Jet Physics at the LHC in ALICE

High P_T observables associated with hard pQCD processes are regarded as tomographic probes of the medium created in ultrarelativistic heavy-ion collisions. Unfortunately, tomography is unexpectedly complicated in practice due to model uncertainties and the highly averaged nature of many observables. However, a systematic comparison study demanding a simultaneous description of many observables within the same framework is sufficiently powerful to rule out a large fraction of...

In high energy proton-proton collisions, collimated sprays of particles, called jets, result from hard scattered quarks or gluons. Jets are copiously produced in these collisions; however, the dynamic process through which quarks and gluons, collectively referred to as partons, become bound state hadrons is still not well understood. Jets provide an excellent tool to study this process as they are proxies for the scattered parton; therefore, final-state hadrons can be measure...

The suppression of large transverse momentum hadrons in heavy-ion (A-A) collisions as compared to their scaled expectation from proton-proton collisions due to the interaction of hard partons with the hot and dense QCD medium in A-A collisions is experimentally a well established phenomenon. Focusing on leading hadrons produced in hard processes, the medium effect appears as energy loss. Beyond that, the question is how the lost energy is redistributed in the medium. With inc...

We present high transverse momentum ($p_T$) measurements made at the Relativistic Heavy Ion Collider (RHIC) for Au+Au, d+Au, and p+p collisions at $\sqrt{s_{NN}} = 200$ GeV, as well as for Au+Au collisions at $\sqrt{s_{NN}} = 62$ GeV. We observe a suppression in the yield of high $p_T$ hadrons measured in central Au+Au collisions, relative to the yield in p+p collisions scaled by the number of binary nucleon-nucleon collisions. This observation, together with the absence of s...

Full jet reconstruction in heavy ion events has been thought to be difficult due to large multiplicity backgrounds. A new generation of jet reconstruction algorithms to search for new physics in high luminosity p+p collisions at the LHC is developed to precisely measure jets over large backgrounds caused by pile up. From simulations it turns out, this new generation of reconstruction algorithms are also applicable in the heavy ion environment. We review the latest results on ...

We present a global fit to all data on the suppression of high energy jets and high energy hadrons in the most central heavy ion collisions at the LHC for two different collision energies, within a hybrid strong/weak coupling quenching model. Even though the measured suppression factors for hadrons and jets differ significantly from one another and appear to asymptote to different values in the high energy limit, we obtain a simultaneous description of all these data after co...

The Quark-Gluon Plasma (QGP) is created in high energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). This medium is transparent to electromagnetic probes but nearly opaque to colored probes. Hard partons produced early in the collision fragment and hadronize into a collimated spray of particles called a jet. The partons lose energy as they traverse the medium, a process called jet quenching. Most of the lost energy is ...

The study of single-particle and jet production in heavy-ion collisions provides insights into the density of the medium and the energy-loss mechanisms. The observed suppression of high-$\pt$ particle production is generally attributed to energy loss of partons as they propagate through the hot and dense QCD medium - Quark-Gluon-Plasma (QGP). Such measurements allow the characterization of the QGP, the deconfined state of quarks and gluons, predicted by QCD. In these proceedi...

Measurements of high-pT particle production in heavy-ion collisions at RHIC have shown that medium-induced energy loss affects the partons produced in the early stage of a heavy-ion col- lision. The increased initial production cross section for partons at LHC energies makes fully reconstructed jets available in a wide kinematic range, which allows for a more differential in- vestigation of parton energy loss. Partonic energy loss allows us to access key observables of the ho...

Azimuthal anisotropies of high-$p_T$ particles produced in heavy-ion collisions are understood as an effect of a geometrical selection bias. Particles oriented in the direction in which the QCD medium formed in these collisions is shorter, suffer less energy loss, and thus, are over-represented in the final ensemble compared to those oriented in the direction in which the medium is longer. In this work we present the first semi-analytical predictions, including propagation th...