Evolution of 4 pi observables in the Vlasov-Uehling-Uhlenbeck theory and the transverse momentum transfer as a barometer for hadronic matter

We study the dynamics of high energy heavy ion collisions through the Vlasov-Uehling-Uhlenbeck approach. Equilibration is observed, for central collisions. It is shown that the produced entropy, the pion multiplicity, flow angle, and transverse momentum distributions saturate at the moment of maximum compression and temperature. The effects of the nuclear equation of state and the Pauli principle are investigated. For the flow angle distribution there is a 20 deg reduction of the peak flow angle due to the Pauli principle. A stiff equation of state results in a 10–20 deg increase over the soft equation of state at all energies. The transverse momentum at projectile rapidity exhibits a peak structure as a function of impact parameter b. A 40% difference between soft and hard equation of state is observed for the peak impact parameter, i.e., for intermediate multiplicities

A Bosonic Model of Quantum Holography

We analyze a model of qubits which we argue has an emergent quantum gravitational description similar to the fermionic Sachdev-Ye-Kitaev (SYK) model. The model we consider is known as the quantum $q$-spin model because it features $q$-local interactions between qubits. It was previously studied as a model of a quantum spin glass, and while we find that the model is glassy for $q=2$, $q=3$, and likely $q=4$, we also find evidence for previously unexpected SYK-like behavior for the quenched free energy down to the lowest temperatures for $q \geq 5$. This SYK-like physics includes power-law correlation functions and an extensive low temperature entropy, so we refer to the model as Spin SYK. The model is generic in that it includes all possible $q$-body couplings, lacks most symmetries, and has no spatial structure, so our results can be construed as establishing a certain ubiquity of quantum holography in systems dominated by many-body interactions. Furthermore, we discuss a generalized family of models which includes Spin SYK and which provably exhibit SYK-like physics in the solvable limit of large local Hilbert space dimension. We also comment on implications of a bosonic system with SYK-like properties for the study of holography, Hamiltonian complexity, and related topics

Emergent Spectral Form Factors in Sonic Systems

We study the spectral form factor (SFF) for hydrodynamic systems with a sound pole, a large class including any fluid with momentum conservation and energy conservation, or any extended system with spontaneously broken continuous symmetry. We study such systems in a finite volume cavity and find that the logarithm of the hydrodynamic enhancement is closely related to the spectral form factor of a quantum particle moving in the selfsame cavity. Depending upon the dimensionality and nature of the effective single-particle physics, we exhibit a range of behaviors including an intricate resonance phenomenon, emergent integrability in the SFF, and anomalously large fluctuations of the SFF.Comment: 26 page

Mean field effects in hot compressed nuclear matter

We study effects of the mean field in hot compressed nuclear matter in the context of the Vlasov Uehling-Uhlenbeck theory. The expansion of a spherical distribution at different temperatures is studied along with collisions of Nb+Nb and Au+Au at lab energies from 50 to 1050 MeV/nucleon. In both the expansion and the actual heavy ion collision simulation, a transition behavior is seen only at the lowest temperature (T<10 MeV) or bombarding energy (E=50 MeV/nucleon), where the attractive part of the mean field is able to bind the expanding matter. At the lowest energy one thus sees the formation of a central residue, whereas at higher bombarding energies there is complete disintegration of the centrally colliding nuclei. The spectrum of emitted nucleons is found to be much hotter than the kinetic energy spectrum of the central emitting region. The extracted temperature slope parameters are in agreement with recent data

Spectral statistics of a minimal quantum glass model

Glasses have the interesting feature of being neither integrable nor fully chaotic. They thermalize quickly within a subspace but thermalize much more slowly across the full space due to high free energy barriers which partition the configuration space into sectors. Past works have examined the Rosenzweig-Porter (RP) model as a minimal quantum model which transitions from localized to chaotic behavior. In this work we generalize the RP model in such a way that it becomes a minimal model which transitions from glassy to chaotic behavior, which we term the "Block Rosenzweig-Porter" (BRP) model. We calculate the spectral form factors of both models at all timescales. Whereas the RP model exhibits a crossover from localized to ergodic behavior at the Thouless timescale, the new BRP model instead crosses over from glassy to fully chaotic behavior, as seen by a change in the slope of the ramp of the spectral form factor.Comment: 41 pages, 10 figure

LVC Interaction within a Mixed Reality Training System

The United States military is increasingly pursuing advanced live, virtual, and constructive (LVC) training systems for reduced cost, greater training flexibility, and decreased training times. Combining the advantages of realistic training environments and virtual worlds, mixed reality LVC training systems can enable live and virtual trainee interaction as if co-located. However, LVC interaction in these systems often requires constructing immersive environments, developing hardware for live-virtual interaction, tracking in occluded environments, and an architecture that supports real-time transfer of entity information across many systems. This paper discusses a system that overcomes these challenges to empower LVC interaction in a reconfigurable, mixed reality environment. This system was developed and tested in an immersive, reconfigurable, and mixed reality LVC training system for the dismounted warfighter at ISU, known as the Veldt, to overcome LVC interaction challenges and as a test bed for cuttingedge technology to meet future U.S. Army battlefield requirements. Trainees interact physically in the Veldt and virtually through commercial and developed game engines. Evaluation involving military trained personnel found this system to be effective, immersive, and useful for developing the critical decision-making skills necessary for the battlefield. Procedural terrain modeling, model-matching database techniques, and a central communication server process all live and virtual entity data from system components to create a cohesive virtual world across all distributed simulators and game engines in real-time. This system achieves rare LVC interaction within multiple physical and virtual immersive environments for training in real-time across many distributed systems

A system for rapid creation and assessment of conceptual large vehicle designs using immersive virtual reality

Currently, new product concepts are often evaluated by developing detailed virtual part and assembly models with traditional computer aided design (CAD) tools followed by appropriate analyses (e.g., finite element analysis, computational fluid dynamics, etc.). The creation of these models and analyses are tremendously time consuming. If a number of different conceptual configurations have been determined, it may not be possible to model and analyze each of them due to the complexity of these evaluation processes. Thus, promising concepts might be eliminated based solely on insufficient time and resources for assessment. In addition, the virtual models and analyses performed are usually of much higher detail and accuracy than what is needed for such early assessment. By eliminating the time-consuming complexity of a CAD environment and incorporating qualitative assessment tools, engineers could spend more time evaluating concepts that may have been previously abandoned due to time constraints. To address these issues, the Advanced Systems Design Suite (ASDS), was created. The ASDS incorporates a PC user interface with an immersive virtual reality (VR) environment to ease the creation and assessment of conceptual design prototypes individually or collaboratively in an immersive VR environment. Assessment tools incorporate metamodeling approximations and immersive visualization to evaluate the feasibility of each concept. In this paper, the ASDS system and interface along with specifically designed immersive VR assessment tools such as state saving and dynamic viewpoint creation are presented for conceptual large vehicle design. A test case example of redesigning an airplane is presented to explore the feasibility of the proposed system

FPGA-Based Tracklet Approach to Level-1 Track Finding at CMS for the HL-LHC

During the High Luminosity LHC, the CMS detector will need charged particle tracking at the hardware trigger level to maintain a manageable trigger rate and achieve its physics goals. The tracklet approach is a track-finding algorithm based on a road-search algorithm that has been implemented on commercially available FPGA technology. The tracklet algorithm has achieved high performance in track-finding and completes tracking within 3.4 $\mu$s on a Xilinx Virtex-7 FPGA. An overview of the algorithm and its implementation on an FPGA is given, results are shown from a demonstrator test stand and system performance studies are presented.Comment: Submitted to proceedings of Connecting The Dots/Intelligent Trackers 2017, Orsay, Franc