Jets in heavy-ion collisions with the ATLAS experiment

Advisor: Martin Spousta (IPNP MFF CUNI)

Funding: Fully funded

Website: http://www-ucjf.troja.mff.cuni.cz/spousta/

Contact: martin.spousta@ipnp.mff.cuni.cz

Heavy-ion collisions at the Large Hadron Collider (LHC) allow studying a hot and dense matter composed of quarks and gluons, which is often called quark-gluon plasma (QGP). The QGP is similar to a matter present in early stages of the evolution of the universe. Studying QGP should bring a better understanding of aspects of strong interaction that are currently not understood from the first principles, such as the transition from quarks and gluons to hadrons or collective aspects of strong interaction.

The team at Charles University works on analyses mainly involving jets and charmonia using data from the ATLAS experiment. In the past ten years, the team has lead or significantly contributed to several key measurements in the field of heavy-ion collisions done using ATLAS, namely measurement of the dijet asymmetry [1], measurements of the inclusive jet production [2,3], and measurements of the jet fragmentation [4,5]. The team also works on phenomenological modeling of jet quenching and charmonia suppression (see e.g. [6,7,8]) as well as on developing new methods for efficient mitigation of large backgrounds present in both proton-proton and heavy-ion collisions at the LHC (see e.g. [9,10]).

The candidate is expected to participate in the experimental program, in particular to analyze the jet production and jet structure in Pb+Pb and proton-proton collisions using the ATLAS experiment. Candidate is expected to have at least a basic knowledge of C++ and an experience with ROOT framework.

References

[1] ATLAS Collaboration. Observation of a Centrality-Dependent Dijet Asymmetry in Lead-Lead Collisions at √sNN=2.77 TeV with the ATLAS Detector at the LHC. Phys. Rev. Lett., 105 (2010) 252303.

[2] ATLAS Collaboration. Measurements of the Nuclear Modification Factor for Jets in Pb+Pb Collisions at sqrt(sNN)=2.76 TeV with the ATLAS Detector. Phys. Rev. Lett., 114 (2015), 072302.

[3] ATLAS Collaboration. Measurement of the nuclear modification factor for inclusive jets in Pb+Pb collisions at √sNN=5.02 TeV with the ATLAS detector. Phys. Lett., B790 (2019) 108.

[4] ATLAS Collaboration. Measurement of inclusive jet charged-particle fragmentation functions in Pb+Pb collisions at sqrt(sNN) = 2.76 TeV with the ATLAS detector. Phys. Lett., B739 (2014) 320.

[5] ATLAS Collaboration. Measurement of jet fragmentation in Pb+Pb and pp collisions at √sNN=2.76 TeV with the ATLAS detector at the LHC. Eur. Phys. J. C77 (2017) no.6, 379.

[6] Martin Spousta. On similarity of jet quenching and charmonia suppression. Phys. Lett., B767 (2017) 10.

[7] Martin Spousta and Brian Cole. Interpreting single jet measurements in Pb+Pb collisions at the LHC. Eur. Phys. J., C76 (2016), no.2, 50.

[8] S.P. Adhya, C.A. Salgado, M. Spousta, K. Tywoniuk. Medium-induced cascade in expanding media. JHEP 2007 (2020) 150.

[9] ATLAS Collaboration. The performance of the jet trigger for the ATLAS detector during 2011 data taking. Eur. Phys. J., C76 (2016) no.10, 526.

[10] P. Berta, L. Masetti, D.W. Miller and M. Spousta. Pileup and Underlying Event Mitigation with Iterative Constituent Subtraction. JHEP 1908 (2019) 175.