Main field of study: 011200 Physics
Area of specialization: Theory of Elementary Particle Interaction and Quantum Field Theory
Department of High Energy and Elementary Particle Physics 
Scientific advisor: Ph.D., M.V.Kompaniets
Reviewer: Ph.D., G.A.Feofilov

Correlation analysis of charged particle yields in data obtained from the ALICE at the LHC
Neverov Dmitrii

Correlation analysis of charged particles yields is an important tool of studying data obtained from ultrarelativistic particle collisions. It provides useful information about mechanisms behind particle production. However there is no unified method of correlation analysis used in scientific papers, which lead to difficulties in comparing results from different collaborations. Recent net-charge correlation analysis revealed peculiar behavior in the near-side region, origin of which was unclear.
The goal of present work was to trace differences in most common approaches to correlation analysis in order to allow comparison of different group’s results and to find reasons for the peculiarity in net-charge correlations.
Two methods of analyzing correlations of yields of charged particles produced in high energy proton-proton and proton-lead collisions at the LHC (Large Hadron Collider) were compared: di-hadron and forward-backward methods. Their connection to the two-particle correlation function C2 was traced and ways to obtain it were proposed.
It was shown in the present work that normalization by the number of particle pairs in each event leads to a disappearance of the plateau in the angular correlation function and also modifies the near-side peak. The former contains valuable information on the fluctuation of the number of particle sources and the latter describe correlation length and intensity according to the model of independent quark-gluon strings as particle sources in protn-proton collisions.
In the case of proton-lead collisions it was shown that the absence of translational invariance in the pseudo-rapidity distribution leads to the necessity of studying two-particle correlations with respect to both particles pseudo-rapidities and not just their difference.
Additionally, it was shown that effects of Bose-Einstein statistics represent themselves as a bump in the net-charge correlation function and a dip in the balance function in the short range region. Different transverse momenta intervals study revealed that these effects dominate at low transverse momenta in proton-proton collisions, yet still non-negligible in full transverse momenta acceptance of the ALICE.
The list of publications:
1.	D.I. Neverov, Bose-Einstein effects in multiplicity and net-charge correlations in pp collisions using Pythia 8 simulations, Proceedings of Science (Baldin ISHEPP XXII) 051.
2.	Vechernin V.V., Neverov D.I., Ivanov K.O. Two-Particle Correlation Function: the Forward-Backward vs Di-Hadron Correlation Approach, Book of abstracts of the LXV International Conference on Nuclear Physics «Nucleus 2015. New Horizons in Nuclear Physics, Nuclear Engineering, Femto- and Nanotechnologies», June 29 – July 3, Saint-Petersburg, 2015 (to be published).