LANL Nuclear Physics 15/10/2006 Cold Nuclear Matter Physics Cold Nuclear Matter Physics Mike Leitch LANL Medium Energy Nuclear Physics Cold Nuclear Matter (CNM) effects in Quarkonia Production the underlying production physics gluon saturation, energy loss, p T broadening PHENIX dAu J/  implications for AA at RHIC Open charm & beauty with single muons complementary to above Future dA at RHIC-II pA at the LHC dbar/ubar & quark energy loss at E906 & JPARC

LANL Nuclear Physics 25/10/2006 Understanding the underlying J/ ψ production physics Production of heavy vector mesons, J/ ,  ’ and  Gluon fusion dominates production: color singlet or octet cc: absolute cross section and polarization? Hadronization time (important for pA nuclear effects) Complications due to substantial feed-down from higher mass resonances, from  ’,  c (  ’ cleaner physics - harder experimentally) χ,1,2  J/  ~30%  ΄  J/  5.5% #J/ψ’s: ~400 (  ), ~100 (ee) √s = 200 GeV PRL 96, (2006) Rapidity

LANL Nuclear Physics 35/10/2006 Gluon Shadowing and Saturation Q = 2 GeV 5 GeV 10 GeV Leading twist gluon shadowing phenomenological fit to DIS & Drell-Yan data, and many other approaches Amount of gluon shadowing differs by up to a factor of three between diff models! Saturation or Color Glass Condensate (CGC) At low-x there are so many gluons that 2  1 diagrams become important and deplete low-x region Nuclear amplification: x A G(x A ) = A 1/3 x p G(x p ), i.e. gluon density is ~6x higher in Gold than the nucleon high x low x

LANL Nuclear Physics 45/10/2006 The J/  - a Cold Nuclear Matter (CNM) Puzzle J/  suppression is a puzzle with possible contributions from shadowing & from: Energy loss of incident gluon shifts effective x F and produces nuclear suppression which increases with x F Absorption (or dissociation) of into two D mesons by nucleus or co-movers (the latter most important in AA collisions where co-movers more copious) 800 GeV p-A (FNAL) PRL 84, 3256 (2000); PRL 72, 2542 (1994) Hadronized J/ ψ ? open charm: no A-dep at mid-rapidity Absorption shadowing, dE/dx, and/or intrinsic charm What is the fundamental QCD description for gluon dE/dx?

LANL Nuclear Physics 55/10/2006 High x 2 ~ 0.09 Low x 2 ~ Transverse Momentum Broadening for J/ψ’s Upsilons Drell-Yan J/  &  ’ PRL 96, (2006) Initial-state gluon multiple scattering causes p T broadening (or Cronin effect) PHENIX 200 GeV results show p T broadening comparable to that at lower energy (  s=39 GeV in E866/NuSea)

LANL Nuclear Physics 65/10/2006 something more, dE/dx? & more? = X 1 – X 2 19 GeV 39 GeV 200 GeV open charm: no A-dep at mid-rapidity J/  for different  s collisions PHENIX J/  Nuclear Dependence from 200 GeV pp and dAu collisions – PRL 96, (2006) Data favors weak shadowing & absorption With limited statistics difficult to disentangle nuclear effects Will need another dAu run! (more pp data also) Klein,Vogt, PRL 91:142301,2003 Kopeliovich, NP A696:669,2001 Low x 2 ~ (shadowing region) Not universal vs x 2 as expected for shadowing, but does scale with x F, why? initial-state gluon energy loss? Sudakov suppression (~energy conservation)? Analysis & paper writing led by MJL

LANL Nuclear Physics 75/10/ mb 3 mb Low x 2 ~ (shadowing region) 0 mb 3 mb R. Vogt CNM calcs. J/  suppression in AA collisions & CNM baseline AA suppression is somewhat stronger than CNM calculations predict but really need more precise dAu constraint! CNM calculations with shadowing & absorption - Vogt & MJL present dAu data probably only constrains absorption to: σ ABS ~ 0-3 mb (CNM = Cold Nuclear Matter) central periph.

LANL Nuclear Physics 85/10/ st measurement of nuclear dependence in d+Au for forward prompt muons (charm & beauty) at RHIC And also of light meson decays to muons Complementary to quarkonia studies comparisons help isolate initial-state from final-state physics Suppression at large rapidity (small-x shadowing region) – see also physics discussion earlier gluon saturation? leading twist shadowing? coherence effects? Sudakov suppression or limiting fragmentation parton recombination? and enhancement at negative rapidity will be greatly improved by FVTX upgrade Heavy Quarks with Single Muons light mesons open charm & beauty led by Ming Liu, Anuj Purwar & Xiaorong Wang

LANL Nuclear Physics 95/10/2006 1st  ’s at RHIC from ~3pb -1 collected during the 2005 run looking for larger signal in run6 & beyond also (mid-rapidity)  ’s that decay into one muon in each muon arm and will extract reliable  ’ signal in the high-mass tail of the J/  & on top of the substantial combinatoric background all of these will be substantially improved by the FVTX upgrade Much More to Come! Analysis done by MJL & Butsyk for QM05

LANL Nuclear Physics 105/10/2006 Cold Nuclear Matter at RHIC-II & the LHC RHIC-II – higher luminosity dA & pp program will enable studies of the most rare processes accurate J/ ,  ’ &  measurements - to solve the physics puzzle in quarkonia production & allow access to gluon saturation explicit B  J/  X and D,B  μ measurements with detached vertices provided by the PHENIX Forward Vertex Detector (FVTX) upgrade - to explore saturation & complement the quarkonia measurements and help isolate the physics also Drell-Yan, single charm pairs, dbar/ubar with W’s RHIC-II spans the transition region in x for gluon saturation while measurements at the LHC will lie deep in that region the LHC pA program would be complementary to that at RHIC-II but pA remains an upgrade at LHC, with the physics case largely undeveloped, and pA running not likely to occur until 2010 or later SignalRHIC Exp. (Au+Au) RHIC I (>2008) RHIC IILHC ALICE J/  →e + e  J/  →     PHENIX3,300 29,000 45, ,000 9, ,000  → e + e -  →     STAR PHENIX ,200 1,040 2,600 8,400 MJL co-convenor of RHIC-II Forward/pA Science group

LANL Nuclear Physics 115/10/2006 LA-LP dbar/ubar > 1 for x 2 < 0.25 probably due to meson cloud of proton, i.e. quark counting (p → n + π + → n + dbar-u) does gluon splitting dominate at larger x 2 and give dbar=ubar? lower energy Drell-Yan D/H measurement needed to push to larger x 2 ! J/  studies could also access dbar/ubar FNAL E906 (120 GeV) or JPARC (50 GeV) flavor asymmetry of the nucleon to larger x

LANL Nuclear Physics 125/10/ GeV FNAL E906 (120 GeV) or JPARC (50 GeV) quark energy loss in nuclei At 800 GeV, the nuclear dependence of Drell-Yan on nuclear targets could not unambiguously separate shadowing and dE/dx effects at low x E866 data are consistent with no energy loss (using EKS shadowing) or Kopeliovich shadowing, Johnson et al. find 2.2 GeV/fm from the same data for 120 or 50 GeV p-A Drell-Yan x > 0.1 & only quark dE/dx remains (no shadowing) also stronger, dE/dx ~ 1/s and important for understanding of RHIC data For Drell-Yan only initial state interactions are important—no final state strong interactions.

LANL Nuclear Physics 135/10/2006 Summary of LANL CNM Program Cold nuclear matter effects with quarkonia –gluon saturation, energy loss,... –get new dA run for much higher accuracy –  ’ &  Charm and beauty via single muons – complement quarkonia studies –also dbar/ubar via W + /W - at 500 GeV RHIC-II to enable rarest probes –Upsilon, Drell-Yan, B  J/  X dbar/ubar & quark energy loss via Drell-Yan process –at E906/FNAL or JPARC Much of RHIC program strengthened by FVTX upgrade pA program at the LHC –LHC (in gluon saturation region) –RHIC-II (covers transition)

LANL Nuclear Physics 145/10/2006 Nucleon Sea Asymmetry & Parton Energy Loss at JPARC? (descendent of E866/NuSea at FNAL) DRAFT Proposal