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Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76$ TeV

The ALICE collaboration
No Journal Information, 2017

Abstract (data abstract)
In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow $v_2$ reflects fluctuations in the shape of the initial state of the system. This allows us to systematically study events corresponding to the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb—Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. The two-particle correlator $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$, calculated for different combinations of charges $\alpha$ and $\beta$, is almost independent of $v_2$ (for a given centrality), while the three-particle correlator $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_2) \rangle$ scales almost linearly both with the event $v_2$ and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on $v_2$ points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10-50% centrality interval is found to be 26-33% at 95% confidence level.

  • Table 1

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t1

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for unbiased events in Pb-Pb collisions at $\sqrt{s_{\rm NN}} =...

  • Table 2

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t2

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (0-10% $q_2$) in Pb-Pb collisions at...

  • Table 3

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t3

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (10-20% $q_2$) in Pb-Pb collisions at...

  • Table 4

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t4

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (20-30% $q_2$) in Pb-Pb collisions at...

  • Table 5

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t5

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (30-40% $q_2$) in Pb-Pb collisions at...

  • Table 6

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t6

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (40-50% $q_2$) in Pb-Pb collisions at...

  • Table 7

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t7

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (50-60% $q_2$) in Pb-Pb collisions at...

  • Table 8

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t8

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (60-70% $q_2$) in Pb-Pb collisions at...

  • Table 9

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t9

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (70-80% $q_2$) in Pb-Pb collisions at...

  • Table 10

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t10

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (80-90% $q_2$) in Pb-Pb collisions at...

  • Table 11

    Data from Fig 1.

    10.17182/hepdata.79482.v1/t11

    $v_2\{EP\}$ with $|\Delta\eta| > 2.0$ as a function of centrality for shape selected events (90-100% $q_2$) in Pb-Pb collisions at...

  • Table 12

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t12

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 13

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t13

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 14

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t14

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 15

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t15

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 16

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t16

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 17

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t17

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 18

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t18

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 19

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t19

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 20

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t20

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 21

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t21

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 22

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t22

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 23

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t23

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 24

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t24

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 25

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t25

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 26

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t26

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 27

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t27

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 28

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t28

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 29

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t29

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 30

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t30

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 31

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t31

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 32

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t32

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 33

    Data from Fig 2 (top).

    10.17182/hepdata.79482.v1/t33

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (same charge pairs) with $|\Delta\eta| > 2.0$ as a function of centrality for...

  • Table 34

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t34

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for unbiased events in Pb-Pb collisions at...

  • Table 35

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t35

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (0-10% $q_2$) in...

  • Table 36

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t36

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (10-20% $q_2$) in...

  • Table 37

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t37

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (20-30% $q_2$) in...

  • Table 38

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t38

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (30-40% $q_2$) in...

  • Table 39

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t39

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (40-50% $q_2$) in...

  • Table 40

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t40

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (50-60% $q_2$) in...

  • Table 41

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t41

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (60-70% $q_2$) in...

  • Table 42

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t42

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (70-80% $q_2$) in...

  • Table 43

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t43

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (80-90% $q_2$) in...

  • Table 44

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t44

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (opposite charge pairs) as a function of centrality for shape selected events (90-100% $q_2$) in...

  • Table 45

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t45

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for unbiased events in Pb-Pb collisions at...

  • Table 46

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t46

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (0-10% $q_2$) in...

  • Table 47

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t47

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (10-20% $q_2$) in...

  • Table 48

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t48

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (20-30% $q_2$) in...

  • Table 49

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t49

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (30-40% $q_2$) in...

  • Table 50

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t50

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (40-50% $q_2$) in...

  • Table 51

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t51

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (50-60% $q_2$) in...

  • Table 52

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t52

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (60-70% $q_2$) in...

  • Table 53

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t53

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (70-80% $q_2$) in...

  • Table 54

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t54

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (80-90% $q_2$) in...

  • Table 55

    Data from Fig 2 (bottom).

    10.17182/hepdata.79482.v1/t55

    $\langle \cos(\varphi_{\alpha} - \varphi_{\beta}) \rangle$ (same charge pairs) as a function of centrality for shape selected events (90-100% $q_2$) in...

  • Table 56

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t56

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 57

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t57

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 58

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t58

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 59

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t59

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 60

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t60

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 61

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t61

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 62

    Data from Fig 3 (top).

    10.17182/hepdata.79482.v1/t62

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ as a function of $v_2\{EP\}$ for...

  • Table 63

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t63

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 64

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t64

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 65

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t65

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 66

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t66

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 67

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t67

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 68

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t68

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 69

    Data from Fig 3 (bottom).

    10.17182/hepdata.79482.v1/t69

    $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| > 2.0$ multiplied by the charged-particle density, $dN/d\eta$,...

  • Table 70

    Data from Fig 5.

    10.17182/hepdata.79482.v1/t70

    $p_1$ parameter from a linear fit to $\langle \cos(\varphi_{\alpha} + \varphi_{\beta} - 2\Psi_{2}) \rangle$ (opposite - same) with $|\Delta\eta| >...

  • Table 71

    Data from Fig 6.

    10.17182/hepdata.79482.v1/t71

    CME fraction extracted from the slope parameter of fits to data and MC—Glauber model as a function of centrality in...

  • Table 72

    Data from Fig 6.

    10.17182/hepdata.79482.v1/t72

    CME fraction extracted from the slope parameter of fits to data and MC—KLN CGC model as a function of centrality...

  • Table 73

    Data from Fig 6.

    10.17182/hepdata.79482.v1/t73

    CME fraction extracted from the slope parameter of fits to data and EKRT model as a function of centrality in...

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