTHIA Tune DWPYTHIA Tune DW
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) (GeV/c)
Ch
arg
ed P
Tsu
m D
ensi
ty (
GeV
/c)
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
900 GeV
7 TeV
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
PT
sum
Den
sity
(G
eV/c
)
RDF PreliminaryATLAS corrected data
Tune DW generator level
900 GeV
7 TeV
Charged Particles (||<2.5, PT>0.5 GeV/c)
CMS ATLAS
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 11
““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)
"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
ns
ve
rse
" C
ha
rge
d D
en
sit
y
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 and 7 TeV as defined by PTmax from PYTHIA Tune DW and at the particle level (i.e. generator level).
factor of 2!
~0.4 → ~0.8
Rick FieldMB&UE@CMS WorkshopCERN, November 6, 2009
Prediction!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 12
PYTHIA Tune DWPYTHIA Tune DW
Ratio of CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dd
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
CMS
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
CMS
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
Ratio
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 13
PYTHIA Tune DWPYTHIA Tune DW
Ratio of CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
Ratio of the ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
"Transverse" Charged Particle Density: dN/dd
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
"Transverse" Charged Particle Density: dN/dd
0.0
1.0
2.0
3.0
0 1 2 3 4 5 6 7 8 9 10 11 12
PTmax (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
Charged Particles (||<2.5, PT>0.5 GeV/c)
RDF PreliminaryATLAS corrected datapyDW generator level
7 TeV / 900 GeV
CMS ATLAS
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 14
PYTHIA Tune DWPYTHIA Tune DW
Ratio of the CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
Ratio of the ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
"Transverse" Charged PTsum Density: dPT/dd
0.0
1.0
2.0
3.0
4.0
0 1 2 3 4 5 6 7 8 9 10 11 12
PTmax (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
Charged Particles (||<2.5, PT>0.5 GeV/c)
RDF PreliminaryATLAS corrected datapyDW generator level
7 TeV / 900 GeV
"Transverse" Charged PTsum Density: dPT/dd
0.0
1.0
2.0
3.0
4.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
CMS ATLAS
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 15
““Transverse” Multiplicity DistributionTransverse” Multiplicity Distribution
CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet, chgjet#1, with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune DW at the detector level (i.e. Theory + SIM).
Same hard scale at two different center-
of-mass energies!
Shows the growth of the “underlying event” as the center-of-mass energy increases.
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
pyDW + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
PT(chgjet#1) > 3 GeV/c
900 GeV 7 TeV
CMS PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 16
““Transverse” Multiplicity DistributionTransverse” Multiplicity Distribution
CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet, chgjet#1, with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune DW at the detector level (i.e. Theory + SIM).
Same center-of-mass energy at two different
hard scales!
Shows the growth of the “underlying event” as the hard scale increases.
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
pyDW + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
PT(chgjet#1) > 20 GeV/c
PT(chgjet#1) > 3 GeV/c
CMS
PT(chgjet#1) Direction
“Toward”
“Transverse” “Transverse”
“Away”
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 17
PYTHIA Tune DWPYTHIA Tune DW
I am surprised that the Tunes did not do a better job of predicting the behavior of the “underlying event” at 900 GeV and 7 TeV!
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity CMS Preliminary
data uncorrectedpyDW + SIM
900 GeV
ChgJet#1
PTmax
Charged Particles (||<2.0, PT>0.5 GeV/c)
"Transverse" Charged Particle Density: dN/dd
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
Tune DW Tune DW
Tune DW
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 18
PYTHIA Tune DWPYTHIA Tune DW
I am surprised that the Tunes did as well as they did at predicting the behavior of the “underlying event” at 900 GeV and 7 TeV!
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity CMS Preliminary
data uncorrectedpyDW + SIM
900 GeV
ChgJet#1
PTmax
Charged Particles (||<2.0, PT>0.5 GeV/c)
"Transverse" Charged Particle Density: dN/dd
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io:
7 T
eV/9
00 G
eV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
Tune DW Tune DW
Tune DW
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 19
UE SummaryUE SummaryThe “underlying event” at 7 TeV and
900 GeV is almost what we expected! With a little tuning we should be able to describe the data very well (see Tune Z1 later in this talk).
“Min-Bias” is a whole different story! Much more complicated due to very soft particles and diffraction!
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
PARP(90)
Color
Connections
PARP(82)
Diffraction
I am surprised that the Tunes did as well as they did at predicting the behavior of the “underlying event” at 900 GeV and 7 TeV! Remember this is “soft” QCD!
Warning! All the UE studies lookat charged particles with pT > 0.5 GeV/c.We do not know if the models correctly
describe the UE at lower pT values!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 20
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”
NDtot = ELIN
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 21
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)!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 22
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”.
1/(pT)4→ 1/(pT2+pT0
2)2
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 23
Model of Model of NDND
Proton Proton
Proton Proton +
Proton Proton
Proton Proton
+
Proton Proton +
+ …
“Semi-hard” parton-parton collision(pT < ≈2 GeV/c)
Allow leading hard scattering to go to zero pT with same cut-off as the MPI!
Model of the inelastic non-diffractive cross section!
Multiple-parton interactions (MPI)!
Proton Proton
1/(pT)4→ 1/(pT2+pT0
2)2
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 24
UE TunesUE Tunes
Proton Proton
Proton Proton +
Proton Proton
Proton Proton
+
Proton Proton +
+ …
“Underlying Event”
“Min-Bias” (ND)
Fit the “underlying event” in a hard
scattering process.
Predict MB (ND)!
1/(pT)4→ 1/(pT2+pT0
2)2
Allow primary hard-scattering to go to pT = 0 with same cut-off!
Single Diffraction
M
Double Diffraction
M1 M2
“Min-Bias” (add single & double diffraction)
Predict MB (IN)!
All of Rick’s tunes (except X2):A, AW, AWT,DW, DWT,
D6, D6T, CW, X1, and Tune Z1,are UE tunes!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 25
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 (non-diffractive cross-section).
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
Charged Particles (||<1.0, PT>0.4 GeV/c)
i
Proton AntiProton
“Minimum 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!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 26
PYTHIA Tune A Min-BiasPYTHIA Tune A Min-Bias“Soft” + ”Hard”“Soft” + ”Hard”
Comparison of PYTHIA Tune A with the pT distribution of charged particles for “min-bias” collisions at CDF Run 1 (non-diffractive cross-section).
Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14
PT(charged) (GeV/c)
Ch
arg
ed D
ensi
ty d
N/d
d d
PT
(1/
GeV
/c)
Pythia 6.206 Set A
CDF Min-Bias Data
CDF Preliminary
1.8 TeV ||<1
PT(hard) > 0 GeV/c12% of “Min-Bias” events have PT(hard) > 5 GeV/c!
1% of “Min-Bias” events have PT(hard) > 10 GeV/c!
PYTHIA Tune A predicts that 12% of all “Min-Bias” events are a result of a hard 2-to-2 parton-parton scattering with PT(hard) > 5 GeV/c (1% with PT(hard) > 10 GeV/c)!
Lots of “hard” scattering in “Min-Bias” at the Tevatron!
Ten decades!
pT = 50 GeV/c!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 27
LHC MB Predictions: 900 GeVLHC MB Predictions: 900 GeV
Proton Proton
“Minimum Bias” Collisions
Compares the 900 GeV ALICE data with PYTHIA 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
“Minimum 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
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)
Off by 11%!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 28
ATLAS INEL dN/dATLAS INEL dN/d
Soft particles!
None of the tunes fit the ATLAS INEL dN/d data with PT > 100 MeV! They all predict too few particles.
The ATLAS Tune AMBT1 was designed to fit the inelastic data for Nchg ≥ 6 with pT > 0.5 GeV/c!
Off by 20-50%!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 29
PYTHIA Tune DWPYTHIA Tune DWCharged Particle Density: dN/d
0
1
2
3
4
5
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
ens
ity
900 GeV
pT > 0.15 GeV/c
RDF PreliminaryALICE INEL data
pyDW generator level
pT > 0.5 GeV/c
pT > 1.0 GeV/c
At Least 1 Charged Particle || < 0.8
ALICE inelastic data at 900 GeV on the dN/d distribution for charged particles (pT > PTmin) for events with at least one charged particle with pT > PTmin and || < 0.8 for PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune DW at the generator level.
If one increases the pT the agreement
improves!
Tune DW
Proton Proton
“Minimum Bias” Collisions
The same thing occurs at 7 TeV! ALICE, ATLAS, and CMS data coming soon.
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 30
PYTHIA Tune DWPYTHIA Tune DW
ALICE inelastic data at 900 GeV on the dN/d distribution for charged particles (pT > PTmin) for events with at least one charged particle with pT > PTmin and || < 0.8 for PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune Z1 at the generator level (dashed = ND, solid = INEL).
Charged Particle Density: dN/d
0
1
2
3
4
5
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
ens
ity
900 GeV
pT > 0.15 GeV/c
RDF PreliminaryALICE INEL data
pyDW generator level
pT > 0.5 GeV/c
pT > 1.0 GeV/c
dashed = ND solid = INEL
At Least 1 Charged Particle || < 0.8
Diffraction contributes less at
harder scales!
Tune DW
Proton Proton
“Minimum Bias” Collisions
Cannot trust PYTHIA 6.2 modeling of diffraction!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 31
Charged Particle Density: dN/d
0
2
4
6
8
-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
ens
ity
7 TeV
RDF PreliminaryCMS NSD data
pyDW generator level
dashed = ND solid = NSD
CMS dN/dCMS dN/d
Generator level dN/d (all pT). Shows the NSD = HC + DD and the HC = ND contributions for Tune DW. Also shows the CMS NSD data.
CMS
Tune DW
All pT
Soft particles!
Proton Proton
“Minimum Bias” Collisions
Off by 50%!
Okay if the Monte-Carlo does not fitthe data what do we do?
We tune the Monte-Carloto fit the data!
Be careful not to tune away new physics!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 32
PYTHIA Tune Z1PYTHIA Tune Z1
Proton Proton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
I believe that it is time to move to PYTHIA 6.4 (pT-ordered parton showers and new MPI model)!
Tune Z1: I started with the parameters of ATLAS Tune AMBT1, but I changed LO* to CTEQ5L and I varied PARP(82) and PARP(90) to get a very good fit of the CMS UE data at 900 GeV and 7 TeV.
UE&MB@CMSUE&MB@CMS
All my previous tunes (A, DW, DWT, D6, D6T, CW, X1, and X2) were PYTHIA 6.4 tunes using the old Q2-ordered parton showers and the old MPI model (really 6.2 tunes)!
PARP(90)
Color
Connections
PARP(82)
Diffraction
The ATLAS Tune AMBT1 was designed to fit the inelastic data for Nchg ≥ 6 and to fit the PTmax UE data with PTmax > 10 GeV/c. Tune AMBT1 is primarily a min-bias tune, while Tune Z1 is a UE tune!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 33
PYTHIA Tune Z1PYTHIA Tune Z1Parameter
Tune Z1
(R. Field CMS)Tune AMBT1
(ATLAS)
Parton Distribution Function CTEQ5L LO*
PARP(82) – MPI Cut-off 1.932 2.292
PARP(89) – Reference energy, E0 1800.0 1800.0
PARP(90) – MPI Energy Extrapolation 0.275 0.25
PARP(77) – CR Suppression 1.016 1.016
PARP(78) – CR Strength 0.538 0.538
PARP(80) – Probability colored parton from BBR 0.1 0.1
PARP(83) – Matter fraction in core 0.356 0.356
PARP(84) – Core of matter overlap 0.651 0.651
PARP(62) – ISR Cut-off 1.025 1.025
PARP(93) – primordial kT-max 10.0 10.0
MSTP(81) – MPI, ISR, FSR, BBR model 21 21
MSTP(82) – Double gaussion matter distribution 4 4
MSTP(91) – Gaussian primordial kT 1 1
MSTP(95) – strategy for color reconnection 6 6
Parameters not shown are the PYTHIA 6.4
defaults!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 34
PYTHIA Tune Z1PYTHIA Tune Z1
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2.0. The data are uncorrected and compared with PYTHIA Tune Z1 after detector simulation (SIM).
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2.0. The data are uncorrected and compared with PYTHIA Tune DW and D6T after detector simulation (SIM).
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
Theory + SIM
7 TeV
DW
D6T
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Ch
arg
ed P
arti
cle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyZ1 + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
Tune Z1 (CTEQ5L)PARP(82) = 1.932PARP(90) = 0.275PARP(77) = 1.016PARP(78) = 0.538
Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and
the new MPI model!
Color reconnection suppression.Color reconnection strength.
CMS CMSTune Z1
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 35
PYTHIA Tune Z1PYTHIA Tune Z1
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2.0. The data are uncorrected and compared with PYTHIA Tune Z1 after detector simulation (SIM).
CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and || < 2.0. The data are uncorrected and compared with PYTHIA Tune DW and D6T after detector simulation (SIM).
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) (GeV/c)
Ch
arg
ed P
Tsu
m D
ensi
ty (
GeV
/c)
CMS Preliminarydata uncorrected
Theory + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
900 GeV
7 TeV
DW
D6T
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) (GeV/c)
Ch
arg
ed P
Tsu
m D
ensi
ty (
GeV
/c)
CMS Preliminarydata uncorrected
pyZ1 + SIM
Charged Particles (||<2.0, PT>0.5 GeV/c)
900 GeV
7 TeV
Tune Z1 (CTEQ5L)PARP(82) = 1.932PARP(90) = 0.275PARP(77) = 1.016PARP(78) = 0.538
Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and
the new MPI model!
Color reconnection suppression.Color reconnection strength.
CMS CMSTune Z1
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 36
PYTHIA Tune Z1PYTHIA Tune Z1
ALICE preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 0.8. The data are corrected and compared with PYTHIA Tune Z1 at the generrator level.
ALICE preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 0.8. The data are corrected and compared with PYTHIA Tune Z1 at the generator level.
ALICE UE Data: Talk by S. ValleroMPI@LHC 2010 Glasgow, Scotland
November 30, 2010
"Transverse" Charged Particle Density: dN/dd
0.0
0.4
0.8
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity RDF Preliminary
ALICE corrected dataTune Z1 generator level
Charged Particles (||<0.8, PT>0.5 GeV/c)
900 GeV
7 TeV
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
0 5 10 15 20 25
PTmax (GeV/c)
PT
sum
Den
sity
(G
eV/c
)
RDF PreliminaryALICE corrected data
Tune Z1 generator level
Charged Particles (||<0.8, PT>0.5 GeV/c)
900 GeV
7 TeV
ALICETune Z1
ALICETune Z1
I read the points off with a ruler!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 37
PYTHIA Tune Z1PYTHIA Tune Z1
ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generrator level.
ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generator level.
ATLAS Note: ATLAS-CONF-2010-029May 29, 2010
"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
erse
" C
har
ged
Den
sity RDF Preliminary
ATLAS corrected dataTune Z1 generator level
900 GeV
7 TeV
Charged Particles (||<2.5, PT>0.5 GeV/c)
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
PT
sum
Den
sity
(G
eV/c
)
RDF PreliminaryATLAS corrected data
Tune Z1 generator level
900 GeV
7 TeV
Charged Particles (||<2.5, PT>0.5 GeV/c)
ATLASATLASTune Z1Tune Z1
I read the points off with a ruler!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 38
PYTHIA Tune Z1PYTHIA Tune Z1
ATLAS preliminary data at 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. Also shows the prediction of Tune Z1 for the “transverse” charged particle density with pT > 0.1 GeV/c and || < 2.5.
ATLAS preliminary data at 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and || < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. Also shows the prediction of Tune Z1 for the “transverse” charged particle density with pT > 0.1 GeV/c and || < 2.5.
"Transverse" Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity RDF Preliminary
ATLAS corrected dataTune Z1 generator level
7 TeV
Charged Particles (||<2.5)
PT > 0.1 GeV/c
PT > 0.5 GeV/c
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" P
Tsu
m D
ensi
ty RDF PreliminaryATLAS corrected data
Tune Z1 generator level
7 TeV
PT > 0.1 GeV/c
PT > 0.5 GeV/cCharged Particles (||<2.5) Tune Z1
ATLASTune Z1
ATLAS
Factor of 2 increase!
"Transverse" Ratio: PT > 0.1 and > 0.5 GeV/c
0.0
1.0
2.0
3.0
4.0
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" R
atio
0.1
/0.5
RDF Preliminary generator levelTune Z1 (solid)
Tune DW (dashed)
7 TeVCharged Particles (||<2.5)
Charge Particle Density
Charge PTsum Density
Rick FieldMPI@LHC 2010 Glasgow, Scotland
December 2, 2010
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 39
PYTHIA Tune Z1PYTHIA Tune Z1
ATLAS preliminary data at 7 TeV on the “transverse” charged PTsum density, dPT/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and pT > 0.1 GeV/c (|| < 2.5). The data are corrected and compared with PYTHIA Tune Z1 at the generator level.
ATLAS preliminary data at 7 TeV on the “transverse” charged particle density, dN/dd, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and pT > 0.1 GeV/c (|| < 2.5). The data are corrected and compared with PYTHIA Tune Z1 at the generator level.
"Transverse" Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" C
har
ged
Den
sity RDF Preliminary
ATLAS corrected dataTune Z1 generator level
7 TeV
Charged Particles (||<2.5)
PT > 0.1 GeV/c
PT > 0.5 GeV/c
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" P
Tsu
m D
ensi
ty RDF PreliminaryATLAS corrected data
Tune Z1 generator level
7 TeV
PT > 0.1 GeV/c
PT > 0.5 GeV/cCharged Particles (||<2.5)
"Transverse" Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
ns
ve
rse
" C
harg
ed
Den
sit
y RDF PreliminaryATLAS corrected data
Tune Z1 generator level
7 TeV
PT > 0.1 GeV/c
PT > 0.5 GeV/cCharged Particles (||<2.5)
Tune Z1 ATLAS
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
PT
su
m D
en
sit
y (
Ge
V/c
)
RDF PreliminaryATLAS corrected data
Tune Z1 generator level
7 TeV
PT > 0.1 GeV/c
PT > 0.5 GeV/c
Charged Particles (||<2.5)
Tune Z1
ATLAS
ATLAS publication – arXiv:1012.0791December 3, 2010
I read the points off with a ruler!
"Transverse" Ratio: PT > 0.1 and > 0.5 GeV/c
0.0
1.0
2.0
3.0
4.0
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsv
erse
" R
atio
0.1
/0.5
7 TeVCharged Particles (||<2.5)
RDF PreliminaryATLAS corrected data
Tune Z1 generator levelCharge Particle Density
Charge PTsum Density
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 40
““Transverse” Multiplicity DistributionTransverse” Multiplicity Distribution
CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune DW and Tune D6T at the detector level (i.e. Theory + SIM).
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
Theory + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
PT(chgjet#1) > 3 GeV/c
900 GeV 7 TeV
D6T
DW
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
pyZ1 + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
PT(chgjet#1) > 3 GeV/c
900 GeV 7 TeV
Tune Z1
CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM).
CMSCMS
Same hard scale at two different center-
of-mass energies!
Difficult to produce enough events with large “transverse” multiplicity at low
hard scale!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 41
““Transverse” PTsum DistributionTransverse” PTsum Distribution
CMS uncorrected data at 900 GeV and 7 TeV on the charged scalar PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune DW, and Tune D6T at the detector level (i.e. Theory + SIM).
"Transverse" Charged PTsum Distribution
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
PTsum (GeV/c)
Pro
bab
ilit
y
Charged Particles (||<2.0, PT>0.5 GeV/c)
CMS Preliminarydata uncorrected
Theory + SIM
Normalized to 1
PT(chgjet#1) > 3 GeV/c
900 GeV
7 TeV
D6T
DW
"Transverse" Charged PTsum Distribution
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
PTsum (GeV/c)
Pro
bab
ilit
y
Charged Particles (||<2.0, PT>0.5 GeV/c)
CMS Preliminarydata uncorrected
pyZ1+ SIM
Normalized to 1
PT(chgjet#1) > 3 GeV/c
900 GeV
7 TeV
CMS uncorrected data at 900 GeV and 7 TeV on the charged scalar PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune Z1, at the detector level (i.e. Theory + SIM).
Tune Z1
CMSCMS
Same hard scale at two different center-
of-mass energies!
Difficult to produce enough events with large “transverse”
PTsum at low hard scale!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 42
““Transverse” Multiplicity DistributionTransverse” Multiplicity Distribution
CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune DW and Tune D6T at the detector level (i.e. Theory + SIM).
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
Theory + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
PT(chgjet#1) > 20 GeV/c
PT(chgjet#1) > 3 GeV/c
D6T
DW
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
pyZ1 + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
7 TeV
PT(chgjet#1) > 20 GeV/c
PT(chgjet#1) > 3 GeV/c
CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM).
Tune Z1CMS
CMS
Same center-of-mass energy at two different
hard scales!
Difficult to produce enough events with large “transverse” multiplicity at low
hard scale!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 43
““Transverse” PTsum DistributionTransverse” PTsum Distribution
CMS uncorrected data at 7 TeV on the charged PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune DW and Tune D6T at the detector level (i.e. Theory + SIM).
"Transverse" Charged PTsum Distribution
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
PTsum (GeV/c)
Pro
bab
ilit
y
Charged Particles (||<2.0, PT>0.5 GeV/c)
CMS Preliminarydata uncorrected
Theory + SIM
Normalized to 1
PT(chgjet#1) > 20 GeV/c
PT(chgjet#1) > 3 GeV/c
7 TeV
D6T
DW
"Transverse" Charged PTsum Distribution
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
PTsum (GeV/c)
Pro
bab
ilit
y
Charged Particles (||<2.0, PT>0.5 GeV/c)
CMS Preliminarydata uncorrected
pyZ1 + SIM
Normalized to 1
PT(chgjet#1) > 20 GeV/c
PT(chgjet#1) > 3 GeV/c
7 TeV
Tune Z1
CMS uncorrected data at 7 TeV on the charged PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM).
CMSCMS
Same center-of-mass energy at two different
hard scales!
Difficult to produce enough events with large “transverse”
PTsum at low hard scale!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 44
CMS dN/dCMS dN/dCharged Particle Density: dN/d
0
2
4
6
8
-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 P
arti
cle
Den
sity
CMS NSD 7 TeV
pyZ1 HC (6.51)
pyZ1 NSD (5.58)
RDF Preliminary
7 TeV
Charged Particle Density: dN/d
0
2
4
6
8
-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 P
arti
cle
Den
sity
CMS NSD 7 TeV
pyX2 NSD (5.91)
pyZ1 NSD (5.58)CMS NSD all pT
RDF Preliminary
7 TeV
Generator level dN/d (all pT). Shows the NSD = HC + DD and the HC = ND contributions for Tune Z1. Also shows the CMS NSD data.
Generator level dN/d (all pT). Shows the NSD = HC + DD prediction for Tune Z1 and Tune X2. Also shows the CMS NSD data.
CMSCMS
Tune Z1
Proton Proton
“Minimum Bias” Collisions
Okay not perfect, but remember we do not know if the DD is correct!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 45
PYTHIA Tune Z1PYTHIA Tune Z1
ALICE inelastic data at 900 GeV on the dN/d distribution for charged particles (pT > PTmin) for events with at least one charged particle with pT > PTmin and || < 0.8 for PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune Z1 at the generator level.
Charged Particle Density: dN/d
0
1
2
3
4
5
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
PseudoRapidity
Ch
arg
ed
Par
ticl
e D
ens
ity
900 GeV
pT > 0.15 GeV/c
RDF PreliminaryALICE INEL data
pyZ1 generator level
pT > 0.5 GeV/c
pT > 1.0 GeV/c
At Least 1 Charged Particle || < 0.8
Proton Proton
“Minumum Bias” Collisions
Okay not perfect, but remember we do not know if the SD & DD are correct!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 46
NSD Multiplicity DistributionNSD Multiplicity Distribution
Generator level charged multiplicity distribution (all pT, || < 2) at 900 GeV and 7 TeV. Shows the NSD = HC + DD prediction for Tune Z1. Also shows the CMS NSD data.
Charged Multiplicity Distribution
1.0E-04
1.0E-03
1.0E-02
1.0E-01
0 20 40 60 80 100
Number of Charged Particles
Pro
ba
bil
ity
Charged Particles (all PT, ||<2.0)
RDF Preliminarydata CMS NSD
pyZ1 generator level
7 TeV
900 GeV
CMS
Tune Z1
Difficult to produce enough events with large multiplicity!
Proton Proton
“Minumum Bias” Collisions
Okay not perfect!But not that bad!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 47
MB & UEMB & UE
Generator level charged multiplicity distribution (all pT, || < 2) at 900 GeV and 7 TeV. Shows the NSD = HC + DD prediction for Tune Z1. Also shows the CMS NSD data.
Charged Multiplicity Distribution
1.0E-04
1.0E-03
1.0E-02
1.0E-01
0 20 40 60 80 100
Number of Charged Particles
Pro
ba
bil
ity
Charged Particles (all PT, ||<2.0)
RDF Preliminarydata CMS NSD
pyZ1 generator level
7 TeV
900 GeV
"Transverse" Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS Preliminarydata uncorrected
pyZ1 + SIM
Normalized to 1
Charged Particles (||<2.0, PT>0.5 GeV/c)
PT(chgjet#1) > 3 GeV/c
900 GeV 7 TeV
CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM).
CMS CMSTune Z1
Tune Z1
“Min-Bias”
“Underlying Event”
Difficult to produce enough events with large multiplicity!
Difficult to produce enough events with large “transverse” multiplicity at low
hard scale!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 48
MB & UEMB & UE
CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, || < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM). Also shows the CMS corrected NSD multiplicity distribution (all pT, || < 2) compared with Tune Z1 at the generator.
CMS
Tune Z1
Charged Particle Multiplicity
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
Number of Charged Particles
Pro
bab
ilit
y
CMS PreliminaryTune Z1
Normalized to 1
Charged Particles (||<2.0)
7 TeV
Underlying Event"Transverse" Region
pT > 0.5 GeV/cPT(chgjet#1) > 20 GeV/c
Min-BiasNSD All pT
Amazing what we are asking the Monte-Carlo models to fit!
Charged Particle Multiplicity
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 20 40 60 80 100
Number of Charged Particles
Pro
bab
ilit
y
CMS PreliminaryTune Z1
Normalized to 1
Charged Particles (||<2.0)
7 TeV
Underlying Event"Transverse" Region
pT > 0.5 GeV/cPT(chgjet#1) > 20 GeV/c
Min-BiasNSD All pT
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 49
Strange Particle ProductionStrange Particle Production
A lot more strange mesons at large pT than predicted by the Monte-Carlo Models!
K/ ratio fairly independent of the center-of-mass energy.
ALICE preliminarystat. error only
PhojetPythia ATLAS-CSCPythia D6TPythia Perugia-0
Factor of 2!
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 50
Min-Bias SummaryMin-Bias Summary
We need a better understanding and modeling of diffraction!
We are a long way from having a Monte-Carlo model that will fit all the features of the LHC min-bias data! There are more soft particles that expected!
PARP(90)
Color
Connections
PARP(82)
Diffraction
It is difficult for the Monte-Carlo models to produce a soft event (i.e. no large hard scale) with a large multiplicity. There seems to be more “min-bias” high multiplicity soft events at 7 TeV than predicted by the models!
The models do not produce enough strange particles! I have no idea what is going on here! The Monte-Carlo models are constrained by LEP data.
LHC2010 Conference at Michigan Ann Arbor MI, December 12, 2010
Rick Field – Florida/CDF/CMS Page 51
The LHC in 2011The LHC in 2011 Beam back around 21st February.
2 weeks re-commissioning with beam (at least).
4 day technical stop every 6 weeks.
4 weeks ion run.
End of run – December 12th.
Approximately 200 days proton physics!
Maybe 8 TeV (4 TeV/beam).
Peak luminosity 6.4 x 1032
Integrated per day 11 pb-1
200 days 2.2 fb-1
Stored energy 72 MJ
Beam back around on February 21st!
This is fun!