Nuclear Gluons with Charm at EIC* · 2016. 2. 17. · Open Charm Production Charles Hyde Old...
Transcript of Nuclear Gluons with Charm at EIC* · 2016. 2. 17. · Open Charm Production Charles Hyde Old...
Nuclear Gluons with Charm at EIC*
*Probing High-x Gluons in Nuclei via
Open Charm Production
Charles Hyde Old Dominion University
Next Generation Nuclear Physics with JLab12 and EIC 10–13 February 2016
Florida International University
Gluons at Large-x in (e,e’)? Gluons are a low-x phenomenon ∼50% of gluon momentum sum rule is at x > 0.1
g(x) ≈ d(x) quarks at x ≥ 0.3 (within errors)
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
EMC Effect’: Anti-Shadowing
Anti-shadowing is not anti-quarks! FermiLab Drell-Yan E722
L. Frankfurt et al. / Physics Reports 512 (2012) 255–393 305
Fig. 34. Prediction for nuclear PDFs and structure functions for 208Pb. The ratios Rj (u and c quarks and gluons) and RF2 as functions of Bjorken x at Q 2 = 4,10, 100 and 10, 000 GeV2. The four upper panels correspond to FGS10_H; the four lower panels correspond to FGS10_L.
The numerical value of the exponent � = 0.25 in Eq. (126) can be understood as follows. The x dependence of nuclearshadowing at small x is primarily driven by the xP dependence of the Pomeron flux fP/p(xP) / 1/x(2↵P�1)
P / 1/x1.22P . There-fore, in the very small x limit, one expects from Eq. (64) that, approximately,
�F2A(x,Q 2)/A /✓1x
◆0.22
,
�xgA(x,Q 2)/A /✓1x
◆0.22
, (127)
which is consistent with our numerical result in Eq. (126).When we present our predictions for nuclear shadowing in the form of the ratios of the nuclear to nucleon PDFs, it is
somewhat difficult to see the leading twist nature of the predicted nuclear shadowing because of the rapid Q 2 dependenceof the free nucleon structure functions and PDFs. In order to see the leading twist nuclear shadowing more explicitly, oneshould examine the absolute values of the shadowing corrections.
Fig. 38 presents |�F2A(x,Q 2)/A| and |�xgA(x,Q 2)/A| as functions of Q 2 at fixed x = 10�4 (first and third rows) andx = 10�3 (second and fourth rows) for 40Ca (four upper panels) and 208Pb (four lower panels). The solid curves correspondto FGS10_H; the dotted curves correspond to FGS10_L. Also, for comparison, presented by the dot-dashed curves, we give
0.7
0.8
0.9
1
1.1
0.01 0.1 1
DY(E772)DIS(NMC)
R(Ca/2 H)
x
Anti-shadowing is glue
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Gluons and Charm @ JLab 12 GeV
First CLAS12 experiment, circa FY17+ e + p à e’ + X, Ee = 11 GeV e + p à e’ + p + (J/Ψ à e+e–)
Gluon GPD at xg = (MJ/Ψ )2/(W2–M2) > 0.5 for Q2≥ 1 GeV2 LHCb resonance in p ✕ J/Ψ channel: PRL 115, 072001 (2015) CLAS12 forward tagger W ≤ 4.5 GeV for Q2<<1 GeV2
Time-like Compton scattering (TCS) up to M( J/Ψ) approved for CLAS12, SoLID (Hall A)
TCS discussions for Halls C & D
higher mass states are 9 and 12 standard deviations,respectively.Analysis and results.—We use data corresponding to
1 fb−1 of integrated luminosity acquired by the LHCbexperiment in pp collisions at 7 TeV center-of-massenergy, and 2 fb−1 at 8 TeV. The LHCb detector [13]is a single-arm forward spectrometer covering thepseudorapidity range, 2 < η < 5. The detector includes ahigh-precision tracking system consisting of a silicon-stripvertex detector surrounding the pp interaction region [14],a large-area silicon-strip detector located upstream of adipole magnet with a bending power of about 4 Tm, andthree stations of silicon-strip detectors and straw drift tubes[15] placed downstream of the magnet. Different types ofcharged hadrons are distinguished using information fromtwo ring-imaging Cherenkov detectors [16]. Muons areidentified by a system composed of alternating layers ofiron and multiwire proportional chambers [17].
Events are triggered by a J=ψ → μþμ− decay, requiringtwo identified muons with opposite charge, each withtransverse momentum, pT , greater than 500 MeV. Thedimuon system is required to form a vertex with a fitχ2 < 16, to be significantly displaced from the nearest ppinteraction vertex, and to have an invariant mass within120 MeV of the J=ψ mass [12]. After applying theserequirements, there is a large J=ψ signal over a smallbackground [18]. Only candidates with dimuon invariantmass between −48 and þ43 MeV relative to the observedJ=ψ mass peak are selected, the asymmetry accounting forfinal-state electromagnetic radiation.Analysis preselection requirements are imposed prior to
using a gradient boosted decision tree, BDTG [19], thatseparates the Λ0
b signal from backgrounds. Each track isrequired to be of good quality and multiple reconstructionsof the same track are removed. Requirements on theindividual particles include pT > 550 MeV for muons,
[GeV]pKm1.4 1.6 1.8 2.0 2.2 2.4
Eve
nts/
(20
MeV
)
500
1000
1500
2000
2500
3000
LHCb(a)
data
phase space
[GeV]pψ/Jm4.0 4.2 4.4 4.6 4.8 5.0
Eve
nts/
(15
MeV
)
200
400
600
800 LHCb(b)
FIG. 2 (color online). Invariant mass of (a) K−p and (b) J=ψp combinations from Λ0b → J=ψK−p decays. The solid (red) curve is the
expectation from phase space. The background has been subtracted.
[GeV]pKm1.4 1.6 1.8 2 2.2 2.4 2.6
Eve
nts/
(15
MeV
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
LHCb
datatotal fitbackground
(4450)cP(4380)cP(1405)Λ(1520)Λ(1600)Λ(1670)Λ(1690)Λ(1800)Λ(1810)Λ(1820)Λ(1830)Λ(1890)Λ(2100)Λ(2110)Λ
[GeV]pψ/Jm4 4.2 4.4 4.6 4.8 5
Eve
nts/
(15
MeV
)
0
100
200
300
400
500
600
700
800
LHCb(a) (b)
FIG. 3 (color online). Fit projections for (a)mKp and (b)mJ=ψp for the reduced Λ" model with two Pþc states (see Table I). The data are
shown as solid (black) squares, while the solid (red) points show the results of the fit. The solid (red) histogram shows the backgrounddistribution. The (blue) open squares with the shaded histogram represent the Pcð4450Þþ state, and the shaded histogram topped with(purple) filled squares represents the Pcð4380Þþ state. Each Λ" component is also shown. The error bars on the points showing the fitresults are due to simulation statistics.
PRL 115, 072001 (2015) P HY S I CA L R EV I EW LE T T ER S week ending14 AUGUST 2015
072001-2
Pc(4450) Pc(4380)
CLAS12
LHCb 2015
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Nuclear gluons with charm at EIC JLab FY16 LDRD Project LD1601
E. Chudakov, D. Higinbotham, C. H., S. Furletov, Yu. Furletova, D. Nguyen, M. Stratmann, M. Strikman, C. Weiss.
https://wiki.jlab.org/nuclear_gluons/index.php/Main_Page
Investigate feasibility of direct measurements (with EIC@JLab) of nuclear gluons at xglue ≥ 0.1, via open-charm (open-beauty) production.
Simulation codes under development Analytic codes, MC + fragmentation via HVQDIS, PYTHIA...
Detector Simulations in GEMC/GEANT4
Initial results
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Gluons & Nuclear Binding
Shadowing (coherent gluons from NN, NNN ...) ALICE data:
ultra-peripheral AAà AA J/Ψ
x = 0.001 — 0.01
Expectation of gluonic anti-shadowing at x ≈ 0.1
L. Frankfurt et al. / Physics Reports 512 (2012) 255–393 305
Fig. 34. Prediction for nuclear PDFs and structure functions for 208Pb. The ratios Rj (u and c quarks and gluons) and RF2 as functions of Bjorken x at Q 2 = 4,10, 100 and 10, 000 GeV2. The four upper panels correspond to FGS10_H; the four lower panels correspond to FGS10_L.
The numerical value of the exponent � = 0.25 in Eq. (126) can be understood as follows. The x dependence of nuclearshadowing at small x is primarily driven by the xP dependence of the Pomeron flux fP/p(xP) / 1/x(2↵P�1)
P / 1/x1.22P . There-fore, in the very small x limit, one expects from Eq. (64) that, approximately,
�F2A(x,Q 2)/A /✓1x
◆0.22
,
�xgA(x,Q 2)/A /✓1x
◆0.22
, (127)
which is consistent with our numerical result in Eq. (126).When we present our predictions for nuclear shadowing in the form of the ratios of the nuclear to nucleon PDFs, it is
somewhat difficult to see the leading twist nature of the predicted nuclear shadowing because of the rapid Q 2 dependenceof the free nucleon structure functions and PDFs. In order to see the leading twist nuclear shadowing more explicitly, oneshould examine the absolute values of the shadowing corrections.
Fig. 38 presents |�F2A(x,Q 2)/A| and |�xgA(x,Q 2)/A| as functions of Q 2 at fixed x = 10�4 (first and third rows) andx = 10�3 (second and fourth rows) for 40Ca (four upper panels) and 208Pb (four lower panels). The solid curves correspondto FGS10_H; the dotted curves correspond to FGS10_L. Also, for comparison, presented by the dot-dashed curves, we give
0.0001 0.001 0.01 xglue
)2 =
2.4
GeV
2 µ(x
, PbR
0.10.20.30.40.50.60.70.80.9
HKN07LOnDSLOEPS08 LOEPS09 LOEPS09 uncertainty
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Tagging Photon-Gluon Fusion via Open Charm Production
xglueG(xglue) support localized near xglue ≥ xBj[1+4mh
2/Q2] .
Results: Sensitivity to large–x′ gluons 8
_
e’
h
h
x, Q2
G ( )x’A
x’
e
= c, b
Fh2 (x,Q
2) =
∫ 1
ax
dx′
x′x′G(x′) F h
g (x/x′, Q2, m2
h, µ2)
coefficient function
a = 1 +4m2
h
Q2sets limit of x′ integral
0
2
4
6
8
0 0.2 0.4 0.6 0.8 1
Inte
gran
d o
f F 2
(cha
rm)
[nor
mal
ized
]
x’
x = 0.1, Q2 = 10 GeV2
x = 0.2, Q2 = 10 GeV2
• Integrand localized in x′ aroundlower limit ax
• Heavy quark production probeslarge–x′ gluons “almost locally”
Results: Sensitivity to large–x′ gluons 8
_
e’
h
h
x, Q2
G ( )x’A
x’
e
= c, b
Fh2 (x,Q
2) =
∫ 1
ax
dx′
x′x′G(x′) F h
g (x/x′, Q2, m2
h, µ2)
coefficient function
a = 1 +4m2
h
Q2sets limit of x′ integral
0
2
4
6
8
0 0.2 0.4 0.6 0.8 1
Inte
gran
d o
f F 2
(cha
rm)
[nor
mal
ized
]
x’
x = 0.1, Q2 = 10 GeV2
x = 0.2, Q2 = 10 GeV2
• Integrand localized in x′ aroundlower limit ax
• Heavy quark production probeslarge–x′ gluons “almost locally”
Results: Sensitivity to large–x′ gluons 8
_
e’
h
h
x, Q2
G ( )x’A
x’
e
= c, b
Fh2 (x,Q
2) =
∫ 1
ax
dx′
x′x′G(x′) F h
g (x/x′, Q2, m2
h, µ2)
coefficient function
a = 1 +4m2
h
Q2sets limit of x′ integral
0
2
4
6
8
0 0.2 0.4 0.6 0.8 1
Inte
gran
d o
f F 2
(cha
rm)
[nor
mal
ized
]
x’
x = 0.1, Q2 = 10 GeV2
x = 0.2, Q2 = 10 GeV2
• Integrand localized in x′ aroundlower limit ax
• Heavy quark production probeslarge–x′ gluons “almost locally”
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Total Open-Charm Rates @ EIC
Tagging efficiency study in-process
Expected ≥ 10%
Results: Total charm rate at EIC 7
102
103
104
105
106
107
108
109
1010
0.001 0.01 0.1 1
Num
ber o
f eve
nts
x
seN = 1000 GeV2, L(int) = 107 nb-1
total
charm
Proton 5 < Q2 < 15 GeV2
5 < Q2 < 50 GeV2
• Here 5 bins per decade in x, single wide bin in Q2
• Rates drop rapidly at large x• Nuclear rates comparable: Structure function Fc
2A ∼ AFc2N , but luminosity LA ≈ LN/A
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Open Charm Reconstruction
cà D0 à π+ K–
c à D*+ à π+slow
+D0 à π+ K–
21 Oct. 2015 Sergey Furletov 5
Charm production in DIS
BGF process provides direct sensitivity to thegluon density in the proton.
Due to the large gluon density in the proton, theBGF processes gives large contributions to DIS
The leading order diagram
The measurement was performed in the kinematic range of 1.5 < Q2 < 1000 GeV 2
and 0.02 < y < 0.7
D0
D* à π D0
ZEUS, Q2 ≥ 1.5 GeV2 Luminosity 80 /pb
EIC Luminosity 10-100 /fb/yr (1033 – 1034 /cm2/s)
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
EIC Kinematic Distributions
Yu. Furletova
Charm and Beauty events are different from inclusive DIS!
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
3
Minimum bias (e/p 10/100)
N~σL ~ 20·10-30·1034 ~200,000/secScattered e π±/K± e± μ± gammas from π0
PhP0.001<Q2<1
DIS1<Q2<100
DISQ2>100
σ~20μb
σ~600nb
σ~2nb
~5/event~0.02/event ~0.001 /event ~4/event
η
Pto
t,G
eV
p e
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
4Yulia Furletova
Charm BGF gγ->QQ
Scattered e π±/K± e± μ±gammas from π0
0.001<Q2<1
1<Q2<100
Q2>100
σ ~60 nb (e/p 10/100) N~60·10-33·1034 ~600/sec
11/event 0.2/event 0.2/event 7/event
Boson Gluon Fusion (BGF)
Pto
t,G
eV
η
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
5Yulia Furletova
Beauty BGF gγ->QQ
Scattered e π±/K± e± μ±gammas from π0
0.001<Q2<1
1<Q2<100
Q2>100
σ ~0.3 nb(e/p 10/100)
N~0.3·10-33·1034~3/sec
16/event 0.5/event 0.4/event 10/event
B¯ -> D0 µ ν, D0 -> K-π+
Pto
t,G
eV
η
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
EIC Charm Reconstruction
S. Furletov HVQDIS + PYTHIA
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
27 Jan. 2016 Sergey Furletov 3
Pt distribution & cuts
c à D*+ à π+slow
+D0 à π+ K–
pT (D*+)
pT(π+slow
)
pT(K–) pT(π+D0)
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Secondary Vertex (D0àπK)
S. Furletov Pythia simulation
EIC Kinematics 10 x 100 GeV2
27 Jan. 2016 Sergey Furletov 6
Vertex distribution
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
LDRD Next Steps Kinematic Distributions
& Reconstruction Efficiencies differential in xglue
Which performance characteristics (and which portions of detector) are crucial to charm and beauty reconstruction
Vertex Tracker Design and performance
(Yu. Furletova)
Kinematics of charm production
0
0.5
1
1.5
2
2.5
3
3.5
4
-1.2 -1 -0.8 -0.6 -0.4 -0.2 0log10(xBJ)
log 10
(Q2 )
S. Furletov 12 Feb 2016 10x100 GeV2
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
EIC @ JLab Vertex Tracker Initial concept, implementation
in GEMC and event simulation Yu. Furletova, 10 Feb 2016
Central beam pipe concept C.H., Z. ZhaoàGEMC 12 Feb 2016
3 m
Central- Solenoid, Detectors, not shown
Forward-ion Dipole
Forward iFFQ
Upstream eFFQ + Shield
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016
Conclusions Exciting program to probe gluon structure on nuclei
Important driver for EIC Detector design
80 m long detector: From 0° electron tagger
& Compton Polarimeter to ion far-forward spectrometer & neutron ZDC
Forward Dipole 6 mrad bend (Pbeam)
Ion FFQ Far-Forward
Dipole
ZDC
High-Dispersion Focus
Tracking Volume
16 m long
C.Hyde, Next Gen. Nucl. Phys. 10–13 Feb 2016