1
Fatiha [email protected]
Studies of Partonic
Distributions using Kaon SIDIS
Duquesne University, Pittsburgh, PA, USA
MENU 2019, Pittsburgh, PA
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Flavor decomposition Program using polarized and unpolarized Semi-
Inclusive hadron production from polarized and unpolarized hydrogen
and deuterium targets using CLAS12 detector enhanced with a RICH
counter
The Hybrid Ring Imaging Cerenkov Counter (RICH)
Expected Precisions and outlook
Outline
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Flavor Contributions to the Nucleon
Spin
Gq LΔGLΔq2
1
2
1
q
S
sΔΔsdΔΔduΔΔuΔq ,,,,,
-Our interest is on getting all the flavors! With a special interest of the strangeness.
« sea= virtual pairs »valence
As you saw, this morning, from M.
Contalbrigo and R. Seidl talks.
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E12‐09‐007 CLAS12 – Jefferson Lab-CLAS12 (H. Avakian, F. Benmokhtar, A. EL Alaoui, K. Hafidi & M. Mirazita)
Goal: Measurements of pions and kaons multiplicities and longitudinal double spin asymmetries using SIDIS off hydrogen and deuterium targets. Extract all the flavors!
Control of the fragmentation functions used in the extraction of the individual quark and antiquark contribution to the nuclear spin.
shape of the strange pdfs.
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Flavor decomposition
Unpolarized Measurements Polarized Measurements
Proton Deuteron Deuteron Proton
E12‐09‐007 CLAS12 – Jefferson Lab (H. Avakian, F. Benmokhtar, A. EL Alaoui, K. Hafidi & M. Mirazita)
Extract shape of
x(s(x) s(x))
Extract
x(s s)
x(u u d d)
Extract
xu,xd,xs,xu,xd,xs,x(ud)
Isoscalar Method
Flavor Decomposition
Measure Multiplicities
(π+ + π-, K+ + K-, Ks0)
Measure Asymmetries
(e-, π+ + π-, K+ + K-, Ks0)
Measure Multiplicities
(π+, π-, π0, K+, K-, Ks0)
Measure Asymmetries
(e-, π+, π-, π0, K+, K-, Ks0)
*Extraction of Δu − Δd to
test whether or not the
light sea is symmetrically
polarized
6
)Xepe( h
μν
μν'4
2
WLE
E
MQ
α
dEd
d
'
2
= E-E’
x = Q 2 /(2M )
y = /E
W 2 = M 2 - 2M - Q2
Q 2 = 4EE’sin 2(θ/2)
Semi Inclusive DIS
Hadron Selection: z = Eh /
xF = 2 |p||| / W
SIDIS Selection:
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Measurement of Δq in Semi-Inclusive DIS
Select PDFs : q -(x) or q +(x) by changing the orientation of target nucleon spin or helicity
of incident lepton beam
Leading order
Double spin asymmetry
xq
xq
zdzDxqe
zdzDxqe
h
h
~2
2
zxPh
q , - Dqh is a measure of the probability that
a quark of flavor q will fragment into a
hadron of type h = fragmentation
function
- Pqh Purity is a conditional probability
that a hadron of type h observed in the final state is originated from a struck quark of flavor q in case of unpolarized beam/target.
A(x,Q2) (A1p,A1p
,A1p
,A1p 0 ,A1p
K
,A1pK
,A1pKs0
,A1d ,A1d
,A1d
,A1d 0 ,A1d
K
,A1dK
,A1dKs0
)
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Deuteron Deuteron
Extract shape of
x(s(x) s(x))
Extract
x(s s)
x(u u d d)
Isoscalar Method
Measure Multiplicities
(π+ + π-, K+ + K-, Ks0)
Measure Asymmetries
(e-, π+ + π-, K+ + K-, Ks0)
Isoscalar MeasurementsUnpolarized Measurements Polarized Measurements For a deuteron target: Assuming isospin symmetry
& charge conjugation invariance:
Ad (x,Q2)
AdH (x,Q2)
CR
PNS (x,Q2) PS (x,Q
2)
PNSH (x,Q2) PS
H (x,Q2)
Q(x,Q2) Q(x,Q2)
S(x,Q2) S (x,Q2)
H = K+ + K-
H = Ks0
H = π+ + π-
Q u u d d
S s s
• Extract isoscalar combinations of ΔQ(x) and ΔS(x)
• Inclusive purities from PDFs (CTEQ-n, MRST, GRV…)
• Example: for Kaons, purities can be computed from the Kaon multiplicities and the pdfs.
Example: Kaon Purities
)()( zDzD KK
q
KK
q
- Using charge symmetry
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FF=Fit parametersMeasure
Multiplicities
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Flavor DecompositionUnpolarized Measurements Polarized Measurements
Proton Proton
Measure Multiplicities
(π+, π-, π0, K+, K-, Ks0)
Measure Asymmetries
(e-, π+, π-, π0, K+, K-, Ks0)
Deuteron Deuteron
Extract
xu,xd,xs,xu,xd,xs,x(ud)
- Purities depend on the unpolarized PDFs and the fragmentation functions.
- For the FFs, one can constrain them using measured pion and kaon multiplicities in the
same kinematical range from unpolarized proton and deuteron data,
- System can be solved by c2 minimization accounting for the correlations between the
various asymmetries.
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Jefferson Lab• Continuous Electron Beam Accelerator
Facility
• Upgrade in energy from 6 GeV to 12 GeV.
• Directed into Halls A, B, C, and D.
• E12-09-007 is taking place in Hall-B.
• Some of the unpolarized measurements were taken.
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Jefferson Lab CLAS12 @ 11GeV
Track resolutions:p (GeV/c) 0.003p + 0.001p2
(mr) < 1
(mr) < 3
Lumi > 1035cm-1s-1
Wide detector and physics
acceptance (current/target fragmentation)
High beam polarization 85%
High target polarization 85%
Hydrogen and Deuterium targets.
GeV/c 1 2 3 4 5 6 7 8 9 10
/K
/p
K/p
e/
HTCC
TOF
TOF
TOF
HTCC
HTCC
HTCCEC/PCAL
LTCC
LTCCRICH
LTCCLTCCRICH
LTCCRICH
Replace two LTTC
with a Ring Imaging
CHerenkov
1 RICH detector is
constructed
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CLAS12 Hybrid RICH Detector
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PhotoMultiplier Tubes
• Uses photoelectric effect• Multiplies photoelectrons using a dynode
system
• 391 mulit-anode photomultiplier tubes (MAPMTs, H12700) in RICH
• 8x8 matrix of pixels for spatial resolution => 25,024 channels
• High-speed electronics for signal processing
• Use ASIC for analog-to-digital conversion• Define thresholds for time-to-digital
conversion• Use Xilinx FPGA for parallel data acquisition• Response time of 0.5 ns• Data Rate: 10 MB/s• Overall Event Rate: 12,000 events/s 15
16F. Benmokhtar, APS 201716
Which Ones?
Assembling of the RICH
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RICH was installed in the CLAS12 spectrometer in January of 2018 and a second is under construction and will be completed by 2022.
Reconstruction programs underway then calibrations!
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Expected Precisions
Kaon Multiplicities and Frag. Func.
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Projections – Isoscalar Method
K+ + K- Ks0
F. Benmokhtar, CIPANP 2018
Corrections:
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Projections – Flavor
decomposition (1) -
10% systematics on
asymmetries
21F. Benmokhtar, CIPANP 2018F. Benmokhtar, CIPANP 2018
Corrections:
Test whether or not the light sea
is symmetrically polarized
Projections – (2) -
10% systematics on
asymmetries
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• Polarized deep-inelastic inclusive scattering(SMC)
-p elastic scattering
• Polarized Semi-Inclusive DIS (HERMES)
* 5 flavor tagging
* Isoscalar method-> published (2008) then reviewed and
published (2014), slightly positive
positive and 0 ~s
(E734 BNL)
World Data on S
• COMPASS: sidis m-NH3 (2010) compatible with zero.
• ATLAS results (2012) suggest that at small x the strangeness contribution
can be substantially larger than assumed. Phys. Rev. Lett. 109, 012001 – Published 5 July 2012
So far, the results vary widely and the uncertainties are big
“Strange quark polarization puzzle”
23F. Benmokhtar, CIPANP 2018
Corrections:
Projections – Flavor
decomposition (2) -
10% systematics on
asymmetries
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Expected Precisions x S(x)
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The systematics related to our knowledge of fragmentation functions
can further be reduced with high precision multiplicity measurements.
Test whether or not the light sea is symmetrically polarized.
Improve NLO global analysis of Helicity Parton densities and their
uncertainties.
Conclusion and Outlook
Thanks!
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Backup Slides
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- Cherenkov angle distributions for 8GeV/c pions tagged by the CERN T9 gas
Cherenkov compared with those of kaons and protons.
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Testing of MA-PMTs
- Hamamatsu H8500 and H12700 MAPMTs
- Inside the testing black-boxa Class 3b picosecond diode laser was used.Study 8x8 pixel per PMT
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