E.C. Aschenauer DNP-2012 HP Town Hall 2 RHICRHICRHICRHIC NSRL LINAC Booster AGS Tandems STAR PHENIX Jet/C-Polarimeters RF EBIS ERL Test Facility CeC-TF STAR Beams: √s GeV pp; 50-60% polarization Lumi: ~10 pb -1 /week Electron-Lenses

3 L avg : +15% P avg : +8% 2012: golden year for polarized proton operation 100 GeV: new records for L peak, L avg, P 255 GeV: new records for L peak, L avg, P highest E for pol. p beam What will come: increased Luminosity and polarization through OPPIS new polarized source OPPIS new polarized source Electron lenses to Electron lenses to compensate beam-beam compensate beam-beam effects effects many smaller incremental many smaller incremental improvements improvements will make luminosity hungry processes, i.e. DY, easier accessible E.C. Aschenauer DNP-2012 HP Town Hall

4 E.C. Aschenauer DNP-2012 HP Town Hall Can  and  G explain it all ?

E.C. Aschenauer DNP-2012 HP Town Hall 5 theory predictions before RHIC theory predictions before RHIC

E.C. Aschenauer DNP-2012 HP Town Hall 6  Scaling violations of g 1 (Q 2 -dependence) give indirect access to the gluon distribution via DGLAP evolution.  RHIC polarized pp collisions at midrapidity direct access to gluons (gg,qg)  Rules out large  G for 0.05 < x < 0.2 Integral in RHIC x-range: DIS RHIC 200 GeV xgxgxgxg

E.C. Aschenauer DNP-2012 HP Town Hall 7 DSSV: arXiv: DSSV+: DSSV+COMPASS DSSV++: DSSV+ & RHIC 2009  strong constrain on  first  completely consistent with DSSV+ in  2 / 2 =2% DSSV+ in  2 / 2 =2% QCDfit PHENIX & STAR fully consistent

E.C. Aschenauer DNP-2012 HP Town Hall 8 DSSV: arXiv: DSSV+: DSSV+COMPASS DSSV++: DSSV+ & RHIC 2009 First time a significant non-zero  g(x) DIS RHIC 200 GeV RHIC 500 GeV forward  Spin of the proton Do things add up? Getting significantly closer to understand the gluon contribution to the proton spin BUT need to reduce low-x (<10 -2 ) uncertainties for ∫  g(x) DSSV

E.C. Aschenauer DNP-2012 HP Town Hall 9 Reduce uncertainties and go to low x  measure correlations (di-jets, di-hadrons)  constrain shape of  g(x)  A LL  0 and jet at √s = 500 GeV  x min > 0.01  measure A LL at forward rapidities  x min > Run : Experimentally Challenging A LL ≲  high Lumi  good control of systematics Many more probes:   ±  sign of  g(x)  direct photon  heavy flavour  ….. theoretically clean luminosity hungry

E.C. Aschenauer RHIC pp data constraining Δg(x) 0.05 < x < < x <0.2 data plotted at x T =2p T /√s 10DNP-2012 HP Town Hall 0.05<x<0.4 novel electroweak probe

11 E.C. Aschenauer Since W is maximally parity violating  W’s couple only to one parton helicity large Δu and Δd result in large asymmetries. x 1 small t large t large x 1 large u large u large forward backward Complementary to SIDIS: very high Q2-scale extremely clean theoretically No Fragmentation function

12 Run-2009: Run-2011: E.C. Aschenauer DNP-2012 HP Town Hall first result from muon arms And then came Run-2012 ∫L del = 130 pb -1 and P B ~ 55%

DSSV E.C. Aschenauer DNP-2012 HP Town Hall 13 Already Run-2012 data alone have a significant impact on and DSSV+: DSSV+COMPASS DSSV++: DSSV+ & STAR-W 2009 DSSV++: DSSV+ & RHIC-W proj.

E.C. Aschenauer DNP-2012 HP Town Hall 14 pseudo-data randomized around DSSV RHIC W ± -data will constrain and DSSV+: DSSV+COMPASS DSSV++: DSSV+ & STAR-W 2009 DSSV++: DSSV+ & RHIC-W proj.

15 E.C. Aschenauer DNP-2012 HP Town Hall

16 Left Right Big single spin asymmetries in p  p !! Naive pQCD (in a collinear picture) predicts A N ~  s m q /sqrt(s) ~ 0 Do they survive at high √s ? YES Is observed p t dependence as expected from p-QCD? NO What is the underlying process? Sivers / Twist-3 or Collins or.. till now only hints ANL ZGS  s=4.9 GeV BNL AGS  s=6.6 GeV FNAL  s=19.4 GeV  s=62.4 GeV FPD: Not jet corrected for kinematic smearing E.C. Aschenauer DNP-2012 HP Town Hall

 Collins / Transversity:  conserve universality in hadron hadron interactions  FF unf = - FF fav and  u ~ -2  d  evolve ala DGLAP, but soft because no gluon contribution (i.e. non- singlet)  Sivers, Boer Mulders, ….  do not conserve universality in hadron hadron interactions  k t evolution  can be strong o till now predictions did not account for evolution  FF should behave as DSS, but with k t dependence unknown till today  u and d Sivers fct. opposite sign d >~ u  Sivers and twist-3 are correlated o global fits find sign mismatch, possible explanations, like node in k t or x don’t work 17 E.C. Aschenauer DNP-2012 HP Town Hall

18 SIVERS Transversity x Collins  A N for jets  A N for direct photons  A N for heavy flavour  gluon   +/-  0 azimuthal distribution in jets  Interference fragmentation function  A N for  0 and eta with increased p t coverage Rapidity dependence of E.C. Aschenauer DNP-2012 HP Town Hall TransversityxInterference FF

19 Q  QCD Q T /P T <<<< Collinear/twist-3 Q,Q T >>  QCD p T ~Q Transversemomentumdependent Q>>Q T >=  QCD Q>>p T Intermediate Q T Q>>Q T /p T >>  QCD Sivers fct. Efremov, Teryaev; Qiu, Sterman DIS: attractive FSI Drell-Yan: repulsive ISI QCD:QCD:QCD:QCD: Sivers DIS = - Sivers DY or Sivers W or Sivers Z0 critical test for our understanding of TMD’s and TMD factorization E.C. Aschenauer

20 PHENIX A N (DY): 1.2<|y|<2.4 Muon-Arms+FVTX  S/B ~ 0.2 STAR A N (W): -1.0 < y < 1.5 W-fully reconstructed Delivered Luminosity: 500pb -1 (~6 weeks for Run14+) Caveat: potentially large evolution effects on A N for DY, W, Z0 not yet theoretically full under control and accounted for E.C. Aschenauer Extremely clean measurement of  A N (Z0)+/-10% for ~0

21 THE RHIC SPIN Program > 2015 polarised p↑A  unravel the underlying sub-processes to A N  getting the first glimpse of GPD E for gluons  A UT (J/ψ ) in p ↑ A going forward:  precision measurements in transverse spin effects  Sivers, Collins, IFF  precision measurements of A N (DY)  precision measurements  g(x) at low-x E.C. Aschenauer DNP-2012 HP Town Hall

E.C. Aschenauer DNP-2012 HP Town Hall 22 Detector Layout for forward physics studies Use open sPHENIX central barrel geometry to introduce  tracking  charged particle identification  electromagnetic calorimeter  hadron calorimeter  muon detection  Use existing equipment where possible

E.C. Aschenauer 23 Forward instrumentation optimized for p+A and transverse spin physics – Charged ‐ particle tracking – e/h and γ/π 0 discrimination – Possibly Baryon/meson separation DNP-2012 HP Town Hall

E.C. Aschenauer DNP-2012 HP Town Hall 24 Yuri Kovchegov et al. r=1.4fm r=2fm strong suppression of odderon STSA in nuclei. r=1fm Q s =1GeV x f =0.9 x f =0.7 x f =0.6 x f =0.5 x f =0.7 x f =0.9 x f =0.6 x f =0.5 cut of large b The asymmetry is larger for peripheral collisions, and is dominated by edge effects.  Very unique RHIC possibility p ↑ A  Synergy between CGC based theory and transverse spin physics theory and transverse spin physics  A N (direct photon) = 0

25  Get quasi-real photon from one proton  Ensure dominance of g from one identified proton by selecting very small t 1, while t 2 of “typical hadronic by selecting very small t 1, while t 2 of “typical hadronic size” size” small t 1  large impact parameter b (UPC) small t 1  large impact parameter b (UPC)  Final state lepton pair  timelike compton scattering  timelike Compton scattering: detailed access to GPDs including E q/g if have transv. target pol. including E q/g if have transv. target pol.  Challenging to suppress all backgrounds  Final state lepton pair not from  * but from J/ ψ  Done already in AuAu  Estimates for J/ ψ ( hep-ph/ )  transverse target spin asymmetry  calculable with GPDs  information on helicity-flip distribution E for gluons golden measurement for eRHIC golden measurement for eRHIC Gain in statistics doing polarized p ↑ A Z2Z2Z2Z2 A2A2A2A2 E.C. Aschenauer DNP-2012 HP Town Hall

Roman Pot detectors to measure forward scattered protons in diffractive processesRoman Pot detectors to measure forward scattered protons in diffractive processes Staged implementation to cover wide kinematic coverageStaged implementation to cover wide kinematic coverage Phase I (Installed): for low-t coverage Phase I (Installed): for low-t coverage Phase II (planned) : for higher-t coverage Phase II (planned) : for higher-t coverage 8(12) Roman Pots at ±15 and ±17m 2π coverage in φ will be limited due to machine constraint (incoming beam)  No special  * running needed any more   250 GeV to 100 GeV scale t-range by 0.16 scale t-range by 0.16 at 15-17m at 55-58m 26 J.H. Lee E.C. Aschenauer DNP-2012 HP Town Hall

 Polarized He 3 is an effective neutron target  d-quark target  Polarized protons are an effective u-quark target 27 Therefore combining pp and pHe 3 data will allow a full quark flavor separation u, d, ubar, dbar Two physics trusts for a polarized pHe3 program:  Measuring the sea quark helicity distributions through W-production  Access to  dbar  Caveat maximum beam energy for He 3 : 166 GeV  Need increased luminosity to compensate for lower W-cross section  Measuring single spin asymmetries A N for pion production and Drell-Yan  expectations for A N (pions)  similar effect for π ± ( π 0 unchanged) 3 He: helpful input for understanding of transverse spin phenomena Critical to tag spectator protons from 3He with roman pots E.C. Aschenauer DNP-2012 HP Town Hall

28 qqqqqqqq GGGG LgLgLgLg qLqqLqqLqqLq qqqq qqqqqqqq GGGG LgLgLgLg qLqqLqqLqqLq qqqq E.C. Aschenauer RHIC SPIN Program  the unique science program addresses all important open questions in spin physics all important open questions in spin physics  uniquely tied to a polarized pp-collider  never been measured before & never without

E.C. Aschenauer DNP-2012 HP Town Hall 29

30 E.C. Aschenauer DNP-2012 HP Town Hall

31 E.C. Aschenauer DNP-2012 HP Town Hall

300 pb -1 -> ~10% on a single bin of A N Clean experimental momentum reconstruction Clean experimental momentum reconstruction Negligible background Negligible background electrons rapidity peaks within tracker acceptance (|  |< 1) electrons rapidity peaks within tracker acceptance (|  |< 1) Statistics limited Statistics limited Generator: PYTHIA E.C. Aschenauer DNP-2012 HP Town Hall

 The same RP configuration with the current RHIC optics (at z ~ 15m between DX-D0)  Acceptance ~ 98% Accepted in RP Passed DX aperture generated  Momentum smearing mainly due to Fermi motion + Lorentz boost to Fermi motion + Lorentz boost  Angle 99.9%) Angle [rad] 33 Study: JH Lee E.C. Aschenauer DNP-2012 HP Town Hall

34 Year  s [GeV] Recorded PHENIX Recorded STARPol [%] 2002 (Run 2)200/0.3 pb (Run 3) pb pb (Run 4) pb pb (Run 5) pb pb (Run 6) pb pb (Run 6) pb (Run9)50010 pb (Run9)20014 pb pb (Run11) / 9.5pb pb (Run12)50030 / 15 pb pb -1 50/54 E.C. Aschenauer DNP-2012 HP Town Hall

35 Year  s [GeV] Recorded PHENIX Recorded STARPol [%] 2001 (Run 2) pb (Run 3)200/ 0.25 pb (Run 5) pb pb (Run 6) pb pb (Run 6) pb (Run8) pb pb (Run11)500/25 pb (Run12)2009.2/4.3 pb pb -1 61/58 E.C. Aschenauer DNP-2012 HP Town Hall