Speaker
Description
The string melting version of a Multi-Phase Transport (AMPT) model
can reasonably describe the $dN/dy$ yields, $p_{T}$ spectra and
anistropic flows of pions and kaons at low $p_{T}$ in heavy ion
collisions at RHIC and LHC energies [1,2].
However, it failed to reproduce the $dN/dy$ and $p_{T}$ spectra of
baryons [2,3]. For example, it overestimates the proton yield at
mid-rapidity but underestimates the slope of the proton $p_{T}$
spectra. In addition, antiparticle/particle ratios
from the current AMPT model are unexpectedly above unity for strange baryons.
In this work we improve the quark coalescence model in AMPT.
In particular, we have removed the previous constraint that forced the total
numbers of mesons, baryons, and anti-baryons in an event to be separately conserved
through quark coalescence. Instead, a quark or anti-quark now has the
freedom to form either a baryon or a meson, depending on the distance
to its coalescence partner(s). We have also changed the order in quark
coalescence: previously coalescence partners of all mesons are
searched first (ahead of baryons), while now the sequence of meson and baryon
formations is dynamically determined.
In this talk we will show that this improved AMPT model can describe
baryons much better. In particular, the $p_{T}$ spectra of
protons and and $\Lambda$-baryons roughly agree with the heavy ion data at RHIC
and LHC, and antiparticle/particle ratios for strange baryons also
reasonably agree with the data.
[1]Z. W. Lin, Phys. Rev. C 90, 014904 (2014).
[2]G. L. Ma and Z. W. Lin, Phys. Rev. C 93, 054911(2016).
[3]Z. W. Lin, C. M. Ko, B. A. Li, B. Zhang and S. Pal, Phys. Rev. C 72, 064901 (2005).
| Preferred Track | New Theoretical Developments |
|---|---|
| Collaboration | Not applicable |
