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The source function projections calculated in the iHKM for pions (Panels (a–c)) and kaons (Panels (d–f)) produced in central Pb + Pb collisions at the LHC energy sNN=2.76 TeV, 0.2<pT<0.36 GeV/c, |y|<0.5. Squares represent the model output, and lines show the corresponding Gaussian fits.
Source publication
The analysis of the spatiotemporal picture of particle radiation in relativistic heavy-ion collisions in terms of correlation femtoscopy scales, emission, and source functions allows one to probe the character of the evolution of the system created in the collision. Realistic models, such as the integrated hydrokinetic model (iHKM), used in the pre...
Citations
... To interpret above mentioned results, one can use a very recent iHKM femtoscopy analysis [51] as follows. When the system has just formed (at times near 0.1 fm/c), huge gradients of density in the transverse direction take place, since the system is essentially finite and borders with vacuum. ...
... In the vicinity of the geomet-rical center of the system, its decay into free particles happens at significantly later proper times than for most other parts of the system. Such a difference in proper times of spectra formation can be up to 5 fm/c [51]. Thus, in the context of the present study, one can expect that maximal formation times (about 15 fm/c) should be typical for the ultrasoft pions with transverse momenta less than 0.3 GeV/c, that are emitted from the central region of the fireball. ...
... Thus, in the context of the present study, one can expect that maximal formation times (about 15 fm/c) should be typical for the ultrasoft pions with transverse momenta less than 0.3 GeV/c, that are emitted from the central region of the fireball. For the pions radiated from other parts of the decaying expanding system and having higher transverse momenta, 0.45-2 GeV/c, the (proper) time of maximal emission is close to 10 fm/c [51]. The situation looks like a pion trap formed in the center of the created quarkgluon-hadron system. ...
Femtoscopy studies of pion radiation in heavy-ion collisions have been conducted extensively at all available collider energies, both theoretically and experimentally. In all these studies special attention is given to m T dependency of pion femtoscopy radii, usually approximated by a power-law function at transverse momenta above 200 MeV / c . However, the radii behavior has been much less explored for the ultrasoft pions, possessing transverse momentum comparable to or lower than the pion mass. For many experimental setups this region is difficult to measure. In this work we present theoretical calculations of pion emission in the ultrasoft region in the two hybrid models iHKM and LHYQUID + th ERMINATOR2 . Along with the particle transverse momentum spectra, we present the calculated femtoscopy radii, in both one-dimensional and three-dimensional representations. We investigate the radii dependence on pair m T and observe, in particular, a departure from the power-law behavior at ultrasoft momenta, potentially reflecting a decoupling of such slow pions from the rest of collectively expanding system. We provide the theoretical interpretation of this result and discuss its significance, in particular, for the ongoing nonidentical particle femtoscopy analysis for pairs consisting of a pion and a baryon (or of a pion and a charmed meson).
Published by the American Physical Society 2024
