K. Barish Kenneth N. Barish for the PHENIX Collaboration 28 th Winter Workshop on Nuclear Dynamics Dorado del Mar, Puerto Rico, April 2012 sPHENIX Spin and Forward Physics

K. Barish Forward Detector at sPHENIX Primarily motivations »p+p: Forward transverse asymmetries –Separation of Sivers and Collins. –Factorization and universality of TMDs. »d+A: Cold Nuclear Matter –Calibration of quarkonium: J/  and  families –Initial state of heavy ion collisions (connections to CGC/TMDs?) »A+A: –3D “image” of medium –System expansion via photons

K. Barish The Proton Spin Structure Polarization experiments »Helicity –Valence quarks –Sea quarks –Gluons DSSV arXiv: momentum

K. Barish The Proton Spin Structure (p+p) Polarization experiments »Helicity –Valence quarks –Sea quarks –Gluons »Transversity What is the connection to orbital angular momentum? momentum

K. Barish Transverse Spin Asymmetries

K. Barish Transverse Spin Asymmetries  In (collinear) pQCD A N should scale like Asymmetries were expected to be very small.

K. Barish Transverse Spin Asymmetry Sources (I) Transversity quark distributions and Collins fragmentation function Correlation between proton & quark spin + spin dependant fragmentation function Collins FF Quark transverse spin distribution J. C. Collins, Nucl. Phys. B396, 161 (1993) (III) Higher-twist effects Twist-3 quark-gluon/gluon-gluon correlators Expectation: at large p T, A N ~ 1/p T So far, fall-off with p T has not been observed. Graphic from Zhongbo Kang »Access to non-collinear PDFs »Needs orbital angular momentum of the quarks (II) Sivers quark-distribution Correlation between proton-spin and intrinsic transverse quark momentum Sivers distribution D. Sivers, Phys. Rev. D 41, 83 (1990) X. Ji, J.-W. Qiu, W. Vogelsang, F. Yuan, PRL 97, (2006)

K. Barish Factorization & Universality  Collinear factorization for hadron-hadron scattering is well established and universality of the parton distributions are justified.  Less experimental data for polarized case, but the data is supportive and most theoretical foundations are common.  Foundation for  G and  q programs.  Going beyond the twist-2 collinearly factorized picture is essential to explore QCD dynamics and fully understand the spin structure of the nucleon  Exploring the validity of factorization and universality of transverse momentum dependent (TMD) parton distributions factorization is key.

K. BarishMeasurements Initial state interaction Sivers effect Initial state interaction Sivers effect Final state interaction Collins effect Final state interaction Collins effect Hard Scattering Transversity Twist-3 Hard Scattering Transversity Twist-3 Transverse Asymmetries  Inclusive A N (central/forward)  Hadron Correlations (back-to-back)  Interference Fragmentation Functions  Jet correlations/structure  Drell-Yan Upgrades Upgrade plans  Separation of Sivers & Collins and test TMD parton distribution factorization and universality

K. Barish Global A N Analysis  A. Prokudin, Z.-B. Kang –arXiv: [hep-ph]  Input HERMES COMPASS STAR  0  Functional form similar to DSSV SIDIS PP d quark Sivers u quark Sivers  Need to map out Drell-Yan Sivers over a wide kinematic range

K. Barish Polarized Drell-Yan Production No fragmentation Direct correlation of intrinsic transverse quark properties and proton spin Solid factorization Fundamental QCD test Estimated DY A N Z. Kang and J. Qiu. Phys. Rev., D81:054020, 2010 Current Acceptance Proposed Acceptance

K. Barish Drell-Yan Feasibility  Fast Monte-Carlo studies with effective detector smearing  QCD background decreases with increasing rapidity  Drell-Yan reduced signal

K. Barish What is Needed for DY Measurements?  Measure DY Sivers via p  +p  e + e — above the J/  but below the  at √s=500 GeV  Asymmetry expected to peak at y~3 –Cover 2<  <4  Charge sign determination –Work ongoing to understand how to shape field in large  region  e/  separation –Hadronic calorimetry, preshower

K. Barish Jet Correlations / Structure Initial State (Sivers)  Jets with identified hadrons (measure A N for jets)  Do jets from certain quarks prefer to go left or right? Goal: Separate the initial state effects (Sivers) from final state effects (Collins). Then compare with other measurements (such as Drell-Yan Sivers). This will provide a stringent test of TMD PDFs factorization and universality. Final State (Collins)  Left-right asymmetry of identified particle inside a jet  Do certain hadrons fragment from certain quarks to the left or right of the jet axis?

K. Barish Jet Asymmetry (Sivers) Initial State (Sivers)  Jets with identified hadrons (measure A N for jets)  Do jets from certain quarks prefer to go left or right? twist 3 Fit of SIDIS SIDIS old √S = 200 GeV y=3.3 jets  Zhong Bo Kang et al. arXiv:  Measurements of jet asymmetry in forward direction sensitive to quark-gluon correlation function.

K. Barish Hadrons in Jets (Collins) Final State (Collins)  Left-right asymmetry of identified particle inside a jet  Do certain hadrons fragment from certain quarks to the left or right of the jet axis? jet  h+X  F. Yuan, PLB 666 (2008)  Direct Collins measurement of fragmentation  Expect large asymmetries in forward direction

K. Barish What is needed for Jet measurements?  Good Jet reconstruction to be able to measure Sivers cleanly –Electromagnetic and hadronic calorimetry  Particle ID to measure Collins effect –Collins effect different for different hadrons  RICH  B Field and tracker to determine charge sign of hadrons Sivers Collins

K. Barish Cold Nuclear Matter (d+Au)  The Physics –Calibration of quarkonium: J/  and  families –Initial state of heavy ion collisions –connection to CGC –connection to spin physics: TMD PDFs  RHIC’s uniqueness –  s dependence –Possibility of different species –Low Q 2  What drives the design –Large data samples –1>  >4 –Detector sensitive to e, , charged hadrons, jets Direct photon Drell- Yan Open Heavy Flavor

K. Barish Calibration of quarkonium Parton initial energy loss Quark pdf Gluon pdf Absorbtion or breakup cross section recombination DY vs √s (quark)  -jet (quark) open heavy (gluon) Quarkonia (gluon) A+A quarkonia centrality A+A open heavy d+A  Each measurement is sensitive to various effects  Using a redundant set of measurements will allow the isolation of the necessary components

K. Barish Color Glass Condensate (CGC) Gluons  High density limit  low-x  forward rapidity  Calculable regime of gluons at high density but weak coupling –Nuclear Amplification xG A ~A 1/3 xG p  Gluon saturation: characterized by Q sat  Predictions –Suppression »Low-x or forward η »More central  “Suppression” of away side jet Low –x is key 20 x Q (GeV) CGCCGC Central Arms Y~0 fsPHENIX Y=1-4 move boundary by changing Centrality to Map out Q S Q S  QCD ~ 220 MeV Prediction; Suppression : Low-x or forward η More central xG(x) x Saturation

K. Barish Connection with TMDs?  Problem: TMD factorization violated for dijet production in hadron+hadron collisions –Solution: Get back effective TMD factorization in case of small x partons at high density (“CGC regime”) – probed by quark, or photon  Problem: TMD parton distributions not universal –Solution: they can be constructed for building blocks which ARE universal. »e.g. Gluon PDF  G (1) (x,q  ), G (2) (x, q  ) »quantities derived via CGC and via TMD identical  Equivalence between TMD and CGC approach in “CGC” regime »Connections to TMD’s in spin? xpfq(xp)xpfq(xp) xG (2) (x,q  )  Measure : photon-jet & dijets at low-x in d+Au Domingues, Marquet, Xiao, Yuan arXiv: v2, PRL 106,

K. Barish Heavy-ions (Au+Au)  3D “image” of medium –At mid-rapidity only see only the evolution/final state of the “slice” of the fluid which is initially at rest longitudinally. –Make flow measurements in forward direction.  Forward photon measurements –Information on system expansion / early evolution. –Access to high baryon density region. T. Renk, PRC71, (2005) Bjorken: boost- invariant expansion Landau: complete initial Talk by P. Stankus

K. Barish 23 PHENIX Design PHENIX Design

K. Barish MuID RICH HCal EMCal Tracker EMcal Hcal 2T Magnet sPHENIX Conceptual Design * Not to scale

K. Barish Mid Rapidity Region  Ali Hanks talk Tuesday  Full 2  coverage  Electromagnetic and Hadronic calorimetry  2T Solenoidal Field  VTX detector for central tracker  Also allow heavy quark jets  Primary (initial) focus of jet and di- jet measurements in HI  Designed to include possible upgrade path: additional tracking, EID, ePHENIX  Will take full advantage of RHIC’s flexibility: d+A, Cu+Au, U+U, etc.

K. Barish Forward Region  Rely on central magnet field  Studying other field/magnet possibilities  EMCal based on restack of current PHENIX calorimetry  PbSc from central arm (5.52 cm 2 )  MPC forward arm (2.2 cm 2 )  For tracker considering GEM technology  Interest of HI in forward direction may influence choices based on expected multiplicity. PbSc restack =12x12 towers 1 tower is 5.5cm 2 MPC restack = 2.2cm 2

K. BarishOutlook  sPHENIX Forward will significantly extend physics capabilities  With new Forward Detector, will be able to understand large SSA, separating contributions from Sivers and Collins.  Forward Detector will also provide calibration for quarkonium measurements and probe CNM effects in d+A (connections with CGC and TMDs?)  Potential exists to explore 3D image of medium in Au+Au  Workshops planned. Multiple funding sources pursued.  Staged implementation approach  Drell-Yan/Quarkonia needs only EMCal, charged particle ID, and charge sign  Then add jet followed by identified hadron capabilities.  The sPHENIX forward would also be well matched with ePHENIX.

K. Barish Backups …

K. Barish Drell-Yan Feasibility

K. Barish Towards eRHIC R [cm      EMCal PID Inner Tracker Outer tracker Additional tracking as needed Magnet Immediate focus: Make sure sPHENIX concept of barrel consistent with upgrade plans for ePHENIX physics sPHENIX central arm proposal (CD0) to be submitted on Jul 1, 2012 Is EMCal resolutions good enough? Enough space for PID? Momentum range for PID Material budget limitation for tracking Minimal configuration/requirements: Backward: electrons, photons Barrel: electron, photons, hadrons Forward: hadrons Roman Pots for forward protons e- p/A  ForwardBackward  Barrel cross section diagram