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        Feasibility study of the Σ c -baryon reconstruction using the ALICE detector at CERN LHC

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        Publication date
        2019
        Author
        Meijers, L.E.
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        Summary
        A recent ALICE paper pointed out that the charmed baryon-to-meson (Λ c /D 0 ) production ratio in pp and p-Pb collisions deviates about a factor of 5 from that same ratio in ee and ep collisions at lower center of mass energies. This deviation breaks the expected universality of the fragmentation function. A large theoretical effort is ongoing to understand the result of the ALICE paper. One of the proposed ideas is that the offset in the ratio could be caused by a difference in the Σ c production rate in pp and p-Pb collisions as opposed to ee and ep collisions. Σ c decays into a Λ c and a π with a probability of 100%. It was impossible to disentangle Λ c coming directly from charm quarks from those coming from Σ c -decay in the ALICE data. The measured Λ c /D 0 -ratio thus contains Λ c from both mentioned sources. For this thesis, Pythia8 was used to study the kinematics of the Σ c → Λ c π decay in order to set selection criteria for the reconstruction of Σ c in real data. The selection cuts proposed √ in this thesis were used to attempt the reconstruction of Σ c in pp data at s = 5 TeV. In the Σ c p t -bin [8,12] GeV/c from the ALICE data, a hint of a signal peak was found. This peak appears at the expected location of the invariant mass difference, which is promising for further research into the value of the Λ c /D 0 -ratio determined in the ALICE paper.
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        https://studenttheses.uu.nl/handle/20.500.12932/31882
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