Centrality and rapidity dependence of inclusive jet production in s - PowerPoint PPT Presentation

Centrality and rapidity dependence of inclusive jet production in √ s NN = 5.02 TeV p +Pb collisions with the ATLAS detector Dennis V. Perepelitsa Brookhaven National Laboratory for the ATLAS Collaboration 20 May 2014 XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions � Darmstadt, Germany

Hard probes of p ( d )+A 2 2 2 2 ch rcBK-MC, kt-factorization ch R pPb ( � =2) rcBK-MC kt-factorization R pPb ( � =0) rcBK-MC, hybrid LO EPS09 nPDF rcBK-MC, hyb LO+inel. term � =0.1 IP-Sat (Tribedy & Venugopalan) 1.5 1.5 1.5 rcBK (Tribedy & Venugopalan) 1.5 EPS09 nPDF 1.4 EPS09 FGS10 1 1 HKN 1 1 1.2 ) 2 =100 GeV nDS 1 0.5 0.5 0.5 0.5 η >0 is proton-going 0.8 0 0 0 0 0 2 4 6 8 10 12 0 2 4 6 8 10 12 2 p t (GeV/c) 0.6 p t (GeV/c) (x,Q 2 2 2 2 ch ch rcBK-MC, min bias rcBK-MC, min bias R pPb ( � =6) R pPb ( � =4) rcBK-MC, Npart >10 rcBK-MC, Npart >10 0.4 Pb cme= 5 TeV rcBK-MC, LO+inelastic term � =0.1 cme= 5 TeV rcBK-MC, LO+inelastic term � =0.1 g R 1.5 1.5 1.5 1.5 EPS09 nPDF EPS09 nPDF 0.2 1 1 1 1 0 -5 -4 -3 -2 -1 10 10 10 10 10 1 x 0.5 0.5 0.5 0.5 Salgado et al., hep-ph/1105.3919 current best knowledge of nPDFs 0 0 0 0 0 2 4 6 8 10 12 0 2 4 6 8 10 12 p t (GeV/c) p t (GeV/c) Albacete et al., hep-ph/1209.2001 η -dependence of CGC vs. nPDF predictions • Hard probes access the partonic structure of the nucleus • Jets allow us to explore this over a large kinematic range • Can probe b -dependent nPDFs, initial state energy loss, saturation phenomena (at very low p T , large y*), etc. 2

Hard probes of p ( d )+A @ RHIC jet R dAu di-hadron J dA 10.1016/j.nuclphysa.2013.02.184 d+Au, s = 200 GeV 60-88% NN 1.6 peripheral PRL 107 172301 (2011) 1.4 1 1.2 dA e n t r a l c dA R 1 J 0-20% fwd fwd d+Au 60-88 p d+Au 0-20 p 0.8 T T -1 10 0.5-0.75 GeV/c 0.5-0.75 GeV/c �� ���� 0.6 =0.3 Gaussian filter jet, 60-88% σ 0.75-1.0 GeV/c 0.75-1.0 GeV/c ����������� =0.3 Gaussian filter jet, 0-20% σ 1.0-1.5 GeV/c 1.0-1.5 GeV/c 0.4 10 15 20 25 30 35 40 -3 frag -2 10 10 x rec p (GeV/c) Au T • At mid-rapidity, anomalous centrality • At forward rapidity, large centrality dependence dependent suppression • for high-p T jets • single- and di-hadrons • central suppression • attributed to shadowing / saturation • enhanced peripheral (!?) / CGC phenomena • What happens in central & peripheral collisions in between? ➡ ATLAS can explore the kinematic range in the middle 3

ATLAS detector Inner Detector -2.5 < η < +2.5 Convention: y * > 0 is proton -going p Pb EMCal+HCal system Pb-going Forward Calorimeter -4.9 < η < +4.9 -4.9 < η < -3.2 + High Level Trigger system 4

p +Pb collisions & centrality [1/GeV] ATLAS Preliminary -2 p +Pb, s = 5.02 TeV 10 NN -1 Pb ∫ L dt = 27.8 nb T • 28 nb -1 of p +Pb/Pb+ p data @ 5.02 TeV E -3 Σ 10 /d N d • Centrality determined using Σ E T in Pb-going evt -4 10 N 1/ FCal, -4.9 < η < -3.2, default Glauber -5 10 • best sensitivity to collision geometry & allows -6 10 measurements of very forward jets 0 100 200 Pb E [GeV] Σ • Reasonable behavior in soft & hard observables T R. Debbe, 10:30 Monday N coll -scaling of Z production in p +Pb ATLAS-CONF-2013-096 10 × ) 60-90% ) 9 ATLAS Preliminary ATLAS Preliminary events 12 s = 5.02 TeV NN -1 | p+Pb L = 1 b -1 µ η p+Pb 2013, L =29 nb 0-90% Centrality 8 int /d 10 int s = 5.02 TeV 0-1% N ch NN ) / (dN 7 y = -0.465 8 〉 1-5% cm coll Z -2.5<y <2.5 6 6 cent. N 5-10% Data 〈 5 | Glauber ( =0) /( Ω N Uncertainty η 〈 〉 4 10-20% /d coll Z N NNLO Prediction ch 4 (dN 20-30% 2 9 10 30-40% 3 40-60% 0 10 20 30 0 10 20 30 2 N 〈 〉 part 1 Z. Citron, 14:40 Tuesday 0 -3 -2 -1 0 1 2 3 ATLAS-CONF-2014-020 5 η

Jets in p +Pb 8 10 ] -1 5 +3.6 < y* < +4.4, 1 +0.3 < y* < +0.8, 10 × × *) [GeV 6 1 +2.8 < y* < +3.6, 10 -0.3 < y* < +0.3, 10 × × 6 10 2 7 +2.1 < y* < +2.8, 10 -0.8 < y* < -0.3, 10 × × y 3 8 +1.2 < y* < +2.1, 10 -1.2 < y* < -0.8, 10 × × d T 9 4 4 +0.8 < y* < +1.2, × 10 -2.1 < y* < -1.2, × 10 10 p N/d p +Pb s = 5.02 TeV NN 2 )(d anti- k , R =0.4 2 t 10 -1 evt ∫ L dt = 27.8 nb (1/N 0-90% 1 -2 10 -4 10 • anti-k t , R=0.4 calorimeter jets -6 10 • UE estimation & subtraction • designed for Pb+Pb, cross-checked in pp -8 10 • Selected by online high-level jet trigger -10 10 ATLAS • 36m PYTHIA pp dijets overlaid onto p +Pb data Preliminary • corrections are modest (10-30%) -12 10 20 100 1000 • and mostly cancel in the R CP and R pPb p [GeV] T 0-90% yields See poster E-15 by T. Kosek 6

y * >0 is proton-going Jet R pPb pPb +2.1 < y* < +2.8 +1.2 < y* < +2.1 R 1.6 1.0 p +Pb, 0-90% 0.4 jet yield in p +Pb ATLAS Preliminary EPS09 calculation +0.8 < y* < +1.2 +0.3 < y* < +0.8 (1/ N evt ) d 2 N /d p T d y * 1.6 R pPb = < T pA > d 2 σ /d p T d y * 1.0 Pb nucleon flux 2013 pp data @ 2.76 TeV 0.4 ( x T -scaled to 5.02 TeV) seen by proton -0.3 < y* < +0.3 -0.8 < y* < -0.3 1.6 1.0 • R pPb for 0-90% events 0.4 • ≈ 5 units of rapidity, 50-1000 GeV -1.2 < y* < -0.8 -2.1 < y* < -1.2 • 5-10% enhancement 1.6 • weak p T dependence? 1.0 • consistent with EPS09 prediction pPb ∫ -1 L dt = 27.8 nb p +Pb s = 5.02 TeV 0.4 NN pp ∫ -1 anti- k , R =0.4 L dt = 4.0 pb t 40 100 1000 40 100 1000 7 p [GeV] T

y * >0 is proton-going CP +3.6 < y* < +4.4 +2.8 < y* < +3.6 1.4 Jet R CP R central yield 1.0 0-10%/60-90% � 0.4 ATLAS 20-30%/60-90% � R CP = Preliminary 40-60%/60-90% � 1.4 +2.1 < y* < +2.8 +1.2 < y* < +2.1 (1/ N evt ) d 2 N /d p T d y * � 1.0 R coll > 100 GeV jets (1/ N evt ) d 2 N /d p T d y * 0.4 suppressed at N coll ratio peripheral +0.8 < y* < +1.2 +0.3 < y* < +0.8 1.4 mid-rapidity! yield 1.0 � 0.4 suppression -0.3 < y* < +0.3 -0.8 < y* < -0.3 1.4 pattern smooth 1.0 with centrality 0.4 � -1.2 < y* < -0.8 -2.1 < y* < -1.2 larger 1.4 1.0 suppression 0-10%/60-90% -1 ∫ L dt = 27.8 nb 0.4 at higher p T 20-30%/60-90% p +Pb s = 5.02 TeV NN anti- k , R =0.4 40-60%/60-90% t 20 100 800 20 100 800 p [GeV] 8 T

y * >0 is proton-going CP +3.6 < y* < +4.4 +2.8 < y* < +3.6 1.4 Jet R CP R 1.0 0.4 ATLAS Preliminary 1.4 +2.1 < y* < +2.8 +1.2 < y* < +2.1 R CP ≈ 0.2 here! 1.0 � 0.4 � +0.8 < y* < +1.2 +0.3 < y* < +0.8 1.4 � 1.0 � 0.4 � increasing -0.3 < y* < +0.3 -0.8 < y* < -0.3 1.4 suppression 1.0 at more 0.4 forward -1.2 < y* < -0.8 -2.1 < y* < -1.2 1.4 rapidities 1.0 0-10%/60-90% -1 � ∫ L dt = 27.8 nb 0.4 20-30%/60-90% p +Pb s = 5.02 TeV NN anti- k , R =0.4 40-60%/60-90% t 20 100 800 20 100 800 p [GeV] 9 9 T

y * >0 is proton-going CP +3.6 < y* < +4.4 +2.8 < y* < +3.6 1.4 Jet R CP R 1.0 0.4 ATLAS Preliminary 1.4 +2.1 < y* < +2.8 +1.2 < y* < +2.1 suppression 1.0 even at 0.4 backward +0.8 < y* < +1.2 +0.3 < y* < +0.8 1.4 rapidities 1.0 0.4 -0.3 < y* < +0.3 -0.8 < y* < -0.3 1.4 1.0 thus, the data 0.4 is incompatible -1.2 < y* < -0.8 -2.1 < y* < -1.2 1.4 with a centrality- 1.0 0-10%/60-90% -1 dependent ∫ L dt = 27.8 nb 0.4 20-30%/60-90% p +Pb s = 5.02 TeV NN anti- k , R =0.4 40-60%/60-90% t y* “shift” 20 100 800 20 100 800 p [GeV] 10 T

y * >0 is proton-going CP +3.6 < y* < +4.4 +2.8 < y* < +3.6 1.4 Jet R CP R 1.0 0.4 ATLAS Preliminary Modification 1.4 +2.1 < y* < +2.8 +1.2 < y* < +2.1 pattern over 1.0 6.5 units of 0.4 rapidity, from +0.8 < y* < +1.2 +0.3 < y* < +0.8 1.4 25-800 GeV! 1.0 0.4 -0.3 < y* < +0.3 -0.8 < y* < -0.3 1.4 How does this 1.0 make sense 0.4 with the R pPb ? -1.2 < y* < -0.8 -2.1 < y* < -1.2 1.4 1.0 0-10%/60-90% -1 ∫ L dt = 27.8 nb 0.4 20-30%/60-90% p +Pb s = 5.02 TeV NN anti- k , R =0.4 40-60%/60-90% t 20 100 800 20 100 800 p [GeV] 11 T

y * >0 is proton-going Jet R pPb +2.1 < y* < +2.8 +1.2 < y* < +2.1 pPb R 1.6 1.0 0-10% 0.4 20-30% 60-90% ➡ Centrality-selected R pPb must +0.8 < y* < +1.2 +0.3 < y* < +0.8 1.6 split the difference 1.0 � 0.4 • 0-10% R pPb suppressed -0.3 < y* < +0.3 -0.8 < y* < -0.3 • 60-90% R pPb enhanced(!) 1.6 � 1.0 • Larger modifications at high-p T ATLAS 0.4 Preliminary and forward rapidities -1.2 < y* < -0.8 -2.1 < y* < -1.2 ➡ Backwards & at low p T , we 1.6 recover geometric scaling 1.0 pPb ∫ -1 L dt = 27.8 nb p +Pb s = 5.02 TeV 0.4 NN pp ∫ -1 L dt = 4.0 pb anti- k , R =0.4 t 40 100 1000 40 100 1000 12 p [GeV] T