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What is going on outside of JLab ??

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Title: What is going on outside of JLab ??


1
What is going on outside of JLab ??
2
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
3
Deep Inelastic Scattering
Important kinematic variables
q
cross section
Spin 1
4
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

5
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
6
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

7
COMPASS Valence PDFs
  • For LO
  • Assuming
  • Gv is 2.5sstat away from flavour
  • symmetric sea scenario

8
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
9
Measured Asymmetries
Deuterium
  • new analysis with
  • improved stat.
  • underway

Proton
10
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
11
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)
12
More on Strangeness FF and PDF
Inclusive Asymmetry
Kaon Asymmetry
13
Unpolarized Gluon Distribution
  • big Q2-x lever arm
  • very accurate G(x)

14
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
15
The golden channels
Idea Direct measurement of DG
16
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
17
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)

18
Selection of Results
Subprocess Fractions
D0 ? K p
nD0 37398
nD 8675
D0 ? K p p0
19
World Data on DG/G
Long way to go till Dg(x) ? RHIC
20
DG and Dq _at_ RHIC
unpolarised cross sections nicely reproduced in
NLO pQCD
21
ALL _at_ RHIC
Dg(x) small !?
22
DSSV QCD-Fits to world data
  • Inclusive DIS-Data

new
input to the old GRSV-analysis
input to the DIS SIDIS analysis by DNS
23
DSSV QCD-Fits to world data
  • Semi-inclusive DIS-Data

not in DNS
24
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

25
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
26
The 3rd Twist-2 structure function
27
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
28
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

29
COMPASS-Deuterium Collins Results
  • all asymmetries are
  • very small
  • du and dd
  • compensate each
  • other !?

30
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.

31
Results from theoretical fits
  • Results from M. Anselmino et al.

How does this fit compare to the new COMPASS
proton data
32
Azimuthal angles and asymmetries
angle of hadron relative to final quark spin
(Collins)
33
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
34
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
35
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
35
36
Transverse Polarization Effects _at_ RHIC
Very precise data, but still a lot of work ahead
to understand underlying processes
37
GPDs Introduction
What does GPDs charaterize?
conserve nucleon helicity
flip nucleon helicity not accessible in DIS
38
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
39
DVCS
HERMES combined analysis of charge
polarization dependent data
? separation of interference term DVCS2
Beam Charge Asymmetry
higher twist
higher twist
40
DVCS - BCA
Beam Charge Asymmetry
HERMES preliminary
41
DVCS - BSA
Beam Spin Asymmetry
HERMES preliminary
42
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

43
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
44
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 ?

45
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

46
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

47
  • 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

48
  • 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
49
BACKUP SLIDES
50
Unpolarised Physics with HERMES
51
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

52
Multiplicity Ratio Different Hadrons
p p- p0 K ? K- p ? p-
  • Clear A-dependence
  • clear z and n dependence
  • very small Q2 dependence

53
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

54
p/- Multiplicity Ratio 2D
  • Cronin effect reduced at high z

55
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
56
  • 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

57
News on the spin structure of the nucleon
58
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
59
Unpolarized Gluon Distribution
  • big Q2-x lever arm
  • very accurate G(x)

60
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

61
HERMES Results
Subprocess Fractions
hh, h
  • Channels

Subprocess Asymmetries (using GRSV std.)
62
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
63
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

64
DVCS
HERMES / JLAB kinematics BH gtgt DVCS
two experimentally undistinguishable processes
First measurement Hermes in 2001
65
Exclusivity _at_ HERMES
e/e- 27.5 GeV Pb55
(detected)
  • missing mass (energy) technique
  • ? background estimated by MC

no recoil detection
66
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
67
(No Transcript)
68
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
69
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

70
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
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