Energy loss signals as a function of the system size
Perhaps the greatest challenge to the consistent understanding of QCD matter formation is the disappearance of the observable energy loss of high momentum hadrons in small collisions systems. As the number of participant nucleons in peripheral lead-lead collisions reduces to order 10, the hadronic and jet nuclear modification factors approach unity. The large systematic uncertainties are preventing an accurate determination of energy loss in centrality selected collisions. However inclusive oxygen-oxygen (OO) collisions planned in the run 3 of LHC are free from such systematic uncertainties.
Together with my colleagues at CERN, I quantified and predicted the expected energy loss signal in OO collisions (Huss et al., 2021; Huss et al., 2021). We employed state-of-the-art perturbative QCD calculations of jet and Z-production cross sections with nuclear parton distribution functions to determine a precise theoretical baseline in the absence of medium induced modification. Combined with a number of energy loss models in small systems, we were able to conclude that OO collisions have sufficient sensitivity to discover energy loss in a system of about 10 colliding nucleons.
To explore the physics opportunities of physics opportunities of OO and pO collisions at the LHC I organised a dedicated workshop in 2021 (see poster above) (Brewer et al., 2021). One of the experimental limitations of a short oxygen run at the LHC, is the lack of corresponding pp reference at the same collision energies. With colleagues we explored different methods of interpolating jet and hadron spectra from neighboring energies (Brewer et al., 2022). We also proposed considering ratios of spectra at different collision energies. With my group, I continue different observables of energy loss in small collision systems. In particular, we computed the no-quenching baseline for semi-inclusive hadron- and jet- triggered nuclear modification factors (Gebhard et al., 2024).
References
2024
No-quenching baseline for energy loss signals in oxygen-oxygen collisions
Jannis Gebhard, Aleksas Mazeliauskas, and Adam Takacs
@article{Gebhard:2024flv,author={Gebhard, Jannis and Mazeliauskas, Aleksas and Takacs, Adam},title={{No-quenching baseline for energy loss signals in oxygen-oxygen collisions}},archiveprefix={arXiv},primaryclass={hep-ph},month=oct,year={2024},}
@article{Brewer:2021tyv,author={Brewer, Jasmine and Huss, Alexander and Mazeliauskas, Aleksas and van der Schee, Wilke},title={{Ratios of jet and hadron spectra at LHC energies: Measuring high-$p_T$ suppression without a pp reference}},archiveprefix={arXiv},primaryclass={hep-ph},reportnumber={CERN-TH-2022-154},doi={10.1103/PhysRevD.105.074040},journal={Phys. Rev. D},volume={105},number={7},pages={074040},year={2022}}
@article{Huss:2020dwe,author={Huss, Alexander and Kurkela, Aleksi and Mazeliauskas, Aleksas and Paatelainen, Risto and van der Schee, Wilke and Wiedemann, Urs Achim},title={{Discovering Partonic Rescattering in Light Nucleus Collisions}},archiveprefix={arXiv},primaryclass={hep-ph},reportnumber={CERN-TH-2020-126},doi={10.1103/PhysRevLett.126.192301},journal={Phys. Rev. Lett.},volume={126},number={19},pages={192301},year={2021},}
@article{Huss:2020whe,author={Huss, Alexander and Kurkela, Aleksi and Mazeliauskas, Aleksas and Paatelainen, Risto and van der Schee, Wilke and Wiedemann, Urs Achim},title={{Predicting parton energy loss in small collision systems}},archiveprefix={arXiv},primaryclass={hep-ph},reportnumber={CERN-TH-2020-127},doi={10.1103/PhysRevC.103.054903},journal={Phys. Rev. C},volume={103},number={5},pages={054903},year={2021}}
Opportunities of OO and pO collisions at the LHC
Jasmine Brewer, Aleksas Mazeliauskas, and Wilke Schee
In Opportunities of OO and pO collisions at the LHC, 2021
@inproceedings{Brewer:2021kiv,author={Brewer, Jasmine and Mazeliauskas, Aleksas and van der Schee, Wilke},title={{Opportunities of OO and $p$O collisions at the LHC}},booktitle={{Opportunities of OO and pO collisions at the LHC}},archiveprefix={arXiv},primaryclass={hep-ph},reportnumber={CERN-TH-2021-028},month=mar,year={2021}}
