Femtoscopic scales in $p+p$ and $p+$Pb collisions in view of the uncertainty principle

Abstract

A method for quantum corrections of Hanbury-Brown/Twiss (HBT) interferometric radii produced by semi-classical event generators is proposed. These corrections account for the basic indistinguishability and mutual coherence of closely located emitters caused by the uncertainty principle. A detailed analysis is presented for pion interferometry in p + p collisions at LHC energy ( √ s = 7 TeV). A prediction is also presented of pion interferometric radii for p+Pb collisions at √ s = 5.02 TeV. The hydrodynamic/hydrokinetic model with UrQMD cascade as 'afterburner' is utilized for this aim. It is found that quantum corrections to the interferometry radii improve significantly the event generator results which typically overestimate the experimental radii of small systems. A successful description of the interferometry structure of p + p collisions within the corrected hydrodynamic model requires the study of the problem of thermalization mechanism, still a fundamental issue for ultrarelativistic A + A collisions, also for high multiplicity p + p and p+Pb events.

Collectivity and electromagnetic radiation in small systems

“…In order to unveil the dynamics in these small systems, one must investigate multiple aspects of experimental observables within a consistent framework. A complete slate of measurements could include hadronic anisotropic flow [17,18], the mass ordering of identified particle v 2 [5,19], particle interferometry [20,21], as well as penetrating probes such as QCD jets [22] and direct real and virtual photons [23]. This last observable, radiated throughout the dynamical evolution of the hot expanding medium and suffering from negligible final state interactions, is a particularly valuable probe since the local properties of the fluid at the photon's production point can be directly carried to the detectors.…”

Two-particle Bose–Einstein correlations in $${ pp }$$ collisions at $$\mathbf {\sqrt{s} = 13}$$ TeV measured with the ATLAS detector at the LHC

“…High-multiplicity data in proton-proton e-mail: atlas.publications@cern.ch interactions can serve as a reference for studies of nucleusnucleus collisions [16]. The effect of BEC is reproduced in both the hydrodynamical/hydrokinetic [17][18][19] and the Pomeron-based [20,21] approaches for modelling of highmultiplicity hadronic interactions. The BEC between a pair of particles depend on the particle multiplicity in the event and on the average transverse momentum of the pair.…”