Long-range rapidity correlations in high multiplicity p-p collisions

Transcription

1 Long-range rapidity correlations in high multiplicity p-p collisions Kevin Dusling North Carolina State University Raleigh, NC 7695 kevin May 9,

2 Contents. Overview of the Ridge. Long range correlations from QCD evolution 3. The CMS Ridge in p+p collisions

3 The ridge at STAR d + Au Au + Au N pairs N trig N pairs N trig η φ η φ Dan Magestro, STAR, Hard Probes 4 Jorn Putschke, STAR, Quark Matter 6

4 Three particle correlation Long range correlation in η, vs. η,3 seen in central Au+Au. η d+au STAR Preliminary (a) η η Au+Au 4-8% STAR Preliminary (b) η η Au+Au -% STAR Preliminary (c) η d η N/d η d P. K. Netrakanti (STAR Coll. - QM8) arxiv:84.447

5 Space Time picture of Heavy Ion collisions I Y YKP PHOBOS GeV PHOBOS 6.4 GeV NA49 7. GeV - - Lisa, Pratt Solt, Wiedemann nucl-ex/ Y π- π -. There is a scale separation between longitudinal and transverse momentum. This leads to a correlation between momentum and position p z E p z t or y η spc. time

6 Space Time picture of Heavy Ion collisions II t A B z detection freeze out latest correlation ( τ τ frz out exp ) y A y B ()

7 Ridge from PHOBOS Near-side, "# <. dn ch /d"! /N trig.5 Au+Au -3% (PHOBOS) p+p (PYTHIA v6.35) v uncertainty ZYAM uncertainty -4 - "! B. Alver (PHOBOS Coll.) J. Phys. G 35, 48 (8). τ τ frz-out exp ( ) y 6 fm exp ( ) 4.8 fm

8 Wavefunction of the proton Low Energy: (Large x) High Energy: (Small x) Figures courtesy of François Gelis.

9 xf(x,q. ).8 g/ MSTW 8 NNLO PDFs (68% C.L.) Q = GeV xf(x,q. ).8 4 Q = GeV g/.6 u.6 b,b u.4 d.4 c,c d. c,c s,s u d. s,s d u x x Growth of gluon distribution function at small x is seen experimentally. Data / figures from:

10 BFKL p z ( x)p z, k k z = xp z, k α s d k dx dp Brem C R π k x x x x x 3 x T (r, Y ) Y = α sn c π dr r r (r r ) [T (r, Y ) + T (r r, Y ) T (r, Y )] x 4 x 3

11 BK evolution equation T (r, Y ) Y = α sn c π dr r r (r r ) [T (r, Y ) + T (r r, Y ) T (r, Y ) T (r, Y )T (r r, Y )]

12 Running BK T (r, Y ) Y = dr K Bal. (r, r, r r ) [T (r, Y ) + T (r r, Y ) T (r, Y ) T (r, Y )T (r r, Y )] K Bal. (r, r, r ) = α s(r)n c π [ r r r + r ( αs (r ) ) α s (r ) + ( αs (r ) )] r α s (r ) Balitsky, Chirilli PRD Kovchegov, Weigert NPA Albacete, Kovchegov PRD 75 5

13 Deep inelastic scattering on the Proton F F F F F F Q =. GeV Q =.5 GeV Q =5 GeV Q = GeV initial conditions solid: GBW dotted: MV Q =8 GeV Q =5 GeV x Q =.5 GeV Q =.5 GeV Q = GeV Q =5 GeV Q = GeV Q =45 GeV Albacete, Armesto, Milhano, Salgado; arxiv: x -

14 Deep inelastic scattering on nuclei.95.9 NMC Calcium NMC Carbon Gold F A /( A F d ) x

15 un integrated gluon distribution UGD 3..5 Q s x.5 GeV Q s x 4.9 GeV Q s x 5.4 GeV k T Φ A, (x, k ) = πn ck α s + r dr J (k r ) [ T A, (r, ln(/x)) ]

16 Power counting p q g -4 g - g p q p q g 4 g g - p+a A+A ρ

17 Power counting d N d p d q dy p dy q : N c (S Q s) Q s p 3 q3 (S Q s) α s Q 4 s p 4 q4

18 Multi particle correlations at LO Q S - R C N (p,, p N ) κ N dn (S Q s) N dy p d p, dn dy pn d p,n. Dumitru, Gelis, McLerran, Venugopalan (arxiv: ). KD, Fernandez-Fraile, Venugopalan (arxiv:9.4435) 3. Gelis, Lappi, McLerran (arxiv:95.334)

19 In heavy ion collisions flow collimates this signal v r

20 PHOBOS /N trig dn ch /d η Au+Au -3% (PHOBOS) p+p (PYTHIA) y trig = y trig =.75 y trig =.5 p T trig =.5 GeV p T assoc = 35 MeV η NOTE: peak is standard PYTHIA and not part of our calculation.

21 LHC d N/(d p T d q T dy p dy q ) [GeV -4 ] - 3. Pb+Pb at LHC p T = GeV q T = GeV y p = y p = -.5 y p = -3 y p = y q - y p Six units of rapidity probing evolution in the gluon wavefunction of Lead.

22 CMS pp Ridge

23 Multiplicity Entries P NB n (n, k) = k = ζ Γ(k + n) n n k k Γ(k)Γ(n + ) (n + k) n+k ( N c ) S Q s π ζ =.55 [Empirical] ζ =.3.5 [Lattice] P(n) 4 6 η <.5 CMS 7 TeV ( ) IP Sat ALICE.36 TeV (.) n ALICE.9 TeV (.) UA5.9 TeV (.) UA5. TeV (.) Tribedy & Venugopalan arxiv:.895,:445 High mulitplicity events are b= events.

24 Angular Structure. In A+A collisions, collimation driven by underlying transverse flow. In addition, there is an intrinisic correlation from the production process itself which will dominate in systems with little or no flow

25 Angular Structure Graph: d N/d φ d N/d φ Angular Structure: π φ π φ

26 Angular Structure B k k B p,y p k k p k Q s q k Q s q k q,y q p k p k A q k A Expect maximum correlation for p q Dumitru, KD, Gelis, Jalilian-Marian, Lappi, Venugopalan: arxiv:9.595

27 Associated yield and ZYAM d N/d φ pqcd jet Associated Yield π φ Jet and underlying event do not contribute to associated yield.

28 Results Assoc.Yield.5. p Assoc T. GeV Η4 KD, RV; arxiv: p Trig T GeV Red: Harder Fragmentation Blue: Softer Fragmentation D = ( x)/x D = 3( x) /x

29 Results Assoc.Yield 3 5. p Assoc T 3. GeV Η p Trig T GeV Assoc.Yield p Assoc T 4. GeV Η p Trig T GeV

30 Centrality Dependence Assoc.Yield.5. p Assoc T. GeV Η4 Trig. p T 3. GeV NN Q s(x =.) =.5,.3,.45,.6 GeV

31 Blast wave d N π d φ = dψj (Ψ, φ) d N ( π d φ φ ) (Ψ, φ) ( sin φ ) = β ( cos ( φ)) ( ). β cos Ψ cos φ + β (cos ( φ) + cos (Ψ)) J = β ( β cos (Ψ + φ/)) ( β cos (Ψ φ/)),

32 Blast wave dn dφ dn dφ. V r =.5. V r =.5.. V r =.. V r =.9.9 φ φ Left: No intrinisic correlation in φ followed by radial boost. Right: Intrinisic azimuthal correlation followed by radial boost.

33 ppridge + Flow Assoc.Yield.5. p Assoc T. GeV Η p Trig T GeV V r =,.,.,.5,.3 Structure of ridge suggests flow contribution is small (V r.c). (In this naive blast wave model)

34 Pb+Pb Ridge Assoc. Yield.. p Assoc T 4.GeV Η4.5 V r.85. V r.65.5 PbPb s.76tev V r p Trig T GeV

35 Summary. Calculations within CGC e.f.t. quantitatively explains:. p dependence. Multiplicity dependence. Measured structure of pp Ridge limits radial flow in p+p 3. In contrast, flow explains PbPb Ridge

36 Backup

37 x ) xf(x,q g d d u u s,s c,c =.5 GeV Q x ) xf(x,q x ) xf(x,q g b,b = GeV Q x ) xf(x,q MSTW 8 NNLO PDFs (68% C.L.)

38 Jet Component d N dy p d p dy q d q.5. BFKL MRK QMRK φ

39 Momentum dependence q T 3 GeV q T 6 GeV q T 8 GeV q T GeV 4 Φ

40 Rapidity dependence y q y q y q 5 y q 3 4 Φ