2. Key measurements for polarized pp scattering E.C. Aschenauer pp-pA-LoI f2f, January 2014 2 deliverablesobservables what we learn requirementscomments/competition HP13 (2015) Test unique QCD predictions for relations between single- transverse spin phenomena in p-p scattering and those observed in deep-inelastic lepton scattering. A N for , W +/-,Z 0, DY Do TMD factorization proofs hold. Are the assumptions of ISI and FSI color interactions in pQCD are attractive and repulsive, respectively correct high luminosity trans pol pp at √s=500 GeV DY: needs instrumentation to suppress QCD backgr. by 10 6 at 3<y<4 A N DY: >=2020 might be to late in view of COMPASS A N W,Z: can be done earlier, i.e. 2016 HP13 (2015) and flavor separation A N for  charged identified(?) hadrons, jets and diffractive events in pp and pHe-3 underlying subprocess causing the big A N at high x f and y high luminosity trans pol pp at √s=200 GeV, (500 GeV jets ?) He-3: 2 more snakes; He-3 polarimetry; full Phase-II RP the origin of the big A N at high x f and y is a legacy of pp and can only be solved in pp what are the minimal observables needed to separate different underlying subprocesses transversity and collins FF IFF and A UT for collins observables, i.e. hadron in jet modulations A TT for DY TMD evolution and transversity at high x cleanest probe, sea quarks high luminosity trans pol pp at √s=200 GeV & 500 GeV how does our kinematic reach at high x compare with Jlab12 A TT unique to RHIC flavour separated helicity PDFs polarization dependent FF A LL for jets, di-jets, h/  -jets at rapidities > 1 D LL for hyperons  g(x) at small x  s(x) and does polarization effect fragmentation high luminosity long. pol pp at √s=500 GeV Forward instrumentation which allows to measure jets and hyperons. Instrumentation to measure the relative luminosity to very high precision eRHIC will do this cleaner and with a wider kinematic coverage Searches for a gluonic bound state in central exclusive diffraction in pp PWA of the invariant mass spectrum in pp  p’M X p’ in central exclusive production can exotics, i.e. glue balls, be seen in pp high luminosity pp at √s=200 GeV & 500 GeV full Phase-II RP how does this program compare to Belle-II & PANDA

3. Key measurements for p ↑ A scattering E.C. Aschenauer pp-pA-LoI f2f, January 2014 3 deliverablesobservables what we learn requirementscomments/competition DM8 (2012) determine low-x gluon densities via p(d) A direct photon potentially correlations, i.e. photon-jet initial state g(x) for AA-collisions A-scan LHC and inclusive DIS in eA eA: clean parton kinematics LHC wider/different kinematic reach; NA61 impact parameter dependent g(x,b) c.s. as fct. of t for VM production in UPC (pA or AA) initial state g(x,b) for AA-collisions high luminosity, clean UPC trigger LHC and exclusive VM production in eA eA: clean parton kinematics LHC wider/different kinematic reach “saturation physics” di-hadron correlations,  -jet, h-jet & NLO DY, diffraction pT broadening for J/Ψ & DY -> Q s is the initial state for AA collisions saturated measurement of the different gluon distributions CNM vs. WW capability to measure many observables precisely large rapidity coverage to very forward rapidities polarized pA A scan complementary to eA, tests universality between pA and eA CNM effects R pA for many different final states K 0, p, K, D 0, J/Ψ,.. as fct of rapidity and collision geometry is fragmentation modified in CNM heavy quarks vs. light quarks in CNM A scan to tag charm in forward direction   -vertex separation of initial and final state effects only possible in eA long range rapidty correlations “ridge” two-particle correlation at large pseudo-rapidity  do these correlations also exist in pA as in AA tracking and calorimetry to very high rapidities interesting to see the √s dependence of this effect compared to LHC is GPD E g different from zero A UT for J/Ψ through UPC Ap ↑ GPD E g is responsible for L g  first glimpse unique to RHIC till EIC turns on underlying subprocess for A N (  0 ) A N for  0 and  underlying subprocess for A N (  0 ) sensitivity to Q s good  0 and  reconstruction at forward rapidities resolving a legacy in transversely polarized pp collisions

4. E.C. Aschenauer pp-pA-LoI f2f, January 2014 4

5. E.C. Aschenauer pp-pA-LoI f2f, January 2014 5 (un-)polarized pp (un-)polarized pA  unravel the underlying subprocesses causing A N causing A N  measure the sign change for the Sivers fct. between pp and SIDIS Sivers fct. between pp and SIDIS  measure  G at low x  central and forward diffractive production in p ( ↑ ) p, p ( ↑ ) A  elastic scattering in p ( ↑ ) p ( ↑ )  study saturation effects  measure g A (x,Q 2 ) and g A (x,Q 2,b)  unravel the underlying subprocess causing A N causing A N  study GPDs what equipment do we need  STAR: main detector and endcap  refurbished FMS  Preshower detector in front of the FMS  talk Akio Sunday  Roman Pot upgrade to Phase-II

6. E.C. Aschenauer pp-pA-LoI f2f, January 2014 6 How well can we do on the physics with this upgrades

7. 7 E.C. Aschenauer pp-pA-LoI f2f, January 2014 Can  and  G explain it all ?

8. 8 Data ≤ 2009 at 200 GeV yield first time a significant non-zero  g(x) Can we improve ? YES add 510 GeV (12+13) and more 200 GeV (15) data E.C. Aschenauer pp-pA-LoI f2f, January 2014 2013 500 GeV 2015 200 GeV   

9. E.C. Aschenauer pp-pA-LoI f2f, January 2014 9  Many different mid-rapidity probes, but not sensitive to low-x. Mid–Rapidity, Single π 0 ~0.01 for π 0 ~0.01 for π 0 ~0.001 for π 0 - π 0 ~0.001 for π 0 - π 0 Fwd–Rapidity (3.1<  <3.9), 500 GeV  Unfortunately, rate drops by x10 for fwd-mid, and x100 for fwd- fwd  Relative Lumi needs to be controlled super well π0π0π0π0 π0-π0π0-π0π0-π0π0-π0 GSC DSSV W. Vogelsang NLO A LL  0

10. 10 E.C. Aschenauer pp-pA-LoI f2f, January 2014

11. 2D+1 picture in momentum space 2D+1 picture in coordinate space transverse momentum generalized parton distributions dependent distributions  exclusive reaction like DVCS 11 Quarks unpolarised polarised Join the real 3D experience !! TMDs GPDs E.C. Aschenauer pp-pA-LoI f2f, January 2014 Physics, which gave Jlab the 12 GeV upgrade and is part of the motivation for eRHIC

12. 12 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 Need 2 scales Q 2 and p t Remember pp: most observables one scale Exception: DY, W/Z-production Need only 1 scale Q 2 or p t But should be of reasonable size should be applicable to most pp observables A N (  0 /  /jet) E.C. Aschenauer pp-pA-LoI f2f, January 2014

13. 13 DIS:  q-scattering attractive FSI pp:qqbar-anhilation 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 Twist-3 formalism predicts the same E.C. Aschenauer pp-pA-LoI f2f, January 2014 For details on A N DY and W/Z see talks this afternoon A N (direct photon) measures the sign change through Twist-3

14.  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)  TMDs Sivers, Boer Mulders, ….  do not conserve universality in hadron hadron interactions  k t evolution  is strong o till now most predictions did not account for evolution  wrong theory approach for hadrons in final state  u and d Sivers fct. opposite sign d >~ u  Sivers and twist-3 qq and qg correlators are correlated o global fits find sign mismatch, if they assume AN is complete caused by Sivers like effect  possible explanations, like node in k t or x don’t work 14 E.C. Aschenauer pp-pA-LoI f2f, January 2014

15. 15 SIVERS/Twist-3 Collins Mechanism  A N for jets  A N for direct photons  A N for heavy flavour  gluon  asymmetry in jet fragmentation   +/-  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 pp-pA-LoI f2f, January 2014 Sensitive to proton spin – parton transverse motion correlations not universal between SIDIS & pp SPSPSPSP p p SqSqSqSq k T, π Sensitive to transversity universal between SIDIS & pp & e+e- SPSPSPSP k T,q p p Goal: measure less inclusive

16. 16 SIVERS/Twist-3 Collins Mechanism Interference fragmentation function  A N for direct photons assumes preshower in front of FMS E.C. Aschenauer pp-pA-LoI f2f, January 2014

17. Collins with positivity bounds as input Also developed: Fast smearing generator tool to smear generator particle responses in p and energy and to include PID responses, “detectors” can be flexible defined in the acceptance.  allows for fast studies of detector effects on physics observables  currently all eSTAR used smearing parameterizations are implemented  Developed by Tom Burton (https://code.google.com/p/tppmc/)  Sivers and Collins asymmetries included  IFF and A N (DY/W) need to be still included Sivers Mechanism E.C. Aschenauer 17 pp-pA-LoI f2f, January 2014

18. E.C. Aschenauer pp-pA-LoI f2f, January 2014 18 Mid Rapidity A N (  0 ) dominated by gg and qg no hint of a non-zero A N (  0 ), A N (J  ) and A N (jet)  gluon Sivers ~ 0  Twist-3 gg correlator ~0 ? Forward Rapidity A N (J  ) only gg: PHENIX 200 GeV p T [GeV/c] Mid Rapidity A N (jet) mainly gg & qg

19. pp-pA-LoI f2f, January 2014 19 E.C. Aschenauer 2013 Final configuration 2011 Configuration Determine A N (jet) at same rapidity of big A N (  0 )  >3 RUN-11: A N DY collected ~ 6.5/pb Remember: Theory: arXiv:1103.1591 A N (jet) from p  +p  “old” Sivers function SIDIS fit “new” Sivers function SIDIS fit  s=200 GeV arXiv: 1304.1454 Twist-3 “Sivers” seems not to be the explanation for the big forward A N (  )

20. pp-pA-LoI f2f, January 2014 20 p + p  p + X + p diffractive X= particles, glueballs p + p  p + p elastic p + p  p + p elastic QCD color singlet exchange: C=+1(IP), C=-1(Ο) p + p  p + X SDD p + p  p + X SDD pQCD Picture Gluonic exchanges Discovery Physics E.C. Aschenauer

21. pp-pA-LoI f2f, January 2014 21 In the double Pomeron exchange process each proton “emits” a Pomeron and the two Pomerons interact producing a massive system M X where M X =      c (  b ), qq(jets), H(Higgs boson), gg(glueballs) The massive system could form resonances. We expect that because of the constraints provided by the double Pomeron interaction, glueballs, hybrids, and other states coupling preferentially to gluons, will be produced with much reduced backgrounds compared to standard hadronic production processes.pp MxMxMxMx For each proton vertex one has t four-momentum transfer  p/p M X =√     s invariant mass Method is complementary to: GLUEX experiment (2015)GLUEX experiment (2015) PANDA experiment (>2015)PANDA experiment (>2015) COMPASS experiment (taking data )COMPASS experiment (taking data ) E.C. Aschenauer

22. pp-pA-LoI f2f, January 2014 22 Note small like sign background after momentum conservation cut E.C. Aschenauer

23. Follow PAC recommendation to develop a solution to run pp2pp@STAR with Follow PAC recommendation to develop a solution to run pp2pp@STAR with std. physics data taking  No special  * running any more std. physics data taking  No special  * running any more  should cover wide range in t  RPs at 15m & 17m  Staged implementation  Phase I (currently installed): low-t coverage  Phase II (proposed) : for larger-t coverage  1 st step reuse Phase I RP at new location only in y  full phase-II: new bigger acceptance RPs & add RP in x-direction  full coverage in φ not possible due to machine constraints  Good acceptance also for spectator protons from deuterium and He-3 collisions deuterium and He-3 collisions at 15-17m at 55-58m 23 full Phase-II Phase-II: 1 st step 1 st step W. Guryn E.C. Aschenauer pp-pA-LoI f2f, January 2014

24.  Rigidity (d:p =2:1)  The same RP configuration with the current RHIC optics (at z ~ 15m between DX and D0)  needs full PHASE-II RP Accepted in RP Passed DX aperture generated 24 pp-pA-LoI f2f, January 2014 Study: JH Lee E.C. Aschenauer

25.  The same RP configuration with the current RHIC optics (at z ~ 15m between DX-D0)  Acceptance ~ 92% with full PHASE-II RP Accepted in RP Passed DX aperture generated  Momentum smearing mainly due to Fermi motion + Lorentz boost to Fermi motion + Lorentz boost Angle [rad] 25 Study: JH Lee E.C. Aschenauer pp-pA-LoI f2f, January 2014

26. 26 The Beauty of RHIC mix and match beams as one likes 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 E.C. Aschenauer pp-pA-LoI f2f, January 2014

27. E.C. Aschenauer 27 the way to 3d imaging of the proton and the orbital angular momentum L q & L g GPDs: Correlated quark momentum and helicity distributions in transverse space Spin-Sum-Rule in PRF: from g 1 e’ (Q 2 ) e L*L*L*L* x+ξ x-ξ H, H, E, E (x,ξ,t) ~ ~  p p’ t Measure them through exclusive reactions golden channel: DVCS responsible for orbital angular momentum pp-pA-LoI f2f, January 2014

28. 28  Get quasi-real photon from one proton/nuclei  Ensure dominance of  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 not from  * but from J/ ψ  Done already in AuAu  Estimates for J/ ψ ( hep-ph/0310223)  transverse target spin asymmetry  calculable with GPDs GPDs  information on helicity-flip distribution E for gluons golden measurement for eRHIC golden measurement for eRHIC Gain in statistics doing polarized p ↑ A ~Z 2 E.C. Aschenauer pp-pA-LoI f2f, January 2014

29. E.C. Aschenauer pp-pA-LoI f2f, January 2014 29 SIGNALBACKGROUND t spectrum for beam generating  t spectrum for target beam RP-Veto Request RP Simulation: planned 2015 p ↑ A run will give 1000 exclusive J/Ψs enough to measure A UT to see it is different from zero

30.  Hard diffraction E.C. Aschenauer 30  Diffraction in p+A:  coherent diffraction (nuclei intact) (nuclei intact)  breakup into nucleons (nucleons intact) (nucleons intact)  incoherent diffraction Predictions: σ diff /σ tot in e+A ~25-40% HERA: 15% of all events are hard diffractive Why is diffraction so important  Sensitive to spatial gluon distribution  Hot topic:  Lumpiness?  Just Wood-Saxon+nucleon g(b)  Incoherent case: measure fluctuations/lumpiness in g A (b) measure fluctuations/lumpiness in g A (b)  VM: Sensitive to gluon momentum distributions   ~ g(x,Q 2 ) 2 pp-pA-LoI f2f, January 2014

31. E.C. Aschenauer 31 Adrian Dumitru To be sure it was diffraction need to make sure p and/or A are intact  RP and ZDC need to look seriously into rapidity gap triggers Big Question: Does the diffractive cross section increase in pA if we are saturated regime like in eA? Current answer is YES pp-pA-LoI f2f, January 2014

32. E.C. Aschenauer pp-pA-LoI f2f, January 2014 32 NSAC performance milestones for pA / AA R pA for photons R pA for J/Ψ will do the trick Can UPC in pA gives us g(x,b)

33. E.C. Aschenauer 33  Unique probe - allows to measure momentum transfer t in pA diffraction  in general, one cannot detect the outgoing nucleus and its momentum Dipole Cross-Section: J/    small size (J/Ψ): cuts off saturation region  large size (φ,ρ,...): “sees more of dipole amplitude” → more sensitive to saturation pp-pA-LoI f2f, January 2014 STAR Preliminary Au+Au UPC  *+Au  Au+ 

34. 34  Idea: momentum transfer t conjugate to transverse position (b T ) o coherent part probes “shape of black disc” o incoherent part (dominant at large t) sensitive to “lumpiness” of the source (fluctuations, hot spots,...) Spatial source distribution: t = Δ 2 /(1-x) ≈ Δ 2 (for small x) ϕ, nosat E.C. Aschenauer pp-pA-LoI f2f, January 2014

35. E.C. Aschenauer pp-pA-LoI f2f, January 2014 35  Improve lepton-photon-hadron separation in the FMS to do  Some examples  J/Ψ physics in pAu and pp at forward rapidities  R dA  current status from chris perkins from run-08 need to simulate J/Ψ signal to background with the FMS preshower

36. E.C. Aschenauer 36 small x large x x=1 x=10 -5 Gluon density dominates at x<0.1  Rapid rise in gluons described naturally by linear pQCD evolution equations  This rise cannot increase forever - limits on the cross-section  non-linear pQCD evolution equations provide a natural way to tame this growth and lead to a saturation of gluons, characterised by the saturation scale Q 2 s (x) pp-pA-LoI f2f, January 2014

37. E.C. Aschenauer pp-pA-LoI f2f, January 2014 37 pA will resolve the question the double interaction mechanism plays a role in dA Hopefully get this time a result which will be published 2008: 2008: 44 nb -1 300 nb -1 2015: 300 nb -1  factor 6 increase inclusive  (  0 ) ~ inclusive  (  0 ) ~ 1/p T 6 going to p T trig >3 GeV luminosity needs to be increased by 11   increased FMS + STAR triggering performance   should be able to go in and out of saturation regime

38. E.C. Aschenauer pp-pA-LoI f2f, January 2014 38 Y. Kovchegov et al. arXiv:1201.5890 r=1.4fm r=2fm strong suppression of odderon STSA in nuclei. r=1fm Q s =1GeV  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  The asymmetry is larger for peripheral collisions peripheral collisions STAR: projection for upcoming pA run Curves: Feng & Kang arXiv:1106.1375 solid: Q s p = 1 GeV dashed: Q s p = 0.5 GeV 0000

39. E.C. Aschenauer pp-pA-LoI f2f, January 2014 39 Carl’s 2015 pp/pA run gets us started on many physics topics to be discussed in the pp-pA-LoI

40. E.C. Aschenauer pp-pA-LoI f2f, January 2014 40 BACKUP

41. 41 Use FCS simulation using only the clusters and tracks within the FMS geometry at 200 GeV. Photon reconstruction efficiency (~100%) and π 0 - ϒ separation are comparable under 80 GeV for the FMS and the FCS EMCal. Energy resolution is better for the FCS. This has not been adjusted for the current estimate because the A N measurement is not very sensitive to the smearing in energy scale. The charged track detection efficiency is set at 86%, per Akio ’ s study of the FMS pre-shower model, which showed that the first layer can be used to accept 98% of the photons and reject 86% of the charged hadrons. SET-UP used: E.C. Aschenauer pp-pA-LoI f2f, January 2014

42. E.C. Aschenauer 42 all cuts no cuts Adding cut by cut:  leptons without cuts   2 : -1 <  < 2   1 and  2 : -1 <  < 2  t 1 >-0.016 and -0.2 -0.016 and -0.2<t 2 <-0.016 Au Au’ p p’ pp-pA-LoI f2f, January 2014

43. E.C. Aschenauer 43 Adding cut by cut:  leptons without cuts   2 : -1 <  < 2   1 and  2 : -1 <  < 2  t 1 >-0.016 and -0.2 -0.016 and -0.2<t 2 <-0.016 J/Ψ reconstructed through e+e- and/or  +  - channels Au Au’ p p’ black p p’ Au Au’ magenta all cuts pp-pA-LoI f2f, January 2014

44.  Polarized He 3 is an effective neutron target  d-quark target  Polarized protons are an effective u-quark target 44 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 pp-pA-LoI f2f, January 2014

45. E.C. Aschenauer 45  Can we increase p-beam energy?  325 GeV: factor 2 in  W BUT despite the original design of magnets can only got to 10% more  275 GeV  Increased beam-energy and polarized He-3 beam  full flavor separation A L W : pp @ 500 GeV A L W : He3-p @ 432 GeV phase 2 of pp2pp@STAR can separate scattering on n or p  polarised He-Beams  had a a workshop to discuss possibilities https://indico.bnl.gov/conferenceDisplay.py?confId=405  no show stoppers, but need most likely one additional pair of snakes  increase luminosity of RHIC pp-pA-LoI f2f, January 2014

46. 46 1 st rough estimate (Vogelsang) : not too bad, about a factor of 4-5 in dσ (bin) [pb] W+W+W+W+ p T > 20 GeV pp @ 500 p 3 He @ 332 y rate is per nucleon i.e. scaled by 1/A E.C. Aschenauer pp-pA-LoI f2f, January 2014

47. 0000 Prompt “Fragmentation” much better called internal bremsstrahlung Induced EM & Weak Decay proton – proton:  Fragmentation Au – Au or d-Au Thermal Radiation QGP / Hadron Gas De-excitation for excited states (1) (2) (3) (4) (5) (6) E.C. Aschenauer pp-pA-LoI f2f, January 2014 47

48. pp-pA-LoI f2f, January 2014 48  Processes included which would fall under prompt (1)  14: qqbar  g   18: qqbar   (19: qqbar   Z 0 20: qqbar   W +  29: qg  q   114: gg    115: gg  g  (106: gg  J/Psi  116: gg  Z 0  )  initial and final internal bremsstrahlung (g and  ) (3) o Pythia manual section 2.2  Process 3 and 4 are for sure not in pythia  I’m still checking 5  the decay of resonances like the  0 is of course in pythia E.C. Aschenauer

49. 49 Year  s [GeV] Recorded PHENIX Recorded STARPol [%] 2002 (Run 2)200/0.3 pb -1 15 2003 (Run 3)2000.35 pb -1 0.3 pb -1 27 2004 (Run 4)2000.12 pb -1 0.4 pb -1 40 2005 (Run 5)2003.4 pb -1 3.1 pb -1 49 2006 (Run 6)2007.5 pb -1 6.8 pb -1 57 2006 (Run 6)62.40.08 pb -1 48 2009 (Run9)50010 pb -1 39 2009 (Run9)20014 pb -1 25 pb -1 55 2011 (Run11)50027.5 / 9.5pb -1 12 pb -1 48 2012 (Run12)50030 / 15 pb -1 82 pb -1 50/54 E.C. Aschenauer High Energy Physics in the LHC era, Chile, December 2013

50. 50 Year  s [GeV] Recorded PHENIX Recorded STARPol [%] 2001 (Run 2)2000.15 pb -1 15 2003 (Run 3)200/ 0.25 pb -1 30 2005 (Run 5)2000.16 pb -1 0.1 pb -1 47 2006 (Run 6)2002.7 pb -1 8.5 pb -1 57 2006 (Run 6)62.40.02 pb -1 53 2008 (Run8)2005.2 pb -1 7.8 pb -1 45 2011 (Run11)500/25 pb -1 48 2012 (Run12)2009.2/4.3 pb -1 22 pb -1 61/58 E.C. Aschenauer High Energy Physics in the LHC era, Chile, December 2013