Transverse expansion and high pT azimuthal asymmetry at RHIC

Rapid (3 + 1)D transverse plus Bjorken collective expansion in A + A collisions at ultra-relativistic energies is shown to reduce substantially the azimuthal asymmetry resulting from jet quenching. While the azimuthal asymmetry in non-central collisions, v(2) (p(T) > 2 GeV/c) similar to 0.15 reported by STAR at RHIC, can be accounted for by spatially an isotropic jet energy loss through a (I + I)D expanding gluon plasma with dN(8)/dy similar to 1000, we show that if rapid transverse collective expansion of the plasma is assumed, then the asymmetry due to jet quenching may be reduced below the observed level. Possible implications of this effect are discussed. (C) 2002 Published by Elsevier Science B.V.