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