Signatures of collective behavior in small systems

Kozlov, I. M.; Luzum, Matthew; Denicol, Gabriel S.; Jeon, Sangyong; Gale, Charles

doi:10.1016/j.nuclphysa.2014.09.054

Cited by 51 publications

(44 citation statements)

References 37 publications

(33 reference statements)

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“…Reasons for this could be the neglected initial state correlations and/or the lack of a detailed description of the fluctuating subnucleonic structure of the proton. Our results for p+A collisions differ significantly from those in [28,29,30,31], suggesting that the details of the initial shape in small systems are of paramount importance. 3 We predict an increase of both v 3 and v 5 in 3 He+Au collisions compared to d+Au collisions, while the even harmonics are comparable in both systems.…”

Section: Discussioncontrasting

confidence: 82%

Collective effects in light–heavy ion collisions

Schenke

Venugopalan

2014

Nuclear Physics A

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We present results for the azimuthal anisotropy of charged hadron distributions in A+A, p+A, d+A, and 3 He+A collisions within the IP-Glasma+music model. Obtained anisotropies are due to the fluid dynamic response of the system to the fluctuating initial geometry of the interaction region. While the elliptic and triangular anisotropies in peripheral Pb+Pb collisions at √ s = 2.76 TeV are well described by the model, the same quantities in √ s = 5.02 TeV p+Pb collisions underestimate the experimental data. This disagreement can be due to neglected initial state correlations or the lack of a detailed description of the fluctuating spatial structure of the proton, or both. We further present predictions for azimuthal anisotropies in p+Au, d+Au, and 3 He+Au collisions at √ s = 200 GeV. For d+Au and 3 He+Au collisions we expect the detailed substructure of the nucleon to become less important.

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Section: Discussioncontrasting

confidence: 82%

Collective effects in light–heavy ion collisions

Schenke

Venugopalan

2014

Nuclear Physics A

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“…Meanwhile, figure 13 shows that for v 2 {2}/v 2 [2] the agreement between data and DPMJET is better in low multiplicity p-Pb collisions, where no evidence of anisotropic collectivity is achieved from previous measurements [36,38]. In addition, the hydrodynamic calculations [62] from MUSIC v2.0 using a modified MC-Glauber initial state and η/s = 0.08 are also presented in figures 12 and 13. These calculations in general underpredict the measured v 2 coefficients but agree better with the data in high multiplicity than in low multiplicity classes.…”

Section: Pb-pb Collisionsmentioning

confidence: 87%

“…Neither the DPMJET model, which does not incorporate anisotropic flow, DPMJET calculations are presented by pink shaded areas. Hydrodynamic calculations (MUSIC) with modified MC-Glauber initial conditions and η/s = 0.08 are shown as magenta lines [62]. nor the hydrodynamic model, which does not include non-flow contributions, could provide a quantitative description of the data.…”

Section: Discussionmentioning

confidence: 99%

Searches for transverse momentum dependent flow vector fluctuations in Pb-Pb and p-Pb collisions at the LHC

Acharya¹,

Adamová²,

Adolfsson³

et al. 2017

J. High Energ. Phys.

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The measurement of azimuthal correlations of charged particles is presented for Pb-Pb collisions at √ s NN = 2.76 TeV and p-Pb collisions at √ s NN = 5.02 TeV with the ALICE detector at the CERN Large Hadron Collider. These correlations are measured for the second, third and fourth order flow vector in the pseudorapidity region |η| < 0.8 as a function of centrality and transverse momentum p T using two observables, to search for evidence of p T -dependent flow vector fluctuations. For Pb-Pb collisions at 2.76 TeV, the measurements indicate that p T -dependent fluctuations are only present for the second order flow vector. Similar results have been found for p-Pb collisions at 5.02 TeV. These measurements are compared to hydrodynamic model calculations with event-by-event geometry fluctuations in the initial state to constrain the initial conditions and transport properties of the matter created in Pb-Pb and p-Pb collisions. The ALICE collaboration 26 Keywords: Heavy Ion Experiments IntroductionThe primary goal of ultrarelativistic heavy-ion collisions is to study the properties of the Quark-Gluon Plasma (QGP), a state of matter predicted by Quantum Chromodynamics to exist at high temperatures and energy densities [1,2]. An important experimental observable used to accomplish this goal is the azimuthal anisotropy of particles emitted in the transverse plane. In non-central heavy-ion collisions, the overlap region of the Lorentzcontracted nuclei is roughly almond-shaped. Nucleons contained in such anisotropic overlap region interact with each other and give rise to a system of high energy density which expands anisotropically. These interactions convert the initial spatial asymmetry into a final-state momentum anisotropy of the produced particles, a phenomenon referred to as collective anisotropic flow [3][4][5]. Anisotropic flow is characterised using a Fourier decomposition of the azimuthal distribution of particles with respect to the flow symmetry planes [6, 7] 1) where N is the number of produced particles, E is the energy, p the momentum, p T the transverse momentum, ϕ the azimuthal angle and η the pseudorapidity of the particle. The n th order flow (vector) V n is defined as: V n ≡ v n e inΨn , where v n is the flow coefficient, and Ψ n represents the azimuth of V n in momentum space (flow angle). For a uniform matter distribution in the initial stage of a heavy-ion collision, Ψ n for n ≥ 1 coincides with the reaction plane defined by the beam direction and impact parameter. Due to event-by-event fluctuations of the participating nucleons distribution inside the overlap region, the Ψ n may -1 - JHEP09(2017)032deviate from the reaction plane and the odd flow coefficients v 2n−1 are non-vanishing [8][9][10][11][12][13][14]. Large flow coefficients were observed at the Relativistic Heavy-Ion Collider (RHIC) [15][16][17][18] and the Large Hadron Collider (LHC) [19][20][21][22][23][24][25][26][27][28][29]. These measurements constrain the initial conditions (e.g. energy and entropy density) and transpo...

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“…The study of these collisions at the Relativistic Heavy Ion Collider (RHIC) and at the Large Hadron Collider (LHC) has demonstrated that matter at temperatures above the crossover between hot hadronic matter and hotter QGP exhibits strong collective phenomena [1][2][3][4][5][6][7] which can be described successfully by hydrodynamic simulations of the rapid expansion and cooling of the initially lumpy droplets of matter produced in the collisions [8][9][10][11][12][13][14][15][16][17][18]. Such strong collectivity has also recently been observed in smaller colliding systems, including p-Pb, p-p or 3 He-Au [19][20][21][22][23][24][25][26][27][28][29], for which hydrodynamic simulations also seem to be successful [30][31][32][33][34][35][36][37]. The applicability of hydrodynamics from early times in the evolution and for small systems suggests that the matter formed in these ultrarelativistic collisions is a strongly coupled liquid.…”

Section: Introductionmentioning

confidence: 99%

Angular structure of jet quenching within a hybrid strong/weak coupling model

Casalderrey-Solana

Gulhan

Milhano

et al. 2017

J. High Energ. Phys.

120

145

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Within the context of a hybrid strong/weak coupling model of jet quenching, we study the modification of the angular distribution of the energy within jets in heavy ion collisions, as partons within jet showers lose energy and get kicked as they traverse the strongly coupled plasma produced in the collision. To describe the dynamics transverse to the jet axis, we add the effects of transverse momentum broadening into our hybrid construction, introducing a parameter K ≡q/T 3 that governs its magnitude. We show that, because of the quenching of the energy of partons within a jet, even when K = 0 the jets that survive with some specified energy in the final state are narrower than jets with that energy in proton-proton collisions. For this reason, many standard observables are rather insensitive to K. We propose a new differential jet shape ratio observable in which the effects of transverse momentum broadening are apparent. We also analyze the response of the medium to the passage of the jet through it, noting that the momentum

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Signatures of collective behavior in small systems

Cited by 51 publications

References 37 publications

Collective effects in light–heavy ion collisions

Collective effects in light–heavy ion collisions

Searches for transverse momentum dependent flow vector fluctuations in Pb-Pb and p-Pb collisions at the LHC

Angular structure of jet quenching within a hybrid strong/weak coupling model

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