We report first study of transverse momentum ($p_\mathrm{ T}$) spectra for $\pi^{ \pm}$, $K^{ \pm}$, $p$, and $\bar{ p}$ in isobar, $^{ 96}_{ 44}$Ru+$^{ 96}_{ 44}$Ru and $^{ 96}_{ 40}$Zr+$^{ 96}_{ 40}$Zr, collisions at $\sqrt{ s_{ \mathrm{ NN}}} = 200$ GeV using a multi-phase transport (AMPT) model. Particle yields ($dN/dy$), average transverse momenta ($\langle p_\mathrm{ T} \rangle$), and particle ratios are reported in various collision systems with different parameterizations of the Woods-Saxon (WS) distribution. We observed a maximum difference of 5% in the particle yields in peripheral collisions when we included a quadrupole and octupole deformation and a nuclear size difference between the isobars. The $\pi^{ -}$/$\pi^{ +}$ ratio is smaller in Ru+Ru collisions compared to Zr+Zr collisions indicating an effect of isospin due to difference in number of protons and neutrons between the two nuclei. The $K^{ -}$/$K^{ +}$ ratio is same in both the systems indicating the dominance of the pair production mechanism in the kaon production. The $\bar{ p}/p$ ratio is further smaller in Ru+Ru collisions than Zr+Zr collisions, indicating the effect of baryon stopping in addition to the isospin effect. A system size dependence is observed in $dN/dy$ and $\langle p_\mathrm{ T} \rangle$ when we compare the results from isobar collisions with Au+Au and U+U collisions.
Categories: hep-ph hep-ex nucl-ex