A study of parton fragmentation using photon-hadron correlation with the ALICE experiment at LHC
Description
The strong interaction theory, Quantum Chromodynamic (QCD), predicts a new phase of nuclear matter at very high temperature and/or very high density. This state is composed of deconfined quarks and gluons known as the quark-gluon plasma (QGP). The measurement of its composition and properties is a challenge for the nuclear physics of the 21. century and should lead to a better understanding of the fundamental symmetries and mechanisms related to the quarks confinement inside hadrons and the strong interaction generally.The Large Hadron Collider (LHC) accelerator at CERN (European Organization for Nuclear Research) allows to reach the thermodynamic conditions required to create the quark-gluon plasma using ultra-relativistic heavy ion collisions (Pb). The ALICE experiment (A Large Ion Collider Experiment) allows to access several probes to characterize the QGP through particles reconstruction and. Among these probes, high energy parton energy loss is used to access medium characteristics such as density or temperature. Parton energy loss is estimated from the modification of the energy distribution of hadrons produced by fragmentation.This thesis is dedicated to the photon-hadron correlations analysis in order to study the modification of the parton fragmentation due to the quark-gluon plasma. First part of this thesis is devoted to the characterization of the electromagnetic calorimeter (EMCal), the central detector for energy measurement and photon identification. The second part is dedicated to the photon-hadron correlation measurement, for the 7 TeV proton-proton collisions and 2.76 TeV Lead-Lead collisions. An important work has been done to improve the prompt photon identification, one of the key point of this analysis. (author)
Abstract (French)
La theorie de l'interaction forte, ou Chromodynamique Quantique (QCD), predit l'existence d'une nouvelle phase de la matiere nucleaire a tres haute temperature et/ou tres haute densite. Cet etat est compose de quarks et de gluons deconfines connu sous le nom de plasma de quarks-gluons (PQG). La mesure de sa composition et de ses proprietes est un enjeu important pour la physique nucleaire du XXIeme siecle afin de parvenir a une meilleure comprehension des symetries et des mecanismes fondamentaux a l'origine du confinement des quarks au sein des hadrons et de l'interaction forte dans son ensemble. L'accelerateur LHC (Large Hadron Collider) au CERN (Organisation Europeenne pour la Recherche Nucleaire) permet d'atteindre les conditions thermodynamiques necessaires a la formation du plasma de quarks-gluons a l'aide de collisions d'ions lourds (Pb) ultra relativistes. L'experience ALICE (A Large Ion Collider Experiment) permet d'acceder a un grand nombre d'observables pour caracteriser le PQG a partir de la reconstruction et de l'identification des particules produites lors des collisions. Parmi ces observables, la perte d'energie des partons (quarks, gluons) de haute impulsion transverse permet une etude des caracteristiques du milieu telle que sa densite et sa temperature. La perte d'energie des partons est mise en evidence par la modification de la distribution en energie des hadrons produits par fragmentation. Cette these s'articule autour de l'analyse des correlations photon-hadron dans le but d'etudier la modification de la fragmentation partonique par le plasma de quarks-gluons. La premiere partie de cette these est consacree a la caracterisation du calorimetre electromagnetique EMCal, detecteur central pour la mesure en energie et l'identification des photons. La seconde partie est dediee a la mesure des correlations photon-hadron, dont l'analyse a portee sur les collisions proton-proton d'energie √s = 7 TeV, avant d'etre appliquee aux collisions Plomb-Plomb d'energie √sNN = 2.76TeV. Un effort particulier a ete fourni pour optimiser l'identification des photons prompts, un des points cles de cette analyse
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Additional details
Additional titles
- Original title (French)
- Etude de la fragmentation des partons par mesure de correlations photon-hadrons aupres de l'experience ALICE au LHC
Identifiers
Publishing Information
- Imprint Pagination
- 229 p.
- Report number
- FRCEA-TH--5675
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 45087452
- Subject category
- S72: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; S43: PARTICLE ACCELERATORS;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- CALORIMETERS; CERN LHC; FRAGMENTATION; GLUONS; HADRONS; MONTE CARLO METHOD; PHOTONS; QUANTUM CHROMODYNAMICS; QUARK MATTER; QUARKS
- Descriptors DEC
- ACCELERATORS; BOSONS; CALCULATION METHODS; CYCLIC ACCELERATORS; ELEMENTARY PARTICLES; FERMIONS; FIELD THEORIES; MASSLESS PARTICLES; MATTER; MEASURING INSTRUMENTS; QUANTUM FIELD THEORY; STORAGE RINGS; SYNCHROTRONS
Optional Information
- Notes
- 215 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS-NKM website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/; Also available from SICD1 BP 66 38402 Saint-Martin d'Heres Cedex (France)