Jussi Viinikainen

QCD color coherence phenomena, like angular ordering, can be studied by looking at jet fragmentation. As the jet is fragmenting, it is expected to go through two different phases. First, there is QCD branching that is calculable in perturbative QCD. Next, the produced partons hadronize in a non-perturbative way later in a hadronization process. The jet fragmentation can be studied using the method of two particle correlations. A useful observable is the jet transverse fragmentation momentum jT, which describes the angular width of the jet. In this contribution, a differential study will be presented in which separate jT components for branching and hadronization will be distinguished from the data measured by the ALICE experiment. The pTt dependence of the hadronization component 〈jT2〉 is found to be rather flat, which is consistent with universal hadronization assumption. However, the branching component shows slightly rising trend in pTt. The s=7 TeV pp and sNN=5.02 TeV p–Pb data give the same results within error bars, suggesting that this observable is not affected by cold nuclear matter effects in p–Pb collisions. The measured data will also be compared to the results obtained from PYTHIA8 simulations.

QCD color coherence phenomena, like angular ordering, can be studied by looking at jet fragmentation. As the jet is fragmenting, it is expected to go through two different phases. First, there is QCD branching that is calculable in perturbative QCD. Next, the produced partons hadronize in a non-perturbative way later in a hadronization process. The jet fragmentation can be studied using the method of two particle correlations. A useful observable is the jet transverse fragmentation momentum $j_{\mathrm{T}}$, which describes the angular width of the jet. In this contribution, a differential study will be presented in which separate $j_{\mathrm{T}}$ components for branching and hadronization will be distinguished from the data measured by the ALICE experiment. The $p_{\mathrm{Tt}}$ dependence of the hadronization component $\sqrt{\left }$ is found to be rather flat, which is consistent with universal hadronization assumption. However, the branching component shows slightly rising trend in $p_{\mathrm{Tt}}$. The $\sqrt{s} = 7\,\mathrm{TeV}$ pp and $\sqrt{s_{\mathrm{NN}}} = 5.02\,\mathrm{TeV}$ p-Pb data give the same results within error bars, suggesting that this observable is not affected by cold nuclear matter effects in p-Pb collisions. The measured data will also be compared to the results obtained from PYTHIA8 simulations.

QCD color coherence phenomena, like angular ordering, can be studied by looking at jet fragmentation. As the jet is fragmenting, it is expected to go through two different phases. First, there is QCD branching that is calculable in perturbative QCD. Next, the produced partons hadronize in a non-perturbative way later in a hadronization process. The jet fragmentation can be studied using the method of two particle correlations. A useful observable is the jet transverse fragmentation momentum $j_{\mathrm{T}}$, which describes the angular width of the jet. In this contribution, a differential study will be presented in which separate $j_{\mathrm{T}}$ components for branching and hadronization will be distinguished from the data measured by the ALICE experiment. The $p_{\mathrm{Tt}}$ dependence of the hadronization component $\sqrt{\left<j_{\mathrm{T}}^{2}\right>}$ is found to be rather flat, which is consistent with universal hadronization assumption. However, the branching component shows slightly rising trend in $p_{\mathrm{Tt}}$. The $\sqrt{s} = 7\,\mathrm{TeV}$ pp and $\sqrt{s_{\mathrm{NN}}} = 5.02\,\mathrm{TeV}$ p-Pb data give the same results within error bars, suggesting that this observable is not affected by cold nuclear matter effects in p-Pb collisions. The measured data will also be compared to the results obtained from PYTHIA8 simulations.

on behalf of the CMS Collaboration.