Polarized p A Physics Hideto En yo Kyoto University

Polarized p. A Physics Hideto En’yo Kyoto University Contents Ø Introduction p Our primary goal in the original plan Ø What the machine can provide ? Ø Single Spin Physics with large Nucleus Ø Double Spin Physics with small Nucleus Ø Summary　(How significant the outcome will be ? ) 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 1

Spin Physics at RHIC = polarized parton collider • Spin Structure of Nucleon – 1/2=(1/2)DS+DG+Lq+Lg • DG: gluon polarization • Dq: Anti-quark polarization – New Structures • Test of p. QCD • Use asymmetries sensitive ONLY to the higher orders (AN at high PT etc. ) • h 1: transversity ? QCD triumph? or ? beyond ? 28 -29/Oct/2000 gq→γq direct γ gg →bb gluon fusion uu →γ* Drell Yan ud →W • NEW TOOL to study hadronic processes • W, Z @500 Ge. V • flavor sensitive studies on the structure functions • cc/bb • Production mechanism • Spin in the fragmentation Hideto En'yo, Kyoto University (RHIC p. A workshop) 2

Polarized beam acceleration Full Snake kill the resonances twisted dipole in RHIC Partial Snake complete spin flip at resonances solenoid in AGS 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 3

Polarized Ions in RHIC BL(p）=10. 48 A/Z / (m A/(2 ZS)-1) < 6 Tm Magnetic Moment Anomaly If Snake is twice strong Z odd Present Snake Power N odd 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 4

Deuteron and Others ? • If Pol. d can be achieved, Most of Ions (spin = 0) can be accelerated without depolarization • Partial Snake (Solenoid) can work to kill the resonances (twice stronger than AGS snake) • Single Snake for Spin manupilation ? • Spin Flip ? 28 -29/Oct/2000 Partial Snake Longitudinal Polarization @ resonances Hideto En'yo, Kyoto University (RHIC p. A workshop) 5

Luminosity & Energy Ions Goal in RHIC Achieved in RHIC Goal in Source Achieved in Source Au 1*109 - - P 2 *1011 P=70% 1*1011 P=20% 9*1011 P>80% 6*10^11 P=72% 2 D- - 1*1013 P=80% 3 He++ - - - 1010~1011 P=70~80% 28 -29/Oct/2000 2*1011 N/bunch Lp. A ~Lpp Hideto En'yo, Kyoto University (RHIC p. A workshop) 6

Working Assumptions Lp. A ~Lpp p 500 Ge. V pp → 200 Ge. V p. A p → 3 He ← → 333 Ge. V p 650 Ge. V pp → 260 Ge. V p. A 3 H → ← Asymmetric( important to have W) 3 He → → 325+230(530) p 3 He ← → 325+130(410) p. A d → AA is not “Best-Buy” ← due to “dilution” F → 3 H = “p” with 1/3 Pol. ← 3 He= “n” with 1/3 Pol. A → 28 -29/Oct/2000 3 H 3 He → ← Hideto En'yo, Kyoto University (RHIC p. A workshop) d → ← F → ← A → 7

Our Surprises (Past) • • Gluons’ momentum fraction Iso spin Structure of Sea Spin Fraction of Quarks EMC effect !? Future ? (QCD perfect? ) 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 8

28 -29/Oct/2000 di n ea r. B in o An ad Sh uc l ti g in w N Sh ad ow in g g EMC effect Hideto En'yo, Kyoto University (RHIC p. A workshop) i m on r Fe oti M Xbj 9

EMC effect is seen any nucleus Fe Be C Al Ca Cu 28 -29/Oct/2000 He Ag Au Hideto En'yo, Kyoto University (RHIC p. A workshop) 10

EMC effect, Not Fundamental? Fermi motion k. F q (g) Off Shell Effect ? N A 28 -29/Oct/2000 Nuclear Binding Final State Interaction e e k. F Hideto En'yo, Kyoto University (RHIC p. A workshop) 11

EMC effect, Not definitive answer Fermi momentum Binding Energy Final State Int. Off Shell Effect MN: Not definitive QPM: Worse 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 12

Weak Boson Detection at PHENIX @500 Ge. V Yield in 1 -RHIC year at 500 Ge. V • W production is – Flavor sensitive – helicity fixed (V-A) 20% Less Kinematics (realized by N. Saito ) • power of the polarized collider with Muon Endcaps 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 30% MORE A/Z ratio in Large Nucleus If dp=dn & up=un 13

LHC-- p. A (reachable in RHIC++) for Flavor Sensitive EMC effect • W+ = d. A(x. A)up(xp)+dp(xp)u. A(x. A) • W = d. A(x. A)up(xp)+dp(xp)u. A(x. A) EMC Effect with flavor • R(W+A/W+p)=d. A(x. A)/dp(xp*) u. A(x. A)/up(xp*) (xp>>0) (x. A>>0) • R(W A/W p)=d. A(x. A)/dp(xp*) (xp>>0) u. A(x. A)/up(xp*) (x. A>>0) EMC Effect with spin (requires polarized proton) • AL(W+A)= d. A(x. A)/d. A (x. A) (xp>>0) D Du. A(x. A)/u. A (x. A) (x. A>>0) • AL(W A)=Dd. A(x. A)/d. A (x. A) (xp>>0) 28 -29/Oct/2000 Should be in Double ratio AL(A)/AL(p) Hideto En'yo, Kyoto University (RHIC p. A workshop) 14

Quark Structure Function in A u(A) In ALICE u(p) /PHENIX/STAR 28 -29/Oct/2000 di n ea r. B in o An ad Sh uc l ti g in w N Sh ad ow in g g Q 2 evolution Neglected Hideto En'yo, Kyoto University (RHIC p. A workshop) i m on r Fe oti M Xbj 15

Why not DG(A) In RHIC @200 Ge. V • must be interesting (the other side of EMC effect) • All the DG channel can be applied, but x determination is crucial. STAR g+Jet or PHENIX + Jet detection upgrade will be suitable for q+g channel • Channel like g+g → bb is feasible & interesting, but x is not well determined in open bb channel. – No real measurements so far ? • Not easy to get DG(A)/G(A) with large Nucleus ALL required. 19 F can be tried. 19 F is a pure proton hole state of 20 Ne(N=Z=10). →　polarized structure function of proton hole. But dilution is large (1/19) 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 16

With light Nuclei: 3 H, 3 He, d 3 He/d • ALL ATT possible 3 H/d • EMC effect exist. d/(2 p) No sh ad ow ing • Almost under control 3 He/3 H: mirror nuclei 28 -29/Oct/2000 3 He/(2 p+n), 3 H/(p+2 n) Hideto En'yo, Kyoto University (RHIC p. A workshop) 17

Nuclear Effect to g 1 is not large (3 He) - model calculations g 1 p Free VS 3 He This is why we can assume that polarized 3 He is a polarized neutron Offshell Effect ? g 1 n Different Model 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 18

But in detail there may be … 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 19

So…. • We can safely repeat the same measurements in p+”n” as p+p. – Note that the effective luminosity is 1/3 lower (dilution) • We believe Isospin Symmetry – u in p = d in n – d in p = u in n – g in p = g in n , Δg in p = Δg in n (RHIC specialty). • With 3 H we can study “ p ” in nuclear matter, but the effect may not be large. • Diagnostics type measurements ( but always SURPRIZE can happen) 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 20

Flavor Structure of Nucleon • No reason to assume d = u in nucleon – Dd Du is natural Recent FNAL Data shows 50% difference in p+p/p+d (D. Y. ) • RHIC@500 Ge. V – W+/W- Yield comparison J. C. Peng, G. T. Garvey d=u PHENIX W m d u PHENIX W m FNAL-E 866 results PRL 80 (1998) 3715 PHENIX W e 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 21

p+3 He / p+3 H for sea quark • Gottfried sum IG=∫dx( F 2 p- F 2 n) = 1/3 +2/3∫dx( up-dp) = 0. 235 (exp. ) • For mirror nucleus • IG=∫dx( F 2 p 3 He- F 23 H) TOTAL = 1/3 +2/3∫dx( up-dp) • Cancel nuclear effects • Easy Spin handling s (p 3 He) - s (p 3 H) s (p 3 He) + s (p 3 H) 1(4 u-d)(u-d) 3(4 u+d)(u+d) ALLp 3 He s (p 3 He) - ALLp 3 H s (p 3 H) s (p 3 He) + s (p 3 H) 28 -29/Oct/2000 Small nuclear effect Valence Sea 1(4 u-d)(Du-Dd) 3(4 u+d)(u+d) Hideto En'yo, Kyoto University (RHIC p. A workshop) 22

ｐ＋ｄ • Ｄ↑＝ｐ↑＋ｎ↑(spin 1) – ALL=Dqd helicity – ATT=DTqd transversity – AUQ=dqd tensor • As a “n” beam vs 3 He – d is less attractive since ALLpd arise also from “p” – d is more attractive since Nuclear effect is better known – d is less attractive from a view point of spin handling • Du = Dd physics – Rpd = Dspd/2 Dspp in D. Y. ( Kumano et al. ) =1/2(1+Dd/Du) 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 23

p+d 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 24

Summary • Two categories are feasible in polarized p. A physics – Single spin p. A – Double spin p( d, 3 He, 19 F) • Reachable in RHIC++, p. A @ >500 Ge. V can provide unique measurements which can address FLAVOR sensitive EMC effect (LHC? ). – A kind of measurements we have to do it at least once. • G(A)/G(p) can be addressed in RHIC. With 19 F ΔG(A)/G(A) can be measured (with 1/19 dilution). • With 3 He, polarized p + polarized “n” can be studied. If Isospin Symmetry holds, this is a kind of diagnostics measurements. (very important, but less interesting) l Du = Dd, u=d can be studied with 3 He, 3 H, d Drell-Yan, complementary to pp→W • Clearly we need more study on this matter. – AN type measurements　(single spin p. A) should also be considered • Higher order QCD, can be a lot different in A 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 25

Spin manipulation is collision geometry change in AA 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 26

The biggest UPGRADE issue in Spin Community is NEW DETECTOR FOR SPIN or not 28 -29/Oct/2000 Hideto En'yo, Kyoto University (RHIC p. A workshop) 27