Jet substructure measurements in pp and heavy-ion collisions with ALICE

Aug 3, 2021, 4:15 PM



James Mulligan (University of California, Berkeley (US))


Jet substructure, defined by observables constructed from the distribution of constituents within a jet, provides the versatility to tailor observables to specific regions of QCD radiation phase space. This flexibility provides exciting new opportunities to study jet quenching in heavy-ion collisions and to
ultimately help reveal the nature of the quark-gluon plasma. The ALICE detector is particularly well-suited to jet substructure measurements in heavy-ion collisions due to its high-precision tracking system. In this talk, we overview recent jet substructure measurements in proton--proton and Pb--Pb collisions with ALICE.

In heavy-ion collisions, these include subjet fragmentation, $N$-subjettiness, the groomed jet momentum fraction, $z_g$, and the groomed jet radius, $\theta_g \equiv R_g/R$. By correcting these measurements for the large heavy-ion underlying event, and by selecting observables that are calculable in proton-proton collisions, these measurements allow direct comparison to theoretical models and begin to establish a phenomenological picture of the physics underlying jet quenching.

In proton--proton collisions, a new measurement of the primary Lund plane density for inclusive charged-particle jets in the transverse momentum range of $20 \leq p_{\rm{T,jet}}^{\rm ch} \leq 120$ GeV$/c$ with the ALICE detector will be presented. This is the first measurement of the Lund plane density in an intermediate jet $p_{\rm T}$ range where hadronization and underlying event effects play a dominant role. In addition to the Lund jet plane, new ALICE measurements of generalized angularities of groomed and inclusive jets, jet axis differences, and dynamically groomed jets will be discussed.

Primary author

James Mulligan (University of California, Berkeley (US))

Presentation materials