Particle spectra in the integrated hydrokinetic model at RHIC Beam-Energy-Scan energies

We study light-hadron production in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mi>Au</a:mi> <a:mo>+</a:mo> <a:mi>Au</a:mi> </a:mrow> </a:math> collisions at <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mrow> <b:msqrt> <b:msub> <b:mi>s</b:mi> <b:mi>NN</b:mi> </b:msub> </b:msqrt> <b:mo>=</b:mo> <b:mn>7.7</b:mn> <b:mo>–</b:mo> <b:mn>39</b:mn> <b:mspace width="0.222222em"/> <b:mi>GeV</b:mi> </b:mrow> </b:math> using an extended Integrated HydroKinetic Model (iHKMe). Focusing on transverse momentum spectra, we investigate the sensitivity to key model parameters, particularly the thermalization timescale. We consider two distinct equations of state: one featuring a crossover and the other a first-order phase transition. In both cases, thermalization begins shortly before full nuclear overlap and lasts approximately <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mn>1</d:mn> <d:mspace width="0.16em"/> <d:mi>fm</d:mi> <d:mo>/</d:mo> <d:mi>c</d:mi> </d:mrow> </d:math> across all energies. Both equations of state provide a similarly good description of the soft particle momentum spectra once the other parameters are slightly adjusted. The most pronounced differences arise at the lower RHIC BES energy of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mrow> <f:msqrt> <f:msub> <f:mi>s</f:mi> <f:mi>NN</f:mi> </f:msub> </f:msqrt> <f:mo>=</f:mo> <f:mn>7.7</f:mn> <f:mspace width="0.222222em"/> <f:mi>GeV</f:mi> </f:mrow> </f:math> , particularly in proton and kaon yields, reflecting their sensitivity to the freezeout parameters.