Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba1 Jet study at RHIC and Jet reconstruction study at LHC energy for ALICE experiment ShinIchi Esumi Inst. of Physics, Univ. of Tsukuba, Japan Contents Jet-Suppression and Modification Mach-cone and Ridge w.r.t. Reaction Plane Jet reconstruction study with pythia at LHC energy Particle identification to Jet identification

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba2 RHIC 200GeVSPS 17GeVRHIC 62GeV PHENIX nucl-ex/ S.Kniege, ISMD 2007 jet pp Au Jet suppression modification with 2-particle  correlation

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba3 p+p, peripheral Au+Au central Au+Au PHENIX QM08 d+Au, 200 GeV STAR QM06  (rad)  Ridge “jet” Au+Au, 200 GeV

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba4 STAR Preliminary T Inclusive ~ T Shoulder ~ T Ridge < T Jet QM06 QM08 ridge jet inclusive << Both ridge and shoulder are almost independent with centrality and trigger p T selections. It’s just like a bulk matter… suspicious on BG(bulk) subtraction… but this is what we see…

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba5 PHENIX preliminary Identified  0 trigger with associate hadron Width does not change with centrality similar to charged hadron triggered case. Surface bias (as in 2+1 correlation case) 7-9 (X) % 7-9 (X) % 7-9 (X) % 7-9 (X) % 7-9 (X) % 7-9 (X) % QM08 PHENIX

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba6 1/Ntrig dN/d  (A.U.) p T, photon GeV Per-Trigger Yield (A.U.) Run GeV 0 Run GeV, cent=0~20%, preliminary Direct  trigger with associate hadron QM08 PHENIX p+p: Consistent with trigger photon carrying the full jet energy, away side jets are similar between  0 and  triggers. Need more studies and statistics for Au+Au case. Run 4/5 200 GeV

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba7 3<p T trig <4GeV/c & 1.0<p T asso <1.5GeV/c 20-60% STAR  =  associate -  trigger (rad) Jet modification and geometry (and v 2 ) QM08: STAR, PHENIX QM04: STAR Mach-cone shape depends on R.P. angle. Mach-cone is a source of of v 2

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba8 STAR Preliminary Ridge Jet 3<p T trig <4, 1.5<p T trig <2.0 GeV/c QM08 STAR STAR  (rad)  Ridge “jet” Au+Au, 200 GeV Ridge shape depends on R.P. angle. Ridge is a source of of v 2 Jet does not depends on it Jet reduces v 2  (rad)  PYTHIA p+p away side (in d  ) of one di-jet can be near side (in d  ) of another di-jet

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba9  ASSO. -  TRIG. < 0  ASSO. -  TRIG. > 0 in-pl. out-of-pl.

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba10 In order to continue and develop the Jet tomography study in Heavy-Ion collisions at LHC, we have started to consider building a new calorimeter in ALICE at azimuthally opposite side of the existing EMcal as Yasuo mentioned. We use control variables like centrality and reaction plane, which have been utilized in the previous Heavy-Ion experiments, which Dousatsu has discussed. We also like to treat a high p T jet axis of an event as another control variable for Heavy-Ion collisions. For this purpose, I just have started to play with PYTHIA p+p events to test the jet finding and reconstruction in the Heavy-Ion collision environment (by superposition of many p+p events) for the detector to be built. Hiroki/Dousatsu will continue to talk about his studies on jets and di-jets using HYDJET model. I’m still in the beginning and learning phase, so I appreciate your suggestions and comments.

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba11 Jet Finder/Reconstruction study for Heavy Ion Collision Environment * superposition of PYTHIA 5.5TeV p+p Min.Bias events N(p+p) max ~ 200 events (~35k final particles/event, dN ch /d  ~2000) * inclusion of single hard scattered p+p event with various p T hat selections (> 20 ~ 90 GeV) * modification of jet finding routine (CellJet) in pythia8.107 with event-by-event BG subtraction, based on an idea from CMS paper E.P.J C50, (2007) (1) get average energy of cell in [  ] space with step of (0.1,0.1) for each event (2) subtract the average energy from all cells, ignore negative cells (3) find the jet seeds with cell energy of more than 5GeV (4) sum-up all the cell energies within a cone of (d   +d     <0.25 from each seed (5) define the jet with the total energy above 20GeV (6) recalculate the average energy by excluding the found jet cones (7) repeat steps (2)-(6) for 3 times

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba12 single p+p event p T hat > 40 GeV14 min.bias p+p events added (Pb+Pb peripheral)  pT max  pT max

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba13 single p+p event p T hat > 40 GeV177 min.bias p+p events added (Pb+Pb central)  pT max  pT max  pT max  pT max

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba14 Jet p T SUM (GeV/c) pythia8.107 p+p 5.5TeV superimposed on Pb+Pb min.bias (p T hat min > 20 / 40 / 60 / 80 GeV) triggered p+p event + superimposed min. bias Pb+Pb alone (BG) triggered p+p event alone BG subtracted signal dN/dp T (a.u.)

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba15 (A) solid lines (B) dashed lines p T Hat Min =20GeVp T Hat Min =40GeVp T Hat Min =60GeVp T Hat Min =80GeV (C) solid lines (A-B) points p TSUM (GeV/c) N(p+p) = 0~50 N(p+p) = 50~100 N(p+p) = 100~150 N(p+p) = 150~200 dN/dp T (a.u.) p TSUM (GeV/c) (A) triggered p+p event + superimposed Pb+Pb (B) superimposed Pb+Pb alone (C) triggered p+p event alone (A-B) BG subtracted signal

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba16 p T Sum > 30GeV p T Sum > 50GeV p T Sum > 70GeV p T Sum > 90GeV Signal to BG noise ratio increases with increasing the jet energy Increased efficiency of jet finding, which could be caused by the upward BG fluctuation… # of found jet in p+p is the reference. (A-B) / (C) (BG subtracted signal) / (triggered p+p event alone) N part ~ 2*N(p+p) (A) / (C) (triggered p+p event + superimposed Pb+Pb) / (triggered p+p event alone) Signal + BG Signal Output Input

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba17 pythia8.107 p+p 5.5TeV (p T hat min >20GeV) p+p event same p+p event + superimposed min. bias Pb+Pb by pile-up p+p events from min. bias p+p QCD hard allqq -> qqqg -> qggg -> gg  pT max  pT max  Trigger(p T max ) - particle(p T >4GeV/c) correlation

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba18 p+p event QCD hard allqq -> qqqg -> qggg -> gg  pT max same p+p event + superimposed min. bias Pb+Pb by pile-up p+p events from min. bias p+p  pT max  pythia8.107 p+p 5.5TeV (p T hat min >50GeV) Trigger(p T max ) - Jet(p T >50GeV/c) correlation

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba19 Jet p T SUM (GeV/c) p+pPb+Pb min.biasPb+Pb central RMS width (  pT max ) at away side [  /2,3  /2] QCD hard all qq -> qq qg -> qg gg -> gg pythia8.107 p+p 5.5TeV Possibility of Jet Identification #1 RMS width (  pT max ) at away side [  /2,3  /2]

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba20 p+pPb+Pb min.bias QCD hard all qq -> qq qg -> qg gg -> gg Pb+Pb central Jet p T SUM (GeV/c) Particle multiplicity within Jet cone (r<0.25) pythia8.107 p+p 5.5TeV Possibility of Jet Identification #2 Particle multiplicity within Jet cone RMS width of this particle multiplicity distribution within jet cone is large, therefore jet by jet identification might not be possible, however statistically feasible.

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba21 Summary * Jet suppression and Jet modification at RHIC * Strong relation between v2 and Jet * Jet reconstruction study with pythia at LHC energy * Particle identification to Jet identification * Surface-bias (particle-particle, jet-particle and jet-jet correlation with respect to reaction plane, centrality)

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba22

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba23 (1) (2) (3) (4) (2) (3) (4) (1) Trigger particle x(R.P.) y    ASSO.  TRIG.  In order to study the jet modification (mach-cone, ridge) and it’s relation with almond geometry in more detail… with and without R.P. aligned event mixing Associate particle 1 Associate particle 2

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba24 Simulation of flow subtraction for jet shape extraction pure flow + jet (~10% of total yield) model R.P. is not biased by the embedded jets 3 different shapes (which do not depend on R.P. orientation) Shape#1, usual jet Shape#2, mach-cone Shape#3, asymmetric Reminder: we should expect the extracted jet shape should look like the jet shape above the pedestal (dashed lines, ZYAM bias). embedded jets shape

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba25 Shape#1, usual jetShape#2, mach-coneShape#3, asymmetric Event mixing method “CASE.B” used for all three cases C 2 flow+jet : Points in the figures are given by MC with pure flow + jet simulation C 2 flow : Lines in the figures are given by MC with pure flow simulation C 2 = (Real pair) / (Mixed pair)

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba26 After the subtraction Shape#1, usual jetShape#2, mach-coneShape#3, asymmetric J = C 2 (flow + jet) - C 2 (flow) Non-R.P. dependence of jet shape recovered!

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba27 single p+p event p T hat > 40 GeV46 min.bias p+p events added (Pb+Pb mid-central)  pT max  pT max

Wuhan meeting, 4-6/Dec/2008ShinIchi Esumi, Univ. of Tsukuba28 pythia8.107 p+p 5.5TeV (p T hat min >20GeV) p+p event QCD hard allqq -> qqqg -> qggg -> gg  pT max same p+p event + superimposed min. bias Pb+Pb by pile-up p+p events from min. bias p+p  pT max  Trigger(p T max ) - Jet(p T >20GeV/c) correlation