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Two particle correlation method to Detect rotation in HIC

Two particle correlation method to Detect rotation in HIC. Dujuan Wang University of Bergen. Supervisor: Laszlo P. Csernai. Outline. Introduction Two particle correlation calculation The DHBT method Results in our FD model Summary. Introduction.

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Two particle correlation method to Detect rotation in HIC

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  1. Two particle correlation method to Detect rotation in HIC Dujuan Wang University of Bergen Supervisor: Laszlo P. Csernai

  2. Outline • Introduction • Two particle correlation calculation • The DHBT method • Results in our FD model • Summary

  3. Introduction • Pre-equilibrium stageinitial state (Yang-Mills flux tube model) • Quark Gluon Plasma  FD/hydrodynamics Particle In Cell (PIC) code • Freeze out, and ~simultaneous “hadronization” • Phase transition on hyper-surface partons/hadrons

  4. For perfect fluid: In Local Rest (LR) frame= (e, P, P, P); 1. Relativistic Fluid dynamics model Relativistic fluid dynamics (FD) is based on the conservation laws and the assumption of local equilibrium ( EoS) 4-flow energy-momentum tensor

  5. 2. FD expansion from the tilted initial state Flow velocity Pressure gradient Freeze Out (FO) at T ~ 200 MeV or ~8 fm/c, but calculated much longer, until pressure is zero for 90% of the cells. Structure and asymmetries of init. state are maintained in nearly perfect expansion. Movie-> [L.P.Csernai, V.K.Magas,H.Stoecker,D.D.Strottman, PRC 84,024914(2011)]

  6. 3. The rotation and Kelvin Helmholtz Instability (KHI) b=0.5 b_max ROTATION  Cell size is (0.35fm)3 and 83 markers/fluid-cell  ~ 10k cells & 1-2 Mill m.p.-s Upper [y,z] layer: blue lower [y-z] layer: red The rotation is illustrated by the dividing plane b=0.7 b_max & smaller cells KHI  Movie-> [L.P.Csernai, D.D.Strottman, Cs.Anderlik, PRC 85, 054901(2012)]

  7. 2.4 fm

  8. 4. The methods to detect rotation The rotation indeed exist in HIC at LHC. How to detect the rotation seems interesting and necessary. Ǝ three suggestions: ->v1 directed flow weak at High HIC ->Diffrential HBT ->Polarization [F. Becattini, L.P. Csernai, D.J. Wang,arXiv:1304.4427v1 [nucl-th]]

  9. Two Particle Correlation Calculation Center of mass momentum Relative momentum

  10. The source function: and are invariant scalars Details in [L.P. Csernai, S. Velle, arXiv:1305.0385]

  11. 1. Two steady sources [T. Csorgo, (2002)] , R is the source size X1 = d X2 = - d d=0 d=1.25 d=2.5

  12. [L.P. Csernai & S. Velle, arXiv:1305.0385] 2. Two moving sources qz qy qx Flow is mainly in x direction! Detectable

  13. 3. Four moving sources Increase the flow v The sources are symmetric  Not sensitive to direction of rotation! Increase in d

  14. 5. Inclusion of emission weights wc ws Introduce ( < 1 ), then wc=1 + , ws=1 -

  15. DHBT method

  16. Differential Correlation Function (DCF) (DHBT) Vz=0.5c Smaller k values Sensitive to the speed and direction of the rotation ! 0.6 c 0.7 c The zero points are senstive to the rotation velocity

  17. Vz=0.7c d c Vz=0.5c Sources c and d lead to bigger amplitude For ±x-symmetric sources without rotation ΔC(k,q)=0 !

  18. Results in our FD model [L.P. Csernai, S. Velle, D.J. Wang, arXiv:1305.0396] Bjorken type of flow  weights [Csorgo]: ~ 10000 fluid cells  numerical, & not symmetric source! Two direction are chosen: 50 degrees 130 degrees For pseudorapidity +/- 0.76

  19. Big different between Initial and later time Flow has a big effect for larger k

  20. Separation of shape & rotation X’ Still both rotation and shape influence the DCF so rotation alone is not easy to identify  We can use the work [G. Graef et al., arXive 1302.3408 ] To reflect an event CF’ := (CF + R[CF])/2 will have no rotation  Rotation and shape effects can be separated [G. Graef et al., arXive 1302.3408]

  21. Summary • Correlation for different source configurations are considered and discussed • DHBT method can detect the rotation and its direction • The flow has a big effect on the correlation function • We plan to separate rotations and shape Thank you for your attention!

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