the spin of the proton___pasquale di nezza_____spin physics at hermes_____ hadronic tensor w µν...
TRANSCRIPT
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The Spin of The Spin of the Protonthe Proton
Pasquale Di NezzaDESY, Hamburg 18/08/05
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HERHERaa MEMEasurementasurement ofof SSpinpin
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza _________________________________________________________Spin Physics at HERMES________
Collaboration of 180 phys., 33 Inst., 12 Countries
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HERHERaa MEMEasurementasurement ofof SSpinpin
Collaboration of 180 phys., 33 Inst., 12 Countries
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza _________________________________________________________Spin Physics at HERMES________
• Introduction to polarised DIS
• Prerequisites
• Polarisedstructure functions
• The Spin of the Nucleon
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fascinatedfascinated by spin …by spin …“You think you understand something? Now add spin…” -- R. Jaffe
W. Pauli
N. Bohr
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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fascinatedfascinated by spin … an analogyby spin … an analogy
Speaking in this analogy our planet has an orbital angular momentum (around the sun / the nucleus) and in addition a spin angular momentum (around its own axis).
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fascinatedfascinated by spin … an analogyby spin … an analogy
Speaking in this analogy our planet has an orbital angular momentum (around the sun / the nucleus) and in addition a spin angular momentum (around its own axis).
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What is Spin ?What is Spin ?[www.markusehrenfried.de/science/physics/whatisspin.html]
• Stern-Gerlach (1921):
• Uhlenbeck, Goudsmit:(1925)explanation of atomic spectra
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
quantum number: ms=1/2
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What is Spin ?What is Spin ?[www.markusehrenfried.de/science/physics/whatisspin.html]
• Stern-Gerlach (1921):
• Uhlenbeck, Goudsmit:(1925)explanation of atomic spectra
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
quantum number: ms=1/2
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What is Spin ?What is Spin ?
Spin and Symmetry: [S.Hawkins: A brief history of time]
180ο 360ο
spin: ?21
2x360ο
math:antisymmetricwave function
spin: 2 spin: 1
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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is spin important ?is spin important ?
half integer SPIN
obey Pauli principle
antisymmetric under exchange
of identical particles
Fermi-Dirac statistics:Fermions MATTER
Pauli principle …
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
integer SPINdon’t care for Pauli principle
symmetric
Bose-Einstein statistics:Bosons
FORCES
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is spin important ?is spin important ?
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
half integer SPIN
obey Pauli principle
antisymmetric under exchange
of identical particles
Fermi-Dirac statistics:Fermions MATTER
integer SPINdon’t care for Pauli principle
symmetric
Bose-Einstein statistics:Bosons
FORCES
Pauli principle …
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how to study the proton spin ?how to study the proton spin ?
… deep-inelastic scattering (DIS)
)cos(12EE'qQlab
22 θ-=−=
,2MνQx
2lab= E'Eν
lab−=
22 MQ >>↔• “deep” high resolution:1MM 22X
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µνW hadronic part of the xsectioncontains info on proton structure+ strong interaction effects
DIS cross sectionDIS cross section
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
µνL leptonic part of the xsectionindependent of proton structurecan be calculated explicitely
)Xepe( →σ
µνµν'4
2
'
2
WLEE
MQα
dEdd
=Ω
σ
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hadronichadronic tensortensor µνWparametrised by structure functions(Lorentz symmetry, current conservation, parity, ecc.)
)Q(x,Fνpp)Q(x,FW 22νµ
21
µνµν +−= g
( ) ⎟⎠⎞
⎜⎝⎛ ⋅−⋅++ )Q(x,gqpSqSp
ν1)Q(x,gS
νqiε 22σσ
21σ
λµνλσ
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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hadronichadronic tensortensor µνWparametrised by structure functions(Lorentz symmetry, current conservation, parity, ecc.)
)Q(x,Fνpp)Q(x,FW 22νµ
21
µνµν +−= g
( ) ⎟⎠⎞
⎜⎝⎛ ⋅−⋅++ )Q(x,gqpSqSp
ν1)Q(x,gS
νqiε 22σσ
21σ
λµνλσ
momentum distribution of quarks
( )∑ ∑=+= −+i i iiii xqexqxqexF )(21)()(
21)( 221
QPM:
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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hadronichadronic tensortensor µνWparametrised by structure functions(Lorentz symmetry, current conservation, parity, ecc.)
)Q(x,Fνpp)Q(x,FW 22νµ
21
µνµν +−= g
( ) ⎟⎠⎞
⎜⎝⎛ ⋅−⋅++ )Q(x,gqpSqSp
ν1)Q(x,gS
νqiε 22σσ
21σ
λµνλσ
momentum distribution of quarks
( )∑ ∑=+= −+i i iiii xqexqxqexF )(21)()(
21)( 221
QPM:
qi(x) = Distribution Functionconnected to the probability to have a struck quark with fractional momentum x
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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hadronichadronic tensortensor µνWparametrised by structure functions(Lorentz symmetry, current conservation, parity, ecc.)
)Q(x,Fνpp)Q(x,FW 22νµ
21
µνµν +−= g
( ) ⎟⎠⎞
⎜⎝⎛ ⋅−⋅++ )Q(x,gqpSqSp
ν1)Q(x,gS
νqiε 22σσ
21σ
λµνλσ
momentum distribution of quarks
( )∑ ∑=+= −+i i iiii xqexqxqexF )(21)()(
21)( 221
QPM:
q+i(x) = Polarized Distribution Functionconnected to the probability to have a struck quark with fractional momentum x and spin in the same direction of the proton
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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hadronichadronic tensortensor µνWparametrised by structure functions(Lorentz symmetry, current conservation, parity, ecc.)
)Q(x,Fνpp)Q(x,FW 22νµ
21
µνµν +−= g
( ) ⎟⎠⎞
⎜⎝⎛ ⋅−⋅++ )Q(x,gqpSqSp
ν1)Q(x,gS
νqiε 22σσ
21σ
λµνλσ
helicity distribution of quarks
( )∑ ∑=−= −+i i i2ii2i1 (x)∆qe21(x)q(x)qe
21(x)g
momentum distribution of quarks
( )∑ ∑=+= −+i i iiii xqexqxqexF )(21)()(
21)( 221
QPM:
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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helicityhelicity densitiesdensities ∆∆qq
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
because of helicity conservation, the virtual photon can couple only to a quark of opposite helicity
23SS Nγ =+
)(2/3 xq−≈σ
by changing the orientation of target nucleon spin or the helicityof incident lepton beam we can select q+(x) or q-(x) ∆q
21SS Nγ =+
)(2/1 xq+≈σ
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the nucleon spin structurethe nucleon spin structure
( )444 3444 21
1 Σsvv ∆q∆d∆u2
121
=∆++=
EMC (‘88) ∆Σ=0.123 ± ...
QPM:
Spin P
uzzle
gluons are important !
GΣ21
21
∆+∆=
don’t forget the orbital angular momentum!
gq LGL∆Σ 21
21
+∆++=SLAC, CERN, DESY: 0.2-0.4
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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polarisedpolarised deep inelastic scatteringdeep inelastic scattering
polarised beam
and/or
polarised target
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
exclusive dis
gq JJ +=
semi-inclusiveDIS
flavour separation
inclusive dis
inclusivehadrons
gq LGL∆Σ 21
21
+∆++=
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Hermes @ DESYHermes @ DESY
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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Hermes @ DESYHermes @ DESY
self-polarised electrons: e
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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Hermes @ DESYHermes @ DESY
self-polarised electrons: e
Stern-Gerlach separation
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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Hermes @ DESYHermes @ DESY
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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how to measure how to measure xsectionsxsections //asymmetriesasymmetries
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
)Qx,()E'θ,( 2σσ ↔
E’ = const.
θ = const.
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how to measure how to measure xsectionsxsections //asymmetriesasymmetries
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
)Qx,()E'θ,( 2σσ ↔
E’ = const.
θ = const.
L)Qx,N()Qx,(
22 ∆∆∝σ
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how to measure ghow to measure g11virtual photon asymmetry:
)Q,(A)γ1(
1)Q,(F)Q,(
Fgγg
σσσσ
A 2||221
21
1
22
1
2321
23211 xDx
xg+
≈≈−
=+
−=
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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how to measure ghow to measure g11virtual photon asymmetry:
)Q,(A)γ1(
1)Q,(F)Q,(
Fgγg
σσσσ
A 2||221
21
1
22
1
2321
23211 xDx
xg+
≈≈−
=+
−=
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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how to measure ghow to measure g11
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
)Q,(F)Q,(F)Q,(g)Q,(g 2param1
meas2
1
212
1 xxxx ⋅⎟⎟
⎠
⎞⎜⎜⎝
⎛=
252 GeV101:Q −
:)Q,(F 2param1 x
0.7 - 0.000005 :x
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how to measure ghow to measure g11
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
)Q,(F)Q,(F)Q,(g)Q,(g 2param1
meas2
1
212
1 xxxx ⋅⎟⎟
⎠
⎞⎜⎜⎝
⎛=
252 GeV101:Q −
:)Q,(F 2param1 x
0.7 - 0.000005 :x
0
0.5
1
1.5
2
2.5
3
3.5
4
1 10 102
E143
Q2 (GeV2)
gp 1(x
,Q2 )
+c(x
)
HERMES
HERMES low-x prel.
E155 prel.
EMC
SMC
phen. fit
222 GeV101:Q −
:)Q,( 2p1 xg
0.75 - 0.006 :x
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helicity distributions
(polarised quark distributions)
the integral of gthe integral of g11
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
( )∑ −+ −= f fff (x)q(x)qe21(x)g 21
∑ ∆= f f x)(qe21 2
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sum rules for gsum rules for g11
∑∫ ∆+∆⎯⎯ →⎯=Γ q 2qQPMnp,11
0
np,1 )qq(e)(d xgx
Bjorken sum rule:(isospin symmetry)
fundamental QCD prediction
21.06a3n
1p
1 ≅=Γ−Γ
Ellis-Jaffe sum rule:∆s=0
)02.0(19.0a121)(a
365
38p(n)
1 −≅−+=Γ
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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sum rules for gsum rules for g11
∑∫ ∆+∆⎯⎯ →⎯=Γ q 2qQPMnp,11
0
np,1 )qq(e)(d xgx
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
Bjorken sum rule confirmed @ 8% C.L.
violated
∆s=0
-
∆∆qq from gfrom g11(x,Q(x,Q22))
∑ ∆= q 22qLO1 )Qq(x,e21)(xg
])Q,(G)Qq(x,[e21
2)( g
2qq
22q
sLO1
NLO1 CxCgxg ⊗∆+⊗∆+= ∑π
αone step further:
parameterised
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
∑ −= data 2stat
2calc1
meas12 )(
σχ gg
minimisation : 2χ
evaluateparameter
-
∆∆qq from gfrom g11(x,Q(x,Q22))
∑ ∆= q 22qLO1 )Qq(x,e21)(xg
])Q,(G)Qq(x,[e21
2)( g
2qq
22q
sLO1
NLO1 CxCgxg ⊗∆+⊗∆+= ∑π
αone step further:
parameterised
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
∑ −= data 2stat
2calc1
meas12 )(
σχ gg
minimisation : 2χ
evaluateparameter
-
∆∆qq andand ∆∆G G from gfrom g11(x,Q(x,Q22))
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
∆uv ∆u
∆dv ∆d
∆s ∆s • ∆uv and ∆dv (quite) well determined
need more direct probes flavour separation∆G
• ∆q and ∆G weakly constraint by data
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polarisedpolarised semisemi--inclusive DISinclusive DIS
π- udK- us
flavour tagging
π+ ud
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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polarisedpolarised semisemi--inclusive DISinclusive DIS
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
π- udK- us
flavour tagging
π+ ud
∑ →⊗⊗∝f
fff zDdxqz )()()(dhqh σσ , z=Eh/ν
distributionfunction
probability that struck quarkof flavour f fragments into hadron of type h with energy fraction z
fragmentationfunction
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polarisedpolarised semisemi--inclusive DISinclusive DIS
∑ ∫∑ ∫≈
+
−=
f fff
f fff
)Q(z,Ddz)Q(x,qe
)Q(z,Ddz)Q(x,∆qe
σσσσ
)Q(x,A2h22
2h22
h23
h21
h23
h212h
1
polarised partondistribution functions !
known quantitieshadron asymmetries to be measured
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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particle identificationparticle identification
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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double radiator RICH for π / K / p separationaerogel: n=1.03C4F10: n=1.0014
Cerenkov light emission:
2c β1mcβp
βn1cos
−=⇒=ϑ
particle identificationparticle identification
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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quark/antiquark/anti--quark quark helicityhelicity distributionsdistributions
∑ ∫∑ ∫≈
+
−=
f fff
f fff
)Q(z,Ddz)Q(x,qe
)Q(z,Ddz)Q(x,∆qe
σσσσ
)Q(x,A2h22
2h22
h23
h21
h23
h212h
1
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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quark/antiquark/anti--quark quark helicityhelicity distributionsdistributions
needs at least six independent asymmetry sets A1h(x) to determine six unknown helicity distributions: ∆u, ∆u, ∆d, ∆d, ∆s, ∆s
PURITY is an unpolarised quantity
)Q,(qq
(z)Ddz)Q(x,q'e
(z)Ddz)Q(x,qe)Q(x,A 2
'h22
h222h
1
),(hqP
xf f f'f'
fff
zx
∆⋅= ∑ ∑ ∫
∫44444 344444 21
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
(x) )A,A,A,A,(AA Kd1,d1,p1,d1,p1,±±±
= ππr
(x) 0ss,
ss,
dd,
dd,
uu,
uuQ ⎟⎟
⎠
⎞⎜⎜⎝
⎛=
∆∆∆∆∆∆=
r
-
measured measured hadronhadron asymmetriesasymmetries
h+
π-
π+
h-
inclproton
deuteron
h+
h-
π+
π-
K+
K-
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
K− us all sea objects
π-h-incl
x
x
-
puritiespuritiesconditional probability that γ* hits a quark of flavour q
when hadron of type h was detected
u u d sd sπ+
K+
π−
K−
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
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quark/antiquark/anti--quark quark helicityhelicity distributionsdistributionsu quarks large positive polarisation
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
-
quark/antiquark/anti--quark quark helicityhelicity distributionsdistributionsu quarks large positive polarisation
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
d quarks negative polarisation
-
quark/antiquark/anti--quark quark helicityhelicity distributionsdistributions
sea quark (u, d, s ,s) compatible with 0
no indication for ∆s < 0
- - -
u quarks large positive polarisation
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
d quarks negative polarisation
-
where do we standwhere do we standthe (spin) structure of the nucleon …
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
H1, ZEUS,++
HERMES, ++
HERMES, COMPASS:first glimpse
HERMESCERNRHIC
?
-
don’t forget the orbital angular don’t forget the orbital angular momentummomentum
gq LGL∆Σ 21
21
+∆++=
hard exclusive processes…
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
polarisedbeam
and/or
polarisedtarget γexclusive dis
-
exclusivity @HERMESexclusivity @HERMES
e+
missing mass technique:
Mx2=(p+q−Pγ,π )
2
σ(Mx)~0.8 GeV
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
detected
detectedNOT detected
-
exclusivity @HERMESexclusivity @HERMES
missing mass technique:
Mx2=(p+q−Pγ,π )
2
σ(Mx)~0.8 GeV
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
detected
detectedNOT detected
e+
-
exclusivity @HERMESexclusivity @HERMES
missing mass technique:
Mx2=(p+q−Pγ,π )
2
σ(Mx)~0.8 GeV
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
detected
detectedNOT detected
2005++2005++
e+
-
Generalized Parton Distributions
Quantum number of final state selects different GPDs:Vector mesons (ρ, ω, φ): H EH EPseudoscalar mesons (π, η): H E H E DVCS (γ) depends on H, E, H, EH, E, H, E~~ ~~
~~ ~~
-
“Tomographic” Images of the Proton’s Quark Content
(In the Infinite Momentum Frame)
transversely polarized target1Impact parameter:-t
b = T
-
where do we stand where do we stand the (spin) structure of the nucleon …
Preface | Introduction to polarised DIS | Prerequisites | polarised Structure Functions | the Spin of the Nucleon___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
H1, ZEUS,++
HERMES, ++
HERMES:first glimpse
HERMESCERNRHICSLAC
? UPCOMING:HERMESJLab?
transversitylecture by its own
HERMESCERNRHICJLabKEK
…ecc.
the nucleon puzzle is goingthe nucleon puzzle is goingto be completedto be completed
-
Still fascinated by Spin ?Still fascinated by Spin ?
Thank you !Thank you !
___Pasquale Di Nezza_________________________________________________________Spin Physics at HERMES________
HERa MEasurement of SpinHERa MEasurement of Spinfascinated by spin …What is Spin ?What is Spin ?What is Spin ?is spin important ?is spin important ?how to study the proton spin ?DIS cross sectionhadronic tensorhadronic tensorhadronic tensorhadronic tensorhadronic tensorhelicity densities Dqthe nucleon spin structurepolarised deep inelastic scatteringhow to measure xsections /asymmetrieshow to measure xsections /asymmetrieshow to measure g1how to measure g1how to measure g1how to measure g1the integral of g1sum rules for g1sum rules for g1Dq and DG from g1(x,Q2)polarised semi-inclusive DISpolarised semi-inclusive DISpolarised semi-inclusive DISparticle identificationparticle identificationquark/anti-quark helicity distributionsquark/anti-quark helicity distributionsmeasured hadron asymmetriespuritiesquark/anti-quark helicity distributionsquark/anti-quark helicity distributionsquark/anti-quark helicity distributionswhere do we standdon’t forget the orbital angular momentumexclusivity @HERMESexclusivity @HERMESexclusivity @HERMESGeneralized Parton Distributionswhere do we stand