Transversely Polarized Proton Spin Measurements in Polarized

p+p Collisions in

Mickey Chiu

2

Left Right

2. Or, take the left-right difference between 2 detectors

This is susceptible to detector Relative Acceptance differences

1. Yield difference between up/down proton in a single detector

This is susceptible to Rel. Luminosity differences

Transverse Single Spin Asymmetries

)(

)(

)()(

)()(AN p

p

pp

pp

NRN

NRN

P

1A

lumi

lumi

beamN

Definition:where p is the 4-momentum of a particle (hadron, jet, photon, etc...)

RLRL

RLRL

beamN

NNNN

NNNN

P

1A

-lumi LLR

Mostly insensitive to Relative Luminosity and Detector Acceptance differences

3. Or, take the cross geometric mean (square-root formula)

Experimentally, there are a variety of (~equivalent) ways this can be measured.

LRdet

LRdet

beamRdetL

RdetL

beamN

NNR

NNR

P

1

NRN

NRN

P

1A

3

Transverse Proton Spin PhysicsgZ

qZ LLG

2

1

2

1 quark helicity distribution – known

transversity distribution – unknown

qqq

qqqT ggG gluon helicity distribution – poorly known

Polarized parton distribution functions

GeV 4.19at sXpp

E704

4q 10,20,3m example, N

qN AGeVsMeV

s

mA

Helicity violation term due to finite quark masses

Naïve LO, Leading Twist, pQCD Result

4

Transverse Proton Spin Physics

)ˆˆ( ),(2

1),(),(

///

ppSpzDpzDpzD qqqh

Nqhqh

•Various possible explanations have been proposed to explain these asymmetries

•Transversity x Spin-dep fragmentation (e.g., Collins effect),

•Intrinsic-kT in proton (Transverse Momentum Dep Functions) ,

•Eg, Sivers Function

•Perturbative LO Twist-3 Calculations (Qiu-Sterman, Efremov, Koike)•These calculations have been related to the Sivers function

•Or some combination of the above•Caveat: The theory is still being actively worked out

A Unified picture for single transverse-spin asymmetries in hard processes,Ji, Qiu, Vogelsang, Yuan PRL97:082002,2006

Anim. courtesy J. Kruhwel, JLAB

5

PHENIX at RHIC Spin

Run02 Run05 Run06

s (GeV/c2) 200 200 200 62.4

Ldt (pb-1) 0.15 0.15 2.7 0.02

<P> 0.15 0.47 0.57 0.50

P2L 0.0034 0.033 0.87 0.05

STARSTAR

PHENIX Transversely Polarized p+p Data Set

•Central Arm Tracking || < 0.35, xF ~ 0•Drift Chamber (DC)

•momentum measurement•Pad Chambers (PC)

•pattern recognition, 3d space point

•Time Expansion Chamber (TEC)•additional resolution at high pt

•Central Arm Calorimetry•PbGl and PbSc

•Very Fine Granularity•Tower x ~ 0.01x0.01

•Trigger•Central Arm Particle Id

•RICH•electron/hadron separation

•TOF /K/p identification

•Global Detectors (Luminosity,Trigger)•BBC 3.0 < || < 3.9

•Quartz Cherenkov Radiators•ZDC/SMD (Local Polarimeter)

•Forward Hadron Calorimeter•Forward Calorimetry 3.1 < || < 3.7

•MPC•PbWO4 Crystal

•Forward Muon Arms 1.2 < || < 2.4

MPC

6

•AN for both charged hadrons and neutral pions consistent with zero at midrapidity.•More statistics needed to map out pT x g/q dependence

•If large asymmetries at forward rapidities is from valence quark motion, does asymmetry at mid-rapidity appear at high enough xT = 2pT/s?

•Mid-rapidity data constrains magnitude of gluon Sivers function

p+p0+X at s=200 GeV/c2

PRL 95, 202001 (2005)

process contribution to 0, =0, s=200 GeV

Single Spin Asymmetries at xF=0

PLB 603,173 (2004)

7

Constraints on Gluon Sivers?Anselmino et al, PRD74:094011,2006

PHENIX 0, PRL 95, 202001 (2005)

•LO QCD Transverse Momentum Dependent parton scattering calculations•Cyan: Gluon Sivers Function at positivity bound, no sea quark Sivers•Thick Red: Gluon Sivers parameterized to be 1 sigma from PHENIX 0 AN

•Blue: Asymmetry from Sea quark Sivers at positivity bound•Green: Asymmetry from Gluon Sivers for case of sea quark at positivity bound

8

3.0<<4.0

p+p0+X at s=62.4 GeV/c2 p+p0+X at s=62.4 GeV/c2

0 AN at High xF

PLB 603,173 (2004)

process contribution to 0, =3.3, s=200 GeV

•Large asymmetries at forward xF

•Valence quark effect?•xF, pT, s, and dependence provide quantitative tests for theories

9

RHIC Forward Pion AN at 62.4 GeV

•Brahms Spectrometer at “2.3” and “3.0” setting <> = 3.44, comparable to PHENIX all eta•Qualitatively similar behavior to E704 data: pi0 is positive and between pi+ and pi-, and roughly similar magnitude: AN(pi+)/AN(pi0) ~ 25-50%•Flavor dependence of identified pion asymmetries can help to distinguish between effects

•Kouvaris, Qiu, Vogelsang, Yuan, PRD74:114013, 2006•Twist-3 calculation for pions for pion exactly at 3.3•Derived from fits to E704 data at s=19.4 GeV and then extrapolated to 62.4 and 200 GeV•Only qualitative agreement at the moment. Must be very careful in comparisons (between expt’s and theories) that kinematics are matched, since AN is a strong function of pT and xF.

PHENIX and Brahms Preliminary

E704, 19.4 GeV, PLB261, (1991) 201

10

Comparison to 0 at s = 200 GeV/c2

STARSTAR

•Trend with seems to disagree with STAR result, but is consistent with theoretical predictions.•This might just be due to the different collision energy and pT coverage

11

Kinematic Cuts and AN

eta<3.5

eta>3.5

•Mean AN is measured to be lower for pT>1, even though mean xF is higher for this pT bin, and higher xF implies higher asymmetry

•This implies that AN is dropping with pt for a given xF slice

•The cut, for a given xF slice, splits that slice into high pt and low pt, with the lower eta selecting higher pt

•This implies that AN at lower should be smaller, consistent with predictions of PRD74:114013

•However, at 62.4 GeV the pT are low (pQCD invalid?)•Cross-section is being analyzed now

Phys.Rev.D74:114013,2006Phys.Rev.D74:114013,2006..

sinhθcotP

p

P

px TTF

12

J/ AN

•Bkg from like-sign and sidebands•J/ Production is gluon dominated at RHIC

•Production thought to be not well understood•NRQCD describes data well?

•Gluon has zero transversity•Collins Effect suppressed•Gluon Sivers Dominant

•Anselmino et al, PRD70:074025 (hep-ph/0407100)•Calculation for Open Charm, NOT J/

Quark Sivers = MaxGluon Sivers = 0

Quark Sivers = 0Gluon Sivers = Max

Submitted to PRL

13

1-dimensional

Summary•Much new data coming from transversely polarized proton interactions

•p+p (RHIC), but also e+p SIDIS (Hermes, Compass, JLab), e+e- (Belle)•Along with new data on the helicity distribution of partons in the proton (gluon spin), transversely polarized proton collisions could add a wealth of new information on proton structure

•Transversity, Orbital angular momentum?•GPD’s may be cleanest way to OAM•However, strongest asymmetries are in p+p

PHENIX preliminary

* See Poster by M. Togawa

•PHENIX has measured the transverse asymmetry of 0, h, and J/, covering an xF from 0 to 0.6 (at two different collision energies).

•There are also sizable asymmetries from forward neutrons out to xF ~ 1.*•In the future, we expect ~25% of the polarized p+p running will be in the transverse mode

•Lots more data coming•New upgrade detectors should significantly enhance physics reach

•Nose Cone Calorimeter•Silicon Detectors (SVTX and FVTX)

proton wave-function

14

Abilene Christian University, Abilene, Texas, USA Brookhaven National Laboratory (BNL), Chemistry Dept., Upton, NY 11973, USABrookhaven National Laboratory (BNL), Collider Accelerator Dept., Upton, NY 11973, USABrookhaven National Laboratory (BNL), Physics Dept., Upton, NY 11973, USAUniversity of California - Riverside (UCR), Riverside, CA 92521, USAUniversity of Colorado, Boulder, CO, USA Columbia University, Nevis Laboratories, Irvington, NY 10533, USA Florida Institute of Technology, Melbourne, FL 32901, USAFlorida State University (FSU), Tallahassee, FL 32306, USA Georgia State University (GSU), Atlanta, GA 30303, USA University of Illinois Urbana-Champaign, Urbana-Champaign, IL, USAIowa State University (ISU) and Ames Laboratory, Ames, IA 50011, USA Los Alamos National Laboratory (LANL), Los Alamos, NM 87545, USALawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA University of Maryland, College Park, MD 20742, USADepartment of Physics, University of Massachusetts, Amherst, MA 01003-9337, USAOld Dominion University, Norfolk, VA 23529, USAUniversity of New Mexico, Albuquerque, New Mexico, USA New Mexico State University, Las Cruces, New Mexico, USA Department of Chemistry, State University of New York at Stony Brook (USB), Stony Brook, NY 11794, USA Department of Physics and Astronomy, State University of New York at Stony Brook (USB), Stony Brook, NY 11794, USA Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA University of Tennessee (UT), Knoxville, TN 37996, USA Vanderbilt University, Nashville, TN 37235, USA

University of São Paulo, São Paulo, BrazilAcademia Sinica, Taipei 11529, ChinaChina Institute of Atomic Energy (CIAE), Beijing, P. R. ChinaPeking University, Beijing, P. R. ChinaCharles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116 Prague, Czech RepublicCzech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Brehova 7, 11519 Prague, Czech RepublicInstitute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague, Czech RepublicUniversity of Jyvaskyla, P.O.Box 35, FI-40014 Jyvaskyla, FinlandLaboratoire de Physique Corpusculaire (LPC), Universite de Clermont-Ferrand, F-63170 Aubiere, Clermont-Ferrand, FranceDapnia, CEA Saclay, Bat. 703, F-91191 Gif-sur-Yvette, FranceIPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406 Orsay, FranceLaboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de Saclay, F-91128 Palaiseau, FranceSUBATECH, Ecòle des Mines at Nantes, F-44307 Nantes, FranceUniversity of Muenster, Muenster, GermanyKFKI Research Institute for Particle and Nuclear Physics at the Hungarian Academy of Sciences (MTA KFKI RMKI), Budapest, HungaryDebrecen University, Debrecen, HungaryEövös Loránd University (ELTE), Budapest, HungaryBanaras Hindu University, Banaras, IndiaBhabha Atomic Research Centre (BARC), Bombay, IndiaWeizmann Institute, Rehovot 76100, IsraelCenter for Nuclear Study (CNS-Tokyo), University of Tokyo, Tanashi, Tokyo 188, JapanHiroshima University, Higashi-Hiroshima 739, JapanKEK - High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan Kyoto University, Kyoto, Japan Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki, JapanRIKEN, The Institute of Physical and Chemical Research, Wako, Saitama 351-0198, JapanRIKEN – BNL Research Center, Japan, located at BNLPhysics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, JapanTokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, JapanUniversity of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi Ibaraki-ken 305-8577, JapanWaseda University, Tokyo, JapanCyclotron Application Laboratory, KAERI, Seoul, South KoreaEwha Womans University, Seoul, KoreaKangnung National University, Kangnung 210-702, South KoreaKorea University, Seoul 136-701, Korea Myong Ji University, Yongin City 449-728, Korea System Electronics Laboratory, Seoul National University, Seoul, South KoreaYonsei University, Seoul 120-749, KoreaIHEP (Protvino), State Research Center of Russian Federation , Protvino 142281, RussiaJoint Institute for Nuclear Research (JINR-Dubna), Dubna, Russia Kurchatov Institute, Moscow, RussiaPNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region 188300, RussiaSkobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Vorob'evy Gory, Moscow 119992, RussiaSaint-Petersburg State Polytechnical Univiversity , Politechnicheskayastr, 29, St. Petersburg 195251, RussiaLund University, Lund, Sweden

*as of July 2006 and growing

14 Countries; 68 Institutions; 550 Participants*

Collaboration, 2006

15

16

Run02 Inclusive AN Systematic Errors

• Measured asymmetry of background– Immediately outside the 0 mass peak– In the mass region between the 0 and the

• Compared independent measurements for two polarized beams • Compared results for left and right sides of detector• Compared minimum bias and triggered data samples• Examined fill-by-fill consistency of asymmetry values• Used the “bunch shuffling” technique to check for systematic errors

– Randomly reassign the spin direction to each bunch in the beam– Recalculate the asymmetry– Repeat many times (1000) to produce a “shuffled” asymmetry

distribution centered around zero– Compare width of shuffled distribution to statistical error on physics

asymmetry

In addition to calculating the asymmetry using more than one method, potential systematic errors have been investigated in the following ways:

17

Muon Piston Calorimeter Performance

MIP Peak

Backgroundsubtracted

All PairsMixed Events

•Photon Pair Cuts•Pair Energy > 8 GeV•Asymmetry |E1-E2|/|E1+E2| < 0.6•Noisy Towers (up to 25% of MPC) Excluded

•Width ~ 20 MeV

•Shower Reconstruction Using Shower Shape Fits •Energy Scale Set by MIP•In Noisy Towers, Used Tower Spectrum

•Confirmed with 0, peaks

18

MPC N Fit Examples, Fill 8015

•Black: Fit of to polarization raw asymmetry•R is consistent with the Relative Luminosity determined from scalers (where possible)

)(N)(N

)(N)(N)(N

R

)sin( NR

•Red: Fit of to square root raw asymm)cos( N )(N)(N)(N)(N

)(N)(N)(N)(N)(

RLRL

RLRLN

•Both polarization and sqrt asymmetries were calculated•Polarization asymmetries were used for the final numbers •The RMS difference between different plot/fit techniques was considered to be a systematic error.

•Other systematic errors (residual relative luminosity in unpolarized beam, background subtraction of pi0) were small.

19

NCCNCC

MP

C

MP

C

VTX & FVTX

-3 -2 -1 0 1 2 3

cove

rage

2

HBD

EM

CA

LE

MC

AL

Future PHENIX Acceptance

•History – PHENIX is a small acceptance, high rate, rare probes (photons, J/Psi, etc.) detector•Future – Add acceptance and add some new capabilities (hadron blind, displaced vertex)

•Muon Piston Calorimeter (2006-end): PbWO4 Electromagnetic Calorimeter•Hadron Blind Detector (2007-2009): CsI Triple GEM Cerenkov Detector•Nose Cone Calorimeter (2010-end): Tungsten-Silicon Electromagnetic Calorimeter with limited Jet Capabilities (1 arm, possibly 2 with funding)•SVTX (2009-end): Central Arm Silicon Tracker•FVTX (2010-end): Muon Arm Silicon Tracker