Speaker
Description
The observation of signs of collectivity in small systems has highlighted the need
for a better understanding of equilibration in small and large collisions systems.
In search of this, the QCD effective kinetic theory formulated by Arnold, Moore
and Yaffe (AMY) [1] has emerged as a promising candidate. In order to fully exploit
the theory also for phenomenology we introduce ALPACA [2], a Lorentz invariant parton
cascade which is a representation of the AMY effective kinetic theory in the form of
a Monte Carlo event generator. It solves the Boltzmann equation with the full AMY
kernels (elastic scattering and splitting/merging processes) by explicitly simu-
lating the evolution of parton ensembles corresponding to single events. It is
constructed in a fully Lorentz invariant way by using a method pioneered in [3],
which also underlies the parton cascade PCPC [4]. A complication arises from
quantities like the screening mass, that enter the AMY kernels and are defined
as integrals over the phase space densities. We develop a method for extracting
these locally from the parton ensemble without the need for further informa-
tion. We perform an extensive validation of the framework in thermal equilibrium
and present first results for out-of-equilibrium simulations for collisions of
light nuclei down to protons. Here we focus on harmonic flow response to initial
geometry deformations and the question to what extent such systems equilibrate.
[1] P. B. Arnold, G. D. Moore and L. G. Yaffe, JHEP 01 (2003), 030 [arXiv:hep-ph/0209353 [hep-ph]]
[2] A. Kurkela, R. Törnkvist and K. Zapp, [arXiv:2211.15454 [hep-ph]]
[3] G. Peter, D. Behrens and C. C. Noack, Phys. Rev. C 49 (1994), 3253-3265
[4] V. Borchers, J. Meyer, S. Gieseke, G. Martens and C. C. Noack, Phys. Rev. C 62 (2000), 064903
[arXiv:hep-ph/0006038 [hep-ph]]
| Category | Theory |
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