We developed the third-order hydrodynamic equations using relativistic extended thermodynamics of gases with 14 independent fields. The resulting fluid equations are based on the relativity principle, the entropy principle, and the requirement of hyperbolic, and hence finite, propagation of disturbances, which is automatically incorporated. The expressions of entropy, four-current, shear-stress tensor, dynamic pressure, and heat flux are expanded up to third order (cubic). We explicitly present the newly calculated coefficients in the equilibrium properties of an ultra-relativistic gas regime and the non-degenerate relativistic gas. Contrary to the general cases, the non-degenerate regime eliminates fugacity from the coefficients, allowing for the easy normalization of these coefficients, and the ultra-relativistic regime provides us with the upper bounds of these coefficients. We found good agreement on some of the coefficients as compared to calculations from earlier models, specifically in kinetic theory, and other coefficients had slightly different values to those obtained in kinetic theory.

This study presents a numerical and analytical model of hydro-dynamic and magnetohydrodynamic piston-driven shock waves, developed to generate benchmark solutions for shock dynamics in the presence and absence of magnetic fields in core-collapse supernovae environments.

This review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effective field theory results. From the experimental side, it includes heavy-ion collision and low-energy nuclear physics results, as well as observations from neutron stars and their mergers. The validity of different constraints, concerning specific conditions and ranges of applicability, is also provided.

The rapid development of vaccines to combat the spread of COVID-19, caused by the SARS-CoV-2 virus, is a great scientific achievement. Before the development of the COVID-19 vaccines, most studies capitalized on the available data that did not include pharmaceutical measures. Such studies focused on the impact of non-pharmaceutical measures such as social distancing, sanitation, use of face masks, and lockdowns to study the spread of COVID-19. In this study, we used the SIDARTHE-V model, an extension of the SIDARTHE model, which includes vaccination rollouts. We studied the impact of vaccination on the severity of the virus, specifically focusing on death rates, in African countries. The SIRDATHE-V model parameters were extracted by simultaneously fitting the COVID-19 cumulative data of deaths, recoveries, active cases, and full vaccinations reported by the governments of Ghana, Kenya, Mozambique, Nigeria, South Africa, Togo, and Zambia. Using South Africa as a case study, our analysis showed that the cumulative death rates declined drastically with the increased extent of vaccination drives. Whilst the infection rates sometimes increased with the arrival of new coronavirus variants, the death rates did not increase as they did before vaccination.

The African School of Fundamental Physics and Applications, also known as the African School of Physics (ASP), was initiated in 2010, as a three-week biennial event, to offer additional training in fundamental and applied physics to African students with a minimum of three-year university education. Since its inception, ASP has grown to be much more than a school. ASP has become a series of activities and events with directed ethos towards physics as an engine for development in Africa. We report on the seven African School of Physics, ASP2022, organized at Nelson Mandela University, on November~28 to December~8, 2022. ASP2022 included programs for university students, high school teachers and high school pupils.

We summarize the current status of high energy physics (HEP) in Africa, Latin America, and other developing regions

Diversity, Equity, Inclusion, and Accessibility (DEIA) are not only called for to ensure morality and justice in our society, they also support ongoing and future excellence in particle physics. Over the past decade, the particle physics community has devised programs to support DEIA along multiple axes, and the way we think about measuring and implementing these initiatives has evolved. DEIA in physics is a broad topic, so in this paper we focus on the experiences of marginalized communities and outline ways different stakeholders can build a culture of equitable access for the success of marginalized individuals. Specifically, we identify urgent needs in the following areas: (1) We need to acquire a better understanding of the status quo, both quantitatively and qualitatively, to assess the effectiveness of existing programs and to develop best practices; (2) we need to develop effective and inclusive ways to engage marginalized communities; (3) we need to create infrastructure to better support members of marginalized communities, on an academic, financial and personal level; (4) we need to create an environment conducive to equitable access and success by establishing community expectations, fostering inclusion in social interactions, and holding individuals and institutions accountable; and (5) we need to establish a mechanism to monitor progress in the area of DEIA, including the implementation of the recommendations enumerated in this paper and others during the Snowmass 2021 process.

This is the summary report of the Community Engagement Frontier for the Snowmass 2021 study of the future of particle physics. The report discusses a number of general issues of importance to the particle physics community, including (1) the relation of universities, national laboratories, and industry, (2) career paths for scientists engaged in particle physics, (3) diversity, equity, and inclusion, (4) physics education, (5) public education and outreach, (6) engagement with the government and public policy, and (7) the environmental and social impacts of particle physics.

Research, education and training in high energy physics (HEP) often draw international collaborations even when priorities and long term visions are defined regionally or nationally. Yet in many developing regions, HEP activities are limited in both human capacity and expertise, as well as in resource mobilisation. In this paper, the benefits – to the U.S. HEP program – of engagements with developing countries are identified and studied through specific examples of Africa and Latin America; conversely, the impact of HEP education and research for developing countries are also pointed out. In the context of the U.S. strategic planning for high energy physics, the authors list recommendations on investments that will benefit both developed and developing nations.

This Snowmass2021 Contributed Paper addresses the role of the Particle Physics community in creating and fostering international connections in American education. It describes the pressing need to introduce students and faculty to the challenges and rewards of international collaboration, not only to develop the next generation of scientists and engineers for particle physics, but to maintain and build U.S. leadership on an increasingly competitive world stage. We present and assess current efforts in education and public engagement with an eye toward identifying those activities in need of change or increased resources to improve audience reach and program efficacy. We also consider possible new activities that might improve upon or complement existing programs, with the common goal of providing all U.S. students with the opportunity to benefit from a quality international scientific experience.

This Snowmass21 Contributed Paper addresses the structural changes that need to occur in the many groups and organizations that intersect with the US particle physics community to enable impactful public engagement to flourish. The impetus for these changes should come from the particle physics community, which should acknowledge the importance of public engagement and act on the recommendations in this Snowmass contributed paper. Scientists have expressed frustration at the barriers, penalties and lack of support that discourage them from participating in public engagement. In this paper, we provide many ways to create a supportive, enabling atmosphere for public engagement among physicists.

We studied the COVID-19 pandemic evolution in selected African countries. For each country considered, we modeled simultaneously the data of the active, recovered and death cases. In this study, we used a year of data since the first cases were reported. We estimated the time-dependent basic reproduction numbers, R0, and the fractions of infected but unaffected populations, to offer insights into containment and vaccine strategies in African countries. We found that R0≤4 at the start of the pandemic but has since fallen to R0∼1. The unaffected fractions of the populations studied vary between 1−10% of the recovered cases.

Nonequilibrium dynamics for relativistic fluid or quark gluon plasma (QGP) have already been calculated earlier up to third order using both kinetic and thermodynamic approaches. Calculations presented in this article are based on thermodynamics principles. The expressions for third order dissipative fluxes have been derived from equation for entropy four-current developed earlier by Muronga. The relaxation equations in the present work have been developed in a simple Bjorken (1 + 1) dimensional scenario and Eckart frame. The relaxation equations are found to have slightly different values for the coupling coefficients as compared to calculations from earlier models. The solutions to the differential equations have been found to be sensitive to values of these coefficients. The shear relaxation equations derived in third order theory are discussed term by term. Effects of third order theory on shear relaxation time have been discussed. Thermodynamic quantities related to hot and dense matter have been calculated as functions of proper time. Moreover, various initial conditions for the relaxation equations have been assumed to study their effects on above mentioned observables. A CERN Large Hadron Collider QGP formation time of tau(0) = 0.4 fm/c and temperature of T-0 = 500 MeV have been assumed.

The thermal conductivity of hadronic matter is studied using a microscopic transport model, which will be used to simulate ultra-relativistic heavy ion collisions at different energy densities ε, namely the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). The molecular dynamics simulation is performed for a system of zero baryon number density and light meson species (π, ρ and K) in a box with periodic boundary conditions. The equilibrium state is investigated by studying the chemical equilibrium and the thermal equilibrium of the system. The particle multiplicity equilibrates with time, and the energy spectra of different light mesons species have the same slopes and common temperatures when thermal equilibrium is reached. The thermal conductivity transport coefficient is calculated from the heat current current correlations using the Green-Kubo relations.

Third order hydrodynamics equations have been developed using thermodynamics approach. Present calculations are based on entropy principle and the differential equations have been developed in Eckart frame and Bjorken (1+1)D scenario. Energy density, and pressure isotropization etc. as function of proper time have been calculated for massless relativistic fluids. The present calculations have been compared to earlier calculations by A. El et al. and A. Jaiswal et al. An initial QGP formation time of τ0 = 0.4 fm/c and temperature of T0 = 500 MeV have been used for calculations.

Thermal conductivity of hadron matter is studied using a microscopic transport model, which will be used to simulate ultra-relativistic heavy ion collisions at different energy densities, namely the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). The molecular dynamics simulation is performed for a system of light mesons species (pion, rho, kaon) in a box with periodic boundary conditions. The equilibrium state is investigated by studying chemical equilibrium and thermal equilibrium of the system. Particle multiplicity equilibrates with time, and the energy spectra of different light mesons species have the same slopes and common temperatures when thermal equilibrium is reached. Thermal conductivity transport coefficient is calculated from the heat current - current correlations using the Green-Kubo relations.

An overview is presented of transverse momentum distributions of particles at the LHC using the Tsallis distribution.The use of a thermodynamically consistent form of this distribution leads to an excellent description of charged and identified particles.The values of the Tsallis parameter q are truly remarkably consistent.

Geant4 is a Monte Carlo simulation toolkit that is used for the simulation of particles through matter. It was developed by a world wide collaboration of about 100 scientists. It has applications in high energy physics, astrophysics, medical physics, nuclear physics experiments, accelerator and space science studies. The Evaluated Nuclear Data File, ENDF/B-VII database is included in the simulation toolkit, making it feasible to use the Geant4 toolkit for low energy neutron-physics simulations. The ENDF/B-VII database stores evaluated nuclear reaction data files from the major evaluated libraries. In this presentation Geant4 was used to perform simple single event neutron scattering simulations on materials that are typical for a nuclear reactor. Some of the materials used are found in the SAFARI 1 reactor at Necsa, Pelindaba. These include Aluminium, Beryllium. This was done in order to validate the Geant4 implementation of primary processes relevant to reactor studies within the ENDF/B-VII database of cross sections.

Nodal diffusion methods are often used to calculate the distribution of neutrons in a nuclear reactor core. They require few-group homogenized neutron cross sections for every heterogeneous sub-region of the core. The homogenized cross sections are pre-calculated at various reactor states and represented in a way that facilitates the reconstruction of cross sections at other possible states. In this study a number of such representations were built for the cross sections of a MOX (mixed oxide) fuel assembly via hierarchical Lagrange interpolation on Clenshaw-Curtis sparse grids. Traditionally, nodal reactor core simulators have employed cross sections with two energy groups, but there is evidence that more energy groups are needed to simulate reactor cores that contain MOX. Representations were therefore constructed for both the traditional two energy groups and a six energy group structure. Both the rate at which the representation accuracy improves with the number of samples and the complexity of the cross section dependence on individual state parameters were examined. The anisotropy feature of the representation procedure, which allows more samples to be taken for state parameters that are known to be more important to the representation accuracy than others, was applied throughout. The results show that the representation method allows both two-group and six-group cross sections to be represented in a computationally efficient manner to an industrially acceptable level of accuracy, despite additional complexity in the dependence of six-group cross sections on the state parameters.

Geant4 is a Monte Carlo based simulation tool that models the passage of particles through matter. It was developed at CERN primarily for High Energy Particle Physics. This research applied Geant4 in a simulation of single event neutron scattering in materials typical of the SAFARI reactor core. Four different materials were used in the simulation: Water, Aluminum(27), Uranium(238) and Beryllium(9). The results of the neutron scattering were compared with MCNPX2.7 results. This was done in order to validate the Geant4 implementation of primary processes within the ENDF/B-VII database of reaction cross sections and also benchmarking this against other simulation programs particular to low energy neutron transport like MCNPX 2.7. It was found that the Geant4 results compare well with MCNPX2.7 results. The total neutron scattering cross sections of Geant4 where also compared with the ENDF/B-VII cross sections and these also compared well.