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ICPAQGP, Kolkata, February 2-6, 2015 Itzhak Tserruya PHENIX highlights

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Introduction Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 2 RHIC is a unique machine for its versatility Can collide any species from p up to U, at any energy from the top energy of s NN = 200 GeV down to 7 GeV PHENIX capitalizes on this versatility performing systematic studies of observables as function of system size and colliding energy This talk will focus on recent PHENIX results on these studies

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Outline Introduction Small vs large systems: change of paradigm? Long range correlations in d, 3 He + Au v 2 in d, 3 He + Au HBT radii in d+Au, Cu+Cu HF and J/ R AA in d+Au, Cu+Cu Lower energies HBT radii vs energy dN ch /d scaling v 2 energy dependence HF R AA vs energy Photons Summary 3

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Small systems: paradigm change? Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 4 p+p: reference baseline p,d+A: System size too small for quark matter formation Reference for cold nuclear matter effects Is that so? Many features seen in A+A collisions are also seen in high multiplicity p,d+A collisions:

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Small systems: paradigm change? Small systems: paradigm change? Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 5 p+p: reference baseline p,d+A: System size too small for quark matter formation Reference for cold nuclear matter effects Is that so? Many features seen in A+A collisions are also seen in high multiplicity p,d+A collisions: Long range correlations in d, 3 He+Au

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Ridge in small systems at RHIC Long-range near-side peak clearly visible in central d+Au collisions Not present in minimum bias p+p collisions Min bias p+pCentral d+Au Two particle correlations measured over a large | | > 2.75 gap (charged track in central arm and tower hit in forward calorimeter) arXiv:1404.7461 Central 3 He+Au Long-range near-side peak clearly visible in central d+Au and central 3 He+Au collisions Not present in minimum bias p+p collisions

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and at LHC 7 ICPAQGP, Kolkata, February 2-6, 2015 Long-range near-side peak clearly visible in high multiplicity p+Pb collisions as observed in AA collisions at RHIC and LHC CMS p+Pb s NN =5.02 TeV N trk > 110STAR Au+Au central s NN =200 GeV PLB 718, 795 (2013)PRC 80, 064912 (2009) very similar to AA Itzhak Tserruya

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Long-range correlations in d+Au No ridge in d-going direction. Shape of correlation changes with centrality Ridge seen only in Au-going direction. Strong centrality dependence Peripheral collisions: very similar correlations in d-going and Au-going sides arXiv:1404.7461

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Ridge in central 3 He+Au Long-range correlations seen on both Au-going and 3 He-going sides 9Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 Hydro can explain and reproduce the ridge Also CGC effective field theory (initial state gluon saturation) can explain the ridge (Phys. Rev. D87, 094034 (2013)).

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Small systems: paradigm change? Small systems: paradigm change? Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 10 p+p: reference baseline p,d+A: System size too small for quark matter formation Reference for cold nuclear matter effects Is that so? Many features seen in A+A collisions are also seen in high multiplicity p,d+A collisions: Long range correlations in d, 3 He+Au Flow in d, 3 He+Au

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Flow in small systems at RHIC 11 ICPAQGP, Kolkata, February 2-6, 2015 Mass ordering seen in d+Au v 2 Data consistent with viscous hydrodynamics (using /s =1/4) at p T

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and at the LHC 12 ICPAQGP, Kolkata, February 2-6, 2015 very similar to AA PLB 726, 164 (2013)PRC 72, 014904 (2005) ALICE Itzhak Tserruya Flow observed in small systems at RHIC and LHC Similar magnitude and mass ordering as observed in AA collisions

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Small systems: paradigm change? Small systems: paradigm change? Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 13 p+p: reference baseline p,d+A: System size too small for quark matter formation Reference for cold nuclear matter effects Is that so? Many features seen in A+A collisions are also seen in high multiplicity p,d+A collisions: Long range correlations in d, 3 He+Au Flow in d, 3 He+Au HBT radii in d+Au

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14 HBT radii scale with size arXiv:1410.2559 PHENIX Au+Au and Cu+Cu: HBT radii scale linearly with initial transverse size ALICE Pb+Pb : same behavior

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15 ICPAQGP, Kolkata, February 2-6, 2015 also in small systems a HBT radii scale linearly with the initial transverse size from small (d+Au, p+Pb) to large (Au+Au, Pb+Pb) systems at RHIC and LHC. Imply radial expansion in small systems and final state interaction arXiv:1404.5291 Itzhak Tserruya

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Small systems: paradigm change? Small systems: paradigm change? Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 16 p+p: reference baseline p,d+A: System size too small for quark matter formation Reference for cold nuclear matter effects Is that so? Many features seen in A+A collisions are also seen in high multiplicity p,d+A collisions: Long range correlations in d, 3 He+Au Flow in d, 3 He+Au HBT radii in d+Au HF and J/ R AA in d+Au and Cu+Cu

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HF R AA system-size dependence Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 17 PRC 90, 034903 (2014) Smooth evolution of HF R AA from enhancement in small systems to suppression in large systems

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18 J/ system-size dependence PRC 90, 064908 (2014) Similar suppression for smaller (CuCu) and larger (AuAu) systems. PRL 101, 122301 (2008) Similar suppression in Cu+Au (Au-going direction) and Au+Au Stronger suppression in Cu+Au (Cu-going direction) opposite of expected trend if suppression is prop to particle density

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Lower energies Lower energies Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 19

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HBT vs. collision energy Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 20 PHENIX, STAR and ALICE results combined Non-monotonic behavior of R out 2 R side 2 (proportional to emission duration and (R side -2R)/ R long (related to medium expansion velocity). softening of equation of state near the CEP? arXiv:1410.2559

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dN ch /d scaling Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 21 N part scalingN quark scaling

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dN ch /d scaling Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 22 N part scalingN quark scaling Normalize highest multiplicity point at each energy to 1 N part scaling works well at low energies N quark scaling works well at high energies Transition at ~ 39 GeV.

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v 2 in Cu+Cu and Au+Au collisions at s NN =62.4 and200 GeV 23 arXiv:1412.1043 Au+Au Cu+Cu Almost no difference in v 2 at 200 and 62 GeV in Au+Au and Cu+Cu

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v 2 energy dependence Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 24 Flow saturates at s NN = 39 200 GeV Significant decrease at s NN = 7.7 GeV

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R AA vs energy Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 25 Central Cu+Cu: Onset of suppression between 22.4 and 62.4 GeV Central Au+Au: Onset of suppression at energies lower than 39 GeV But very different N part Cu+Cu PRL 101, 162301 (2008) Au+Au PRL 109, 152301 (2012) N part 90-98 N part 315-325

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HF R AA in Au+Au Strong suppression Large v 2 Enhancement opposite to energy loss models Same v 2 within uncertainties arXiv:1405.3301PRC 84, 044905 (2011) 200 GeV62.4 GeV 26

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Photons Photons Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 27

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Direct photons Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 28 New measurement using external conversion of real photons Consistent with previous result Extend range to lower p T, higher statistics arXiv:1405.3940 v 2 remains a challenge for theory. New v 3 data provide additional constraint

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Direct photons excess: Centrality dependence Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 29 Subtract N coll scaled p+p spectrum excess photon yield Fit excess photon yield with Y = A exp(-p T /T) Inverse slope T independent of centrality arXiv:1405.3940 Integrated excess yield scale as dN/dy = B N part with =1.480.080.04

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Future Future Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 30

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The future: sPHENIX Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 31 arXiv:1501.06197 Excellent jet, dijet, h, -jet quarkonia capabilities Designed to be the basis for a future eIC detector DOE Science Review in July 2014 1.5 T BaBar magnet being moved to BNL

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Summary Many phenomena observed in A+A collisions are also seen in small systems p,d+A. Interesting features observed at low energies. Direct photons remain a puzzle sPHENIX 32 ICPAQGP, Kolkata, February 2-6, 2015 Itzhak Tserruya

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Other recent PHENIX results Itzhak Tserruya ICPAQGP, Kolkata, February 2-6, 2015 33 arXiv:1412.1038 HF and J/ in d+Au at 200 GeV in Au+Au J/ in U+U, Au+Au, Cu+Cuv 2, v 3, v 4 in Au+AuDark Photons arXiv:1404.2246 arXiv:1409.0651