What is going on outside of JLab ??

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What is going on outside of JLab ??
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The contemporary experiments
Beams vs200 GeV pp 50 polarization Lumi 50
pb-1
Beam 27.5 GeV e lt50gt polarization Target
(un)-polarized gas targets lt85gt
polarization Lumi pol 5x1031 cm-2/s-1 unpol
3x1032-33 cm-2/s-1 Data taking finished June 2007
Beam 160 GeV m 80 polarization Target 6LiD
50 polarization (2002-2006) NH3 80
polarisation (2007) Lumi 5x1032 cm-2s-1
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Deep Inelastic Scattering
Important kinematic variables
q
cross section
Spin 1
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World data on inclusive DIS

• New data from COMPASS,
• HERMES JLab very precise
• high x-behaviour consistent with
• A?1 with x?1
• A1d consistent with zero
• for x lt 0.05

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World data on inclusive DIS
Combine p and d to get n
or 3He

• What can we learn on the PDFs

Compass hep-ex/0609038
Hermes hep-ex/0609039
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HERMES Integrals

• Saturation in deuteron integral is assumed
• use only deuterium

From hyperon beta decay a80.5860.031
From neutron beta decay a31.2690.003

• COMPASS

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COMPASS Valence PDFs

• For LO

• Assuming

• Gv is 2.5sstat away from flavour
• symmetric sea scenario

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Polarised quark distributions
Correlation between detected hadron and struck
qf Flavor Separation
Inclusive DIS
Semi-inclusive DIS
FF
DF
In LO-QCD
Extract Dq by solving
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Measured Asymmetries
Deuterium

• new analysis with
• improved stat.
• underway

Proton
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Polarized Quark Densities

• First complete separation of
• pol. PDFs without assumption on
• sea polarization

• Du(x) gt 0

Dd(x) lt 0
good agreement with NLO-QCD
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More on Strangeness FF PDF

• Kaon multiplicities from Deuterium target
• strange quark sea in proton and neutron
  identical
• fragmentation simplifies

• Only assumptions used
• isospin symmetry between proton and neutron
• charge-conjugation invariance in fragmentation

solid S(x) Q(x) CTEQ-6L DSS
s(x) sbar(x)
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More on Strangeness FF and PDF
Inclusive Asymmetry
Kaon Asymmetry
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Unpolarized Gluon Distribution

• big Q2-x lever arm
• very accurate G(x)

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How to measure DG

• fixed target experiments
• small Q2-x lever arm
• even sign of DG unknown

• Indirect from scaling violation

Lets measure DG more directly
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The golden channels
Idea Direct measurement of DG
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The golden channels
Idea Direct measurement of DG
Isolate the photon gluon fusion process

• detection of hadronic final states with high pT
• high pT pairs of hadrons
• single high pT hadrons

• Several possible contributions to the measured
  asymmetry
• MC needed to determine R and aLL

hh vs. h
h more inclusive ? pQCD NLO calculations
(easier) possible
Important at Q2lt0.1
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Analyzed Channels

• analysed data sets
• high-pT hadron pairs (no ID, pions/kaons)
• Q2 gt 1 GeV2
  LEPTO
• Q2 lt 1 GeV2 or unmeasured PYTHIA
• high-pT single hadron
• small Q2 or unmeasured PYTHIA
• single charmed meson
• quasi-real photons AROMA,
  RAPGAP
• All analyses in LO till now (plus parton showers)

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Selection of Results
Subprocess Fractions
D0 ? K p
nD0 37398
nD 8675
D0 ? K p p0
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World Data on DG/G
Long way to go till Dg(x) ? RHIC
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DG and Dq _at_ RHIC
unpolarised cross sections nicely reproduced in
NLO pQCD
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ALL _at_ RHIC
Dg(x) small !?
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DSSV QCD-Fits to world data

• Inclusive DIS-Data

new
input to the old GRSV-analysis
input to the DIS SIDIS analysis by DNS
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DSSV QCD-Fits to world data

• Semi-inclusive DIS-Data

not in DNS
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NLO FIT to World Data
NLO _at_ Q210 GeV2
D. De Florian et al. arXiv0840.0422

• includes all world data from DIS, SIDIS and pp
• Kretzer FF favor SU(3) symmetric sea, not so for
  KKP, DSS
• DS 25-30 in all cases

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Fragmentation Functions

• Latest FF by DSS
• fit ee-, SIDIS, and pp Data
• include the first time charge dependence
• include the first time data from pp
• Isospin breaking allowed

Enormous Improvement
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The 3rd Twist-2 structure function
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The History of Single Spin Asymmetries
RHIC
RHIC
Bunce,Lambda
E704,pp to Pi
JLab
COMPASS
HERMES

BELLE
BHS
Factorization
unify
(non)Universality
Efremove-Teryav
Sivers
Jaffe-Ji
Collins
Mulders et al.
CSS
Ralston-Soper
Collins-Soper
Collins
Qiu-Sterman
BJY
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HERMES-Proton Collins moments

• Collins moment
• p gt 0 p- lt 0 p0 p p- /2

• K gt 0 K- gt 0
• K in agreement with p

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COMPASS-Deuterium Collins Results

• all asymmetries are
• very small
• du and dd
• compensate each
• other !?

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Collins-FF from Belle

• Significant non zero asymmetries
• Rising behaviour vs. z
• UL/C asymmetries about 40-50 of UL/L
  assymmetries
• First direct measurements of the Collins fct.

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Results from theoretical fits

• Results from M. Anselmino et al.

How does this fit compare to the new COMPASS
proton data
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Azimuthal angles and asymmetries
angle of hadron relative to final quark spin
(Collins)
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HERMES COMPASS Measurements

• Proton
• Sivers moment
• p gt 0 p- 0

• K gt 0 K- 0
• K gt p
• importance of sea quarks?
• Deuterium 0
• u and d quark cancel

Deuterium
Proton
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Results from theoretical fits

• Results from M. Anselmino et al.

• FF important to describe K-asym.

How does this fit compare to the new COMPASS
proton data
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Transverse Polarization Effects _at_ RHIC
p
Comparing 200 and 62.4 GeV
200 GeV
Note different scales
K
K
K- asymmetries underpredicted
200 GeV
62.4 GeV
p
p
Large antiproton asymmetry?? Unfortunately no
62.4 GeV measurement
200 GeV
62.4 GeV
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Transverse Polarization Effects _at_ RHIC
Very precise data, but still a lot of work ahead
to understand underlying processes
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GPDs Introduction
What does GPDs charaterize?
conserve nucleon helicity
flip nucleon helicity not accessible in DIS
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DVCS ASYMMETRIES
? different charges e e- (only _at_HERA!)
H
H

H
DsUT sinfImk(H - E)
H, E
kinematically suppressed
x xB/(2-xB ),k t/4M2
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DVCS
HERMES combined analysis of charge
polarization dependent data
? separation of interference term DVCS2
Beam Charge Asymmetry
higher twist
higher twist
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DVCS - BCA
Beam Charge Asymmetry
HERMES preliminary
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DVCS - BSA
Beam Spin Asymmetry
HERMES preliminary
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Hermes Charge and Beam Spin Asymmetry Heavy
Targets
Beam Charge Asymmetry
Beam Spin Asymmetry

• Why nuclear DVCS
• constrain nuclear GPDs
• constrain models attempting
• to describe nuclear matter
• neutron and proton matter
• distribution in nuclei

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First model dependent attempt to constrain Jq
observables sensitive to E (Jq input parameter
in ansatz for E)

• DVCS AUT HERMES
• nDVCS ALU Hall A

Hermes DVCS-TTSA arXiv 0802.2499
dual
VGG
Hall A nDVCS-BSA (PRL99 (2007))
x0.36 and Q21.9GeV2
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First model dependent attempt to constrain Jq
Jq input parameter in ansatz for E

• demonstrates model
• dependence of these
• analyses

• data are free to be
• re-used at any time
• with new models ?

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Exclusive p production

PLB659(2008)
GPD model for sL VGG
Regge model JML
ds/dt
LO
dsL/dt
LOpower corrections

• data support order of power corrections

• NLO corrections moderate ltlt size of power
  corrections Diehl,Kugler

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Summary

• Not covered
• fantastic unpolarized data from H1/Zeus and Fermi
• q(x) and G(x)
• DVCS and excl. VM data from H1 and Zeus
• Diffractive data
• There is an enormous amount of data out there
• Statistics has be come better and better
• FF and polarized PDF QCD fits have become
  impressive
• DS 0.3 from data and fits
• DG small
• Transversity and Sivers data compatible for
  Compass, HERMES and RHIC
• Exception Compass proton data for Sivers
• low vs data to constrain GPDs are improving

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• HERMES
• 1fb-1 proton data and 800 pb-1 on tape
• DVCS ALU with recoil and a lot of other
  exclusive observables
• unpolarized PDFs uv/dv and ubar dbar
• multiplicities binned in several dimensions
• polarized physics
• final results for Transversity and Sivers
  asymmetries
• COMPASS
• finished data taking with muon beams ? running
  pion beams now (Spectroscopy, DY, Boer Mulders
  SF)
• preparing a LOI for exclusive physics with
  COMPASS
• wait for identified hadron asymmetries for
  deuterium and proton data ALL ?Ds excess to xBj
  10-3
• nice exclusive VM statistics ?GPDs
• final results for Transversity and Sivers
  asymmetries

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• RHIC
• go to vs 500 GeV
• continue measurment for DG to small x
• can we find a way to measure GPDs at RHIC ?
  Diffraction ??
• polarised quark distributions via W-production ?
  nice cross check for DIS
• Drell Yang measurements to disentangle
  contributions to SSA
• Belle and Babar
• Belle and Babar contributions to FF
• JPARC
• 3GeV protons injected to main ring ? acceleration
  to 30GeV planned till end of 2008

A lot of exciting results ahead of us
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BACKUP SLIDES
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Unpolarised Physics with HERMES
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Fragmentation in Nuclear Medium

• Leptonic variables ? (or x) and Q2
• Hadronic variables z and pt2
• Different nuclei size and density
• Different hadrons flavors and mixing of FFs
• Double-ratio approx. evaluation of FF medium
  modification
• Systematic uncertainties are minimized in the
  double-ratio

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Multiplicity Ratio Different Hadrons
p p- p0 K ? K- p ? p-

• Clear A-dependence
• clear z and n dependence
• very small Q2 dependence

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Multiplicity Ratio vs. pt2

• In pA and AA collisions hadrons gain extra
  transverse momentum due to the multiple
  scattering of partons
• Cronin effect

• DIS shows a pt enhancement
• similar to that observed in HIC
• (SPS, RHIC non-central)
• Cronin effect without ISI
• Larger pt enhancement for
• proton vs. pion

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p/- Multiplicity Ratio 2D

• Cronin effect reduced at high z

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Pt-Broadening vs A
D?pt2? ?pt2?A - ?pt2?D D?pt2? tp Mainly
partonic scattering Incoherent ? linear in
nuclear size In later stages no
broadening elastic scattering very small
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• D?pt2? up to 0.25 GeV2
• No n dependence
• prehadron formed
• outside
• in favor of partonic
• effects
• No effect at z1
• (tp0)
• Increase with Q2
• gluon radiation
• Clear evidence for partonic effects
• Constraints on pre-hadronic effects

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News on the spin structure of the nucleon
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How to measure Quark Polarizations

• Virtual photon g can only couple to quarks of
  opposite helicity

• Select q(x) or q-(x) by changing the
  orientation of
• target nucleon spin or helicity of incident
  lepton beam

Asymmetry definition
inclusive DIS only e info used
semi-inclusive DIS eh info used
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Unpolarized Gluon Distribution

• big Q2-x lever arm
• very accurate G(x)

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NLO FIT to DIS SIDIS Data
D. De Florian et al. hep-ph/0504155
NLO _at_ Q210 GeV2

• SIDIS data improves description of all Dq,
  especially light sea
• Kretzer FF favor SU(3) symmetric sea, not so for
  KKP
• DS 30 in all cases

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HERMES Results
Subprocess Fractions
hh, h

• Channels

Subprocess Asymmetries (using GRSV std.)
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The History of Single Spin Asymmetries
RHIC
RHIC
hep-ex/9910062
Bunce,Lambda
E704,pp to Pi
JLab
COMPASS
HERMES

BELLE
BHS
Factorization
unify
(non)Universality
Efremove-Teryav
Sivers
Jaffe-Ji
Collins
Mulders et al.
CSS
Ralston-Soper
Collins-Soper
Collins
Qiu-Sterman
BJY
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Access to Lq in semi-inclusive scattering

• New structure function accessible with SSA

Side view
Front view
NOTE QCD tells us that the FSI has to be
attractive, since quark and remnants form a color
antisymmetric state

• The presence of spin can distort the
  distribution of quarks in transverse space
  (orbital angular momentum of quarks is required)

• A distortion in the distribution of quarks in
  transverse space can give rise to a nonzero
  Sivers function

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DVCS
HERMES / JLAB kinematics BH gtgt DVCS
two experimentally undistinguishable processes
First measurement Hermes in 2001
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Exclusivity _at_ HERMES
e/e- 27.5 GeV Pb55
(detected)

• missing mass (energy) technique
• ? background estimated by MC

no recoil detection
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The GPD Models
VGG Vanderhaegen, Guichon, Guidal 1999

• double distributions factorized or
  regge-inspired t-dependence

• D-term to restore full polynomiality

• skweness depending on free parameters bval bsea

• includes tw-3 (WW approx)

dual Guzey, Teckentrup 2006

• GPDs based on infinite sum of t channel
  resonances

• factorized or regge-inspired t-dependence

• tw-2 only

? call for new, more sophisticated
parameterizations of GPDs
more models on the way e.g. generalization of
Mellin transform technique
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What does theory tell
M. Burkardt, M. Diehl 2002
FT (GPD) momentum space ? impact parameter
space
polarized nucleon
u-quark
d-quark
x0
from lattice
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Space Time Evolution of Hadronization

• Parton propagation (tlttp)
• Gluon radiation (mainly energy loss)
• Partonic scattering (mainly pt broadening)
• Pre-hadron propagation (tplttlttf)
• Off shell and virtual hadrons
• Colorless qqbar
• Increasing transverse dimension interaction
  probability
• Hadronic FSI (tgttf)
• Full hadronic cross section (10-30 mbarn)
• Mainly formed after several tens of fm i.e. out
  of the nucleus

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DIS vs. HIC
h
q
E q pT / z
E q ? Ee-Ee' ? 13 GeV
E h pT ? 2 - 20 GeV
E h z ? ? 2 - 15 GeV
Hermes kinematics is relevant to Ion Ion
mid-rapidity