Transcript arXiv: 1304.0079 Jet/C-Polarimeters Electron-Lenses RHIC CeC-TF Beams: √s 200 - 500 GeV pp; 50-60% polarization RF Lumi: ~10 pb-1/week PHENIX Detector PHENIX PC3 PC2 PbSc PC3 TEC Central Magnet PbSc PbSc PbSc BBC NSRL EBIS BB Booster RICH MPC (F)VTX PC1 PbSc RICH PbGl AGS PC1 7.9 m = 26 ft TOF-W LINAC PbSc DC DC STAR STAR ERL.

arXiv: 1304.0079
Jet/C-Polarimeters
Electron-Lenses
RHIC
2012
CeC-TF
Beams: √s 200 - 500 GeV pp;
50-60% polarization RF
Lumi: ~10 pb-1/week
PHENIX Detector
PHENIX
PC3
PC2
PbSc
PC3
TEC
Central
Magnet
PbSc
PbSc
PbSc
BBC
NSRL
EBIS BB
Booster
RICH
MPC (F)VTX
PC1
PbSc
RICH
PbGl
AGS
PC1
7.9 m = 26 ft
TOF-W
LINAC
PbSc
DC
DC
STAR
STAR
ERL Test Facility
PbGl
Aerogel
TOF-E
Beam View
West
RPC3
So
u
MuID
2
10.9 m = 36 ft
ZDC South
th
M
uo
nM
East
Central Magnet
rth
No
ag
ne
t
M
uo
ag
nM
t
ne
RPC3
Tandems
MPC
BBC
ZDC North
MuID
(F)VTX
MuTr
South
RPC1
Side View
18.5 m = 60 ft
North
JLAB UGM, Newport News May 2013
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>= Lavg: +15%
Pavg: +8%
2013 P~55%
2012:
golden year for polarized
proton operation
100 GeV:
new records for Lpeak, Lavg, P
255 GeV:
new records for Lpeak, Lavg, P
highest E for pol. p beam
What will come:
increased Luminosity and
polarization through
• OPPIS new polarized source
• Electron lenses to
compensate beam-beam
effects
• many smaller incremental
improvements
will make luminosity hungry processes,
i.e. DY, easier accessible
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Is the proton looking like this?
DG
SqDq
dq

f1T
S
Lg SqLq
qLq
SqDq
DG

f1T
dq
Lg
“Helicity sum rule”
gluon
spin
1 = P, 1 | J z | P, 1 = 1S z +S z + Lz + Lz
q
g å q
g
2
2 QCD 2 å
q 2
q
total u+d+s
quark spin
4
Where do we stand
solving the “spin puzzle” ?
angular
momentum
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P1
q(x1)
x1P1
Hard Scattering Process
sˆ
P2
x2P2
X
g(x2)
“Hard” (high-energy) probes have predictable rates given:
Partonic hard scattering rates (calculable in pQCD)
Parton distribution functions (need experimental input)
Fragmentation functions (need experimental input)
DIS, pp
5
pQCD
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Universal
nonperturbative
functions
e+eE.C. Aschenauer
contributing sub-processes:
 low pT  low x
 scale uncertainty
 high √s  low x
 forward rapidity  low x
changing vs pT and rapidity
2-2.5 GeV/c
4-5 GeV/c
9-12 GeV/c
=3.3, s=200 GeV
6
2-2.5 GeV/c
4-5 GeV/c
9-12 GeV/c
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s=62 GeV (PRD79, 012003)
s=200 GeV (PRD76, 051106)
s=500 GeV (Preliminary)
PRL 97, 152302
Data compared to NLO pQCD calculations:
 s=62 GeV calculations may need inclusion of NLL (effects of threshold logarithms)
 s=200 and 500 GeV: NLO agrees with data within ~30%
 Input to qcd fits of gluon fragmentation functions  DSS
 √s=200 GeV Jet Cross Sections agree with data in ~20%
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1 = P, 1 | J z | P, 1 = 1S z +S z + Lz + Lz
q
g å q
g
2
2 QCD 2 å
q 2
q
Can DS and DG explain it all ?
8
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theory predictions before RHIC
T
h
e
o
r
e
t
i
c
a
l
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xDg
RHIC
DIS
200 GeV
xDg
0.2
 Scaling violations of g1
0.1
(Q2-dependence) give indirect access
to the gluon distribution via DGLAP
 RHIC polarized pp collisions at midrapidity
direct access to gluons (gg,qg)
evolution.
0 Rules out large DG for 0.05 < x < 0.2
GRSV std
2
Q = 10 GeV
-0.1
DSSV
10
-3
10
-2
2
DIS + RHIC £ run 6
10
-1
x
1
Integral in RHIC x-range:
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truncated moment
(“RHIC pp region”)
DSSV: Phys.Rev.D80:034030,2009
DSSV+: DSSV+new DIS/SIDIS data
truncated moment
(“high x”)
bottom line:
 RHIC pp data clearly needed
(current DIS+SIDIS data alone do not constrain Δg)
 new (SI)DIS data do not change much for Δg
 trend for positive Δg at large x (as before)
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DSSV: arXiv:0904.3821
DSSV+: DSSV+COMPASS
DSSV++: DSSV+ & RHIC 2009
15
2
Q = 10 GeV
2
DSSV++
Dc2
QCD
fit
 strong constrain on
 first
 completely consistent with
DSSV+ in D𝛘2/𝛘2=2%
10
Dc = 2% in DSSV analysis
2
5
DSSV
DSSV+
p0 p (GeV/c)
0
T
-0.1
0 0.2
ò
0.1
0.2
0
Dg(x,Q ) dx
5
10
15
2
PHENIX Prelim. p 0 , Run 2005-2009
0.05
PHENIX shift uncertainty
0.04
DSSV++ for p 0
STAR Prelim. jet, Run 2009
STAR shift uncertainty
A LL
PHENIX & STAR
fully consistent
DSSV++ for jet
0.02
0
PHENIX / STAR scale uncertainty 6.7% / 8.8% from pol. not shown
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0
10
20
30
Jet p (GeV/c)
E.C.
Aschenauer
T
DSSV: arXiv:0904.3821
DSSV+: DSSV+COMPASS
DSSV++: DSSV+ & RHIC 2009
15
2
Q = 10 GeV
2
DSSV
DSSV++
Dc2
10
xDg
Dc = 2% in DSSV analysis
2
0.2
5
Q2 = 10 GeV 2
DSSV
RHIC 200 GeV
0.1
DSSV+
0
-0.1
0 0.2
ò
0.1
Do things add up?
0.2
Dg(x,Q ) dx
2
0
0.05
DSSV
-0.1
First time a significant
non-zero Dg(x)
DSSV++
10
-2
10
-1
x
1
1
in units of h
DSSV+
Spin of the proton
ò Dg(x,Q2) dx
xmin
0.8
2
Q = 10 GeV
2
forward  RHIC
500 GeV
0.6
0.4
DIS
RHIC
200 GeV
DSSV++
0.2
0
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10
-3
-2
-1
10
xmin
E.C. Aschenauer
10
Reduce uncertainties and go to low x
 measure correlations (di-jets, di-hadrons)  constrain shape of Dg(x)
 ALL p0 and jet at √s = 500 GeV  xmin > 0.01
Experimentally Challenging
 measure ALL at forward rapidities  xmin > 0.001 ALL ≲ 0.001
 high Lumi
 good control of systematics
x_T
0.2
0.15
0.1
A0.05
LL
pp ® p0X
-0.015
-0.010
-0.005
0.000
0.005
0.010
0.015
0.020
0.025
0
Runs 9+14 Proj (200)
Run 12 Proj (500)
GRSV-Std (500)
DSSV (500)
GRSV-Std (200)
DSSV (200)
Inclusive Jet A_LL for |eta|<1
0.25
0.3
0.35
Run 2009 - 2015:
0.001
-max
DSSV
3.1<|h|<3.9
Many more probes:
A_LL




0
-0.001
PHENIX proj. for s=510 GeV:
-1
L=630 pb P=0.55
2
14
4
p±  sign of Dg(x)
direct photon theoretically clean
heavy flavour luminosity hungry
…..
6
p (GeV/c)
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May 2013
T
E.C. Aschenauer
Impact of inclusive jet data 2009 to 2015 at √s=200 GeV and √s=500 GeV
on Dg(x)  uncertainties reduce by factor 2
15
15
Dci
2
Dci
2
10
10
Dc2=2%
Dc2=2%
5
5
DSSV++
2013 (500x2)
500 GeV
2013
2015
200 GeV
2015 (200x1.4-2)
2013+2015
0
0
15
0.05
0.1
1, [ 0.05-0.2]
Dg
0.15
0.2
DSSV++
2013
(500x2)
2013 500
GeV
2015
200
GeV
2015 (200x1.4-2)
2013+2015
0
0
0.1
JLAB UGM, Newport News May 2013
Dg
0.2
1, [ 0.01-0.2]
0.3
E.C. Aschenauer
novel electroweak
0.05<x<0.4
probe
RHIC pp data
constraining Δg(x)
0.01 < x <0.2
data plotted at xT=2pT/√s
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Since W is maximally parity violating
 W’s couple only to one parton helicity
large Δu and Δd result in large asymmetries.
Complementary to SIDIS:
very high Q2-scale
extremely clean theoretically
No Fragmentation function
backward
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x1 small
t large
x1 large
u large
forward
E.C. Aschenauer
Run-2009:
stot
× BR(W ® l n ) (pb)
W
104
Theory: FEWZ and MSTW08 NLO PDFs
3
10
pp ® W
102
pp ® W
+
pp ® W
-
STAR
Phenix
ATLAS
CMS
UA1
UA2
CDF
D0
tot
sZ/
× BR(Z/ g * ® ll) (pb)
g*
10
3
10
102
pp ® Z/ g *
10
pp ® Z/ g *
3
10
s (GeV)
PHENIX Run 2009-2012:
first result from
muon arms
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DSSV
STAR Preliminary Run 2012
AL
±
0.5
w/ proj.
W data
Dc
2
e±
p+p ® W ® e + n
e
e
25 < ETT < 50 GeV
s=510 GeV
DSSV++
15
10
DSSV
2
Dc =2%
-
W-
5
DSSV++
w/ STAR W data
DSSV+
0
Rel lumi
lumi
Rel
syst
syst
0
-0.06 -0.04 -0.02
-0.5
0.02 1 0.04 0.06
ò Du(x,Q2) dx
+
W
0.05
15
DSSV++
w/ proj. W data
Dc
2
DSSV08
DSSV08
DSSV08
DSSV08
-1
0
RHICBOS
RHICBOS
CHE NLO
NLO
CHE
10
2
DSSV08 L0
L0 with
with D
Dcc2=1
=1 pdf
pdf error
error
DSSV08
2
DSSV
2
Dc =2%
3.4% beam
beam pol
pol scale
scale uncertainty
uncertainty not
not shown
shown
3.4%
Remaining syst
syst <10%
<10% of
of stat
stat errors
errors
Remaining
-2
-1
0
DSSV+: DSSV+COMPASS
DSSV++: DSSV+ & STAR-W 2009
DSSV++: DSSV+ & RHIC-W proj.
19
1
lepton
2
h
5
DSSV+
DSSV++
w/ STAR W data
2
Q = 10 GeV
2
0
-0.08
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-0.06
-0.04
-0.02
1
0
0.02
) dx
òDd(x,Q
E.C.
Aschenauer
0.05
2
AL
pseudo-data randomized around DSSV
®
p + p ® W ± + X ® e± + X
®
p + p ® W ± + X ® m± + X
0.6
0.4
–
DSSV++
15
0.02
2
xDu
w/ proj.
W data
Dc
2
Q = 10 GeV
25 GeV<E eT <50 GeV
m
2
10 0
15 GeV<E T
DSSV
2
Dc =2%
STAR PHENIX
-0.02
5
DSSV
DSSV+
0.2
W
0
-0.04
-
DSSV+
DSSV++
STAR W data
DSSV++ with proj. Ww/data
0
Systematic Uncertainty
-0.06-2 -0.04 -0.02
10
W+
-0.2
0
0.02 1 0.04
0.06
-1
10
ò Du(x,Q2) dx
x
0.05
15
0.02
2
-0.4
–
DSSV++
xDd
w/ proj. W data
Dc
2
Q = 10 GeV
2
-1
-0.6
L 09-13 = 630 pb , P = 55%
W
-
W+
10
0
DSSV
2
Dc =2%
e, m
CHE-DSSV (25 GeV<ET )
e, m
CHE-DSSV (15 GeV<E )
-2
-1
h
0
T
1
2
-0.02
5
DSSV+
lepton
DSSV+: DSSV+COMPASS
DSSV++: DSSV+ & STAR-W 2009
DSSV++: DSSV+ & RHIC-W proj.
20
DSSV++
-0.04
w/ STAR W data
2
Q = 10 GeV
2
0
-0.08
-2
10
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-0.06
-0.04
-0.02 -11 0
0.02
10
2
òDd(x,Q ) dxx
E.C.
Aschenauer
0.05
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Big single spin asymmetries in pp !!
Naive pQCD (in a collinear picture)
predicts AN ~ asmq/sqrt(s) ~ 0
Left
Do they survive at high √s ? YES
Is observed pt dependence as expected
from p-QCD? NO
Right
What is the underlying process?
Sivers / Twist-3 or Collins or ..
till now only hints
ANL ZGS
s=4.9 GeV
BNL AGS
s=6.6 GeV
FNAL
s=19.4 GeV
BRAHMS@RHIC
s=62.4 GeV Collins Asy
Collins Asymmetry A º 2 <sin( f f )> vs. z
S
0.1
h
p+ Asymmetry
S
p
p Asymmetry
-
2 <sin(f
S
h
f )>
0.05
0
systematic uncertainties
systematic uncertaintie
-0.05
RHIC 2006
Systematic effects contributing to <1% of total uncertainty excluded
p­p ® jet( p
-0.1
0
22
0.1
Thu Oct 18 08:33:04 2012
0.2
JLAB UGM, Newport News May 2013
0.3
0.4
0.5
z
0.6
0.7
0.8
0.9
E.C. Aschenauer
10
-1
Sivers/twist-3 mechanism:
asymmetry in jet or γ production
SP
Collins mechanism:
asymmetry in jet fragmentation
SP
kT,q
p
p
p
Sensitive to proton spin –
parton transverse motion
correlations
• Signatures:
– AN for jets or direct photons
• NOT universal
– Sign change from SIDIS to DY
23
p
Sq
Sensitive to transversity
kT,π
• Signatures:
– Collins effect
– Interference fragmentation functions
• Believed to be universal
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 Collins / Transversity:
 conserve universality in hadron hadron interactions
 FFunf = - FFfav
and
du ~ -2dd
 evolve ala DGLAP, but soft because no gluon contribution (i.e.
non-singlet)
 Sivers, Boer Mulders, ….
 do not conserve universality in hadron hadron interactions
 kt evolution  can be strong
o till now predictions did not account for evolution
 FF should behave as DSS, but with kt dependence unknown till
today
 u and d Sivers fct. opposite sign d >~ u
 Sivers and twist-3 are correlated
o global fits find sign mismatch, possible explanations,
24
like node in kt or x don’t work
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Transversity x Collins
SIVERS
Rapidity dependence of
 AN for p0 and eta with increased pt coverage
 p+/-p0 azimuthal distribution in jets
 AN for jets
 AN for direct photons
 AN for heavy flavour  gluon
 Interference fragmentation function
AN
Collins Asymmetry A º 2 <sin( f
0.12
0.1
Expected Asymmetries of Prompt Photons
p+
S
f )> vs. z
h
Collins Asymmetry A º 2 <sin(f
Asymmetry
f )> vs. jT
h
p data horizontally offset for clarity
p- Asymmetry
0.1
S
TransversityxInterference
FF
STAR
Preliminary
h
f )>
0.05
0.06
0.04
S
arXiv: 1208.1962
Tq,F pp p0
Tq,F SIDIS new
Tq,F SIDIS old
2 <sin(f
0.08
0
systematic uncertainties
systematic uncertainties
-0.05
RHIC 2006
Systematic effects contributing to <1% of total uncertainty excluded
s = 200 GeV
±
p­p ® jet( p ) ; jet p T>10 GeV
0.02
-0.1
0
0
0.1
Thu Oct 18 08:33:04 2012
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
z
10
-1
j (GeV) 1
10
T
-0.02
-0.04
-0.06
-0.08
25
s = 200 GeV, P=60%, Ldt=50 pb -1
0.4
0.5
0.6
0.7
0.8
xF
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E.C. Aschenauer
Central Rapidity AN(p0) dominated by gg and qg
no hint of a
non-zero
AN(p0)
Forward Rapidity AN(J/) only gg:
no hint of a
non-zero
AN(J/)
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Intermediate QT
Q>>QT/pT>>LQCD
Transverse
momentum
dependent
Q>>QT>=LQCD
Q>>pT
Collinear/
twist-3
Q,QT>>LQCD
pT~Q
Efremov, Teryaev;
Qiu, Sterman
Sivers fct.
LQCD
<< QT/PT <<
Q
QT/PT
critical test for our understanding of TMD’s and TMD factorization
QCD:
27
DIS:
attractive FSI
SiversDIS =
-
Drell-Yan:
repulsive ISI
SiversDY or SiversW or SiversZ0
E.C. Aschenauer
Delivered Luminosity: 500pb-1 (~6 weeks for Run14+)
STAR AN(W):
-1.0 < y < 1.5
W-fully reconstructed
-
0.4
s = 510 GeV
0 < q < 3 GeV/c
s = 510 GeV
0 < q < 3 GeV/c
0.15
T
0.35
Projection, Ldt=500 pb
T
-1
Projection, Ldt=500 pb
0.1
STAR
0.3
AN
Expected asymmetries for W + -bosons
AN
AN
Expected asymmetries for W -bosons
PHENIX AN(DY):
1.2<|y|<2.4
Expected asymmetries in Drell-Yan
s = 510 GeV
0 < q < 1 GeV/c
T
0.02
4 < mg * < 8 GeV/c
-1
STAR
arXiv: 0903.3629
0.04
2
0
arXiv: 0903.3629
0.25
0.2
0.05
-0.02
0
-0.04
0.15
-0.06
-0.05
0.1
Projection, Ldt=500 pb -1
-0.08
0.05
-0.1
arXiv: 0912.1319
-0.1
0
-2
-1
0
1
2
y
-0.15
-2
-1
0
1
Extremely clean measurement of dAN(Z0)+/-10%
for <y> ~0
28
PHENIX
W
2
y
-4
-2
0
2
4
y
W
JLAB UGM, Newport News May 2013
g*
E.C. Aschenauer
Aybat-Prokudin-Rogers, 2011
Sun-Yuan, 2013
Many calculations on energy dependence of DY and
now TMDs
 Collins-Soper Evolution, 1981
 Collins-Soper-Sterman, 1985
 Boer, 2001
 Idilbi-Ji-Ma-Yuan, 2004
 Kang-Xiao-Yuan, 2011
 Collins 2011
 Aybat-Collins-Rogers-Qiu, 2011
 Aybat-Prokudin-Rogers,2012
 Idilbi, et al., 2012
 Boer 2013
 Sun, Yuan, arXiv: 1304.5037
Need Measurements:
to see how strong evolution effects
for TMDs are
till now many predictions neglect
TMD evolution effects
W+ √s=500 GeV
DY √s=200 GeV
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The Beauty of RHIC
mix and match beams as one likes
polarised p↑A
 unravel the underlying sub-processes to AN
 getting the first glimpse of GPD E for gluons
 AUT(J/ψ) in p↑A
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the way to 3d imaging of the proton and the orbital angular momentum Lq & Lg
Measure them through exclusive reactions
golden channel: DVCS
e’
e
(Q2)
g
gL*
x+ξ
x-ξ
~
p
~
H, H, E, E (x,ξ,t)
p’
t
Spin-Sum-Rule in PRF:
from g1
GPDs:
Correlated quark momentum
and helicity distributions in
transverse space
31
responsible for orbital angular momentum
E.C. Aschenauer
 Get quasi-real photon from one proton
 Ensure dominance of g from one identified proton
by selecting very small t1, while t2 of “typical hadronic
size”
small t1  large impact parameter b (UPC)
 Final state lepton pair  timelike compton scattering
 timelike Compton scattering: detailed access to GPDs
including Eq/g if have transv. target pol.
 Challenging to suppress all backgrounds
Z2
A2
 Final state lepton pair not from g* but from J/ψ
 Done already in AuAu
 Estimates for J/ψ (hep-ph/0310223)
 transverse target spin asymmetry  calculable with GPDs
AUT (t ,t) ~
t0 - t Im(E * H)
mp
|H|
M J2 /Y
t=
s
 information on helicity-flip distribution E for gluons
golden measurement for eRHIC
Gain in statistics doing polarized p↑A
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E.C. Aschenauer
at 15-17m
at 55-58m
• Roman Pot detectors to measure forward scattered protons in
diffractive processes
• Staged implementation to cover wide kinematic coverage
Phase I (Installed): for low-t coverage
Phase II (ongoing) : for higher-t coverage
8(12) Roman Pots at ±15 and ±17m
 No special b* running needed any more
2
 t = -2 p (1- cosQ)  250 GeV to 100 GeV
scale t-range by 0.16
33
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Gluon density dominates at x<0.1
10 6
10
xg
10
xS
5
Q2 = 10HERA
GeV2I NC e+p
x = 0.00005, i=21
x = 0.00008, i=20
x = 0.00013, i=19
x = 0.00020, i=18
x = 0.00032, i=17
x = 0.0005, i=16
10
-2
large x
10
-3
10-2
xuv
JIMWLK
BK
10
BFKL
xdv
x = 0.13, i=4
HERAPDF1.0
x = 0.18, i=3
10-1
x = 0.40, i=1
x
1
x = 0.65, i=0
x=1
-3
exp. uncert.
10
saturation
-2
x = 0.25, i=2
parametrization uncert.
10-3 -4
10
DGLAP
x = 0.08, i=5
model uncert.
1
as << 1
-1
x = 0.05, i=6
exp. uncert.
10-2
xS
g
in
x = 0.032, i=7
HERAPDF1.0
Q2 = 10 GeV2
al
sc
x = 0.013, i=9
x = 0.02, i=8
10 2
xg
1
ri c
10-1
10
et
m
x = 0.005, i=11
x = 0.008, i=10xdv
10 3
-1
2
Qs(x) 10
o
ge
10 4
10
H1 and ZEUS
Fixed Target
HERAPDF1.0
x = 0.0008, i=15
x = 0.0013, i=14
x = 0.0020, i=13
xuv
x = 0.0032, i=12
1
10
x=10-5
ln Q2
+
H1 and ZEUS
xf
xf
10
Gluon density dominates at x<0.1
H1 and ZEUS
7
2
sr,NC(x,Q ) x 2
i
small x
model uncert.
parametrization
non-perturbative
regionuncert.
10-3 -4
10
10
-3
ln x 10
-2
10-1
as ~ 1
x
1
1
10 in gluons
10
10
10
10
 Rapid
rise
described
naturally
by
linear pQCD evolution equations
2
2
Q / GeV
 This rise cannot increase forever - limits on the cross-section
 non-linear pQCD evolution equations provide a natural way to tame this growth and
lead to a saturation of gluons, characterised by the saturation scale Q2s(x)
34
2
3
4
5
E.C. Aschenauer
 At y=0, suppression of away-side
jet is observed in A+A collisions
 No suppression in p+p or d+A
 x~10-2

 However, at forward
rapidities (y ~ 3.1), an awayside suppression is observed
in dAu
 Away-side peak also much
wider in d+Au compared to pp
 x ~ 10-3
35
E.C. Aschenauer
Yuri Kovchegov et al.
strong suppression of odderon STSA in nuclei.
 Very unique RHIC possibility p↑A
 Synergy between CGC based
theory and transverse spin physics
 AN(direct photon) = 0
 The asymmetry is larger for
peripheral collisions
r=1fm
r=1.4fm
r=2fm
p0
36
Qs=1GeV
STAR: projection for upcoming pA run
Curves: Feng & Kang arXiv:1106.1375
solid: Qsp = 1 GeV
dashed: Qsp = 0.5 GeV
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Multi Year Run Plan
DG
SqDq
dq

f1T
S
Lg SqLq
qLq
SqDq
DG

f1T
dq
Lg
RHIC SPIN Program
 the unique science program addresses
all important open questions in spin physics
 uniquely tied to a polarized pp-collider
 never been measured before & never without
37
JLAB UGM, Newport News May 2013
E.C. Aschenauer
38
JLAB UGM, Newport News May 2013
E.C. Aschenauer
significant experimental and theoretical progress in past 25+ years, yet many unknows …
Δg(x,Q2)
can hide one
unit of here
0.2
• found to be not big at 0.05 < x < 0.2
• RHIC/EIC can extend x range & reduce uncertainties
[500 GeV running & particle correlations]
yet, will full 1st moment [proton spin sum]
still will remain to have significant uncertainties
from unmeasured small x region?
GRSV std
0.1
0
-0.1
Δq’s
(x,Q2)
xDg
DSSV
10
-3
10
-2
DIS
RHIC2 & 2
Q = 10 GeV
pp
pp
DIS + RHIC £ run 6
10
-1
• known: quarks contribute much less to proton spin
than expected from quark models
x
x
1
large uncertainties in ΔΣ from unmeasured small x
39
• surprisingly small/positive Δs from SIDIS: large SU(3)
breaking?
_
_
• flavor separation not well known, e.g., Δu Δd
JLAB UGM, Newport News May 2013
E.C. Aschenauer
 PDFs do not resolve transverse momenta or positions in the nucleon
 fast moving nucleon turns into a `pizza’ but transverse size remains about 1 fm
compelling questions
 how are quarks and gluons spatially distributed
 how do they move in the transverse plane
 do they orbit and do we have access to spin-orbit correlations
 required set of measurements & theoretical concepts
1-D
parton densities
form factor
not related by
2+1-D
transv. mom. dep. PDF
semi-inclusive DIS
Fourier transf.
Wigner function
4+1-D
40
impact par. dep. PDF
generalized PDF
exclusive processes
high-level connection
measurable ?
important in other branches of Physics
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Detector Layout for forward physics studies
Use open sPHENIX central barrel geometry to introduce





tracking
charged particle identification
electromagnetic calorimeter
hadron calorimeter
muon detection
 Use existing equipment where possible
41
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Forward instrumentation optimized for p+A and transverse spin physics
– Charged‐particle tracking
– e/h and γ/π0 discrimination
– Possibly Baryon/meson separation
42
JLAB UGM, Newport News May 2013
E.C. Aschenauer
• how well are we doing ?
• refit/new analysis necessary ?
• impact on uncertainties ?
• DIS: A1p from COMPASS
arXiv:1001.4654
• SIDIS: A1,dπ,K from COMPASS
arXiv:0905.2828
• SIDIS: A1,pπ,K from COMPASS
arXiv:1007.4061
extended x coverage w.r.t. HERMES
43
JLAB UGM, Newport News May 2013
E.C. Aschenauer
x-range
not covered
by HERMES

DSSV works well:
no surprises at small x
 2 numerology:
arXiv:0905.2828
DSSV
2008
DSSV+
44
JLAB UGM, Newport News May 2013
DSSV 08
data sets
with
392.5
420.8
A1d,π,K
418.9
E.C. Aschenauer
COPING WITH NEW DATA: SIDIS A1P,p,K
1st kaon data on p-target
(not available from HERMES)
x-range
not covered
by HERMES
 2 numerology:
DSSV 08
arXiv:1007.4061
DSSV+

DSSV 08
data sets
with
392.5
456.4
A1p&d,π,K
453.0
no refit required
(Δχ2=1 does not reflect
faithful PDF uncertainties)

trend for somewhat less
polarization of sea quarks;
45
JLAB UGM, Newport News May 2013
less significant
E.C. Aschenauer
Δq’s (x,Q2)
• known: quarks contribute much less to proton spin
than expected from quark models
large uncertainties in ΔΣ from unmeasured small x
• surprisingly small/positive Δs from SIDIS: large SU(3)
breaking?
_
_
• flavor separation not well known, e.g., Δu Δd
46
JLAB UGM, Newport News May 2013
E.C. Aschenauer
current value for ΔΣ strongly depends on assumptions on low-x behavior of Δs
• new COMPASS data support
small/positive Δs(x) at x > 0.01
• they also prefer a sign change
>0
<0
at around x=0.01
• but large negative 1st moment entirely driven by assumptions on SU(3)
• caveat: dependence on FFs
COMPASS
0.004 < x < 0.3
47
JLAB UGM, Newport News May 2013
E.C. Aschenauer
M. Diehl
To improve imaging on gluons
add J/ψ observables
 cross section
 AUT
 …..
48
JLAB UGM, Newport News May 2013
E.C. Aschenauer
pp ®Z 0 ®e +e 300 pb-1 -> ~10% on a single bin of AN
Generator: PYTHIA 6.8
• Clean experimental momentum
reconstruction
• Negligible background
• electrons rapidity peaks within
tracker acceptance (||< 1)
• Statistics limited
49
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Angle [rad]
 Momentum smearing mainly due
to Fermi motion + Lorentz boost
 Angle <~3mrad (>99.9%)
Study: JH Lee
generated
Passed DX aperture
Accepted in RP
 The same RP configuration with the current RHIC optics (at z ~ 15m between DX-D0)
 Acceptance ~ 98%
50
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Year
s [GeV]
Recorded
PHENIX
2002 (Run 2)
200
/
0.3 pb-1
15
2003 (Run 3)
200
0.35 pb-1
0.3 pb-1
27
2004 (Run 4)
200
0.12 pb-1
0.4 pb-1
40
2005 (Run 5)
200
3.4 pb-1
3.1 pb-1
49
2006 (Run 6)
200
7.5 pb-1
6.8 pb-1
57
2006 (Run 6)
62.4
0.08 pb-1
2009 (Run9)
500
10 pb-1
10 pb-1
39
2009 (Run9)
200
14 pb-1
25 pb-1
55
2011 (Run11)
500
27.5 / 9.5pb-1
12 pb-1
48
2012 (Run12)
500
30 / 15 pb-1
82 pb-1
50/54
51
Recorded
STAR
Pol [%]
48
JLAB UGM, Newport News May 2013
E.C. Aschenauer
Year
s [GeV]
Recorded
PHENIX
2001 (Run 2)
200
0.15 pb-1
0.15 pb-1
15
2003 (Run 3)
200
/
0.25 pb-1
30
2005 (Run 5)
200
0.16 pb-1
0.1 pb-1
47
2006 (Run 6)
200
2.7 pb-1
8.5 pb-1
57
2006 (Run 6)
62.4
0.02 pb-1
2008 (Run8)
200
5.2 pb-1
7.8 pb-1
45
2011 (Run11)
500
/
25 pb-1
48
2012 (Run12)
200
9.2/4.3 pb-1
22 pb-1
61/58
52
Recorded
STAR
Pol [%]
53
JLAB UGM, Newport News May 2013
E.C. Aschenauer
 Polarized He3 is an effective neutron target  d-quark
target
 Polarized protons are an effective u-quark target
Therefore combining pp and pHe3 data will allow a full
quark flavor separation u, d, ubar, dbar
Two physics trusts for a polarized pHe3 program:
 Measuring the sea quark helicity distributions through W-production
 Access to Ddbar
 Caveat maximum beam energy for He3: 166 GeV
 Need increased luminosity to compensate for lower W-cross section
 Measuring single spin asymmetries AN for pion production and Drell-Yan
 expectations for AN (pions)
 similar effect for π± (π0 unchanged)
3He:
helpful input for understanding
of transverse spin phenomena
Critical to tag spectator protons from 3He with roman pots
53
JLAB UGM, Newport News May 2013
E.C. Aschenauer