Separation of the Charm and Beauty Production in p_Pb and Pb_Pb Collisions with ALICE

Workshop for young scientists on the physics of ultrarelativistic nucleus-nucleus collisions 2016

Völkl, Martin^1

Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany^1

关键词: Disentangle effects;    Final-state effects;    Measurement-based;    Particle identifications;    Pb-Pb collisions;    Proton proton collisions;    Quark-gluon plasma;    Transverse momentum distributions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/832/1/012024/pdf
DOI  :  10.1088/1742-6596/832/1/012024

来源: IOP

【 摘 要 】

Measurements of heavy (charm and beauty) quarks provide useful insights into the properties of the quark-gluon plasma. The good particle identification capabilities of ALICE make a measurement based on the electrons from semi-leptonic decays of heavy-flavour hadrons feasible. This approach makes use of the large branching ratios (≈ 10 - 20%) of heavy-flavour hadrons into electrons. Separation of the contribution from beauty-hadron decay electrons was achieved by utilizing the large decay length of the associated hadrons, making the investigation of beauty quarks in the medium possible. By comparing measurements in p-Pb and Pb-Pb collisions, it is possible to disentangle effects of cold nuclear matter from those of the hot and dense medium. The results show a strong change in the transverse momentum distribution of electrons from beauty-hadron decays in central Pb-Pb collisions with respect to the proton-proton case. No significant change from proton-proton collisions can be seen in the p-Pb case, suggesting that the modification is a final state effect.