Latest results of nucleon spin structure measurements from PHENIX
RIKEN/RBRCItaru Nakagawa
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The Relativistic Heavy Ion Collideraccelerator complex
at Brookhaven National Laboratory
PHENIXSTAR
Brahmspp2pp
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RHIC p+p accelerator complex
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v vv
BRAHMS & PP2PP
STARPHENIX
AGS
LINACBOOSTER
Pol. Proton Source
Spin Rotators
20% Snake
Siberian Snakes
200 MeV polarimeter Rf Dipoles
RHIC pC “CNI” polarimeters
PHOBOS
RHIC
absolute pHpolarimeter
SiberianSnakes
AGS pC “CNI” polarimeter
5% Snake
Coulomb-Nuclear Interference
PHENIX Experiment
4Pioneering High Energy Nuclear Interaction EXperiment
13 Countries; 70 Institutions
Abilene Christian University, Abilene, TX 79699, U.S.Baruch College, CUNY, New York City, NY 10010-5518, U.S.Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.University of California - Riverside, Riverside, CA 92521, U.S.University of Colorado, Boulder, CO 80309, U.S.Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, NY 10533, U.S.Florida Institute of Technology, Melbourne, FL 32901, U.S.Florida State University, Tallahassee, FL 32306, U.S.Georgia State University, Atlanta, GA 30303, U.S.University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.Iowa State University, Ames, IA 50011, U.S.Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.University of Maryland, College Park, MD 20742, U.S.Department of Physics, University of Massachusetts, Amherst, MA 01003-9337, U.S. Morgan State University, Baltimore, MD 21251, U.S.Muhlenberg College, Allentown, PA 18104-5586, U.S.University of New Mexico, Albuquerque, NM 87131, U.S. New Mexico State University, Las Cruces, NM 88003, U.S.Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.Department of Physics and Astronomy, Ohio University, Athens, OH 45701, U.S.RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.Chemistry Department, Stony Brook University,SUNY, Stony Brook, NY 11794-3400, U.S.Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, NY 11794, U.S.University of Tennessee, Knoxville, TN 37996, U.S.Vanderbilt University, Nashville, TN 37235, U.S.
Universidade de São Paulo, Instituto de Física, Caixa Postal 66318, São Paulo CEP05315-970, BrazilInstitute of Physics, Academia Sinica, Taipei 11529, TaiwanChina Institute of Atomic Energy (CIAE), Beijing, People's Republic of ChinaPeking University, Beijing, People's Republic of ChinaCharles University, Ovocnytrh 5, Praha 1, 116 36, Prague, Czech RepublicCzech Technical University, Zikova 4, 166 36 Prague 6, Czech RepublicInstitute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech RepublicHelsinki Institute of Physics and University of Jyväskylä, P.O.Box 35, FI-40014 Jyväskylä, FinlandDapnia, CEA Saclay, F-91191, Gif-sur-Yvette, FranceLaboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128, Palaiseau, FranceLaboratoire de Physique Corpusculaire (LPC), Université Blaise Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere Cedex, FranceIPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406, Orsay, FranceDebrecen University, H-4010 Debrecen, Egyetem tér 1, HungaryELTE, Eötvös Loránd University, H - 1117 Budapest, Pázmány P. s. 1/A, HungaryKFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences (MTA KFKI RMKI), H-1525 Budapest 114, POBox 49, Budapest, HungaryDepartment of Physics, Banaras Hindu University, Varanasi 221005, IndiaBhabha Atomic Research Centre, Bombay 400 085, IndiaWeizmann Institute, Rehovot 76100, IsraelCenter for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, JapanHiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, JapanKEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, JapanKyoto University, Kyoto 606-8502, JapanNagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki 851-0193, JapanRIKEN, The Institute of Physical and Chemical Research, Wako, Saitama 351-0198, JapanPhysics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, JapanDepartment of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, JapanInstitute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305, JapanChonbuk National University, Jeonju, KoreaEwha Womans University, Seoul 120-750, KoreaHanyang University, Seoul 133-792, KoreaKAERI, Cyclotron Application Laboratory, Seoul, South KoreaKorea University, Seoul, 136-701, KoreaMyongji University, Yongin, Kyonggido 449-728, KoreaDepartment of Physocs and Astronomy, Seoul National University, Seoul, South KoreaYonsei University, IPAP, Seoul 120-749, KoreaIHEP Protvino, State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, 142281, RussiaINR_RAS, Institute for Nuclear Research of the Russian Academy of Sciences, prospekt 60-letiya Oktyabrya 7a, Moscow 117312, RussiaJoint Institute for Nuclear Research, 141980 Dubna, Moscow Region, RussiaRussian Research Center "Kurchatov Institute", Moscow, RussiaPNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region, 188300, RussiaSaint Petersburg State Polytechnic University, St. Petersburg, RussiaSkobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Vorob'evy Gory, Moscow 119992, Russia Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden
Feb 2011
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PHENIX detector
• Global detectors– beam-beam counter (BBC),
zero-degree calorimeter (ZDC)• Minimum-bias trigger• Luminosity measurement• Local polarimeter
• Philosophy– high resolution at the cost of
acceptance– high rate capable DAQ– excellent trigger capability for
rare events• Central Arms
– |h| < 0.35, Df = /p 2×2– Momentum and energy
measurement, particle-ID– Detecting electron, photon,
hadron– Small amount of material to
reduce conversion background
• Muon Arms– 1.2 < |h| < 2.4– Momentum measurement and
muon-ID– Hadron absorber (muon piston)
DG DOUBLE HELICITY ALL RESULTS
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Probe Advantage
p0 Statistics
h Different fragmentation
p0 - p0 correlation Kinematic constraint
charged p DG sign
heavy flavor decay e- Lower x, g-g dominant
MPC cluster Lower x
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PDFs from Asymmetries
• Example:o Choose channel with high statistics: p + p → π0 + Xo Complicated mixture of amplitudes, changes
as a function of kinematics.
o How does one extract ΔG from the experimentally determined:
o Requires calculational techniques based on factorization.
gqgq G
G
q
q
qqqqq
q
q
q
gggg G
G
G
G
1LL
B Y
N N R N NA
P P N N R N N
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Factorization
,
ˆ a bf f fX hLL a b f
a b
f f D
f h z
Δfa,b = polarized quark and gluon distribution functions
Δ
Δ
Δ Dhf = fragmentation
function for
Partonic cross section from pQCD
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Polarized gluon distribution (I) • Central Rapidity
p0
Phys. Rev. D83,032001 (2011)
Abundant Statistics
Sensitive to sign of gp0 , p+/-
h Different fragmentation
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Polarized gluon distribution (II) • Central + Forward Rapidity, Low Energy
Phys. Rev. D87, 012011 (2013)
Single e High purity of glue-glue subprocess
Forward Cluster Small x ~ 10-3 0 at s = 62.4 GeV
Phys. Rev. D79, 012003 (2009)
High x
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Extraction of Gluon Polarization
Quark
Strangeness
Gluon
Anti-quark
QCD Global
Fit
DISSIDIS
pp
PHENIXSTAR(2005,2006)
HERMESCOMPASSJlab…
RHIC data constrain ongluon polarization!
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QCD global analysis Interpretation
DSSV++ (with latest results)
First Positive Polarization DG Result :
SEA QUARK POLARIZATIONPRELIMINARY AL
W FROM RUN12
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Probe Rapidity Advantage
W->e central Good S/N
W->m forward Enhanced sea quark
W-Boson Production @ √s = 500 GeV
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Parity Violation AsymmetryClean flavor separationw/o fragmentation uncertainty
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Single e,m PT Spectra
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W->e+ (Mid Rapidity)
W+BG
BG only
W->m+ (Forward Rapidity)
Signal
Background PT [GeV/c]
S/B ~ 1/3
Background estimation in data driven manner
Resolution Improvement for better S/N in progress
W-boson Asymmetry (Run12)
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Poor knowledge of Sea quark Polarization
Wide rapidity coverage
• Boxes are systematic uncertainties from background
• Run 2012 Beam Polarization uncertainty P/P = 3.4% (not shown)
W measurement Run13 Projections
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Existing data + Run13 Data
Delivered Luminosity
RHIC white paper
Existing data
TRANSVERSE SINGLE SPIN ASYMMETRY AN
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Probe Rapidity Advantage
p0, eta central Good S/N
MPC Cluster forward Enhanced sea quark
neutron Very Forward
Transverse structure of the nucleon
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• Single transverse-spin asymmetry
– Expected to be small in hard scattering at high energies
• FNAL-E704– Unexpected large asymmetry found
in the forward-rapidity region– Development of many models
based on perturbative QCD
RightLeft
RightLeftN dd
ddA
p
p
Transverse-spin physics• For establishment of TMD and higher-
twist approach– Single transverse-spin asymmetry (SSA)
of inclusive hadrons– Sivers effect
• Sivers distribution function (initial state)– transverse-momentum dependence of
partons inside the transversely-polarized nucleon
– Collins effect• Transversity distribution (initial state)
– correlation between transversely-polarized nucleon and transversely-polarized partons inside
• Collins fragmentation function (final state)
– Higher-twist effect• quark-gluon & multi-gluon correlation 22
S
P
kT
,pp
p
S
Pp
p
S
q
kT
,π
Sivers effect
Collins effect
Inclusive 0
Transverse-spin physics
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Forward EM cluster at s = 200 GeV
no decrese at high pT expected from higher-twist effect
constrains gluon Sivers effect
arXiv:1312.1995 To be published from PRD
Midrapidity 0 and
neutron
neutronBBC hits
Very Forward Neutron
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large negative asymmetryused for local polarimetry!
Phys. Rev. D88, 032006 (2013)
Single pion exchange?
3-dimensional nucleon structure• Nucleon structure beyond the simple parton picture• Many-body correlation of partons
– To describe the orbital motion inside the nucleon
• Parton distribution in transverse direction– Extended/generalized picture of the parton distribution– Transverse-momentum dependence (TMD)– Space distribution (tomography)
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Phenomenological modelwith GPD data
Lattice QCD calculation
MPC-EX upgrade
• MPC (Muon Piston Calorimeter) – Electromagnetic calorimeter
• MPC-EX– Preshower detector– Commissioning in 2014– Experiment in 2015-2016
• 3.1 < || < 3.8– Installed in the muon piston
• Direct photon asymmetry– To distinguish the Sivers effect and
the higher-twist effect• Collins asymmetry in jets
– 0 correlation with jet-like clusters26
MPC
MPC-EX
49pb-1, P=0.6
Twist-3 p+p prediction
SIDIS (TMD) p+p prediction
Phys Rev. D 83 094001 (2011)arXiv 1208.1962v1 (2012)
AN
xF
Charged clusters with >=3 tracks, single-track p0’s
sPHENIX upgrade• sPHENIX– Barrel upgrade– Forward upgrade– Partial installation and commissioning in
2018-2019– Completion and experiment in 2021-
2022• Barrel upgrade baseline
– Compact jet detector– Using upgraded RHIC accelerator– For precision measurement of jet, dijet,
photon-jet correlation to understand the nature of QGP
• Barrel upgrade extension– Additional tracking layers– Preshower detector– For heavy-flavor and internal jet
structure measurements27
sPHENIX forward upgrade• Open geometry
– Wide kinematic coverage of photon, jet, leptons and identified hadrons
• Compatible design for eRHIC detector (ePHENIX)– Constraint from IR design of eRHIC (|z| < 4.5m)– Hermeticity for exclusive measurements
28GEMStation4
EMCal
HCal
GEMStation2
z (cm)
R (cm)
HCal
η~1
η~4
η~-1
R (cm)
SiliconStation1
MuID
Central silicon tracking
EMCal& Preshower RICH
GEMStation3
Aerogel
twist 3
Fit of SIDIS
SIDIS olds = 200 GeVy=3.3 jets
sPHENIX forward upgrade• Sivers effect in Drell-Yan process
– Valence quark region at x0.2 with 1 < < 4 coverage
• Jet asymmetry– Sivers effect or higher-twist effect
• Asymmetry inside of jets– Collins effect
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jet ® h+X
Summary• Origin of the nucleon spin 1/2
– Gluon-spin contribution AL• First non-zero positive gluon polarization by pQCD fit on Run9 data
– Sea-quark contribution• Wide rapidity coverage. Sensitive to sea quark polarization at
forward
• Understanding of transverse-spin phenomena– Sivers effect / Collins effect / higher-twist effect– 3-dimensional nucleon structure– Many-body correlation of partons
• AN measurements
• The forward sPHENIX upgrades toward understanding of the 3-dimensional nucleon structure– Polarized Drell-Yan measurement / jet asymmetry and
asymmetry inside of jets– Evolution to ePHENIX toward electron-proton collisions at
eRHIC 30
BACKUP
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Run11 Central Arm W->e
32Backgrounds could be mitigated by relative isolation cut
Run9 PRL106,062001 (2011)
Signal electron :• High momentum electron• Isolated
Single Electron PT Spectra
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Back
grou
nd D
omin
ant
Sign
al +
Bac
kgro
und
Signal
Background
• Power Law Counting
Background Shape Fixed in
10<PT<20 GeV/c
• Jacobian Peak (PYTHIA+GEANT)
+ Power Low Background Fitting• Resulting Background
contamination 14 ~ 17%.
Run11
Forward W-> m Analysis
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Single Muon PT Spectra
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Efficiency corrections W/Z cross section employed
RHICBOS NLO S/B estimation from fixed W/Z
cross section (RHICBOS NLO)
S/B ~ 1/3
Background estimation in data driven manner
Resolution Improvement for better S/N
The First Forward ALW
Results
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More to come!
Run11 Run12Luminosity 25 50
First Forward W Asymmetry Results!
References
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[1]
Global Fit including Run9 0 ALL 38
By S.Taneja et al (DIS2011)ala DSSV with slightly different uncertainty evaluation approach
DSSV DSSV + PHENIX Run9 0 ALL
No node …Uncertainties decreasedA node at x~0.1 ?
Charged pion Cross Section
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Charge separated fragmentation functions are not well constrained in DSS FFs
In good agreement with STAR
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HBD Analysis for Heavy Flavor Decay e-
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HBD Signal Occupancy
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DG Extraction from ALLHFe
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Open charm production dominates in pT range of 0.50 < pT < 1.25 GeV/c (J/ψ <2%, b quark<5%)
pQCD prediction for ALLopen charm
obtained from CTEQ6M PDFs + PYTHYA + LO hard scattering cross section
ALLopen charm ~|∆g/g(x, µ)|2
|∆g(x, µ)| = C g(x, µ) is assumed
Results: |∆g/g( logx ,µ)|⟨ ⟩ 2 <3.3 ×10 −2 (1σ)
and 10.9 ×10 −2 (3σ)
Central W Analysis
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Central Arm AL
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The PHENIX Detector• Philosophy
– high resolution & high-rate at the cost of acceptance
– trigger for rare events
• Central Arms– |h| < 0.35, Df ~ p– Momentum, Energy, PID
• Muon Arms– 1.2 < |h| < 2.4– Momentum (MuTr)
• Muon Piston Calorimeter– 3.1 < |h| < 3.9
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h+
,0
m
MPC
Further Sea Quark Measurement w/ DY
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FVTX (S) FVTX (N)
VTX
VTX
ϒ-states
J/Ψ
Drell Yan
charmbeauty
Invariant mass (GeV)
S/B contributionsw/o vertex detector
Low
-mass
DY
High-mass DY
Extract DY events from heavy flavorsusing FVTX