Transverse Spin Physics at RHIC M. Grosse Perdekamp (University of Illinois and RBRC) International Workshop on Semi-Inclusive Reactions and 3D-Parton Distributions May 18-20, 2005 Jefferson Lab, Newport News, Virginia, USA

Transverse Spin Physics at RHIC2 May 18 Transverse Spin Physics at RHIC oMotivation  Measurement of the Sivers function  Extract transversity distributions from QCD analysis: SIDIS + pp + e+e- oPolarized p-p at RHIC  Polarized collider + experiments  Does NLO pQCD provide stable framework for the extraction of polarized PDFs? oTransverse Spin Physics  A N  Sivers, transversity/Collins, sub-leading twist  back-to-back correlations in Jets  Sivers  A T (Collins, IFF)  Transversity/Collins  A T (Drell Yan)  Sivers  A TT (Drell Yan)  Transversity oSummary

Transverse Spin Physics at RHIC3 May 18 Motivation: Global Transversity Analysis Transversity Tensor Charge BLT sum rule and Lattice QCD Factorization and Universality? Does pQCD provide a stable frame work for a global transversity analysis? RBRC workshop September 2000

Transverse Spin Physics at RHIC4 May 18 Collins FF (and IFF): e+e-  hadrons (see Akio Ogawa’s talk)       2-hadron inclusive transverse momentum dependent cross section:  e + e - CMS frame: e-e- e+e+

Transverse Spin Physics at RHIC May 18 AGS LINAC BOOSTER Polarized Source Spin Rotators Partial Snake Siberian Snakes 200 MeV Polarimeter AGS Internal Polarimeter Rf Dipole RHIC pC Polarimeters Absolute Polarimeter (H jet) P HENIX P HOBOS B RAHMS & PP2PP S TAR Siberian Snakes Run 04 P b ~45%, 55 bunches Run 05 AGS pC Polarimeter Polarized p-p at RHIC 2005: complete instrumentation! Helical Partial Snake Strong Snake Spin Flipper = 45% Commision strong snake

Transverse Spin Physics at RHIC6 May 18 RHIC 2005: 200 GeV pp, ∫Ldt, May 17 th 2.88 pb -1 live ZDCLL1 PHENIX Goal 5.5 pb -1 live BBCLL1 (5/17/05) 27.7 B BBCLL1 events sampled 1.23 pb -1 live BBCLL1 June 25, 2005 (3.56 pb -1 projected)

Transverse Spin Physics at RHIC7 May 18 (5/17/05) PHENIX Goal 226 nb nb -1 June 25, 2005 (190 nb -1 projected) RHIC 2005: 200 GeV pp, FoM, May 17th

Transverse Spin Physics at RHIC8 May 18 GRSV standard ∆G(x)  Gluon distribution from NLO pQCD fit to DIS data on A 1, Gluck Reya, Stratmann, Vogelsang Phys. Rev. D63:094005, 2001 A LL in inclusive π 0 production (PHENIX) A LL ( π 0 ) ∫Ldt=3pb -1 P=0.4 Vogelsang hep-ph/ Input: ∆G(x)=G(x) GRSV: standard ∆G(x) ∆G(x)=0 ∆G(x)= -G(x) A LL in inclusive jet production (STAR) Jager, Stratmann, Vogelsang hep-ph/ A LL (Jets) ∫Ldt=3pb -1 P=0.4 Input: ∆G(x)=G(x) GRSV: standard ∆G(x) ∆G(x)= -G(x) ∆G(x)=0 p T [GeV/c] Expected in run 05: ∫Ldt =5pb -1 P =0.5 All required instrumentation in STAR and PHENIX is in place! Goals for 2005:  (a) 1 st look at the Gluon Polarization (b) precision measurment of A N

Transverse Spin Physics at RHIC9 May 18 Experiments with polarized protons at RHIC polarization measurements STAR STAR 75% longitudinal, 25% transverse A LL (hadrons, jets, direct photons) A L (W-bosons) A N (hadrons, jets), A T (Drell Yan, Collins, IFF) A TT (Jets, Drell Yan) PHENIX PHENIX 75% longitudinal, 25% transverse BRAHMS BRAHMS 100% transverse A N (identified charged hadrons) PHOBOS, pp2pp  no “active” spin program

Transverse Spin Physics at RHIC10 May 18 Does pQCD provide a stable for the extraction of PDFs at NLO from RHIC data? o Good agreement between NLO pQCD calculations and experiment  can use a NLO pQCD analysis to extract spin dependent quark and gluon distributions from RHIC data! PHENIX π 0 cross section a |η|<0.35 Phys.Rev.Lett.91:241803,2003 STAR π 0 cross section a 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004 gluon fragmentation !?

Transverse Spin Physics at RHIC11 May 18 NLO-pQCD calculation –Private communication with W.Vogelsang –CTEQ6M PDF. –direct photon + fragmentation photon –Set Renormalization scale and factorization scale p T /2,p T,2p T Direct Photons: NLO pQCD vs RHIC data Scale dependence of Cross sections in NLO pQCD calculations

Transverse Spin Physics at RHIC12 May 18 E704: AN The observed asymmetries could result from Transversity x Spin-dep.fragmentation (Collins-Heppelmann effect), or Sivers effect or Higher-twist effects Sterman and Qiu Initial State Twist 3 Koike Final State Twist or a combination of the above left right Fermilab E-704 reported large asymmetries A N in pion productions E704 P T =0.5~2 GeV/c   0 – E704, PLB261 (1991) 201. π +/- - E704, PLB264 (1991) 462.

Transverse Spin Physics at RHIC13 May 18 Transverse Spin Physics at RHIC, first Results: A N o Experiments are ready for spin measurements at low luminosity  relative luminosity ~ 5x10 -4  trigger  polarization analysis  data analysis PHENIX A N (π 0 ) and A N (π0) at |η|<0.35 C. Aidala, DIS 2004, to be published STAR A N (π 0 ) at 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004 Run 02, ∫Ldt ~ 0.2pb -1, P~0.15 o First spin results from RHIC  A N sizeable in forward X F  A N compatible with 0 at η~0

Transverse Spin Physics at RHIC14 May 18 Run 3 preliminary backward angle data  no significant asymmetry (hep-ex/ ) STAR: A N for backward angles from 2003 data

Transverse Spin Physics at RHIC15 May 18 BRAHMS: A N for charged pions x F x 100 p T vs X F x F x 100 A N for pions:  N = [0.02] in 0.17 < x F < 0.32 in 0.17 < x F < 0.32  N = [0.015] o From the ongoing 2005 run the statistical errors will be reduced by a factor 6-7 o New absolute RHIC polarimeter will reduce the systematic error by a factor 4  What can be learned from confronting model calculations with precision data on A N ?

Transverse Spin Physics at RHIC16 May 18 A N for Protons from BRAHMS BRAHMS preliminary  Proton A N is compatible with 0 A N will be available for pions, kaons and protons from run 2005  What do we learn from comparing A N for different fragmentation functions?

Transverse Spin Physics at RHIC17 May 18 Future: RHIC Spin Longitudinal vs Transverse Running …. pp  156pb -1 √s= ……………………… GeV ………………… | P= …………………………………………. Inclusive hadrons + Jets ~ 25% Transverse Physics Charm Physics direct photons Bottom physics W-physics A LL (hadrons, Jets)A LL (charm) A LL (γ) AL(W)AL(W) L= 6x10 30 cm -2 s -1 8x10 31 cm -2 s -1

Transverse Spin Physics at RHIC18 May 18 (A) Transverse Spin Physics Channels at RHIC for “Low” Luminosity STAR Phys. Rev. Lett. 92:171801, 2004 Boer and Vogelsang (hep-ph/ ): azimuthal back to back correlation between hadrons in opposite hemisphere jets: Separation of intrinsic transverse quark spin (transversity) from trans- verse momentum effects (Sivers)? Clean channel for Sivers effect! STAR, PHENIX and BRAHMS STAR and PHENIX (I) (II)

Transverse Spin Physics at RHIC19 May 18 Sensitivity Check for Back-to-Back Sivers Asymmetry (based on 2003 pp sample) Full di-jet Sivers Reduced by lower, di-hadron smearing Run03 p+p gamma-charged, 0.35/pb Given 0.35/pb of data, we should be able to get 1% statistical significance in A N using gamma-charged measurements of jet dphi Expected raw A N could be 3.5% Could also be as low as 0.5%, or as large as 10% x-dependence of Sivers? Effects from P=0.5, jet angle not aligned with transverse polarization, and fragmentation reduces raw A N to ~1.0% Have not evaluated systematic errors yet (underlying event…)

Transverse Spin Physics at RHIC20 May 18 J.C. Collins, Nucl. Phys. B396, 161(1993) R. Jaffe, X.Jin, J. Tang Phys. Rev. D57 (1999)5920 J. Collins, S. Heppelmann, G. Ladinsky, Nucl.Phys. B420 (1994)565 Statistical sensitivity for A T with 32pb -1 STAR and PHENIX (B) Transverse Spin Physics Channels at RHIC for “High” Luminosity STAR and PHENIX W. Vogelsang and M. Stratmann, RBRC Wrkshp on Transversity (2000)

Transverse Spin Physics at RHIC21 May 18 EIC J.Ralston and D.E. Soper, Nucl. Phys. B152, 109(1979) RHIC II (C) Transverse Spin Physics Channels at RHIC II and e-RHIC Drell Yan 8fb -1, large acceptance detector for Drell Yan

Transverse Spin Physics at RHIC22 May 18 Collins Effect in SIDIS at e-RHIC Projected errors on A in 5 z- bins

Transverse Spin Physics at RHIC23 May 18 Summary oAll instrumentation for polarized proton collisions has been installed: Unique tool to study proton structure! oFirst results on A N  2005 precision measurements comparisons between pions, kaons and protons oBroad program with transverse spin with increasing luminosity: A N in inclusive hadrons and jet production Sivers type back-to-back correlation between jets A T for Collins and IFF analysis A T and A TT for Drell Yan o Supporting effort to measure spin dependent fragmentation functions at Belle (RBRC/UIUC)