Event by event < p(t) > fluctuations in Au - Au collisions at s(NN)**(1/2) = 130-GeV

The STAR collaboration
Phys.Rev.C 71 (2005) 064906, 2005.

We present the first large-acceptance measurement of event-wise mean transverse momentum mean p_t fluctuations for Au-Au collisions at nucleon-nucleon center-of-momentum collision energy sqrt{s_{NN}} = 130 GeV. The observed non-statistical mean p_t fluctuations substantially exceed in magnitude fluctuations expected from the finite number of particles produced in a typical collision. The r.m.s. fractional width excess of the event-wise mean p_t distribution is 13.7 +/- 0.1(stat) +/- 1.3(syst)% relative to a statistical reference, for the 15% most-central collisions and for charged hadrons within pseudorapidity range |eta|<1, 2pi azimuth and 0.15 < p_t < 2 GeV/c. The width excess varies smoothly but non-monotonically with collision centrality, and does not display rapid changes with centrality which might indicate the presence of critical fluctuations. The reported mean p_t fluctuation excess is qualitatively larger than those observed at lower energies and differs markedly from theoretical expectations. Contributions to mean p_t mean fluctuations from semi-hard parton scattering in the initial state and dissipation in the bulk colored medium are discussed.

  • Table 1a

    Data from Figure 1a


    Event frequency distribution on $\sqrt{n}(\langle p_t\rangle - \hat{p}_t)/\sigma\hat{p}_t$ for 80% of primary charged hadrons in $|\eta|$ < 1 for 183k...

  • Table 1b

    Data from Figure 1b


    Difference in upper panel between data and gamma reference

  • Table 2

    Data from Figure 2


    Centrality dependences of the measured charge independent (CI) and charge dependent (CD) difference factors $\Delta\sigma_{p_t:n}$ plus the corresponding values extrapolated...

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