Speaker
Ruediger Haake
(University of Muenster)
Description
Highly energetic jets are sensitive probes for the kinematics and the topology of nuclear collisions. Jets are collimated sprays of charged and neutral particles, which are produced in the fragmentation of hard scattered partons in an early stage of the collision. The measurement of jet spectra in p-Pb collisions provides an important way of quantifying the effects of cold nuclear matter in the initial state on jet production, fragmentation, and hadronization. Unlike in Pb-Pb collisions, strong hot nuclear matter effects - e.g. from quark-gluon plasma formation - are not expected to occur in p-Pb collisions. Hence, cold nuclear matter effects can be investigated in isolation.
The impact of cold nuclear matter effects on charged jet spectra is expected to depend on the event centrality. Higher event centralities are principally connected to a higher probability for an interaction of proton and lead-nucleus and therefore also for a possible nuclear modification.
For the extraction of a jet signal, the exact evaluation of the background density in the underlying event is an especially important ingredient. Besides the background energy density, also intra-event background fluctuations must be taken into account in p-Pb collisions. The finite resolution and detector efficiency is corrected for by using a full detector Monte Carlo simulation. The fully corrected charged jet spectra are obtained through applying an unfolding procedure.
In this talk, centrality-dependent properties of charged jets in p-Pb measured by ALICE will be shown for the first time. The focus is on the nuclear modification factors and ratios connecting the central to the peripheral and minimum bias jets. Additionally, the jet radial structure is explored by comparing jet spectra reconstructed with different resolution parameters.
Summary
First presentation of centrality-dependent charged jets in p-Pb with ALICE
Primary author
Ruediger Haake
(University of Muenster)
