Fixed particle number constraint in a simple model of a thermal expanding system and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math> collisions at the LHC

Two-boson momentum correlations at fixed particle number constraint are studied in a simple analytically solvable model of thermal expanding system. We show that the increase expansion rate, as well multiplicity, enhances ground-state contribution to spectra and leads suppression Bose-Einstein correlations. The relations these findings multiplicity-dependent measurements high-multiplicity $p+p$ collision events LHC discussed.