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My PhD thesis describes the analysis of
the D+ meson in its purely hadronic decay channel
D+ -> K-pi+pi+ performed at the Large Hadron
Collider with A Large Ion Collider Experiment in
proton-proton collisions at √s =2.76 TeV and √s
= 7 TeV and in Pb-Pb collision at √sNN =
2.76 TeV.
The study of open charm meson (mesons made by one
light quark and one charm quark) are an
interesting tool to probe pQCD and the
Quark-Gluon-Plasma properties and the study of the
open charm meson production cross section is an
interesting test of QCD calculations based on
factorization approach in an energy domain yet
unexplored.
In the first chapter I introduce the main topics
related to the physics of the Quark-Gluon-Plasma,
presenting the main experimental observables and
the measurement obtained at RHIC and SPS as well
as last results from LHC experiments, including
the observables related to the measurement of
charm properties.
Chapter 2 describes the ALICE experimental
apparatus and its main characteristics. Thanks to
the very good tracking, vertexing and PID
capabilities ALICE is very well suited for the
open-charm studies. The main detectors used for
the D+ analysis are the Inner Tracking System, the
Time Projection Chamber, the Time Of Flight and
the VZERO detectors. All these detectors and their
performances will be described in detail in this
chapter and the ALICE computing framework will be
introduced. Some emphasis is placed on the SDD
detector, on which I worked during my PhD.
The description of the analysis strategy is given
in chapter 3. Here I describe the D+ meson
reconstruction in proton-proton collisions and I
give the details of cut selection strategy, signal
extraction, particle identification and data
quality selections. The ALICE open-charm results
obtained in proton-proton collisions at centre of
mass energies of √s = 2.76 TeV and √s
= 7 TeV are also showed in this chapter.
I present here the details of the cross-section
measurements and the description of systematic
uncertainties affecting it. The D+ pt differential
cross-section and the total charm production
cross-section compared to theoretical models
(FONLL, GM-VFNS)
and other LHC experiments (ATLAS, LHCb)
measurements made at the centre of mass energy of √s
= 7 TeV.
Chapter 4 presents the result of the D+
measurements in Pb-Pb collisions. at √sNN =
2.76 TeV. The main differences arising when
analysing Pb-Pb data instead of proton-proton data
(higher multiplicities, centrality selection) will
be described. In the first part of this chapter I
present the D+ energy loss measured using the
nuclear modification factor RAA and a complete
description of how this measurement is performed.
The comparison of the D+ nuclear modi cation
factor as measured at ALICE with the one of light
hadrons will be showed as well as with theoretical
predictions from several different models. The
second part of the chapter shows the preliminary
results on D+ elliptic flow in semi-peripheral
Pb-Pb collisions. Although the
2010 statistics is not enough to allow us to make
any conclusive statement on charm elliptic flow
yet, the details of the analysis and prospects for
the analysis of 2011 Pb-Pb data are given.
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My PhD research was funded by a
3-year (2009-2011) grant obtained from University of Torino
after winning a competitive selection.
During my PhD I also won a 1-year associate fellowship at
CERN, Geneva, for which candidtate selection was made by INFN.
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2010: XX giornate di studio sui
rivelatori (Torino, Italy).
2009: Nuclear Physics School R. Anni (Otranto, Lecce, Italy).
2009: UFRJ: Studies at Federal University of Rio de Janeiro
(UFRJ), Brazil as part of the HELEN program, working on elliptic
flow in p-p collisions.
2008: Villa Gualino: International school on QGP and Heavy Ion
Collisions (Torino, Italy)
2008: ECT*: Doctoral Training Programme Nuclear Matter under
Extreme Conditions (Trento, Italy)
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