RHIC AGS Annual Users Meeting BNL June 1

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RHIC & AGS Annual Users’ Meeting, BNL, June 1 -5, 2009 Measuring Transverse Spin

RHIC & AGS Annual Users’ Meeting, BNL, June 1 -5, 2009 Measuring Transverse Spin Phenomena at PHENIX Ruizhe Yang, RHIC & AGS Users' Meeting 1

Physics motivation Spin structure of transversely polarized proton Left Define left-right asymetry Right Theory

Physics motivation Spin structure of transversely polarized proton Left Define left-right asymetry Right Theory Expectation: Small asymmetries at high energies (Kane, Pumplin, Repko, PRL 41, 1689– 1692 (1978) ) AN ~10 -4 from theory E 704 π+ π0 π- Experiment: E 704, Fermilab, 1991 AN ~10 -1 measured Ruizhe Yang, RHIC & AGS Users' Meeting

Possible origins of large AN Proton Structure p. QCD Quark Fragmentation Sivers Effect: Collins

Possible origins of large AN Proton Structure p. QCD Quark Fragmentation Sivers Effect: Collins Effect: Correlation between proton spin and quark transverse momentum Correlation between proton & quark spin + spin dependent fragmentation function Quark transversity Sivers distribution D. Sivers, Phys. Rev. D 41, 83 (1990) Ruizhe Yang, RHIC & AGS Users' Meeting Collins FF J. C. Collins, Nucl. Phys. B 396, 161 (1993) 3

Global analysis Ruizhe Yang, RHIC & AGS Users' Meeting

Global analysis Ruizhe Yang, RHIC & AGS Users' Meeting

Polarized p+p at RHIC p. C Polarimeters Absolute Polarimeter (H jet) Siberian Snakes PHOBOS

Polarized p+p at RHIC p. C Polarimeters Absolute Polarimeter (H jet) Siberian Snakes PHOBOS BRAHMS & PP 2 PP Siberian Snakes Spin Flipper STAR PHENIX • 2008 Run Spin Rotators Polarized Source Partial Snake Strong Snake LINAC 200 Me. V Polarimeter BOOSTER Helical Partial Snake • 2009 Run AGS Rf Dipole AGS Internal Polarimeter AGS p. C Polarimeter Ruizhe Yang, RHIC & AGS Users' Meeting 5 Large transverse data sample collected Excellent performance during first 500 Ge. V run at RHIC ~10 pb-1 200 Ge. V run ongoing Avg. polarization at 55%

PHENIX Detector at RHIC Central Arms | η | < 0. 35 • Identified

PHENIX Detector at RHIC Central Arms | η | < 0. 35 • Identified charged hadrons • Neutral Pions • Direct Photon • J/Psi • Heavy Flavor Muon Arms 1. 2 < | η | < 2. 4 • J/Psi • Unidentified charged hadrons Contribution to • Process Heavy Flavor 0, η=0, s=200 Ge. V MPC 3. 1 < | η | < 3. 9 • Neutral Pion’s • Eta’s ZDC • Neutrons Ruizhe Yang, RHIC & AGS Users' Meeting 6 | | ~ 5. 9

Cross section measurement 0 Cross-Sections at ~ 0 § Compare with p. QCD calculation

Cross section measurement 0 Cross-Sections at ~ 0 § Compare with p. QCD calculation § Agreement at 200 Ge. V (RHIC) § Agreement at 62. 4 Ge. V (RHIC) de Florian, Vogelsang, Wagner PRD 76, 094021 (2007) Bourrely and Soffer Eur. Phys. J. C 36: 371 -374 (2004) Ruizhe Yang, RHIC & AGS Users' Meeting 7

AN from 0, h+/- at central rapidity PHENIX transverse running at 2002 PHENIX transverse

AN from 0, h+/- at central rapidity PHENIX transverse running at 2002 PHENIX transverse running in 2005 PRL 95, 202001 (2005) Analysis with high statistics 2006+2008 data in progress Smaller statistical uncertainties (more than factor of 7 improvement) Higher p. T data points possible Ruizhe Yang, RHIC & AGS Users' Meeting

Constrain gluon Sivers effect 0 AN from PHENIX 2002 data Anselmino et al, Phys.

Constrain gluon Sivers effect 0 AN from PHENIX 2002 data Anselmino et al, Phys. Rev. D 74, 094011 Upper bound for gluon Sivers function that is consistent with PHENIX results, assuming vanishing sea contribution Ruizhe Yang, RHIC & AGS Users' Meeting

Forward 0 AN Forward asymmetries contain mixture of n Sivers n Transversity x Collins

Forward 0 AN Forward asymmetries contain mixture of n Sivers n Transversity x Collins PHENIX 0 results available for s=62 Ge. V Analysis of large 2008 s=200 Ge. V dataset – AN of 0 and – 5. 2 pb-1, 46% Polarization – work in progress Asymmetries could enter a global analysis on transverse spin asymmetries Ruizhe Yang, RHIC & AGS Users' Meeting 10 PLB 603, 173 (2004) Process contribution to 0, =3. 3, s=200 Ge. V

SSA from di-hadron production SSA from Interference Fragmentation Function (IFF) • Measure di-hadron asymmetry

SSA from di-hadron production SSA from Interference Fragmentation Function (IFF) • Measure di-hadron asymmetry with hadron pairs in central arm ( 0, h+) ( 0, h-), (h+, h-) • • Transversity extraction will become possible with Interference Fragmentation Function measurement in progress at BELLE (see A. Vossen’s talk in the same session) • Two different theoretical models gave different prediction of mass dependence • Sign change is not observed in HERMES/COMPASS results Jaffe, Jin and Tang, PRL 80 (1998) 1166 Bacchetta and Radici , Phys. Rev. D 74, 114007 (2006) Ruizhe Yang, RHIC & AGS Users' Meeting 11

IFF: Definition of Vectors and Angles Bacchetta and Radici, PRD 70, 094032 (2004) Ruizhe

IFF: Definition of Vectors and Angles Bacchetta and Radici, PRD 70, 094032 (2004) Ruizhe Yang, RHIC & AGS Users' Meeting

SSA from di-hadron production No significant asymmetries seen at mid-rapidity. Added statistics from 2008

SSA from di-hadron production No significant asymmetries seen at mid-rapidity. Added statistics from 2008 running Ruizhe Yang, RHIC & AGS Users' Meeting 13

SSA from di-hadron production No significant asymmetries seen at mid-rapidity. Added statistics from 2008

SSA from di-hadron production No significant asymmetries seen at mid-rapidity. Added statistics from 2008 running Ruizhe Yang, RHIC & AGS Users' Meeting 14

Sivers effect in di-jet production Azimuthal distribution of Di-Jet production in pp Boer and

Sivers effect in di-jet production Azimuthal distribution of Di-Jet production in pp Boer and Vogelsang, PRD 69, 094025 (2004) Counts Proton Spin k. T df Beam is in and out of page Look at back-to-back jet opening angles df Sensitive to Sivers function only! No Collins-type effects Ruizhe Yang, RHIC & AGS Users' Meeting Sivers distribution 15

Sivers effect in di-hadron production 0 h+/- Similar analysis possible in different combinations of

Sivers effect in di-hadron production 0 h+/- Similar analysis possible in different combinations of rapidity PHENIX Result from 2006 data: § Di-hadrons at central rapidities § Asymmetry consistent with zero § Analysis with large 2008 data in progress Ruizhe Yang, RHIC & AGS Users' Meeting 16 ηmin -3. 7 -2. 0 -0. 35 1. 4 3. 1 ηmax -3. 1 -1. 4 +0. 35 2. 0 3. 9 (Work in progress)

Sivers effect in heavy flavor production n D meson production dominated by gluon-gluon fusion

Sivers effect in heavy flavor production n D meson production dominated by gluon-gluon fusion at RHIC energy n Sensitive to gluon Sivers effect n AN measured for muons from D decay (“prompt muons”) n Smear by decay kinematics Gluon Sivers=Max Measurement for m- Gluon Sivers=0 Calculations for D mesons Anselmino et al, PRD 70, 074025 (2004) Ruizhe Yang, RHIC & AGS Users' Meeting 17

Sivers effect in J/Y production Exploratory measurement of AN J/Psi • J/Y production mechanism

Sivers effect in J/Y production Exploratory measurement of AN J/Psi • J/Y production mechanism not well understood • Single spin asymmetries may shed light on production mechanism • Constraints on gluon Sivers function Yuan, PRD 78: 014024, 2008 AN x. F (Yuan) Ruizhe Yang, RHIC & AGS Users' Meeting 18

Neutron production at very forward region n Large negative SSA observed for x. F>0

Neutron production at very forward region n Large negative SSA observed for x. F>0 n Diffractive physics n Useful for local polarimetry at PHENIX neutron Ruizhe Yang, RHIC & AGS Users' Meeting 19

Summary and outlook Figure of merit : LP 2 (pb 1) Future high luminosity

Summary and outlook Figure of merit : LP 2 (pb 1) Future high luminosity transverse running at RHIC (after 2011) 2002 2005 2006 2008 Central rapidity 0, h+/- IFF Sivers (Di-jet) J/Y h+/- IFF 0 Sivers (Di-jet) Ruizhe Yang, RHIC & AGS Users' Meeting FOCAL 1 < |h| < 3 (2011) FVTX |h| < 2. 4 (2012) n Heavy flavor n Precise measurement Forward rapidity J/Y PHENIX upgrades m. J/Y 0 (62 Ge. V) 20 0, , Ks, g IFF Sivers (Di-jet) of Collins effect n g-jet

PHENIX upgrades n Vertex Detectors (2011 -2012) n | | < 2. 4 n

PHENIX upgrades n Vertex Detectors (2011 -2012) n | | < 2. 4 n Heavy flavor tagging n Separation of c/b n Jet measurement n Forward Calorimetery (2012 -2013) n 1 < | | < 3 n AN 0, Direct γ, γ-Jet n Collins-type analyses Ruizhe Yang, RHIC & AGS Users' Meeting 21