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Semihard scattering unraveled from collective dynamics at $\sqrt{s}=17$ GeV

We present a study of elliptic flow ($v_2$) and two-particle azimuthal correlations of charged hadrons and high transverse momentum ($p_T$) pions measured by the CERES experiment in Pb+Au collisions at $\sqrt{s}$~=~17 GeV. Azimuthal anisotropy $v_2$ increases linearly with $p_T$ to a value of 10% at...

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Detalles Bibliográficos
Autor principal: Bielcikova, Jana
Lenguaje:eng
Publicado: 2004
Materias:
Acceso en línea:https://dx.doi.org/10.1088/0954-3899/31/4/057
http://cds.cern.ch/record/812423
Descripción
Sumario:We present a study of elliptic flow ($v_2$) and two-particle azimuthal correlations of charged hadrons and high transverse momentum ($p_T$) pions measured by the CERES experiment in Pb+Au collisions at $\sqrt{s}$~=~17 GeV. Azimuthal anisotropy $v_2$ increases linearly with $p_T$ to a value of 10% at $p_T$~=~1.5 GeV/$c$. Beyond this $p_T$ the slope decreases indicating a possible saturation at high $p_T$. Two-pion azimuthal anisotropies ($p_T>$~1.2 GeV/$c$) exceed $v_2$ by about 60% in semicentral collisions and reveal non-harmonic contributions at close ($\Delta\phi\approx0$) and back-to-back ($\Delta\phi\approx\pi$) angles that can be attributed to semihard processes. While the close-angle peak remains unchanged, the back-to-back peak is broadened and disappears in central collisions.