Study Of Higher Moments Of Net-Electric Charge & Net-Proton Number Fluctuations In Pb+Pb Collisions At $\sqrt{s_{NN}}$=2.76 TeV In ALICE At LHC

Lattice QCD predicts that at extreme temperature and energy density, QCD matter will undergo a phase transition from hadronic matter to partonic matter called as QGP. One of the fundamental goals of heavy ion collision experiments to map the QCD phase diagram as a function of temperature (T) and baryo-chemical potential ($\mu_{B}$). There are many proposed experimental signatures of QGP and fluctuations study are regarded as sensitive tool for it. It is proposed that fluctuation of conserved quantities like net-charge and net-proton can be used to map the QCD phase diagram. The mean ($\mu$), sigma ($\sigma$), skewness (S) and kurtosis ($\kappa$) of the distribution of net charge and net proton are believed to be sensitive probes in fluctuation analysis. It has been argued that critical phenomena are signaled with increase and divergence of correlation length. The dependence of $n^{th}$ order higher moments (cumulants, $c_{n}$) with the correlation length $\xi$ is as $c_{n}\sim\xi^{2.5n-3}$. At LHC energy, the phase transition is a crossover and the crossover transition line will appear close to the freeze-out line. The various order of cumulants of conserved quantities are also directly proportional to respective order of susceptibilities. So the higher moments analysis of fluctuations of conserved quantities like net charge and net baryon (proton) will allow to compare the experimental results directly with lattice QCD predictions. Moreover, recent theoretical developments suggest that the ratio of cumulants are useful to quantify the freeze-out parameters at LHC. \par The data analysis is carried out using the Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76TeV data of ALICE experiment of 2010 run at LHC. The analysis methodology and different methods of statistical error estimations are discussed. Toy model study is carried out to understand the behavior of higher moments results with detector and statistics effects. Various methods for detector efficiency correction for higher moments are discussed with the help of this toy model. The higher moments of net-charge and net-proton distributions are calculated and compared with HIJING and HIJING+GENAT results. The systematic uncertainties are estimated and the pseudorapidity dependence of net-charge and net-proton higher moments also studied. The baseline estimation from Poissonian and Negative Binomial Distributions are also compared with the data.