Parton Physics – from Fermilab to RHIC

1. Parton Physics – from Fermilab to RHIC Mike Leitch – LANL Peter Barnes, Jan Boissevain(Eng), Melynda Brooks, Allan Hansen(PD), Dave Lee, Ming Liu, Pat McGaughey, Joel Moss, Andrea Palounek, Walter Sondheim(Eng), John Sullivan, Hubert vanHecke • FNAL: parton structure & processes; their modification in nuclei – nucleon flavor asymmetry, DY & J/Y Adep, parton dE/dx … • RHIC: QGP and spin physics – muons at PHENIX, QGP via J/Y’s, gluon shadowing • PHENIX Run-II & the MVD • Silicon-vertex upgrades for open heavy-mesons? E772 - 1991

2. A measurement of Anti-quark asymmetry in the Nucleon Sea FNAL E866/NuSea ACU, ANL, FNAL, GSU, IIT, LANL, LSU, NMSU, UNM, ORNL, TAMU, Valpo

3. From Draft NSAC Long Range Plan : “The Structure of the Nuclear Building Blocks”

4. Nuclear modification of parton level structure & dynamics Drell-Yan Ratio(W/Be) Drell-Yan Process 1.0 0.9 0.8 NMC DIS E772 R(W/D) E866 R(W/Be) 0.7 • Modification of parton momentum distributions of nucleons embedded in nuclei • e.g. shadowing – depletion of low-momentum partons. Process dependent? • Nuclear effects on parton “dynamics” • energy loss of partons as they propagate through nuclei • and (associated?) multiple scattering effects

5. Nuclear Dependence for heavy vector mesons, e.g. J/Ψ, Ψ ',  • production: color singlet or octet ( ) and color neutralization timescale • hadronization time: • Coherence length for cc fluctuations: • absorption on nucleons or co-movers • feed-down from higher mass resonances, e.g. χc E789

6. E866/NuSea: 800 GeV p-A (Fermilab) PRL 84, 3256 (2000) PT Broadening at 800 GeV open charm: no A-dep at mid-rapidity Hadronized J/Y? • J/Ψ and Ψ’ similar at large xF where they both correspond to a traversing the nucleus • but Ψ’ absorbed more strongly than J/Ψ near mid-rapidity (xF ~ 0) where the resonances are beginning to be hadronized in nucleus. a(pT) shape is independent of xF & same for NA3 at a lower energy

7. PT Broadening in Drell-Yan and associated Radiative Energy Loss Baier et al. NP B484, 265 (1987) E866 – Preliminary or So energy loss associated with observed pT broadening is tiny, e.g. for W:

8. Quark energy loss in nuclear matter Johnson, Kopeliovich et al., PRL 86, 4483 (2001) Shadowing dE/dx = 0 dE/dx & Shadowing dE/dx =0.25 Charged hadron and p0 production at PHENIX versus pT for central collisions which, when compared to pQCD models that work well for peripheral collisions, suggests that jet-quenching or energy-loss may be present. Analysis of our p-A Drell-Yan data (E772 - PRL 64, 2479 (1990) using the Kopeliovich model. Dashed lines with shadowing only; solid lines with parton energy loss of, dE/dz = 2.32 ± 0.52 ± 0.5 GeV/fm

9. Theoretical Models for PT Broadening • Predicts a different dominant mechanism for pT broadening in DY at RHIC & LHC energies: • For lower energy fixed target measurements initial-state multiple scattering is most important • But at RHIC & LHC color filtering preserves small dipole configurations which have high-pT and therefore give larger pT broadening Kopeliovich et al, hep-ph/0110221 “Light Cone Dipole” approach (full) RHIC LHC R(Au/H) (longitudinal only) DY as bremsstrahlung in the target rest frame

10. J/Ψ Polarization • NRQCD based predictions (color octet model) necessary to explain CDF charm cross sections • E866 J/Y measurement not in agreement with NRQCD based predictions [Beneke & Rothstein, PRD 54, 2005 (1996)] which give • 0.31 < λ < 0.63 • Complicated by feedown (~40%) from higher mass states. E866/NuSea E866/NuSea – PRL 86, 2529 (2001). However U(2S+3S), which should not suffer from feeddown, have maximal polarization consistent with the Octet model!

11. 11 Physics Questions for the New Century The February 2002 issue of Discover magazine based its cover story on the recent 105-page public draft of the National Research Council Committee on Physics of the Universe report, Connecting Quarks with the Cosmos: 11 Science Questions for the New Century. 7. Are there new states of matter at ultrahigh temperatures and densities? The theory of how protons and neutrons form the atomic nuclei of the chemical elements is well developed. At extremely high densities and temperatures, protons and neutrons may "dissolve" into an undifferentiated "soup" of quarks and gluons, which can be probed in heavy-ion accelerators. Still higher densities occur and can be probed in neutron stars and the early universe. The Relativistic Heavy Ion Collider (RHIC) is in operation at the DOE's Brookhaven National Laboratory to study of extremely hot, dense nuclear matter. It collides beams of gold nuclei at energies sufficient to form brief microcosms of the hot, dense soup of elementary particles (quarks and gluons) that previously existed only for the first microseconds after the Big Bang origin of our universe. The experimental data to date have revealed unexpected characteristics and provide the first tantalizing clues of possible quark-gluon plasma formation. Physicists around the world are interested in the RHIC collisions, which occur thousands of times per second. Each one acts as a microscopic pressure cooker, producing temperatures and pressures more extreme than exist now even in the cores of the hottest stars. In fact, the temperature inside a RHIC collision can exceed 1,000,000,000,000 degrees above absolute zero - about ten thousand times the temperature of the sun. Although RHIC collisions may be super-fast and super-hot, which makes them interesting to physicists, they're too small and too brief to be dangerous. In a RHIC experiment using the massive PHENIX detector, the impact of two gold nuclei ejected fewer particles transverse to the collision axis than standard theory predicts. This is the first indicator of an exotic state of matter, but much more evidence is needed. By combining this finding with many to come in the next few years, researchers may be able to understand a state of matter that hasn't existed since the dawn of the universe. From Science Highlights – DOE Office High Energy & Nuclear Physics. http://www.science.doe.gov/feature_articles_2002/February/eleven_questions/eleven-questions.htm

12. J/Ψ suppression – an effective signature of Quark-gluon plasma (QGP) formation? • Color screening in a QGP would destroy pairs before they can hadronize into charmonium • But ordinary nuclear effects also absorb or modify J/Ψ’s • We need a comprehensive understanding of charmonium production in nuclei • Competing effects may be identified in p-A collisions by their strong kinematic dependencies, together with complementary studies of Drell-Yan scattering and open-charm production NA50 -- Anomalous J/ suppression. Evidence for QGP??

15. J.C.Peng, LANL Eskola, Kolhinen, Vogt hep-ph/0104124 PHENIX μ+μ- E866/NuSea e+e- PHENIX μ PHENIX e E866 (mid-rapidity) NA50 Kopeliovich, Tarasov, & Hufner hep-ph/0104256 Expected statistical errors from a 2-week d-A run at PHENIX and measurements form E866/NuSea Gluon Shadowing for J/Ψ’s – predictions? • In PHENIX μ acceptance for Au-Au collisions? • Eskola… : ~ 0.8 • Kopeliovich… : ~ 0.4 • Strikman…[hep-ph/9812322] : ~ 0.4 PHENIX μ+μ- (Au)

16. Charmonium at PHENIX - Coming soon! m+m- • PHENIX: South Muon & Electrons taking first data now (Au-Au over; p-p in progress) • North Muon in 2003 (after shutdown) • d-A collisions: strong consensus building; hopefully coming soon. Simulated e+e- Simulated * Min-bias/RHIC-year for a = .92 (Nagle & Brooks) ** E866 nuclear dependence data only *** Upsilons from E772

17. Summary of PHENIX Run-II Accumulations

18. Distributions for 1615 Accepted J/Y Simulated Events xF Mass(GeV) x1 x2 pT cos(qcs)

19. From Draft NSAC Long Range Plan : “The Structure of the Nuclear Building Blocks”

20. m Physics Program - High-pT Single m’s • High-pT single-m’s come from heavy mesons, i.e. D’s or B’s • These mesons are produced primarily through gluon fusion and thus are sensitive to the gluon structure functions. • In p-A collisions the shadowing of gluons can be studied Simulated • With polarized beams the gluon polarization, G, can be studied. • W±m±νm can be identified by high-pT single-m’s and W+/W- can be used to measure the flavor asymmetry in the nucleon sea including its spin decomposition Simulated

21. PHENIX Muliplicity & Vertex Detector (MVD) • dN/dη for charged particles over very broad rapidity range • Provides s(Zvertex) < 2 mm for the rest of PHENIX, muon spectrometer needs vertex to maintian good J/Y mass resolution • Reaction plane for in- & out-of-plane comparisons for various signals in PHENIX, e.g. J/Y suppression, “jet-quenching”. PHENIX w/o MVD : | η | < 0.35 dN/dη from MVD for 125 Au-Au events dN/dη from MVD for one Au-Au event

22. MVD vertex resolution & efficiency for p-p, p-Au & Au-Au collisions

23. PHENIX Silicon Vertex Upgrade • Matching tracklets in silicon to tracks in m-arms • Momentum measurement • displaced vertex And also detect h in silicon LANL LDRD supporting R&D for us ($250K/yr) • Gluon polarization in proton • Nuclear dependence of open charm: • Gluon shadowing • Charm cross section • To understand J/Y in A-A collisions Accurate projection to collision vertex => close, thin detector

24. Extra Slides

25. History of the LANL HENP Program E772 (1987 - …) DY, J/Y, Y’, U Nuclear Dep. Spokesman: Moss NA44 (1990 - …) Bose-Einstein Correlations,… Jacak, Sullivan,van Hecke E789 (1990 - …) sbb, sJ/Y, D0 Nuclear Dep. Spokesman: Peng SSC (GEM,SLD 1990 - …) GEM Silicon tracker (Brooks, Lee, Palounek) E866/NuSea (1996 - …) , J/Y, Y’, Nuclear Dep. Spokesmen: Garvey,McGaughey,Leitch PHENIX (1990 - …) Muons: J/Y, single-m, open-charm, spin, p-A, QGP MVD: dN/dη, ZVERTEX E906 (2006?) at high-x, parton dE/dz Spokesman: Reimer (ANL)

26. PHENIX Timetable Jan 2001 May 2001 Jan 26 2002 March 2002 June 2002 Sept 2002 FY 2003 FY 2002 Prepare Sm Sm with Au-Au beams p-p Run Nm & Sm 1stmm physics (J/ suppression & single m’s) 2-Arm physics Install Nm chambers Build Nm chambers Install Nm FEE Start Building Nm FEE Complete Nm FEE Fix Sm Run MVD Prepare MVD (60%) Run MVD Finish MVD 1st MVD physics (dN/dη, vertex & fluctuations) p-p Au-Au Beams Beam Si vertex upgrade R&D for charm physics In FY2003 d-A, p-p and Au-Au collisions are all likely

27. The North-m Arm • North-m arm advantages: • Superior arm with more kick, better momentum resolution & better mass resolution than South (for ’s: sNorth= 190 MeV compared to sSouth = 240 MeV ) • While J/’s should melt in a QGP, ’s are smaller and should not, so a well separated  peak (separation of 1S &2S is 563 MeV) is critical •  mesons may be broadened, shifted in mass or even enhanced in a QGP. With its 10o (as opposed to 12o for South) minimum theta, the North-m arm has much larger acceptance for ’s which tend to decay into m’s are small angles. • The mID is directly behind the tracking volume (in contrast with the South-m arm which has a large gap). This should help reduce backgrounds and improve matching between tracking and mID. • Two m-arms: • Doubles the counting rate • Allows measuring forward and backwardm+m- simultaneously, i.e. negative & positive rapidity at the same time. Important for the study of formation-time effects in p-A. • Allows for events with one m in each arm, e.g. mid-rapidity ’s • Required for W±m±νmspin measurements since the Z0m+m- backgrounds can be determined only using two arms. South m arm North m arm

28. Physicists: • Barnes (1/2 on EDM, return-to-research funding ended last year) : chamber construction, PHENIX physics. • Brooks: m-tracking detector council representative, m-software leader, m-electronics, PHENIX Institutional Board representative. • Garvey(retired) : E866, eRHIC, advisor to BNL management & John Browne, RHIC program supporter but no direct involvement in PHENIX. • Hansen (postdoc) : hadron physics, MVD electronics & software. • Lee : chamber construction manager, silicon-vertex upgrade. • Leitch: HENP team leader , m-electronics, m-calibration system, m-software, J/ suppression, p-A, shadowing, parton energy-loss, E866 spokesman, PHENIX Executive Council • McGaughey : m-electronics, m-calibration system, m-software, parton enegy-loss, silicon-vertexupgrade LDRD spokesman, former E866 spokesman, E906. • Liu (newest staff member) : m-electronics, m-software, online monitoring, spin physics • Mischke(now off the program) : was m-electronics manager & is now expert consultant. • Moss : spin physics, parton energy-loss, silicon-vertex upgrade, APS DNP chair. • Peng (1/4 time on EDM; leaving LANL in Jan) : E866 physics, parton energy-loss, p-A and parton physics at RHIC, PHENIX upgrades, extensive long-range planning work, FNAL/E906, JHF. • Silvermyr: new postdoc (April 2002). • Sullivan :MVD PHENIX detector council representative, hadron physics, MVD electronics & software. • Van Hecke :MVD ancillary systems & DAQ, hadron physics • Engineers • Boissevain (1/4) : MVD constuction, m layout engineering. • Sondheim (funded by construction $’s) : PHENIX mlead engineer & system integration