Bose–Einstein correlation measurements at CMS

Abstract

Multidimensional and one-dimensional quantum-statistical (Bose-Einstein) correlations are measured in proton-proton collisions at 0.9, 2.76 and 7 TeV, in proton-lead collisions at 5.02 TeV/nucleon pair and peripheral lead-lead collisions at 2.76 TeV/nucleon pair center-of-mass energy with the CMS detector at the LHC. The correlation functions are extracted in terms of different components of the relative momentum of the pair, in order to investigate the extension of the emission source in different directions. The results are presented for different intervals of transverse pair momentum, k T , and charged particle multiplicity of the collision, N tracks , as well as for their integrated values. Besides inclusive charged particles, charged pions and kaons, identified via their energy loss in the silicon tracker detector, can also be correlated. The extracted source radii increase with increasing multiplicity, and decreases with increasing k T . The results open the possibility to study scaling and factorization properties of these radii as a function of multiplicity, k T , colliding system size and center-of-mass energy. Presented at QM2014 Quark Matter 2014Nuclear Physics A 00 (2014) AbstractMultidimensional and one-dimensional quantum-statistical (Bose-Einstein) correlations are measured in proton-proton collisions at 0.9, 2.76 and 7 TeV, in proton-lead collisions at 5.02 TeV/nucleon pair and peripheral lead-lead collisions at 2.76 TeV/nucleon pair center-of-mass energy with the CMS detector at the LHC. The correlation functions are extracted in terms of different components of the relative momentum of the pair, in order to investigate the extension of the emission source in different directions. The results are presented for different intervals of transverse pair momentum, k T , and charged particle multiplicity of the collision, N tracks , as well as for their integrated values. Besides inclusive charged particles, charged pions and kaons, identified via their energy loss in the silicon tracker detector, can also be correlated. The extracted source radii increase with increasing multiplicity, and decreases with increasing k T . The results open the possibility to study scaling and factorization properties of these radii as a function of multiplicity, k T , colliding system size and center-of-mass energy.

Particle yields in pp interactions at s=17.3 GeV interpreted in the statistical hadronization model

“…The kaon emission radius (all events) was determined to be 2.4 ± 0.9 fm compared to minimum-bias pion emission radius 1.5 ± 0.1 fm. The CMS collaboration obtained [53] the radius of kaon emission source of 2.08 ± 0.30 fm (Lévy distribution), while the radius obtained for pions equals 1.90 fm (all results at the same bin of charged particle multiplicity around 34). The low accuracy of all the reported measurements with kaon pairs prevents to draw any definite conclusion concerning the comparison of the pion and kaon emission zones.…”

“…Within this approach we find the canonical radius R C to be around 0.5 fm larger than the R parameter. This effect could be manifested in the results of Hanbury-Brown-Twiss interferometry measurements of ππ and KK pairs performed for the pp system at √ s = 27.4, 63 and 900 GeV by [50,52,53]. The uncertainty of the determination of the size of kaon emission zone in these measurements does not allow to draw any conclusion: within the experimental precision the size is the same as for pions.…”