Signatures of collective flow in high-multiplicityppcollisions

Abstract

A blast-wave parametrization, including a full set of hadronic resonances, is used to model a small system, with total particle multiplicity comparable to the one measured in the high-multiplicity pp collisions at the Large Hadron Collider (LHC). Calculations are preformed for three cases: with negligible, moderate, and strong radial flow on the blast-wave hypersurface. We investigate the effects of flow on inclusive p T spectra as well as on 1D and 3D femtoscopic radii for pions. Special emphasis is put on the role of pions from resonance decays. In particular we show that they magnify the flow effects present in the blast-wave stage and significantly influence the shape of the correlation functions. A specific observable, the R E out /R G side ratio is proposed as a sensitive probe of the collective effects. Model results for the high multiplicity pp collisions, for scenarios with small and large radial flow are compared. Several features of soft particles production in the medium multiplicity pp events at the LHC are identified as sensitive probes of the collective behavior of the medium.

Charged kaon femtoscopic correlations inppcollisions ats=7 TeV

“…As shown in [23], due to the small size of the created system in pp collisions, the flow of resonances may play a significant role in large multiplicity bins, where essential hydrodynamic collective flow is expected [11]. According to simple chemical model calculations [10], the influence of this flow should be relatively smaller for kaons than for pions, leading to the effect that the kaon radii can be larger than the pion ones.…”

Color Reconnection and Flowlike Patterns inppCollisions

“…The CR mechanism, which was originally introduced in PYTHIA [11], is microscopic and does not require a medium to be formed. This flow mechanism is very important because it could provide an explanation of the observed flowlike patterns in pp collisions [12] and the collective phenomena seen in p-Pb collisions [13]. Note that here we shall only show evidence for radial flow, but the discussion will mention how higher order flow, e.g.…”

Pion-proton correlations and asymmetry measurement in Au + Au collisions at √s NN = 200 GeV data

“…However such information is most efficiently encoded in a spherical harmonics representation of the correlation function [4]. In case of limited momentum acceptance of the detector or big difference in mass between particles, when some orientation in space of the k * vector are not registered by the detector, calculation of correlation function directly in spherical harmonics is the most effective method [5]. Functions calculated directly in spherical harmonics are less sensitive to momentum acceptance limitations than functions calculated from 3-dimensional correlation function.…”

“…Distributions are directly binned in spherical harmonics. Detailed explanation of the formalism can be found in [5].…”