Speaker
Description
The modifications imprinted on jets due to their interaction with QGP are assessed by comparing samples of jets produced in AA collisions and pp collisions. The standard procedure compares jets with the same reconstructed transverse momentum ($p_T$), ignoring the effect of $p_T$ migration and thus confounding QGP induced modifications by comparing jets that started out differently. Brewer et al. [1] introduced a quantile matching procedure that directly estimates average fractional jet energy loss ($Q_{AA}$) and can thus mitigate this migration effect.
In this work, we explore the potential of this procedure and apply it to establish that the difference between inclusive jet and $\gamma+$jet $R_{AA}$ is dominated by differences in the spectral shape, leaving the colour charge of the jet initiating parton with a lesser role to play. Furthermore, we show that isospin and nuclear PDF effects on the jet $p_T$ spectrum, which are unrelated to the presence of QGP, are quite sizeable for $\gamma+$jet events, confounding even further conclusions about QGP induced jet modifications. $Q_{AA}$ sensitivity to these effects is studied. Finally, we show the size of the $p_T$ migration correction for a number of observables and we present a detailed protocol of how the quantile procedure can be reliably used experimentally to improve existing observable measurements.
[1] Brewer, J., Milhano, J. G., & Thaler, J. (2019). Sorting out quenched jets. Physical Review Letters, 122(22), 222301.
| Category | Theory |
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