Measurement of Bose--Einstein Correlations in $pp$ Collisions at $\sqrt{s}=0.9$ and $7$ TeV

Bose--Einstein correlations between identical particles are measured in samples of proton-proton collisions at 0.9 and 7 TeV centre-of-mass energies, recorded by the CMS experiment at the LHC. The signal is observed in the form of an enhancement of number of pairs of same-sign charged particles with small relative momentum. The dependence of this enhancement on kinematic and topological features of the event is studied. The first observation in $pp$ interactions of anticorrelations between same-sign charged particles in the region of relative momenta higher than those in the signal region will be discussed.