Measurement of inclusive charged-particle jet production in Au + Au collisions at s N N = 200 GeV

Le résumé fourni par la source

The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at $\sqrt{{s}_{NN}}=200$ GeV. Jets are reconstructed with the anti-${k}_{T}$ algorithm using charged tracks with pseudorapidity $|\ensuremath{\eta}|<1.0$ and transverse momentum $0.2<{p}_{T,\mathrm{jet}}^{\mathrm{ch}}<30$ $\mathrm{GeV}/c$, with jet resolution parameter $R=0.2$, 0.3, and 0.4. The large background yield uncorrelated with the jet signal is observed to be dominated by statistical phase space, consistent with a previous coincidence measurement. This background is suppressed by requiring a high-transverse-momentum (high-${p}_{T}$) leading hadron in accepted jet candidates. The bias imposed by this requirement is assessed, and the ${p}_{T}$ region in which the bias is small is identified. Inclusive charged-particle jet distributions are reported in peripheral and central Au+Au collisions for $5<{p}_{T,\mathrm{jet}}^{\mathrm{ch}}<25 \mathrm{GeV}/c$ and $5<{p}_{T,\mathrm{jet}}^{\mathrm{ch}}<30 \mathrm{GeV}/c$, respectively. The charged-particle jet inclusive yield is suppressed for central Au+Au collisions, compared to both the peripheral Au+Au yield from this measurement and to the $pp$ yield calculated using the PYTHIA event generator. The magnitude of the suppression is consistent with that of inclusive hadron production at high ${p}_{T}$ and that of semi-inclusive recoil jet yield when expressed in terms of energy loss due to medium-induced energy transport. Comparison of inclusive charged-particle jet yields for different values of $R$ exhibits no significant evidence for medium-induced broadening of the transverse jet profile for $R <0.4$ in central Au+Au collisions. The measured distributions are consistent with theoretical model calculations that incorporate jet quenching.

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