[Brahms-l] Fwd: STAR new paper on elliptic flow, v2, in Cu+Cu collisions at 62.4 and 200 GeV

FYI


Flemming Videbaek
videbaek @ bnl.gov
Brookhaven National Lab
Physics Department
Bldg 510D
Upton, NY 11973

phone: 631-344-4106
cell     :  631-681-1596





Begin forwarded message:

> From: Nu Xu <NXu_at_lbl.gov>
> Date: January 23, 2010 12:35:30 AM EST
> To: Barbara Jacak <jacak_at_skipper.physics.sunysb.edu>, Flemming  
> Videbaek <videbaek_at_bnl.gov>, Wit Busza <busza_at_MIT.EDU>, Steven  
> Vigdor <vigdor_at_bnl.gov>
> Cc: Nu Xu <NXu_at_lbl.gov>
> Subject: STAR new paper on elliptic flow, v2, in Cu+Cu collisions at  
> 62.4 and 200 GeV
>
> Dear Barbara, Wit, Flemming and Steve,
>
> I am pleased to announce that the STAR collaboration will submit to  
> Physical Review C,  in one week's time,  a new paper on elliptic  
> flow, v2, in Cu+Cu collisions at 62.4 and 200 GeV. The title and  
> abstract are included below.
>
> Best regards,
>
> Nu Xu
>
> -----------------------------------------------------------------------
> Nu Xu
>
> Build. 510A, I-181	    Phone:  (631)344-3471
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> -----------------------------------------------------------------------
>
> Title: Charged and strange hadron elliptic flow in Cu+Cu collisions  
> at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV
>
> Abstract: We present the results of an elliptic flow, $v_{2}$,  
> analysis of  Cu+Cu collisions recorded with the STAR detector at  
> RHIC at $\sqrt{s_{NN}}$= 62.4 and 200 GeV. Elliptic flow as a  
> function of transverse momentum, $v_{2}$($p_{T}$), is reported for  
> different collision centralities for charged hadrons $h^{\pm}$, and  
> strangeness containing hadrons $K_{S}^{0}$, $\Lambda$, $\Xi$, $\phi$  
> in the midrapidity region $|\eta| < 1.0$. Significant reduction in  
> systematic uncertainty of the measurement due to non-flow effects  
> has been achieved by correlating particles at midrapidity, $|\eta| <  
> 1.0$, with those at forward rapidity, $2.5 < |\eta| < 4.0$.  We also  
> present azimuthal correlations in p+p collisions at $\sqrt{s_{NN}}$=  
> 200 GeV to help estimating non-flow effects. To study the system- 
> size dependence of elliptic flow, we present a detailed comparison  
> with previously published
> results from Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV. We  
> observe that  $v_{2}$($p_{T}$) of strange hadrons has similar  
> scaling properties as were first observed in Au+Au collisions, i.e.:  
> (i) at low transverse momenta, $p_T < 2 GeV/c$, $v_{2}$ scales with  
> transverse kinetic energy, \$m_{T} - m$, and (ii) at intermediate  
> $p_T$, $2 < p_T < 4 GeV/c$, it scales with the number of constituent  
> quarks, $n_q$. We have found that ideal hydrodynamic calculations  
> fail to reproduce the centrality dependence of $v_{2}$($p_{T}$) for  
> $K_{S}^{0}$ and $\Lambda$. Eccentricity scaled $v_2$ values, $v_{2}/ 
> \varepsilon$, are larger in more central collisions, suggesting  
> stronger collective flow develops in more central collisions. The  
> comparison with Au+Au collisions which go further in density shows  
> $v_{2}/\varepsilon$ depend on the system size, number of  
> participants $N_{part}$. This indicates that the ideal hydrodynamic  
> limit is not reached in Cu+Cu collisions, presumably because the  
> assumption of thermalization is not attained.



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