Mass-Dependent Non-Extensivity in Tsallis Blast-Wave Fits to Identified Hadron pT Spectra at RHIC and LHC
Abstract
We analyze identified-hadron transverse-momentum spectra from STAR Au+Au and ALICE Pb+Pb collisions over √(sNN) = 7.7~GeV--$5.02$~TeV using an extended Tsallis Blast-Wave (TBW) framework, which includes a non-extensivity parameter q to quantify the degree of incomplete thermal equilibrium. Conventionally, either a common value of q, or two separate q values, one for mesons and one for baryons, are used to describe particle spectra in the TBW framework, with the latter being referred to as TBW4 in Ref.~\cite{Chen:2020zuw}. This work extends the TBW framework by studying the dependence of q on different kinds of particles in detail. Fits allowing independent non-extensivity parameters q for each species reveal a systematic correlation between q and particle mass, except for quarkonia. Motivated by this trend, we introduce two new parameterizations: TBW5, which posits that q depends linearly on particle mass, and TBW6, which allows the q intercepts for mesons and baryons to differ. Across all energies and centralities considered in this study, TBW5 improves χ2/NDF relative to the TBW4 fit in 74\% of the datasets, while TBW6 shows improvement in 93\% of the datasets. They perform especially well in central collisions. These results demonstrate a robust mass ordering in non-equilibrium behavior at kinetic freeze-out and provide a more accurate description of hadron spectra from RHIC to LHC energies.
Related
- Final-state effects on the transverse-momentum spectra of charged hadrons in p+Pb and Pb+Pb collisions at √(sNN) = 5.02~TeV using the modified Tsallis distribution
- Rényi and Tsallis information entropies for a harmonic position-dependent mass
- Phantom-Divide Crossing in Barrow-Tsallis Holographic Dark Energy with a Scale-Dependent Barrow Exponent
- Hadron resonance gas with density-dependent interactions for neutron stars and heavy-ion collisions
- Measurements of time-dependent b-hadron properties in LHCb
BibTeX
@misc{tsang2026massdependent,
title = {{Mass-Dependent Non-Extensivity in Tsallis Blast-Wave Fits to Identified Hadron $p_T$ Spectra at RHIC and LHC}},
author = {C. Y. Tsang and Z. Xu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.24777},
eprint = {2606.24777},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.24777},
}
RIS
TY - UNPB
TI - Mass-Dependent Non-Extensivity in Tsallis Blast-Wave Fits to Identified Hadron p_T Spectra at RHIC and LHC
AU - C. Y. Tsang
AU - Z. Xu
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2606.24777
UR - https://arxiv.org/abs/2606.24777
AB - We analyze identified-hadron transverse-momentum spectra from STAR Au+Au and ALICE Pb+Pb collisions over √(s_NN) = 7.7~GeV--$5.02$~TeV using an extended Tsallis Blast-Wave (TBW) framework, which includes a non-extensivity parameter q to quantify the degree of incomplete thermal equilibrium. Conventionally, either a common value of q, or two separate q values, one for mesons and one for baryons, are used to describe particle spectra in the TBW framework, with the latter being referred to as TBW4 in Ref.~\cite{Chen:2020zuw}. This work extends the TBW framework by studying the dependence of q on different kinds of particles in detail. Fits allowing independent non-extensivity parameters q for each species reveal a systematic correlation between q and particle mass, except for quarkonia. Motivated by this trend, we introduce two new parameterizations: TBW5, which posits that q depends linearly on particle mass, and TBW6, which allows the q intercepts for mesons and baryons to differ. Across all energies and centralities considered in this study, TBW5 improves χ^2/NDF relative to the TBW4 fit in 74\% of the datasets, while TBW6 shows improvement in 93\% of the datasets. They perform especially well in central collisions. These results demonstrate a robust mass ordering in non-equilibrium behavior at kinetic freeze-out and provide a more accurate description of hadron spectra from RHIC to LHC energies.
ER -