Lepton-Hadron and Hadron-Hadron Scattering
CIPANP Summary of SessionCrack of Dawn, May 24, 2003
Volker BurkertAbhay Deshpande
Kevin McFarland
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
covered
lsewhere
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Factory for, e.g.,"high mass states"quark-gluon plasma"exotic hadrons
! Precision studies at high rate facilities"“Medium-energy”
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
e
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Precision studies at high rate facilities"“Medium-energy”
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
hadron structureHard QCD
S. Boyd ν DIS and charm production (NuTeV)P. Reimer Drell-Yan Cross Section in pp and pdR. Yoshida HERA II Weak SF MeasurementsC. Mesropian Hard QCD at the TeVatronM. Tuts W/Z Production at the TeVatron
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Hadron Structure: Particle Motivation
But how much glue is at high x?
!Searches for new physics relies on understanding how to produce it!
-25
0
25
50
75
100
125
150
% D
iffe
renc
e fr
om N
LO
QC
D w
ith
MR
SD0/
CDFMRSA/
CTEQ 2MCTEQ 2ML
10-6
10-4
10-2
1
10 2
10 4
10 5
0 100 200 300 400
CDFNLO QCD
1/∆
η ∫ d
2 σ/(
dETdη
) dη
nb/G
eVGeV-50
-25
0
25
50
75
100
125
150
% D
iffe
renc
e fr
om N
LO
QC
D w
ith
MR
SD0/
CDFMRSA/
MRSG
CTEQ 2MCTEQ 2MLGRV-94
0
20
0 50 100 150 200 250 300 350 400 450
Systematic uncertainties
10-6
10-4
10-2
1
10 2
10 4
10 5
0 100 200 300 400
CDFNLO QCD
1/∆
η ∫ d
2 σ/(
dETdη
) dη
nb/G
eV
GeV
! E.g., “Rutherford” at TeVatron (Liss)
GeV-50 MRSG GRV-94
0
20
0 50 100 150 200 250 300 350 400 450
Systematic uncertainties
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Charm production
D. Mason (U. Oregon)
•A charm quark can be produced when a neutrino scatters off a s(d) quark in the nucleon.
•Independent probe of strange and anti-strange seas if different.
(Boyd)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Drell-Yan µ+µ- Production and PDF’s
• Possibly related to d/u ratio as x→1, but requires full PDF fit.
• Working with CTEQ to incorporate data in global fit.
• Radiative corrections under study.
(Reimer)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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HERA I high-x measurementsare statistics limited
HERA II Physics Summary
HERA II projection
1 fb-1 of data # high statistics at high Q2 and Et.
Access to high-x partons at high Q2. Jets at high Et and Q2
#pQCD studies (PDF’s, jet cross-sections) at higher scales.Further improve understanding of QCD.
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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QCD at TeVatron(Mesropian, Tuts)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Precision studies at high rate facilities"“Medium-energy”
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
hadron structure…beyond inclusive DISWG1/WG8 – Generalized Parton Distributions
A. Belitsky - GPD OverviewH. Avakian - Single Spin Asymmetries with CLASJ. Volmer - DVCS at HERMES/DESYE. Smith - DVCS with CLAS/Jefferson Lab
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Generalized Parton Distributions
!What is a GPD?
Quark longitudinalmomentum & helicitydistributions
Proton form factors,transverse charge & current distributions
GPDs connect form factorsand parton distribution
(Belitsky)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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GPDs Contain Much More Information than DIS
Quark distribution q(x)
qq distribution
Antiquark distribution q(x)DIS only measures a cut at ξ=0
Ji’s Spin Sum Rule
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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GPDs accessible in Deeply Virtual Exclusive & Semi-Inclusive Processes
Q2 = 2. - 2.5 GeV2x = 0.25 - 0.325
φ
γx+ξ x-ξ
t
CLAS@JLabDVCS on protons
HERMES@DESY DVCS on nuclei
DVCS
Azimuthal dependencedue to DVCS/BH inter-ference
DVCS
BH
(Volmer, Smith)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Single Spin Asymmetry for ep eπ+XFor factorizable processes, single-spin asymmetries are sensitive to various GPDs inaccesible in inclusive DIS.
qqLq
qqLUL HxheS
⊥⊥−
Σ∝ 1)1(
12
,
2sin )(φσ
)()( 12
,
sin zHxxheQMS qLq
qqLUL
⊥−
Σ∝φσ
)()( 112
,
sin zDxfeS qqTqqq
TUT⊥
−Σ∝φσ
)()( 112
,
sin zHxheS qqqq
TUT⊥
−Σ∝φσ
CLAS/JLab
CLAS/JLab
sin2φ moment is a cleansource of Collins SSA
φ
xB
(Avakian)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Factory for, e.g.,"high mass states"quark-gluon plasma"exotic hadrons
! Precision studies at high rate facilities"“Medium-energy”
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
soft processesDiffractive QCD
K. Goulianos Diffraction at the TeVatronI. Gialas Diffraction at HERAW. Lorenzon Exclusive rho Production at HERMES
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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! Common fit at fixed lc yields positive slope of Q2-dependence ofnuclear transparency in nitrogen HERMES collab., PRL 90, 052501 (Feb 2003)⇒ signature of Color Transparency B.Z. Kopeliovich et al., PR C65, 035201 (2002)
0.0600.048
0.070 ± 0.021 ± 0.0120.089 ± 0.046 ± 0.008
coherentincoherent
PredictionMeasured Q2 slopeData sample
(Lorenzon)
Nuclear Transparency in Exclusive ρ0 Production at HERMES
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Run II Diffraction at the Tevatron
ROMANPOTS
CDF
TOROID
MINIPLUG
z 56.40 m 31.63 m 23.23 m 6.59 m 0
BSC-4 BSC-3 BSC-2 BSC-1
QUADSDIPOLES
A - 4 8
ESS
ELE
CT
RO
ST
AT
ICS
EP
AR
AT
OR
$ MiniPlug calorimeters (3.5
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Run II Dijets in Single Diffraction (CDF)
Agreement with Run INo Q2 dependence
R=(SD/∆ξ)/ND
ND+SD & SD+MBoverlap events
ξ ~ 1SD
events0.03
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Run II: Exclusive DPE Dijets ?
No exclusive dijetbump observed
Generous upper limiton exclusive dijets
(Goulianos)
e
pIPIP
p
η
φ
Double PomeronExchange (DPE)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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(Pitzl)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Precision studies at high rate facilities"“Medium-energy”
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
dynamics and phenomenaC. Keppel Quark-Hadron Duality
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Quark-Hadron Duality(Keppel)
! Duality between quark and hadron descriptions" reflects relationship between confinement and asymptotic
freedom" intimately related to nature and transition from non-
perturbative to perturbative QCD
24 May 2003
CIPANP WG1 Summary: Burkert, Deshpande,
McFarland23
Duality now observed in all unpolarizedstructure functions
2xF1 FL
(Keppel)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Precision studies at high rate facilities"“Medium-energy” lepton
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
understanding of σLHFuture neutrino beams“Medium enegy” leptonfacilities
A. Bodek Modeling Electron and NeutrinoCross-Sections at a few GeV
H. Gallagher Neutrino Cross-Section Generators
CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Neutrino cross sections at low energy(Bodek)
% Quasi-Elastic / Elastic (W=Mn)– νµ + n µ- + p & Input from both Electron and
Neutrino Experiments and and described by form factors
% Resonance (low Q2, W< 2)νµ + p µ- + p + π
& Can be well measured in electonscattering but poorly measured in neutrino scattering (fits by Rein
and Seghal
% Deep Inelastic– νµ + p µ- + X& well measured in high energy
experiments and well described by quark-parton model (pQCD with NLO PDFs, but doesn’t work well at low Q2).
' Resonance scattering and low Q2 DIS contribution meet, (difficult to avoid double counting problem ).
& Challenge: to describe all these three processes at all neutrino (or electron) energies.
Issues at few GeV
Generator Physics Overview(Gallagher)
NuTeVMINOS Contained Atmos ν
Eν(GeV)101 102100
PhysicsProcess:
Primarily Quasi-Elastic
QEL, RES,DIS
Predominantly deepinelastic scattering (DIS)
Target: Single Nucleon ? ‘free’ quarks
Good: quark parton modelperturbative QCD
Good: free nucleon ?Theory:Nuclear Physics..
Data: Low Eν bubblechamber data: ANL,
BNL, Gargamelle
Bubble Chamber:BNL, ITEP, BEBC
Good: High StatisticsCCFR,NuTeV, CHARM...
CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Fit with ξwPredictions modified GRV98 PDFs
(Bodek)
from Bodekand Yang, a
unified description of all this data!
Photo-production (P)F2(P) resonance
Neutrino Xsection on iron at 55GeV (CCFR)
PWIA and Quasi-Free Kinematics
Nuance
Yie
ld
0.6 GeV^2
1.3 GeV^2
Data on A(e,e’p) also gives information about the modeling of final state interactions.
Proton yield relative to q.
(Gallagher)
Steve Wood: compare ν MC to electron data
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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A Fruitful Collaboration…
!NuInt workshop series"driven by need to understand GeV cross-
sections at K2K, Mini-BooNE!JLab E03-110 (Bodek, Keppel) proposed to
study resonances in nuclei (ν detectors)!High rate ν experiments at FNAL?
"FINESSE (Booster, ~1 GeV): ∆s, exclusive σ"MINERνA (MINOS beam, few GeV): exclusive σ,
DIS regime, nuclear targets…
HEP/NP
collaborations!
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Purposes of & Prospects for LH-HHS
! Studies of QCD"hadron structure"soft processes"dynamics & phenomena
! Neutrino detection"understanding of σLH
! Precision studies at high rate facilities"“Medium-energy”
facilities, e.g., CEBAF"Future neutrino beams:
NUMI, J-PARC
! Future e-A colliders"ELIC, eRHIC, HERA 3
Future e-A collidersWG1/WG10 - Physics at eRHIC, ELIC, HERAIII
R. Ent Physics with ELIC at JLabR. Milner Physics with eRHIC at BNLD. Pitzl HERA III PhysicsS. Chattopadhyay JLab Overview
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Scientific Highlights for Electron-Ion Colliders
! nucleon structuresea quarks and gluespin and flavor structurenew parton distributions
! Meson structureπ, K are Goldstone Bosons of QCDessential to nuclear binding
! hadronizationevolution of parton into hadronprocess in nuclei of fundamental interest
! nucleirole of partonsinitial conditions for relativistic heavy ion collisions
! matter under extreme conditionssaturation of parton distributionsnew phenomena, e.g. colored glass condensate
(Milner)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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ELIC Layout One accelerating & one decelerating pass through CEBAFIon Source
IR
IR
Beam Dump
Snake
Snake
CEBAF with Energy Recovery
5 GeV electrons 50-100 GeV light ions
Solenoid
Injector
ECM up to 45 GeV
(Ent, Chattopadhyay)
25 GeV Fixed Targetis an option
Complementarity of 25-GeVfixed-target and ELIC for this
example! # Glue at low Q2
1
10
10 2
10-3
10-2
10-1
1xBj
Q2
(GeV
2 )
ELIC
W2 > 4 GeV2
W2 > 1.2 GeV2>>
Luminosity of up to 1035 cm-2 sec-1
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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eRHIC collider layout ! e-ring is 5/16 of RHIC ring ! Collisions at one IP! 28 MHz collision rate! Unpolarized electron source! Electron beam polarization by
the synchrotron radiation! e-ring lattice based on
”superbend” magnets
p
e 2GeV (5GeV)
2-10 GeVIP12
RHICp 50-250 GeVAu 100 Gev/u
ep -> eX
Kinematic Range
10 x
250
GeV
12 G
eV
Fixe
d Ta
rget
0.0001 0.001 0.01 0.1 1.0
x
110
100
1000
10000
Q^2
(Milner)
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Parameters for Electron-Ion Colliders
e- /e+?e+/e-e+/e-Leptons
103510331031L, cm-2/sec-1
P, d, 3He (pol)others need study
P, 3He, (pol.) others up to U
p,d, .. CaHadrons
10-410-510-6Xmin
25 - 6520 - 100~ 320Sqrt(s) , GeV
~104~105~106Q2maxep (GeV2)
3 - 72 - 1027Ee , GeV
30 - 15030 - 250920Ep , GeV
ELICLinac x Ring
eRHICRing x Ring
HERA IIIRing x Ring
Machine #Parameters
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Other topics covered in WG1
D. Goldin Determination of scattering lengths of the p-p atomsin the DIRAC experiment
E. Kinney Measurement of quark hadronization in the nuclear environment
R. Muto Measurement of invariant mass spectra of vector mesondecay in nuclear matter at KEK-PS
B. Fox Neutral pion production in pp collisions (K. Okada) at sqrt(s) = 200GeV at RHIC
M. Islam pp elastic scattering at LHC and nucleon structure
24 May 2003 CIPANP WG1 Summary: Burkert, Deshpande, McFarland
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Conclusions
!Lepton-Hadron and Hadron-Hadronexperiments still tell us much about QCD"Active and broad programs at both particle and
nuclear physics facilities!New facilities for the future
"JLab upgrade"FNAL and JPARC neutrino beams"Electron-Ion program
Lepton-Hadron and Hadron-Hadron ScatteringPurposes of & Prospects for LH-HHSPurposes of & Prospects for LH-HHSHadron Structure: Particle MotivationDrell-Yan m+m- Production and PDF’sQCD at TeVatronPurposes of & Prospects for LH-HHSGeneralized Parton DistributionsPurposes of & Prospects for LH-HHSRun II Dijets in Single Diffraction (CDF)Run II: Exclusive DPE Dijets ?Purposes of & Prospects for LH-HHSDuality now observed in all unpolarized structure functionsPurposes of & Prospects for LH-HHSNeutrino cross sections at low energyGenerator Physics OverviewPWIA and Quasi-Free KinematicsA Fruitful Collaboration…Purposes of & Prospects for LH-HHSScientific Highlights for Electron-Ion CollidersConclusions