Research Article Out-Of-Equilibrium Transverse Momentum Spectra of Pions at LHC Energies Abdel Nasser Tawfik 1,2 1 Nile University, Egyptian Center for Teoretical Physics, Juhayna Square of 26th-July-Corridor, 12588 Giza, Egypt 2 World Laboratory for Cosmology And Particle Physics (WLCAPP), 11571 Cairo, Egypt Correspondence should be addressed to Abdel Nasser Tawfk; atawfk@nu.edu.eg Received 9 March 2019; Revised 10 May 2019; Accepted 20 May 2019; Published 2 June 2019 Guest Editor: Sakina Fakhraddin Copyright © 2019 Abdel Nasser Tawfk. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In order to characterize the transverse momentum spectra (  ) of positive pions measured in the ALICE experiment, two thermal approaches are utilized; one is based on degeneracy of nonperfect Bose-Einstein gas and the other imposes an ad hoc fnite pion chemical potential. Te inclusion of missing hadron states and the out-of-equilibrium contribute greatly to the excellent characterization of pion production. An excellent reproduction of these   -spectra is achieved at   = 0.12 GeV and this covers the entire range of   . Te excellent agreement with the experimental results can be understood as a manifestation of not-yet- regarded anomalous pion production, which likely contributes to the long-standing debate on “anomalous” proton-to-pion ratios at top RHIC and LHC energies. 1. Introduction Te collective properties of strongly interacting matter (radial fow, for instance) and dynamics of colliding hadrons can be explored from the study of transverse momentum dis- tributions (  ) of produced particles. RHIC results on well- identifed particles produced at low   , especially pions, have shown that the bulk matter created can be well described by hydrodynamics [1]. It should be emphasized that the high-   spectra, especially for the lowest-lying Nambu-Goldstone bosons, pions, likely manifest dynamics and interactions of partons and jets created in the earliest stage of nuclear collisions [2]. For instance, the collective expansion in form of radial fow might be caused by internal pressure gradients. Furthermore, the   -distributions are assumed to determine conditions, such as temperature and fow velocity, gaining dominance during the late eras of the evolution of the high-energy collision which is generically well-described as kinetic freeze-out, where the elastic interactions are ceased, conclusively. From the theoretical point of view, the   -spectra are excellent measurements enabling us a better understanding of the QCD interactions. Sof nonperturbative QCD can be well applied to low   -regime (below a few GeV/c) [3]. Fragmentation of QCD string [4], parton wave functions in fux tube [5], parton thermodynamics [6], and parton recom- bination [7] are examples on underlying physics. At high-  , hard-scattering cross-section from QCD perturbative calcu- lations, parton distribution functions, and parton-to-hadron fragmentation functions have been successfully utilized in reproducing   -spectra of various produced particles [8]. It is worth mentioning that there is no well-defned line separating nonperturbative from perturbative   -regimes [3]. Even the various theoretical studies are not distinguishing sharply between both of them. For instance, when con- structing partition functions, extensive and nonextensive statistical approaches are frequently misconducted [9–11]. For instance, the claim that high   -spectra of diferent produced particles are to be reproduced by Tsallis statistics seems being incomplete [11, 12]. Tis simply inspires a great contradiction between nonperturbative and perturbative QCD [12]. Te statistical cluster decay could be scaled as power laws very similar to the ones of Tsallis statistics. Te earlier is conjec- tured to cover a wide range of   , while the latter is limited to a certain   -regime. Tis would lead to an undesired mixing up that the observed power laws might be stemming from Hindawi Advances in High Energy Physics Volume 2019, Article ID 4604608, 7 pages https://doi.org/10.1155/2019/4604608