Collider overview and kinematicsweb.mit.edu/8.712/www/Lecture/lecture1.pdfParticle identification 12...
Transcript of Collider overview and kinematicsweb.mit.edu/8.712/www/Lecture/lecture1.pdfParticle identification 12...
Bernd Surrow
8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010 Bernd Surrow
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Collider overview and kinematics
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
QCD studies at colliders
PEP,PETRA,Cornell,LEP,SLD,NLC
SLAC,FNAL,CERN,HERA,eRHIC
FNAL,CERN,Tevatron,RHIC,RHICII,LHC
Short Long
distance
Q: large momentum scale
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ee - ep - pp QCD collider studies
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
e+e- QCD collider programExperimental QCD tests in e+e-
Measurement of αs
Fragmentation functions
Color/spin dynamics
Quark-Gluon jet properties
Event shape variables (Sphericity, thrust, …)
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Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
LEP at CERN, Geneva
LEP: Centre-of-mass energy (e+e-) up to 205GeV
Circumference: 27km
e+e- QCD collider program4
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
LEP at CERN, GenevaLuminosity
LEP
10 weeks
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e+e- QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
e+e- collisions: Here OPAL at LEP
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e+e- QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Experimental QCD tests in ep
Measurement of αs
Fragmentation functions
Extraction of parton distribution
functions
Color/spin dynamics
Quark-Gluon jet properties
Event shape variables (Sphericity,
thrust, …)
Diffraction
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
ep kinematics (1)
Four vectors:
Neutral current exchange (NC):
Charged current exchange (CC):
Measurement of structure functions:
• NC: Scattered electron and/or hadronic final state
• CC: Hadronic final state (neutrino escapes detection)
Determine kinematics!
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Kinematic variables
fraction of the proton momentum carried by the charged parton
fraction of the electronenergy carried by the virtual photon(ʺ″inelasticityʺ″)
(mass)2 of γ* p system
center of mass energyof ep system
(momentum transfer)2
virtuality of γ*, Z0, W±
⇒ (ʺ″sizeʺ″ of the probe)-1
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Ee = 27.5 GeV Ep = 920 GeV
Equivalent to fixed target of Ee = 50600 GeV:
Collider experiment: Electron-Proton collisions at HERA (DESY, Hamburg, Germany)
Circumference: 6.3km
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Collider experiment: Electron-Proton collisions at HERA (DESY, Hamburg, Germany)
Luminosity:
HERA
10 weeks
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
ep collisions: Here ZEUS at HERA
Onion-shell structure of various detector systems around the collision point:
Energy measurementMomentum measurementParticle identification
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
2. Determination of cross-section and extraction of F2:
Efficiency Luminosity
Number of selected
events Background
bin inx and Q2
1. Determination of kinematics (e.g. electron method):
Structure function measurement: Kinematic coverage and measurement
ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Electron method: scattered electron
Jacquet-Blondel method: hadronic final state
Reconstruction of event kinematics
ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Electron method: scattered electron
Jacquet-Blondel method: hadronic final state
Resolution of event kinematics
ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Reconstruction of F2
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Reconstruction of F2
Correct for FL to get F2!Requires unfolding!
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ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Lines of constant electron energy (E’e)
Lines of constant electron angle (ϑ’e)
Lines of constant hadron energy (F)
Lines of constant hadron angle (γ)
Event kinematics (10GeV electron on 250GeV proton)
ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
• Low-x-low Q2: Electron and current jet (low energy) predominantly in rear direction
• High-x-low Q2: Electron in rear and current jet (High energy) in forward direction
• High-x-high Q2: Electron predominantly in barrel/forward direction (High energy) and current jet in forward direction (High energy)
barrel
forward rear
Event topology (10GeV electron on 250GeV proton)
ep QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Experimental QCD tests in pp
Measurement of αs
Fragmentation functions
Extraction of parton
distributionfunctions
Color/spin dynamics
Quark-Gluon jet properties
Event shape variables (Sphericity,
thrust, …)
Diffraction
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
pp kinematics (1)
Two incoming hadron beams:
Spectrum of longitudinal momenta determined by parton distribution functions
Centre-of-mass of parton-parton system is boosted with respect to two incoming hadrons, i.e. x1 ≠ x2
Therefore: Classify final state using variables that transform simply under longitudinal boosts:
Rapidity: y
Transverse momentum: pT
Azimuthal angle: φ
Four-vector formulation:
f1
f2
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
pp kinematics (2)
Property of rapidity:Additive under the restricted class of Lorentz transformations corresponding to a boost along the z direction.
Therefore: Rapidity differences (Δy) are boost invariant!
Pseudorapidity: y for m → 0
Transverse energy: Measured quantity in a calorimeter system, rather than pT!
Jet definition: Cone jet finder
Concentration of transverse energy ET in a cone of radius R:
Invariant under longitudinal boost!
In the two-dimensional plane, curves of constant R are circles around the jet axis!
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
pp kinematics (3)
Partonic centre-of-mass energy:
Bjorken x1 and x2 and rapidity y:
Partonic centre-of-mass angle!
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
LHC at CERN, Geneva (1)
LHC: Centre-of-mass energy (pp): 14000GeV = 14TeV
Circumference: 27km
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
LHC at CERN, Geneva (2)
LHC: Centre-of-mass energy (pp): 14000GeV = 14TeV
Circumference: 27km
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
LHC at CERN, Geneva (3)
Luminosity
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pp QCD collider program
ICHEP2010 status
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
World’s Highest Energy proton-anti-proton collider - Tevatron (1)
Centre-of-Mass Energy: Ecm=1.96 TeV
Circumference: 6.85km
Tevatron p
p CDF DØ
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
World’s Highest Energy proton-anti-proton collider - Tevatron (2)
CME: √s = 1.96 TeV (Run I 1.8 TeV)
Peak luminosity is now ~ 1032 cm-2 s-1
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pp QCD collider program
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Summary29
Collider comparison
Bernd Surrow8.712 - Advanced Topics in Nuclear PhysicsCambridge, MA, September 15, 2010
Summary30
Collider overview
Particle data group:
http://pdg.lbl.gov/2010/reviews/rpp2010-rev-hep-collider-params.pdf
M. Tigner, Physics Today, January 2001