THE DEEP INELASTIC SCATTERING ON THE POLARIZED NUCLEONS AT EIC E.S.Timoshin, S.I.Timoshin.
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Transcript of THE DEEP INELASTIC SCATTERING ON THE POLARIZED NUCLEONS AT EIC E.S.Timoshin, S.I.Timoshin.
We have two pictures about the nucleon spin:
Jaffe-Manohar, 1990
It is simple parton picture for longitudinal polarization
X.Ji, 1996
It is relate to the partons in transverse polarized nucleon
gq LLG 2
1
2
1
Quark
helicity Gluon
helicity Orbital
momentumof quarks and
gluons
gqgq JLJJ 2
1
2
1
Total
angular momentum
of quarks
Total
angular momentum
of gluons
What do we know?
We know fairly well the quark contribution
~ 30%
However, the information on polarization of the flavor and sea are still sketchy.
Contribution from small ?
We know with large uncertains about the gluon contribution
~ 20% (with RHIC data)
There not have direct information on the quark and gluon orbital angular momentum.
Lattice QCD → and are large, but ~ 0
ssdduudx
)x(gdxG
uL dL du LL
x
Major advance since 2007:
We have new phenomenology to study nucleon structure:
Generalized Parton Distributions (GPDs) (3D “imaging”) that provide access to orbital angular momentum in DVCS and Exclusive production.
These studies will require high luminosity and polarized beams.
Electron–Ion Collider (EIC)
High luminosity
Low regime
High polarization 70% electron and nucleon beams
Ion beams from deuteron to the heaviest nuclei
Center mass energies 20-100 GeV (upgradable 150 GeV)
,,/J
410xx
123410 scm
What can to explore at EIC:
Sea/gluon (inclusive DIS, SIDIS at low ), flavor separation.
GPD (DVCS, Exclusive meson production) => angular momentum
The first constraint on quark orbital contribution to proton spin
by combining the sea from EIC and valence from JLab 12
42 1010 ~x
.J,J gq
x
qqqt
q Lt,,xEt,,xHxdxlimJ 2
1
2
10
GPD
The inclusive DIS with charged current
Here are 2 independent polarized structure functions (SF)
flavor separation
In contrast with SIDIS here not have the fragmentation functions that give essential uncertains.
XNl
qq~g
,qq~g
6
1
q,q
The polarization asymmetries through SF are
,
)Q,x(Fy
)Q,x(Fy
)Q,x(gy)Q,x(gy
dd
dd)Q,x(A
l,ll,l
l,ll,l
,l,l
,l,l
,l,l
,l,l
l,l
23
1211
211
261
22
222
2
Where
.
)Q,x(F)Q,x(Fy
)Q,x(F)Q,x(Fy
)Q,x(g)Q,x(gy)Q,x(g)Q,x(gy
dddd
dddd)Q,x(A
llll
llll
llll
llll
23
23
121
211
21
211
26
261
2222
22222
2
.yy,yy 11 1211
The polarized SF in leading order QCD (improved parton model)
where and for
lepton (antilepton).
q q
q q
),Q,x(q)Q,x(q)Q,x(g
),Q,x(q)Q,x(q)Q,x(g
2226
2221
b,s,dqt,c,uq t,c,uqb,s,dq
The first moment polarized SF
where is the quark
(antiquark) contribution to the nucleon spin
dx)x(q)x(q)q(q 1
0
,qqdx)Q,x(g)Q(q,q
,, 1
0
261
261
The proton
where
We use also the measurable quantity – the axial charge that in parton model:
,qdu
),ss()dd()uu(
VVVplpl
plpl
66
66
.ddd,uuu VV
.du
),ss()dd()uu(
VVplpl
plpl
11
11
00350267013 ..DFa
.dduua 3
The quark contributions to the nucleon spin:
The quark flavors
.ass
),a(dd
),(uu
plpl
plplplpl
plplplpl
366
36611
6611
22
1
2
1
The valence quarks
The sea quarks
.)(d
,)(u
plplplplV
plplplplV
6611
1166
2
12
1
).a(s
)a(d
),(u
plpl
plpl
plpl
366
361
61
2
12
12
1
We are obtained the quark contributions for the neutron and the deutron.
The deutron
where is the probability D-state in the wave function of the deuteron.
.,
du
,,
ss
dldl
VV
dldl
511
511
66
66
,,
dldl
51111
050.
Fig.5. QED correction to asymmetry in leading log approximation (LLA)
A. De Rujula et al. Nucl. Phys. 1979. V. B154 P.394.
J. Blŭmlein. Prog. Part. Nucl. Phys. 2013. V.69. P.28.
(%)l p
eA
Fig.6. QED correction to asymmetry in LLA
NLO QCD correction to the asymmetries CC DIS are small and LO accuracy is very good approximation ( E.C.Aschenauer et al. Phys. Rev. D 88(2013) 114025).
(%)n,l n
eA
CONCLUSION
Data from CC DIS experiments provide complementary
information on the spin structure nucleon as they probe
combinations of quark flavours different from those accessible
in purely electromagnetic DIS.
CC DIS can only be studied in high-energy lepton-nucleon
collisions (EIC).
The quark contributions to the nucleon spin are obtained
through the first moments of the polarized SF that
can be to extract from the measurable asymmetries CC DIS.
61 g,g