How do the Quarks and Gluons spin in theProton ?

— The View from HERMES —

E.C. Aschenauer

DESY

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 1

The Spin Structure of the Nucleon

Naive Parton Model:∆uv + ∆dv = 1

=⇒ ∆uv =4

3,∆dv =

−13

BUT

1988 EMC measured:Σ = 0.123 ± 0.013 ± 0.019

=⇒ Spin Puzzle

1

2=

1

2(∆uv + ∆dv)

F2 from HERA tells:

Gluons are important !

=⇒ sea quarks ∆qs=⇒ ∆G

1

2=

1

2(∆uv + ∆dv + ∆qs

︸︷︷︸) + ∆G

∆us,∆ds,∆ū,∆d̄,∆s,∆s̄

Full description of Jq & Jgneeds

orbital angular momentum1

2=

1

2(∆uv + ∆dv + ∆qs)︸ ︷︷ ︸

+Lq + (∆G + Lg)

∆Σ

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 2

The Spin Structure of the Nucleon

Naive Parton Model:∆uv + ∆dv = 1

=⇒ ∆uv =4

3,∆dv =

−13

BUT

1988 EMC measured:Σ = 0.123 ± 0.013 ± 0.019

=⇒ Spin Puzzle

1

2=

1

2(∆uv + ∆dv)

F2 from HERA tells:

Gluons are important !

=⇒ sea quarks ∆qs=⇒ ∆G

1

2=

1

2(∆uv + ∆dv + ∆qs

︸︷︷︸) + ∆G

∆us,∆ds,∆ū,∆d̄,∆s,∆s̄

Full description of Jq & Jgneeds

orbital angular momentum1

2=

1

2(∆uv + ∆dv + ∆qs)︸ ︷︷ ︸

+Lq + (∆G + Lg)

∆Σ

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 2

The Spin Structure of the Nucleon

Naive Parton Model:∆uv + ∆dv = 1

=⇒ ∆uv =4

3,∆dv =

−13

BUT

1988 EMC measured:Σ = 0.123 ± 0.013 ± 0.019

=⇒ Spin Puzzle

1

2=

1

2(∆uv + ∆dv)

F2 from HERA tells:

Gluons are important !

=⇒ sea quarks ∆qs=⇒ ∆G

1

2=

1

2(∆uv + ∆dv + ∆qs

︸︷︷︸) + ∆G

∆us,∆ds,∆ū,∆d̄,∆s,∆s̄

Full description of Jq & Jgneeds

orbital angular momentum1

2=

1

2(∆uv + ∆dv + ∆qs)︸ ︷︷ ︸

+Lq + (∆G + Lg)

∆Σ

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 2

HERA at DESY

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 3

HERA at DESY

BeamDirection

Polarimeter

TransversePolarimeter

Spin Rotator

Spin Rotator

pe

Spin RotatorSpin Rotator

Spin Rotator

Spin Rotator

Longitudinal

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• HERA-e self-polarizing by emissionof synchrotron radiation−→ Transverse Polarization

• Longitudinal polarization at HERMESvia spin-rotators

• Online measurement of beampolarization with two Comptonback scattering polarimeters

Comparison of rise time curves

0

20

40

60

80

6 6.5 7 7.5 8Time [hours]

Pol

ariz

atio

n [%

]

Transverse Polarimeter

Longitudinal Polarimeter

Beam Polarisation < PB >∼ 55%∆PB/PB = 1.8− 3.4%

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 3

The HERMES Detector

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 4

The HERMES Detector

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−2

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LUMINOSITY

CHAMBERSDRIFT

FC 1/2

TARGETCELL

DVC

MC 1−3

HODOSCOPE H0

MONITOR

BC 1/2

BC 3/4 TRD

PROP.CHAMBERS

FIELD CLAMPS

PRESHOWER (H2)

STEEL PLATE CALORIMETER

DRIFT CHAMBERS

TRIGGER HODOSCOPE H1

0 1 2 3 4 5 6 7 8 9 10

RICH

SILICON

270 mrad

270 mrad

MUON HODOSCOPEWIDE ANGLE

FRONTMUONHODO

MAGNET

m

IRON WALL

MUON HODOSCOPES

e+

27.5 GeV

140 mrad

170 mrad

170 mrad

140 mrad

Kinematic Range: 0.02 ≤ x ≤ 0.8 at Q2 ≥ 1GeV2 and W ≥ 2GeVΘx ≤ 175 mrad, 40 mrad ≤ Θy ≤ 140 mrad

Reconstruction: δp/p 1.0 - 2.0%, δΘ ≤ 1.0mrad

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 4

The HERMES Detector

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2

−1

−2

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m

LUMINOSITY

CHAMBERSDRIFT

FC 1/2

TARGETCELL

DVC

MC 1−3

HODOSCOPE H0

MONITOR

BC 1/2

BC 3/4 TRD

PROP.CHAMBERS

FIELD CLAMPS

PRESHOWER (H2)

STEEL PLATE CALORIMETER

DRIFT CHAMBERS

TRIGGER HODOSCOPE H1

0 1 2 3 4 5 6 7 8 9 10

RICH

SILICON

270 mrad

270 mrad

MUON HODOSCOPEWIDE ANGLE

FRONTMUONHODO

MAGNET

m

IRON WALL

MUON HODOSCOPES

e+

27.5 GeV

140 mrad

170 mrad

170 mrad

140 mrad

Kinematic Range: 0.02 ≤ x ≤ 0.8 at Q2 ≥ 1GeV2 and W ≥ 2GeVΘx ≤ 175 mrad, 40 mrad ≤ Θy ≤ 140 mrad

Reconstruction: δp/p 1.0 - 2.0%, δΘ ≤ 1.0mrad

Internal Gas Target:−→He ,

−→D ,

−→H ,H↑ unpol: H2, D2, He, N2, Ne, Ar, Kr, Xe

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 4

The HERMES Detector

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0

2

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−2

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m

LUMINOSITY

CHAMBERSDRIFT

FC 1/2

TARGETCELL

DVC

MC 1−3

HODOSCOPE H0

MONITOR

BC 1/2

BC 3/4 TRD

PROP.CHAMBERS

FIELD CLAMPS

PRESHOWER (H2)

STEEL PLATE CALORIMETER

DRIFT CHAMBERS

TRIGGER HODOSCOPE H1

0 1 2 3 4 5 6 7 8 9 10

RICH

SILICON

270 mrad

270 mrad

MUON HODOSCOPEWIDE ANGLE

FRONTMUONHODO

MAGNET

m

IRON WALL

MUON HODOSCOPES

e+

27.5 GeV

140 mrad

170 mrad

170 mrad

140 mrad

Kinematic Range: 0.02 ≤ x ≤ 0.8 at Q2 ≥ 1GeV2 and W ≥ 2GeVΘx ≤ 175 mrad, 40 mrad ≤ Θy ≤ 140 mrad

Reconstruction: δp/p 1.0 - 2.0%, δΘ ≤ 1.0mrad

Internal Gas Target:−→He ,

−→D ,

−→H ,H↑ unpol: H2, D2, He, N2, Ne, Ar, Kr, Xe

Particle ID: TRD, Preshower, Calorimeter⇒ 1997: Čerenkov 1998 ⇒: RICH + Muon-ID

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 4

DIS Kinematics

Inclusive Scattering:

u

*γ

u

(E’, p’)

d

e

q

(E, p)

N

detect scattered lepton

Q2lab= 4EE′ sin2( θ2) ν

lab= E − E′

W 2lab= M2 + 2Mν − Q2

xlab= Q

2

2Mν ylab= ν

E= p·q

p·k

Q2 determines what can be resolved in theproton

Semi-Inclusive Scattering:

u

*γ

π+

u

(E’, p’)

d

e

q

π

(E, p)

p

KN

detect scattered lepton and

produced hadrons

η =log(Ehcm−p

h||)

2∗(Ehcm+ph||)

zlab= Eh

ν

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 5

DIS Kinematics

Inclusive Scattering:

u

*γ

u

(E’, p’)

d

e

q

(E, p)

N

detect scattered lepton

Q2lab= 4EE′ sin2( θ2) ν

lab= E − E′

W 2lab= M2 + 2Mν − Q2

xlab= Q

2

2Mν ylab= ν

E= p·q

p·k

Q2 determines what can be resolved in theproton

Semi-Inclusive Scattering:

u

*γ

π+

u

(E’, p’)

d

e

q

π

(E, p)

p

KN

detect scattered lepton and

produced hadrons

η =log(Ehcm−p

h||)

2∗(Ehcm+ph||)

zlab= Eh

ν

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 5

Deep Inelastic Scattering

Cross Section: d2σ

dΩdE2= α

2E′

Q2ELµν(k, q, s)︸ ︷︷ ︸

Wµν(P, q, S)︸ ︷︷ ︸

leptonic hadronic

Lµν : purely electromagnetic =⇒ calculable in QED

Wµν = −gµνF1(x,Q2

)+p

µpν

νF2

(x,Q2

)

+i�µνλσ qλν

(Sσg1

(x,Q2

)+ 1

ν(p · qSσ − S · qpσ)g2

(x,Q2

))

(for spin 1) −b1(x,Q2

)rµν +

16b2

(x,Q2

)(sµν + tµν + uµν)

+12b3

(x,Q2

)(sµν − uµν) + 12b4

(x,Q2

)(sµν − tµν)

F1,F2: Unpolarized Structure Functions=⇒ describe momentum distribution of quarks

g1,g2: Polarized Structure Functions=⇒ describe helicity distribution of quarks

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 6

Virtual Photon Asymmetry

σ3/2 ∼ q−(x)

~Sγ + ~SN = 3/2

~SN = − ~Sq

• Virtual photon γ∗ can only couple to quarks of opposite helicity

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 7

Virtual Photon Asymmetry

σ3/2 ∼ q−(x)

~Sγ + ~SN = 3/2

~SN = − ~Sq

σ1/2 ∼ q+(x)

~Sγ + ~SN = 1/2

~SN = ~Sq

• Virtual photon γ∗ 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

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 7

Virtual Photon Asymmetry

σ3/2 ∼ q−(x)

~Sγ + ~SN = 3/2

~SN = − ~Sq

σ1/2 ∼ q+(x)

~Sγ + ~SN = 1/2

~SN = ~Sq

• Virtual photon γ∗ 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

• Different targets =⇒ sensitivity to different quark flavors

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 7

Virtual Photon Asymmetry

σ3/2 ∼ q−(x)

~Sγ + ~SN = 3/2

~SN = − ~Sq

σ1/2 ∼ q+(x)

~Sγ + ~SN = 1/2

~SN = ~Sq

• Virtual photon γ∗ 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

• Different targets =⇒ sensitivity to different quark flavors

Quark Helicity Distributions:

∆qf (x) := q+f (x) − q−f (x) ( f : u,d, s,u,d, s )

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 7

F1(x) = 12∑

i e2i (q

+i (x) + q

−

i (x)) =12

∑

i e2qi(x)

momentum distribution of quarks

g1(x) = 12∑

i e2i (q

+i (x) − q−i (x)) = 12

∑

i e2∆qi(x)

helicity distribution of quarks

Virtual Photon Asymmetries:

A1 =σ 1

2−σ 3

2

σ 12+σ 3

2

= g1−γ2g2

F1A2 =

σTLσT

= γ(g1+g2)F1

Measurable Asymmetries:

A‖ =σ→⇐−σ

→⇒

σ→⇐+σ

→⇒

A⊥ =σ↑→−σ↑←σ↑→+σ↑←

A‖ = D(A1 + ηA2) A⊥ = d(A2 + ξA1)

With: D, d,R, �, γ, ξ, η being kinematic factorsE.C. Aschenauer Pan Pacific, Tokyo, July 2005 8

World data on g1/F1Proton > Deuterium

0

0.2

0.4

0.6

0.8

1

10-4

10-3

10-2

10-1

1

E 143

E 155 (Q2-averaged by HERMES)

SMC

HERMES

g1p /

F1p

x

/GeV

2

10-1

1

10

10-4

10-3

10-2

10-1

1

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

10-4

10-3

10-2

10-1

1

HERMES

E 143

E 155 (Q2-averaged by HERMES)

SMC

COMPASS

g1d /

F1d

x

/GeV

2

10-1

1

10

10-4

10-3

10-2

10-1

1

Data given at measured < Q2 >: 0.02 - 58 GeV2

A|| =1

PbPt

N→⇐L

→⇒

− N→⇒L

→⇐

N→⇐L

→⇒ + N

→⇒L

→⇐

g1

F1=

1

1 + γ2

»

A||

D+ (γ − η)A2

–

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 9

World data on xg1(x,Q2)

0

0.02

0.04

0.06

10-4

10-3

10-2

10-1

0

0.02

0.04

10-4

10-3

10-2

10-1

-0.04

-0.02

0

0.02

10-4

10-3

10-2

10-1

xg1

HERMESSMCE155E143

proton

COMPASS

deuteron

E142E154JLAB

neutron (3He)

x

gp1 > g

D1 > g

3He1

very precise proton data

most precise deuteron data

0

0.02

0.04

0.06

10-4

10-3

10-2

10-1

0

0.02

0.04

10-4

10-3

10-2

10-1

-0.04

-0.02

0

0.02

10-4

10-3

10-2

10-1

xg1

HERMESSMCE155E143

proton

COMPASS

deuteron

x

neutron (from g1p and g1

d)

gp1 > g

D1 > g

n1

very precise proton data

most precise deuteron data

most precise neutron data

gd1 =1

2(1− 3

2wD)(g

p1 + g

n1)

in measured range (0.021-0.9):∫

gp1 = 0.1246 ± 0.0032 ± 0.0074

∫

gd1 = 0.0452 ± 0.0015 ± 0.0017

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 10

World data on xg1(x,Q2)

0

0.02

0.04

0.06

10-4

10-3

10-2

10-1

0

0.02

0.04

10-4

10-3

10-2

10-1

-0.04

-0.02

0

0.02

10-4

10-3

10-2

10-1

xg1

HERMESSMCE155E143

proton

COMPASS

deuteron

E142E154JLAB

neutron (3He)

x

gp1 > g

D1 > g

3He1

very precise proton data

most precise deuteron data

0

0.02

0.04

0.06

10-4

10-3

10-2

10-1

0

0.02

0.04

10-4

10-3

10-2

10-1

-0.04

-0.02

0

0.02

10-4

10-3

10-2

10-1

xg1

HERMESSMCE155E143

proton

COMPASS

deuteron

x

neutron (from g1p and g1

d)

gp1 > g

D1 > g

n1

very precise proton data

most precise deuteron data

most precise neutron data

gd1 =1

2(1− 3

2wD)(g

p1 + g

n1)

in measured range (0.021-0.9):∫

gp1 = 0.1246 ± 0.0032 ± 0.0074

∫

gd1 = 0.0452 ± 0.0015 ± 0.0017

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 10

The structure function b1(x,Q2)

Tensor structure function:

b1 =1

2

∑

q

e2q(2q0 − (q+ + q−))

Adzz =(σ

→⇐ + σ

→⇒) − 2σ0

σ→⇐ + σ

→⇒ + σ0

= −32

b1

F1

L µν

Wµν

k

e

k’e’

γ∗ q

p

d

Θ

γ∗

z q q+ 0q

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 11

The structure function b1(x,Q2)

• First measurement of Adzz and bd1• Adzz 6= 0• Adzz ∼ 1%

• bd1 > 0 at small x• in measured range (0.002-0.85):∫

bd1 = (1.05± 0.34± 0.35) · 10−2

• Qualitative agreement withcoherent double-scatteringmodels

-0.02

-0.01

0

0.01

0.02

10-2

10-1

1x

Azzd

-0.05

0

0.05

0.1

0.15

10-2

10-1

1

b1d

10-1

1

10-2

10-1

1x

〈Q2 〉

/GeV

2

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 12

The structure function b1(x,Q2)

• First measurement of Adzz and bd1• Adzz 6= 0• Adzz ∼ 1%• bd1 > 0 at small x• in measured range (0.002-0.85):∫

bd1 = (1.05± 0.34± 0.35) · 10−2

• Qualitative agreement withcoherent double-scatteringmodels

-0.02

-0.01

0

0.01

0.02

10-2

10-1

1x

Azzd

-0.05

0

0.05

0.1

0.15

10-2

10-1

1

b1d

10-1

1

10-2

10-1

1x

〈Q2 〉

/GeV

2

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 12

Semi-inclusive DIS

String Breaking

u_

d_

π0

u_

u_

u_

ρ−

ud0

ud0

π0

π+

π0

−π

u_

u

ud

u

d

u

uu

u

p

incoming leptonscattered lepton

virtual photon

uud

target nucleon

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 13

Semi-inclusive DIS

String Breaking

u_

d_

π0

u_

u_

u_

ρ−

ud0

ud0

π0

π+

π0

−π

u_

u

ud

u

d

u

uu

u

p

incoming leptonscattered lepton

virtual photon

uud

target nucleon

Correlation between detected hadron and struck qf=⇒ ’Flavor - Separation’

Inclusive DIS:∆Σ = (∆u + ∆ū + ∆d + ∆d̄ + ∆s + ∆s̄)Semi-inclusive DIS:∆u,∆ū,∆d,∆d̄,∆s,∆s̄

In LO-QCD:

Ah1(x,Q2) =

σh1/2 − σh3/2

σh1/2 + σ

h3/2

=1 + R(x,Q2)

1 + γ2·∑

f e2f ∆qf (x,Q

2)∫

dzDhf (z,Q2)

∑

f e2f qf (x,Q

2)∫

dzDhf (z,Q2)

(∆qf ),qf (Polarized) quark distributionsDhf (z) fragmentation functions giving the probability that a (struck) quark

of flavor f fragments into a hadron of type h

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 14

∆q-Extraction• Rewrite Photon-Nucleon Asymmetry

Ah1(x)g2=0' C ·

∑

q

e2qq(x)∫

dzDhq (z)∑

q′ e2q′q′(x)

∫dzDhq′(z)

︸ ︷︷ ︸

∆q(x)

q(x)

Phq (x, z)

• Purity P hq (x, z): probability hadron h originates from an event with struckquark f; completely unpolarized quantity

• Extract ∆q by solving:

~A = P ~Q

~A= (A1,p(x),A1,d(x),Aπ±

1,p(x),Aπ±

1,d(x),AK±

1,d(x))

~Q= (∆uu

, ∆dd

, ∆ūū

, ∆d̄d̄

, ∆ss

, ∆s̄s̄

)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 15

Measured Hadron Asymmetries

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1

A1,d

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAh+

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAπ+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAK+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1,dA

h−

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

A1,dAπ−

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4x

A1,dAK−

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1

x

A1

A1,p

0

0.2

0.4

0.6

0.8

10 -1

A1,pAh+

SMC

0

0.2

0.4

0.6

0.8

10 -1

A1,pAπ+

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4

x

A1,pAh−

SMC

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4x

A1,pAπ−

Deuterium

Proton

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1

A1,d

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAh+

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAπ+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAK+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1,dA

h−

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

A1,dAπ−

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4x

A1,dAK−

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1

x

A1

A1,p

0

0.2

0.4

0.6

0.8

10 -1

A1,pAh+

SMC

0

0.2

0.4

0.6

0.8

10 -1

A1,pAπ+

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4

x

A1,pAh−

SMC

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4x

A1,pAπ−

Deuterium

Proton

• AK−1 (x) ≈ 0 !! =⇒ K− = (ūs)is an all–sea object

• statistics sufficient for5-parameter fit

Q̃ = (∆u

u,∆d

d,∆ū

ū,∆d̄

d̄,∆s

s,∆s̄

s̄= 0)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 16

Measured Hadron Asymmetries

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1

A1,d

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAh+

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAπ+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAK+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1,dA

h−

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

A1,dAπ−

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4x

A1,dAK−

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1

x

A1

A1,p

0

0.2

0.4

0.6

0.8

10 -1

A1,pAh+

SMC

0

0.2

0.4

0.6

0.8

10 -1

A1,pAπ+

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4

x

A1,pAh−

SMC

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4x

A1,pAπ−

Deuterium

Proton

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1

A1,d

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAh+

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAπ+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

A1,dAK+

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

-0.1

0

0.1

0.2

0.3

0.4

0.5A1,dA

h−

SMC

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4

x

A1,dAπ−

-0.1

0

0.1

0.2

0.3

0.4

0.5

10 -1

0.03 0.1 0.4x

A1,dAK−

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1

x

A1

A1,p

0

0.2

0.4

0.6

0.8

10 -1

A1,pAh+

SMC

0

0.2

0.4

0.6

0.8

10 -1

A1,pAπ+

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4

x

A1,pAh−

SMC

0

0.2

0.4

0.6

0.8

10 -1

0.03 0.1 0.4x

A1,pAπ−

Deuterium

Proton

• AK−1 (x) ≈ 0 !! =⇒ K− = (ūs)is an all–sea object

• statistics sufficient for5-parameter fit

Q̃ = (∆u

u,∆d

d,∆ū

ū,∆d̄

d̄,∆s

s,∆s̄

s̄= 0)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 16

Quark Polarizations0

0.5

10-1

∆u/u

-0.5

0

10-1

∆d/d

-1

0

1

10-1

∆u–/u–

-1

0

1

10-1

∆d–/d–

-1

0

1

10-1

∆s/s

0

5

10

10-1

〈Q2〉/GeV2

0.03 0.1 0.6

x

∆qf (x)

qf (x):=

q+f (x)

qf (x)− q

−f (x)

qf (x)

• ∆u(x)/u(x) > 0=⇒ polarized parallel to theproton spin

• ∆d(x)/d(x) < 0=⇒ polarized opposite tothe proton spin

• ∆ūū

∼ ∆d̄d̄

∼ ∆ss

∼ 0

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 17

Quark Polarizations0

0.5

10-1

∆u/u

-0.5

0

10-1

∆d/d

-1

0

1

10-1

∆u–/u–

-1

0

1

10-1

∆d–/d–

-1

0

1

10-1

∆s/s

0

5

10

10-1

〈Q2〉/GeV2

0.03 0.1 0.6

x

∆qf (x)

qf (x):=

q+f (x)

qf (x)− q

−f (x)

qf (x)

• ∆u(x)/u(x) > 0=⇒ polarized parallel to theproton spin

• ∆d(x)/d(x) < 0=⇒ polarized opposite tothe proton spin

• ∆ūū

∼ ∆d̄d̄

∼ ∆ss

∼ 0

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 17

Quark Polarizations0

0.5

10-1

∆u/u

-0.5

0

10-1

∆d/d

-1

0

1

10-1

∆u–/u–

-1

0

1

10-1

∆d–/d–

-1

0

1

10-1

∆s/s

0

5

10

10-1

〈Q2〉/GeV2

0.03 0.1 0.6

x

∆qf (x)

qf (x):=

q+f (x)

qf (x)− q

−f (x)

qf (x)

• ∆u(x)/u(x) > 0=⇒ polarized parallel to theproton spin

• ∆d(x)/d(x) < 0=⇒ polarized opposite tothe proton spin

• ∆ūū

∼ ∆d̄d̄

∼ ∆ss

∼ 0

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 17

Quark Polarizations0

0.5

10-1

∆u/u

-0.5

0

10-1

∆d/d

-1

0

1

10-1

∆u–/u–

-1

0

1

10-1

∆d–/d–

-1

0

1

10-1

∆s/s

0

5

10

10-1

〈Q2〉/GeV2

0.03 0.1 0.6

x

∆qf (x)

qf (x):=

q+f (x)

qf (x)− q

−f (x)

qf (x)

• ∆u(x)/u(x) > 0=⇒ polarized parallel to theproton spin

• ∆d(x)/d(x) < 0=⇒ polarized opposite tothe proton spin

• ∆ūū

∼ ∆d̄d̄

∼ ∆ss

∼ 0

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 17

Polarized Quark Densities

0

0.2

10-1

x⋅∆u

-0.2

0

10-1

x⋅∆d

-0.1

0

10-1

GRSV 2000LO val

BB 01 LOx⋅∆u

–

Q2=2.5GeV2

-0.1

0

10-1

x⋅∆d–

-0.1

0

10-1

x⋅∆s

0.03 0.1 0.6

x

∆qf (x) := q+f (x) − q−f (x)

• ∆u(x) and ∆d(x)good agreement with NLO-QCD fit

• ∆ū(x),∆d̄(x) ∼ 0

• No indication for ∆s(x) < 0• in measured range (0.023-0.6):

∫

∆ū = -0.002 ± 0.043∫

∆d̄ = -0.054 ± 0.035∫

∆s = +0.028 ± 0.034

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 18

Polarized Quark Densities

0

0.2

10-1

x⋅∆u

-0.2

0

10-1

x⋅∆d

-0.1

0

10-1

GRSV 2000LO val

BB 01 LOx⋅∆u

–

Q2=2.5GeV2

-0.1

0

10-1

x⋅∆d–

-0.1

0

10-1

x⋅∆s

0.03 0.1 0.6

x

∆qf (x) := q+f (x) − q−f (x)

• ∆u(x) and ∆d(x)good agreement with NLO-QCD fit

• ∆ū(x),∆d̄(x) ∼ 0

• No indication for ∆s(x) < 0• in measured range (0.023-0.6):

∫

∆ū = -0.002 ± 0.043∫

∆d̄ = -0.054 ± 0.035∫

∆s = +0.028 ± 0.034

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 18

Polarized Quark Densities

0

0.2

10-1

x⋅∆u

-0.2

0

10-1

x⋅∆d

-0.1

0

10-1

GRSV 2000LO val

BB 01 LOx⋅∆u

–

Q2=2.5GeV2

-0.1

0

10-1

x⋅∆d–

-0.1

0

10-1

x⋅∆s

0.03 0.1 0.6

x

∆qf (x) := q+f (x) − q−f (x)

• ∆u(x) and ∆d(x)good agreement with NLO-QCD fit

• ∆ū(x),∆d̄(x) ∼ 0

• No indication for ∆s(x) < 0• in measured range (0.023-0.6):

∫

∆ū = -0.002 ± 0.043∫

∆d̄ = -0.054 ± 0.035∫

∆s = +0.028 ± 0.034

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 18

SU(2)-Flavor Symmetry Breaking(?)

Unpolarized

0

0.5

1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Systematic Error

x

d_ -

u_

CTEQ5M CTEQ4M

MRST GRV98

HermesE866

Strong breaking of SU(2)-Flavor Symmetry

Polarized

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

10 -1

0.03 0.1 0.6

x

χQSMmeson cloud

x(∆u–-∆d

–)

Q2 = 2.5 GeV2

No significant breaking ofSU(2)-Flavor Symmetry ∆ū ∼ ∆d̄More Data needed

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 19

SU(2)-Flavor Symmetry Breaking(?)

Unpolarized

0

0.5

1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Systematic Error

x

d_ -

u_

CTEQ5M CTEQ4M

MRST GRV98

HermesE866

Strong breaking of SU(2)-Flavor Symmetry

Polarized

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

10 -1

0.03 0.1 0.6

x

χQSMmeson cloud

x(∆u–-∆d

–)

Q2 = 2.5 GeV2

No significant breaking ofSU(2)-Flavor Symmetry ∆ū ∼ ∆d̄More Data needed

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 19

How to measure ∆G• ”Indirect” from scaling violation

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Polarized case:

10-4

10-3

10-2

10-1

1

10

10 2

10 3

10 4

10-1

1 10 102

E143

Q2, GeV2

HERMES

E155

EMC

SMC

• fixed target experiments=⇒ small Q2 − xbj lever arm

• determines only sign of ∆G(x)

-0.4

-0.2

0

0.2

0.4

0.6

0.8

10-3

10-2

10-1

1x

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 20

How to measure ∆G• ”Indirect” from scaling violation

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Polarized case:

10-4

10-3

10-2

10-1

1

10

10 2

10 3

10 4

10-1

1 10 102

E143

Q2, GeV2

HERMES

E155

EMC

SMC

• fixed target experiments=⇒ small Q2 − xbj lever arm

• determines only sign of ∆G(x)

-0.4

-0.2

0

0.2

0.4

0.6

0.8

10-3

10-2

10-1

1x

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 20

How to measure ∆G• ”Indirect” from scaling violation

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Polarized case:

10-4

10-3

10-2

10-1

1

10

10 2

10 3

10 4

10-1

1 10 102

E143

Q2, GeV2

HERMES

E155

EMC

SMC

• fixed target experiments=⇒ small Q2 − xbj lever arm

• determines only sign of ∆G(x)

-0.4

-0.2

0

0.2

0.4

0.6

0.8

10-3

10-2

10-1

1x

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 20

How to measure ∆G• ”Indirect” from scaling violation

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Remember unpolarized case:HERA F2

0

1

2

3

4

5

1 10 102

103

104

105

F2 em

-log

10(x

)

Q2(GeV2)

ZEUS NLO QCD fit

H1 PDF 2000 fit

H1 94-00

H1 (prel.) 99/00

ZEUS 96/97

BCDMS

E665

NMC

x=6.32E-5 x=0.000102x=0.000161

x=0.000253

x=0.0004x=0.0005

x=0.000632x=0.0008

x=0.0013

x=0.0021

x=0.0032

x=0.005

x=0.008

x=0.013

x=0.021

x=0.032

x=0.05

x=0.08

x=0.13

x=0.18

x=0.25

x=0.4

x=0.65

=⇒ big Q2 − xbj lever arm=⇒ very accurate G(x)

0

5

10

15

20

-410 -310 -210 -110 10

5

10

15

20

x

xg

2 = 5 GeV2Q

2 = 20 GeV2Q

2 = 200 GeV2Q

0

5

10

15

20 ZEUS-JETS (prel.) 94-00

H1 PDF 2000

total uncert.

exp. uncert.

total uncert.

H1+ZEUS

Polarized case:

10-4

10-3

10-2

10-1

1

10

10 2

10 3

10 4

10-1

1 10 102

E143

Q2, GeV2

HERMES

E155

EMC

SMC

• fixed target experiments=⇒ small Q2 − xbj lever arm

• determines only sign of ∆G(x)

-0.4

-0.2

0

0.2

0.4

0.6

0.8

10-3

10-2

10-1

1x

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 20

Direct Measurements of ∆G/G

Isolate the photon-gluon fusion process (PGF)

• Select pairs of high-PT oppositely charged hadronsOR

Select single high-PT hadrons

• Reaction: γ∗p → h±1 + h∓2 + X OR γ∗p → h±1 + X

• A|| =N

→⇐h

±1h

∓2

−N→⇒h

±1h

∓2

N→⇐h

±1h

∓2

+ N→⇒h

±1h

∓2

vs. pT(h±1 ,h∓2 ); A|| =

N→⇐h

±1

− N→⇒h

±1

N→⇐h

±1

+ N→⇒h

±1

vs. pT(h±1 )

• low Q2 range (Q2 > 0 GeV2)=⇒ increase statistics=⇒ scale of hard sub-processes p̂2T

• require pT (h1,h2) > 0.5 GeV,M(2π) > 1.0 GeV =⇒ removes resonances ρ and φ

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 21

Direct Measurements of ∆G/G

Isolate the photon-gluon fusion process (PGF)

• Select pairs of high-PT oppositely charged hadronsOR

Select single high-PT hadrons

• Reaction: γ∗p → h±1 + h∓2 + X OR γ∗p → h±1 + X

• A|| =N

→⇐h

±1h

∓2

−N→⇒h

±1h

∓2

N→⇐h

±1h

∓2

+ N→⇒h

±1h

∓2

vs. pT(h±1 ,h∓2 ); A|| =

N→⇐h

±1

− N→⇒h

±1

N→⇐h

±1

+ N→⇒h

±1

vs. pT(h±1 )

• low Q2 range (Q2 > 0 GeV2)=⇒ increase statistics=⇒ scale of hard sub-processes p̂2T

• require pT (h1,h2) > 0.5 GeV,M(2π) > 1.0 GeV =⇒ removes resonances ρ and φ

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 21

Interpretation ?!

Four different processes can contribute:

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

VMDAVMD = 0 DIS

ADIS ∼∆q

q

QCDC

AQCDC ∼∆q

q

PGF

APGF ∼∆G

G

A‖ ∼4∑

i=1

fi ·Ai ∼ (fQCDCAQCDC + fPGFAPGF + fDISADIS + fXAX)

APGF ≈ 〈â(γg → qq̄)〉〈∆G

G

〉= 〈âPGF〉

︸ ︷︷ ︸

〈∆G

G

〉

-1

AQCDC ≈ 〈â(γq → qg)〉〈∆q

q

〉= 〈âQCDC〉

︸ ︷︷ ︸

〈∆q

q

〉

+ 12

.. estimate theirrelative contributions fiusing Monte Carlo (PYTHIA-6)=⇒ ∆G/G

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 22

Interpretation ?!

Four different processes can contribute:

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

VMDAVMD = 0 DIS

ADIS ∼∆q

q

QCDC

AQCDC ∼∆q

q

PGF

APGF ∼∆G

G

A‖ ∼4∑

i=1

fi ·Ai ∼ (fQCDCAQCDC + fPGFAPGF + fDISADIS + fXAX)

APGF ≈ 〈â(γg → qq̄)〉〈∆G

G

〉= 〈âPGF〉

︸ ︷︷ ︸

〈∆G

G

〉

-1

AQCDC ≈ 〈â(γq → qg)〉〈∆q

q

〉= 〈âQCDC〉

︸ ︷︷ ︸

〈∆q

q

〉

+ 12

.. estimate theirrelative contributions fiusing Monte Carlo (PYTHIA-6)=⇒ ∆G/G

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 22

Interpretation ?!

Four different processes can contribute:

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

VMDAVMD = 0 DIS

ADIS ∼∆q

q

QCDC

AQCDC ∼∆q

q

PGF

APGF ∼∆G

G

A‖ ∼4∑

i=1

fi ·Ai ∼ (fQCDCAQCDC + fPGFAPGF + fDISADIS + fXAX)

APGF ≈ 〈â(γg → qq̄)〉〈∆G

G

〉= 〈âPGF〉

︸ ︷︷ ︸

〈∆G

G

〉

-1

AQCDC ≈ 〈â(γq → qg)〉〈∆q

q

〉= 〈âQCDC〉

︸ ︷︷ ︸

〈∆q

q

〉

+ 12

.. estimate theirrelative contributions fiusing Monte Carlo (PYTHIA-6)=⇒ ∆G/G

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 22

Interpretation ?!

Four different processes can contribute:

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

VMDAVMD = 0 DIS

ADIS ∼∆q

q

QCDC

AQCDC ∼∆q

q

PGF

APGF ∼∆G

G

A‖ ∼4∑

i=1

fi ·Ai ∼ (fQCDCAQCDC + fPGFAPGF + fDISADIS + fXAX)

APGF ≈ 〈â(γg → qq̄)〉〈∆G

G

〉= 〈âPGF〉

︸ ︷︷ ︸

〈∆G

G

〉

-1

AQCDC ≈ 〈â(γq → qg)〉〈∆q

q

〉= 〈âQCDC〉

︸ ︷︷ ︸

〈∆q

q

〉

+ 12

.. estimate theirrelative contributions fiusing Monte Carlo (PYTHIA-6)=⇒ ∆G/G

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 22

Pairs of high-PT Hadrons

pTh2 (GeV/c)

f i (i

= Q

CD

C, P

GF

, VM

D)

pTh1>1.5 GeV/c

fPGFfQCDCfVMD

0

0.2

0.4

0.6

0.8

1

0.6 0.8 1 1.2 1.4 1.6 1.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.6 0.8 1 1.2 1.4 1.6 1.8 2

GSA ( ~ 0.4)GSB ( ~ 0.3)GSC ( ~ -0.1)

pTh2 (GeV/c)

A||(

pTh

1 ,p

Th2 )

pTh1>1.5 GeV/c ∆G/G=-1

∆G/G=0

∆G/G=+1

∆G/G=0.41

Published: within LO pQCD and PYTHIA5 MC model

∆G/G = 0.41 ± 0.18 (stat.) ± 0.03 (exp.syst.)at 〈xG〉 = 0.17 and 〈p̂2T 〉 = 2.1 GeV2

6 x more data on polarized Deuterium and new Pythia modified for HERMES

SMC Q2 > 1 GeV2

COMPASS Q2 < 1 GeV2

COMPASS Q2 > 1 GeV2

HERMES Q2

Pairs of high-PT Hadrons

pTh2 (GeV/c)

f i (i

= Q

CD

C, P

GF

, VM

D)

pTh1>1.5 GeV/c

fPGFfQCDCfVMD

0

0.2

0.4

0.6

0.8

1

0.6 0.8 1 1.2 1.4 1.6 1.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.6 0.8 1 1.2 1.4 1.6 1.8 2

GSA ( ~ 0.4)GSB ( ~ 0.3)GSC ( ~ -0.1)

pTh2 (GeV/c)

A||(

pTh

1 ,p

Th2 )

pTh1>1.5 GeV/c ∆G/G=-1

∆G/G=0

∆G/G=+1

∆G/G=0.41

Published: within LO pQCD and PYTHIA5 MC model

∆G/G = 0.41 ± 0.18 (stat.) ± 0.03 (exp.syst.)at 〈xG〉 = 0.17 and 〈p̂2T 〉 = 2.1 GeV2

6 x more data on polarized Deuterium and new Pythia modified for HERMES

SMC Q2 > 1 GeV2

COMPASS Q2 < 1 GeV2

COMPASS Q2 > 1 GeV2

HERMES Q2

Why is a FF extraction important for HERMES

• enter in ∆q, δq and f⊥1T extraction• test factorization at HERMES

energies√

s ∼ 7GeV• are the FF from e+e− applicable at ep

and/or〈Q2

〉= 2.5GeV

Extract π,K,p multiplicities:

1

NDIS· dN

h(z,Q2)

dz=

∑

f

e2f∫ 1

0dxqf (x,Q

2)Dhf (z,Q2)

∑

f

e2f∫ 1

0dxqf (x,Q2)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 24

Why is a FF extraction important for HERMES

• enter in ∆q, δq and f⊥1T extraction• test factorization at HERMES

energies√

s ∼ 7GeV• are the FF from e+e− applicable at ep

and/or〈Q2

〉= 2.5GeV

Extract π,K,p multiplicities:

1

NDIS· dN

h(z,Q2)

dz=

∑

f

e2f∫ 1

0dxqf (x,Q

2)Dhf (z,Q2)

∑

f

e2f∫ 1

0dxqf (x,Q2)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 24

How to extract FF/Multiplicities at HERMESunpolarisedH & D data

experimentalmultiplicitiesin acceptance

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Born level z bin (j)

Exp

erim

enta

l bin

(i)

n(i,j) for all pions

0.04

0.05

0.060.070.080.090.1

0.2

0.3

0.4

0.5

0.60.70.80.9

1

2

0 20 40 60 80 100

Q2 (GeV2/c2)

Du

π+ in

PK

H p

aram

etri

sati

on

z = 0.3

z = 0.7

LONLO

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

Q − Evolution2

acceptance correctionradiative unfolding

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 25

How to extract FF/Multiplicities at HERMES

unpolarisedH & D data

experimentalmultiplicitiesin acceptance

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Born level z bin (j)

Exp

erim

enta

l bin

(i)

n(i,j) for all pions

0.04

0.05

0.060.070.080.090.1

0.2

0.3

0.4

0.5

0.60.70.80.9

1

2

0 20 40 60 80 100

Q2 (GeV2/c2)

Du

π+ in

PK

H p

aram

etri

sati

on

z = 0.3

z = 0.7

LONLO

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

Q − Evolution2

acceptance correctionradiative unfolding

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 25

How to extract FF/Multiplicities at HERMES

unpolarisedH & D data

experimentalmultiplicitiesin acceptance

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Born level z bin (j)

Exp

erim

enta

l bin

(i)

n(i,j) for all pions

0.04

0.05

0.060.070.080.090.1

0.2

0.3

0.4

0.5

0.60.70.80.9

1

2

0 20 40 60 80 100

Q2 (GeV2/c2)

Du

π+ in

PK

H p

aram

etri

sati

on

z = 0.3

z = 0.7

LONLO

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

Q − Evolution2

acceptance correctionradiative unfolding

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 25

How to extract FF/Multiplicities at HERMES

unpolarisedH & D data

experimentalmultiplicitiesin acceptance

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Born level z bin (j)

Exp

erim

enta

l bin

(i)

n(i,j) for all pions

0.04

0.05

0.060.070.080.09

0.1

0.2

0.3

0.4

0.5

0.60.70.80.9

1

2

0 20 40 60 80 100

Q2 (GeV2/c2)

Du

π+ in

PK

H p

aram

etri

sati

on

z = 0.3

z = 0.7

LONLO

unpolarisedH & D data

e+

e−c.s. background

correction

experimentalmultiplicitiesin acceptance

born levelmultiplicities

Q − Evolution2

acceptance correctionradiative unfolding

γ

T T

e+

e+’

’

q

V

h,v

*q

h,

q

+

−

l

−

+

lt

excl. VM correction

PID using RICH

MC

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 25

Data - MC Agreement• MC: Lepto in combination with JETSET; PDF: CTEQ-6L

Fragmentation parameters tuned to HERMES multiplicities in acceptance

• Data: Q2 > 1GeV2,W2 > 10GeV2, z > 0.2,2GeV < p(π,K,p)± < 15GeVPID and background corrections as described before applied

0

0.1

0.2

0.3

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pip

0

0.1

0.2

0.3

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pim

0

0.02

0.04

0.06

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

kp

0

0.01

0.02

0.03

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

km

0

0.05

0.1

0.15

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pp

0

0.005

0.01

0.015

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pm

Exp.

2004c

2004a

F. all W2

Jetset

0

0.02

0.04

0.06

0.08

0.1

0 1 2 3

rap

Mu

ltip

licit

y

pip

0

0.02

0.04

0.06

0.08

0.1

0 1 2 3

rap

Mu

ltip

licit

y

pim

0

0.01

0.02

0.03

0.04

0 1 2 3

rap

Mu

ltip

licit

y

kp

0

0.005

0.01

0.015

0.02

0 1 2 3

rap

Mu

ltip

licit

y

km

0

0.02

0.04

0.06

0.08

0.1

0 1 2 3

rap

Mu

ltip

licit

y

pp

0

0.002

0.004

0.006

0 1 2 3

rap

Mu

ltip

licit

y

pm

Exp.

2004c

2004a

F. all W2

Jetset

Excellent agreement; also on cross section level (Data/MC < 10%)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 26

Data - MC Agreement• MC: Lepto in combination with JETSET; PDF: CTEQ-6L

Fragmentation parameters tuned to HERMES multiplicities in acceptance

• Data: Q2 > 1GeV2,W2 > 10GeV2, z > 0.2,2GeV < p(π,K,p)± < 15GeVPID and background corrections as described before applied

0

0.1

0.2

0.3

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pip

0

0.1

0.2

0.3

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pim

0

0.02

0.04

0.06

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

kp

0

0.01

0.02

0.03

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

km

0

0.05

0.1

0.15

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pp

0

0.005

0.01

0.015

0 0.25 0.5 0.75 1 1.25

pt

Mu

ltip

licit

y

pm

Exp.

2004c

2004a

F. all W2

Jetset

0

0.02

0.04

0.06

0.08

0.1

0 1 2 3

rap

Mu

ltip

licit

y

pip

0

0.02

0.04

0.06

0.08

0.1

0 1 2 3

rap

Mu

ltip

licit

y

pim

0

0.01

0.02

0.03

0.04

0 1 2 3

rap

Mu

ltip

licit

y

kp

0

0.005

0.01

0.015

0.02

0 1 2 3

rap

Mu

ltip

licit

y

km

0

0.02

0.04

0.06

0.08

0.1

0 1 2 3

rap

Mu

ltip

licit

y

pp

0

0.002

0.004

0.006

0 1 2 3

rap

Mu

ltip

licit

y

pm

Exp.

2004c

2004a

F. all W2

Jetset

Excellent agreement; also on cross section level (Data/MC < 10%)

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 26

Exclusive VM Contamination

• exclusive VM production:totally different process than SIDIS

• estimate contribution from PYTHIA-6:changes: QED-radiation, VMD-model,...

• ratio: Nhexcl.VM(z)/NhSIDIS(z)• large contribution for π at high z

contribution for K moderate vs z• contribution growing for small xbj for

both π and K

00.5

11.5

22.5

33.5

44.5

0 5 10 15

∆E (GeV)

σ (p

b)

00.20.40.60.8

11.21.41.61.8

2

0 5 10 15

∆E (GeV)

σ Dat

a/σ M

C

0

0.2

0.4

0.6

0.8

1

1.2

0.4 0.6 0.8 1

M(π+π-) (GeV)

σ (p

b)

00.20.40.60.8

11.21.41.61.8

2

0.4 0.6 0.8 1

M(π+π-) (GeV)

σ Dat

a/σ M

C

zN

h V

M(z

)/N

h(z

)

0

0.2

0.4

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.2

0.4

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

π+ Target:ProtonNeutronDeuterium

0

0.2

0.4

0.6

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.2

0.4

0.6

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

π-

0

0.025

0.05

0.075

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.025

0.05

0.075

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K+

0

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K-

xBjN

h V

M(x

Bj)/

Nh(x

Bj)

0

0.2

0.4

0.6

10 -1 1

0

0.2

0.4

0.6

10-1

1

π+ Target:ProtonNeutronDeuterium

0.25 < z < 0.350.60 < z < 0.75

0

0.2

0.4

0.6

10-1

1

0

0.2

0.4

0.6

10-1

1

π-

0

0.025

0.05

0.075

0.1

10-1

1

0

0.025

0.05

0.075

0.1

10-1

1

K+

0

0.025

0.05

0.075

0.1

10-1

10

0.025

0.05

0.075

0.1

10-1

1

K-

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 27

Exclusive VM Contamination

• exclusive VM production:totally different process than SIDIS

• estimate contribution from PYTHIA-6:changes: QED-radiation, VMD-model,...

• ratio: Nhexcl.VM(z)/NhSIDIS(z)• large contribution for π at high z

contribution for K moderate vs z

• contribution growing for small xbj forboth π and K

00.5

11.5

22.5

33.5

44.5

0 5 10 15

∆E (GeV)

σ (p

b)

00.20.40.60.8

11.21.41.61.8

2

0 5 10 15

∆E (GeV)

σ Dat

a/σ M

C

0

0.2

0.4

0.6

0.8

1

1.2

0.4 0.6 0.8 1

M(π+π-) (GeV)

σ (p

b)

00.20.40.60.8

11.21.41.61.8

2

0.4 0.6 0.8 1

M(π+π-) (GeV)

σ Dat

a/σ M

C

zN

h V

M(z

)/N

h(z

)

0

0.2

0.4

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.2

0.4

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

π+ Target:ProtonNeutronDeuterium

0

0.2

0.4

0.6

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.2

0.4

0.6

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

π-

0

0.025

0.05

0.075

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.025

0.05

0.075

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K+

0

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K-

xBj

Nh V

M(x

Bj)/

Nh(x

Bj)

0

0.2

0.4

0.6

10 -1 1

0

0.2

0.4

0.6

10-1

1

π+ Target:ProtonNeutronDeuterium

0.25 < z < 0.350.60 < z < 0.75

0

0.2

0.4

0.6

10-1

1

0

0.2

0.4

0.6

10-1

1

π-

0

0.025

0.05

0.075

0.1

10-1

1

0

0.025

0.05

0.075

0.1

10-1

1

K+

0

0.025

0.05

0.075

0.1

10-1

10

0.025

0.05

0.075

0.1

10-1

1

K-

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 27

Exclusive VM Contamination

• exclusive VM production:totally different process than SIDIS

• estimate contribution from PYTHIA-6:changes: QED-radiation, VMD-model,...

• ratio: Nhexcl.VM(z)/NhSIDIS(z)• large contribution for π at high z

contribution for K moderate vs z• contribution growing for small xbj for

both π and K

00.5

11.5

22.5

33.5

44.5

0 5 10 15

∆E (GeV)

σ (p

b)

00.20.40.60.8

11.21.41.61.8

2

0 5 10 15

∆E (GeV)

σ Dat

a/σ M

C

0

0.2

0.4

0.6

0.8

1

1.2

0.4 0.6 0.8 1

M(π+π-) (GeV)

σ (p

b)

00.20.40.60.8

11.21.41.61.8

2

0.4 0.6 0.8 1

M(π+π-) (GeV)

σ Dat

a/σ M

C

zN

h V

M(z

)/N

h(z

)

0

0.2

0.4

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.2

0.4

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

π+ Target:ProtonNeutronDeuterium

0

0.2

0.4

0.6

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.2

0.4

0.6

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

π-

0

0.025

0.05

0.075

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.025

0.05

0.075

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K+

0

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K-

xBjN

h V

M(x

Bj)/

Nh(x

Bj)

0

0.2

0.4

0.6

10 -1 1

0

0.2

0.4

0.6

10-1

1

π+ Target:ProtonNeutronDeuterium

0.25 < z < 0.350.60 < z < 0.75

0

0.2

0.4

0.6

10-1

1

0

0.2

0.4

0.6

10-1

1

π-

0

0.025

0.05

0.075

0.1

10-1

1

0

0.025

0.05

0.075

0.1

10-1

1

K+

0

0.025

0.05

0.075

0.1

10-1

10

0.025

0.05

0.075

0.1

10-1

1

K-

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 27

π± - Multiplicity vs. z

10-2

10-1

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1z

mu

ltip

licit

y

HERMES Preliminary

π+

excl. VM substractedexcl. VM included

proton target

Q2=2.5 GeV2/c210

-2

10-1

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1z

mu

ltip

licit

y

HERMES Preliminary

π-

excl. VM substractedexcl. VM included

proton target

Q2=2.5 GeV2/c2

• Systematic uncertainty mainly from hadron PID correction• Q2 > 1GeV2,W2 > 10GeV2

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 28

π± - Multiplicity vs. z

10-2

10-1

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1z

mu

ltip

licit

y

HERMES Preliminary

π+

excl. VM substractedexcl. VM includedEMC D(u→π+) FF

proton target

Q2=25.0 GeV2/c2

10-3

10-2

10-1

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1z

mu

ltip

licit

y

HERMES Preliminary

π-

excl. VM substractedexcl. VM includedEMC D(u→π-) FF

proton target

Q2=25.0 GeV2/c2

• Comparison with EMC, Nucl. Phys. B321 (1989) 541

• EMC: Fragmentation Function Dπ±u

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 29

π± - Multiplicity vs. Q2 and xbj

10-1

1

1 10 Q2

(d2 N

π /d

z d

Q2 )

/ (d

Nd

is/d

Q2 )

: 0.25 < z < 0.35: 0.35 < z < 0.45

: 0.45 < z < 0.60: 0.60 < z < 0.75

HERMES Preliminary

π+/-

excl. VM substractedexcl. VM included

Kretzer FF

proton target

10-1

1

10

10-1

1xbj(d

2 (N

π++N

π-)

/dz

dx)

/ (d

Nd

is/d

x)

: 0.25 < z < 0.35: 0.35 < z < 0.45

: 0.45 < z < 0.60: 0.60 < z < 0.75

HERMES 2000 Preliminary

π

excl. VM substractedexcl. VM includedEMC (charged had.)

proton target

Q2 = 2.5 GeV2/c2

• Reasonable agreement with results using S. Kretzter FF• very weak xbj dependence

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 30

K± - Multiplicity vs. z

10-2

10-1

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1z

mu

ltip

licit

y

HERMES Preliminary

K+

excl. VM substractedexcl. VM included

proton target

Q2=2.5 GeV2/c2

10-3

10-2

10-1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1z

mu

ltip

licit

y

HERMES Preliminary

K-

excl. VM substractedexcl. VM included

proton target

Q2=2.5 GeV2/c2

• charge separated Kaon multiplicities• Systematic uncertainty mainly from hadron PID correction• low K− statistics =⇒ more statistics under way

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 31

and Summary

• HERMES continues happily taking data with a transverse polarized p-target

Integrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

and Summary

• HERMES continues happily taking data with a transverse polarized p-targetIntegrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

and Summary

• HERMES continues happily taking data with a transverse polarized p-target

Integrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

and Summary

• HERMES continues happily taking data with a transverse polarized p-target

Integrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

and Summary

• HERMES continues happily taking data with a transverse polarized p-target

Integrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

and Summary

• HERMES continues happily taking data with a transverse polarized p-target

Integrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

and Summary

• HERMES continues happily taking data with a transverse polarized p-target

Integrated DIS HERA Run II (polarized)

0

500

1000

1500

2000

2500

3000

x 10 3

0 50 100 150 200 250 300Day of Running

Nu

mb

er o

f p

ol.

DIS

eve

nts

2002/03

2003

2004

2005

• Transversity, Sivers and friends =⇒ G. Schnell• Exclusive reactions =⇒ Lq

DVCS: AUT =⇒ sensitive to GPD H + E =⇒ Ju =⇒ Y. Miyachiexclusive ρ0 / π+: AUT =⇒ sensitive to GPD E / H̃+ Ẽ =⇒ A. Rostomyan

• finalize most of HERA-I analysis• gd1 ,gp1 ,gn1 ,b1,∆q

• Extraction of FF very close• new Millennium extraction of ∆q (Purity free)• new ∆s + ∆s̄ extraction using isoscalor method

• the nice description of HERMES data by Monte Carlo will allowa new extraction of ∆G/G

Many more results to come from physics topics not touched in this talk

E.C. Aschenauer Pan Pacific, Tokyo, July 2005 32

The Spin Structure of the NucleonHERA at DESYThe HERMES DetectorDIS KinematicsDeep Inelastic Scattering Virtual Photon AsymmetryWorld data on $mathbf {g_1/F_1}$World data on $mathbf {xg_1(x,Q^2)}$The structure function $mathbf {b_1(x,Q^2)}$The structure function $mathbf {b_1(x,Q^2)}$Semi-inclusive DISSemi-inclusive DIS$Delta $q-ExtractionMeasured Hadron AsymmetriesQuark PolarizationsPolarized Quark DensitiesSU(2)-FlavorSymmetry Breaking(?)How to measure $Delta G$Direct Measurements of $displaystyle mathbf {Delta G/G}$ Interpretation ?!Pairs of high-$P_T$ HadronsWhy is a FF extraction important for HERMESHow to extract FF/Multiplicities at HERMESData - MC AgreementExclusive VM Contamination$displaystyle mathbf {pi ^{pm }}$ - Multiplicity vs. z$ displaystyle mathbf {pi ^{pm }}$ - Multiplicity vs. z$displaystyle mathbf {pi ^{pm }}$ - Multiplicity vs. $displaystyle mathbf {Q^2}$ and $displaystyle mathbf {x_{bj}}$ $ displaystyle mathbf {K^{pm }}$ - Multiplicity vs. zand Summary