At very high energies, the relevant component of the hadron wavefunction can be described as a Color Glass Condensate, i.e., a state of high density gluonic matter whose distribution is random, but frozen over the relevant time scales. The weight function for this distribution obeys a renormalization group equation in the form of a functional Fokker-Planck equation. Its solution leads to an effective theory which predicts gluon saturation at sufficiently high energy, or small Bjorken's $x$.

We present our work on the simulation of the early stages of heavy-ion collisions with finite longitudinal thickness in the laboratory frame in $3+1$ dimensions. In particular we study the effects of nuclear thickness on the production of a glasma state in the McLerran-Venugopalan model within the color glass condensate framework. A finite thickness enables us to describe nuclei at lower energies, but forces us to abandon boost invariance. As a consequence, random classical color sources within the nuclei have to be included in the simulation, which is achieved by using the colored particle-in-cell method. We show that the description in the laboratory frame agrees with boost-invariant approaches as a limiting case. Furthermore we investigate collisions beyond boost invariance, in particular the pressure anisotropy in the glasma.

Gluon Saturation at small x

Simulating collisions of thick nuclei in the color glass condensate framework

The University of Bergen, Norway is currently involved in the development and building of the Forward Calorimeter (FoCal) as an upgrade to the ALICE (A Large Ion Collider Experiment) detector at CERN (European Organization for Nuclear Research). In the case of particle detectors, as at CERN, trigger systems are utilized for data acquisition (DAQ). Data to be acquired pertains to charged particles passing through a charged particle detector. However, it is not desirable that data pertaining to absolutely all such events is data stored for further processing, as this would waste an incredible amount of memory and time. Therefore, a trigger system in this context must include a mask which can discard events which are considered uninteresting so that only relevant data is stored. At the same time, events of interest must be immediately allowed to be measured and stored. The focus of this work has been to develop the trigger readout system in the hardware description language called VHDL. The system allows a user to configure the aforementioned mask such that only desired events are recorded. The result of this work is a trigger readout system which functions in simulation, yet remains to be tested and verified on physical devices.

Gluon Saturation at small x

Citations

Simulating collisions of thick nuclei in the color glass condensate framework

A trigger readout system for the Forward Calorimeter(FoCal)

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