Computer Physics Communications最新文献

{"title":"Covariant implementation of bi-particle force for simulation of relativistic many-body systems with reactions","authors":"I.V. Grossu ,&nbsp;Al. Jipa ,&nbsp;T. Esanu ,&nbsp;M. Ablai","doi":"10.1016/j.cpc.2025.109850","DOIUrl":"10.1016/j.cpc.2025.109850","url":null,"abstract":"<div><div>In this work we present a covariant implementation of force for Chaos Many-Body Engine (CMBE - Grossu et al., 2021) .Net application. Thus, supposing the expression of bi-particle force is known in the center-of-mass frame, we applied specific relativistic transformations for obtaining the corresponding value in laboratory frame. As an example of use, we discuss a toy-model for relativistic nuclear collisions at Facility for Antiproton and Ion Research (FAIR) energies.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109850"},"PeriodicalIF":3.4,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physics informed neural network-based framework for two-dimensional phase change problems","authors":"Sanjeet Patra ,&nbsp;Manish Agrawal ,&nbsp;Prasenjit Rath ,&nbsp;Anirban Bhattacharya","doi":"10.1016/j.cpc.2025.109854","DOIUrl":"10.1016/j.cpc.2025.109854","url":null,"abstract":"<div><div>In this work, we propose a framework to solve two-dimensional phase change problems with arbitrary shaped interfaces using physics-informed neural network. These problems are characterized by moving interfaces driven by the heat flux distribution during the phase change process. We model the phase change using a diffuse interface enthalpy formulation, where the interface has a finite width and phase change occurs over a specified temperature range. A loss function only based on the temperature field is formulated, by reframing the latent enthalpy change in terms of the temperature field and phase change temperature range. This allows us to predict the transient temperature field and interface position with the help of a simple PINN architecture consisting of a single neural network. Further the loss function does not consist of any terms related to the interface condition, making the overall implementation simple in nature. We demonstrate the effectiveness of our approach by solving a series of problems with different combinations of boundary conditions and heat sources without using any prior data and illustrate how the proposed framework can capture solution of phase change problems with arbitrary-shaped dynamic interfaces.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109854"},"PeriodicalIF":3.4,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SKiES: The program for ab initio calculations of transport properties based on Allen's method for solving Boltzmann equation","authors":"I.S. Galtsov ,&nbsp;V.B. Fokin ,&nbsp;D.V. Minakov ,&nbsp;P.R. Levashov","doi":"10.1016/j.cpc.2025.109834","DOIUrl":"10.1016/j.cpc.2025.109834","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Accurate modeling of transport properties, such as electrical resistivity and electronic contribution to thermal conductivity, is essential for understanding charge and heat transport in materials. We introduce &lt;span&gt;SKiES&lt;/span&gt;, an open-source code for calculating temperature-dependent transport properties using Allen's lowest-order variational approximation. Being integrated with &lt;span&gt;Quantum ESPRESSO&lt;/span&gt; &lt;em&gt;ab initio&lt;/em&gt; package and &lt;span&gt;EPW&lt;/span&gt; software for electron–phonon coupling calculations, &lt;span&gt;SKiES&lt;/span&gt; leverages maximally localized Wannier functions and advanced Brillouin zone sampling techniques, including Allen's tetrahedron method, to achieve high accuracy. Application to silver demonstrates excellent agreement with experimental data, showcasing the capabilities of &lt;span&gt;SKiES&lt;/span&gt; for precise and efficient transport property evaluations. This tool provides a robust framework for researchers investigating electronic transport phenomena in solids.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Program summary&lt;/h3&gt;&lt;div&gt;&lt;em&gt;Program Title:&lt;/em&gt; SKiES&lt;/div&gt;&lt;div&gt;&lt;em&gt;CPC Library link to program files:&lt;/em&gt; &lt;span&gt;&lt;span&gt;https://doi.org/10.17632/t45c7kc6gt.1&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;em&gt;Developer's repository link:&lt;/em&gt; &lt;span&gt;&lt;span&gt;https://github.com/JLab-MatSci/SKiES&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;em&gt;Licensing provisions:&lt;/em&gt; GNU General Public Licence 3.0&lt;/div&gt;&lt;div&gt;&lt;em&gt;Programming language:&lt;/em&gt; C++, Fortran, CMake&lt;/div&gt;&lt;div&gt;&lt;em&gt;External routines/libraries:&lt;/em&gt; Quantum Espresso v. 7.1, C++17 standard, Intel TBB library&lt;/div&gt;&lt;div&gt;&lt;em&gt;Nature of problem:&lt;/em&gt; First-principle transport properties calculations of solid materials for a temperature range.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Solution method:&lt;/em&gt; The implementation is based on Allen's method [1] for solving the kinetic equation, allowing for evaluation of temperature-dependent transport properties in metals. As a central output, Allen's electron–phonon transport spectral function is computed, both in the low-temperature limit and in the general case. Electrical resistivity and electronic thermal conductivity are later evaluated using the spectral function data. The code employs Wannier interpolation techniques as implemented in EPW package [2], which interfaces with the Quantum ESPRESSO suite [3] for preliminary &lt;em&gt;ab initio&lt;/em&gt; calculations.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Additional comments including restrictions and unusual features:&lt;/em&gt; C++17 parallel algorithms based on Intel TBB library are used to handle complex computations and benefit from high-performance computing.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;References&lt;/h3&gt;&lt;div&gt;&lt;ul&gt;&lt;li&gt;&lt;span&gt;[1]&lt;/span&gt;&lt;span&gt;&lt;div&gt;P. B. Allen, New method for solving Boltzmann's equation for electrons in metals, Phys. Rev. B 17 (1978) 3725–3734.&lt;/div&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;[2]&lt;/span&gt;&lt;span&gt;&lt;div&gt;S. Poncé, E. Margine, C. Verdi, F. Giustino, EPW: electron–phonon coupling, transport and superconducting properties using maximally localized Wannier functions, Comp","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109834"},"PeriodicalIF":3.4,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145026727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FeynRules implementation of the minimal Stueckelberg extension of the SM","authors":"Abdelkader Yanallah","doi":"10.1016/j.cpc.2025.109830","DOIUrl":"10.1016/j.cpc.2025.109830","url":null,"abstract":"<div><div>We implement the Stueckelberg minimal extension of the standard model for the <span><math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span> boson within a FeynRules model file. With the FeynRules package, we use the fields belonging to the representation of the Lorentz and minimally extended gauge symmetries and the BRST symmetry to construct the entire Lagrangian. The package permitted us to reduce the parameter number of the model and the computation of the mass spectrum. We obtained Feynman's rules for all vertices, followed by the decay widths of the massive particles. For the validation procedure, we focused first on the induction of the <span><math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span> mass range from its decay widths at the tree level for several values of the model parameters. After exporting the model to the FeynArts and FeynCalc packages for semi-automatic computation, the second validation concerned the study of the scattering processes <span><math><mi>e</mi><mo>+</mo><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub><mo>→</mo><mi>e</mi><mo>+</mo><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></math></span>, where the total cross-section is obtained and discussed. In the last validation test, we evaluated the amplitude of one triangular loop diagram with three identical legs. We studied the process <span><math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>→</mo><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>+</mo><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span> and <span><math><mi>Z</mi><mo>→</mo><mi>Z</mi><mo>+</mo><mi>Z</mi></math></span> as samples, and we established their amplitude cancellation conditions.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109830"},"PeriodicalIF":3.4,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"YAM2 2.0: Yet another M2 with on-shell mass constraints and beyond","authors":"Chan Beom Park","doi":"10.1016/j.cpc.2025.109835","DOIUrl":"10.1016/j.cpc.2025.109835","url":null,"abstract":"<div><div>We present a new version of YAM2 (“Yet Another <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> calculator”), a C++ library for computing the <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> class of kinematic variables widely used in collider phenomenology with invisible particles. The main upgrade is the incorporation of new kinematic constraints: on-shell mass conditions implemented as equality constraints and vertex-reconstruction information as inequality constraints. The former enables precise treatment of the antler decay topology and generalizations such as <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn><mrow><mi>Cons</mi></mrow></mrow></msub></math></span>-like variables, while the latter extends applicability to cases where parent-particle flight directions can be inferred. Both extensions are implemented and validated within the sequential quadratic programming framework, ensuring robust performance in large-scale Monte Carlo studies. Additional improvements include CMake build support, extended example codes, and general code optimizations. With these updates, YAM2 2.0 provides a more versatile and user-friendly toolkit for collider analyses at both hadron and lepton colliders.</div></div><div><h3>New version program summary</h3><div><em>Program Title:</em> YAM2</div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/4g7wfd5fpb.2</span><svg><path></path></svg></span></div><div><em>Developer's repository link:</em> <span><span>https://github.com/cbpark/YAM2</span><svg><path></path></svg></span></div><div><em>Licensing provisions:</em> BSD 3-clause</div><div><em>Programming language:</em> C++</div><div><em>Journal reference of previous version:</em> Comput. Phys. Commun. 264 (2021) 107967</div><div><em>Does the new version supersede the previous version?:</em> Yes</div><div><em>Reasons for the new version:</em> YAM2 2.0 incorporates recent theoretical advances in <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> variables, including on-shell mass and vertex-reconstruction constraints, to ensure consistency with the latest developments in the field. In parallel, user-driven improvements such as CMake support, example codes, ROOT integration, and performance optimizations enhance usability and portability. These updates make the package both more powerful and easier to use for collider analyses at hadron and lepton colliders.</div><div><em>Summary of revisions:</em> One of the main enhancements in the present version is the incorporation of additional kinematic constraints into the <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> variables: on-shell mass conditions implemented as equality constraints and vertex-reconstruction information realized as inequality constraints. The on-shell mass condition is particularly relevant for handling th","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109835"},"PeriodicalIF":3.4,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CONFLUX: A standardized framework to calculate reactor antineutrino flux","authors":"Xianyi Zhang ,&nbsp;Anosh Irani ,&nbsp;Michael P. Mendenhall ,&nbsp;Nathan Rybicki ,&nbsp;Leendert Hayen ,&nbsp;Nathaniel Bowden ,&nbsp;Patrick Huber ,&nbsp;Bryce Littlejohn ,&nbsp;Sandra Bogetic","doi":"10.1016/j.cpc.2025.109831","DOIUrl":"10.1016/j.cpc.2025.109831","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Nuclear fission reactors are abundant sources of antineutrinos for neutrino physics experiments. The flux and spectrum of antineutrinos emitted by a reactor can indicate its activity and composition, suggesting potential applications of neutrino measurements beyond fundamental scientific studies that may be valuable to society. The utility of reactor antineutrinos for applications and fundamental science is dependent on the availability of precise predictions of these emissions. For example, in the last decade, disagreements between reactor antineutrino measurements and models have inspired revision of reactor antineutrino calculations and standard nuclear databases as well as searches for new fundamental particles not predicted by the Standard Model of particle physics. Past predictions and descriptions of the methods used to generate them are documented to varying degrees in the literature, with different modeling teams incorporating a range of methods, input data, and assumptions. The resulting difficulty in accessing or reproducing past models and reconciling results from differing approaches complicates the future study and application of reactor antineutrinos. The CONFLUX (Calculation Of Neutrino FLUX) software framework is a neutrino prediction tool built with the goal of simplifying, standardizing, and democratizing the process of reactor antineutrino flux calculations. CONFLUX includes three primary methods for calculating the antineutrino emissions of nuclear reactors or individual beta decays that incorporate common nuclear data and beta decay theory. The software is prepackaged with the current nuclear databases, including ENDF.B/VIII, JEFF-3.3, and ENSDF, and it includes the capability to predict time-dependent reactor emissions, adjust nuclear database or beta decay inputs/assumptions, and propagate related sources of uncertainty. This paper describes the CONFLUX software structure, details the methods used for flux and spectrum calculations, and provides examples of potential use cases.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Program summary&lt;/h3&gt;&lt;div&gt;&lt;em&gt;Program Title:&lt;/em&gt; CONFLUX&lt;/div&gt;&lt;div&gt;&lt;em&gt;CPC Library link to program files:&lt;/em&gt; &lt;span&gt;&lt;span&gt;https://doi.org/10.17632/hvkr4bff8v.1&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;em&gt;Developer's repository link:&lt;/em&gt; &lt;span&gt;&lt;span&gt;https://github.com/CNFLUX/conflux&lt;/span&gt;&lt;svg&gt;&lt;path&gt;&lt;/path&gt;&lt;/svg&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;em&gt;Licensing provisions:&lt;/em&gt; MIT&lt;/div&gt;&lt;div&gt;&lt;em&gt;Programming language:&lt;/em&gt; Python, C++&lt;/div&gt;&lt;div&gt;&lt;em&gt;Nature of problem:&lt;/em&gt; The reactor antineutrino flux were calculated with various nuclear theories of beta-decay and different nuclear databases. The prediction of neutrino produced from nuclear reactors was hard to repeat, or used for in reactor-specific models. Calculations of the covariance among fission products and beta decay branches need more standard approaches.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Solution method:&lt;/em&gt; We implement the CONFLUX software framework to standardize and simplify the calc","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109831"},"PeriodicalIF":3.4,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Lattice Boltzmann method for free surface flows over partially submerged structures","authors":"Baoming Guo ,&nbsp;Jianping Meng ,&nbsp;Zhihua Xie ,&nbsp;Dezhi Ning ,&nbsp;Shunqi Pan","doi":"10.1016/j.cpc.2025.109852","DOIUrl":"10.1016/j.cpc.2025.109852","url":null,"abstract":"<div><div>The Lattice Boltzmann method (LBM) has been extensively developed to efficiently simulate free surface flows and interactions between single-phase flows and fully immersed structures. However, few studies have focused on modelling partially submerged structures, particularly on accurately evaluating their hydrodynamic forces under gravity and wave dynamic conditions. To advance the application of LBM in this area, this study presents a dynamic-pressure Lattice Boltzmann model tailored for simulating partially submerged stationary structures in free surface flows. In the free surface section, the volume-of-fluid method is implemented and the advection of volume fraction is governed by the streaming of intrinsic density distribution functions. For the fluid-structure interface, an interpolated bounce-back scheme is imposed on the no-slip fluid-structure boundary and an improved momentum exchange method is employed to assess the fluid loads, accounting for the effects of gravity and external sources. This paper details the implementation of modelling framework and presents the outcomes of five benchmark simulations conducted for model verification and validation. These cases include flows over a circular cylinder and a square cylinder, Rider-Kothe single vortex evolution, dam-break flows, and wave impact on two partially submerged fixed boxes. The developed numerical model yields satisfactory agreement with experimental and numerical results in terms of the hydrodynamic force evaluation and free surface deformation. The final case demonstrates the capability of the LBM model in investigating frequency response of wave impact on partially submerged structures, highlighting its potential for broader applications in coastal and ocean engineering.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109852"},"PeriodicalIF":3.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The non-SUSY orbifolder: A tool to build promising non-supersymmetric string models","authors":"Enrique Escalante-Notario ,&nbsp;Ricardo Pérez-Martínez ,&nbsp;Saúl Ramos-Sánchez ,&nbsp;Patrick K.S. Vaudrevange","doi":"10.1016/j.cpc.2025.109829","DOIUrl":"10.1016/j.cpc.2025.109829","url":null,"abstract":"<div><div>We introduce the <span>non-SUSY orbifolder</span>, which is a program developed in <span>C++</span>that computes the low-energy effective theory of non-supersymmetric heterotic orbifold compactifications. The program includes routines to compute the massless spectrum, to automatically generate large sets of orbifold models, to identify phenomenologically interesting models (e.g. models sharing features of the Standard Model (SM) or Grand Unified Theories (GUT)) and to analyze their vacuum-configurations.</div></div><div><h3>Program summary</h3><div><em>Program Title:</em> <span>non-SUSY orbifolder</span></div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/gkjrn42xvt.1</span><svg><path></path></svg></span></div><div><em>Developer's repository link:</em> <span><span>https://github.com/StringsIFUNAM/nonSUSYorbifolder</span><svg><path></path></svg></span></div><div><em>Licensing provisions:</em> GPLv3</div><div><em>Programming language:</em> C++</div><div><em>External libraries:</em> Boost, GSL, Readline</div><div><em>Nature of problem:</em> Calculating the low-energy spectrum of non-supersymmetric heterotic orbifold compactifications.</div><div><em>Solution method:</em> Quadratic equations on a lattice; representation theory; polynomial algebra.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109829"},"PeriodicalIF":3.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NGAMMA: A Monte Carlo generator for multiphoton production in e+e− annihilation","authors":"L.V. Kardapoltsev ,&nbsp;N.A. Melnikova","doi":"10.1016/j.cpc.2025.109826","DOIUrl":"10.1016/j.cpc.2025.109826","url":null,"abstract":"<div><div>We present the NGAMMA Monte Carlo event generator for QED processes of <span><math><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></math></span> annihilation into a multiphoton final state, <span><math><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><mi>N</mi><mi>γ</mi><mo>(</mo><mi>N</mi><mo>≥</mo><mn>2</mn><mo>)</mo></math></span>. These processes are an important source of background in the study of <span><math><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo></math></span><em>hadrons</em> processes with a multiphoton final state, especially for experiments at low energy <span><math><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></math></span> colliders like SND, CMD-3, KLOE and for the BESIII experiment. For generation, NGAMMA exploits the exact tree-level amplitude.</div></div><div><h3>Program summary</h3><div><em>Program Title:</em> NGAMMA</div><div><em>CPC Library link to program files:</em> <span><span>https://doi.org/10.17632/rj9ntc7tzn.1</span><svg><path></path></svg></span></div><div><em>Developer's repository link:</em> <span><span>https://git.inp.nsk.su/ngamma/ngamma</span><svg><path></path></svg></span></div><div><em>Licensing provisions:</em> LGPL</div><div><em>Programming language:</em> C++</div><div><em>Nature of problem:</em> The NGAMMA generator was developed to simulate the background for <span><math><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo></math></span><em>hadrons</em> processes with a multiphoton final state coming from the QED processes <span><math><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><mi>N</mi><mi>γ</mi><mo>(</mo><mi>N</mi><mo>≥</mo><mn>2</mn><mo>)</mo></math></span>.</div><div><em>Solution method:</em> Events consisting of momenta of the outgoing particles are generated by Monte Carlo methods. The generated events are distributed according to the exact tree-level cross section [1].</div></div><div><h3>References</h3><div><ul><li><span>[1]</span><span><div>R. Kleiss, W.J. Stirling, Phys. Lett. B 179 (1986) 159–163.</div></span></li></ul></div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109826"},"PeriodicalIF":3.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Construction and analysis of guiding center distributions for tokamak plasmas with ambient radial electric field","authors":"Andreas Bierwage ,&nbsp;Philipp Lauber ,&nbsp;Noriyoshi Nakajima ,&nbsp;Kouji Shinohara ,&nbsp;Guillaume Brochard ,&nbsp;Young-chul Ghim ,&nbsp;Wonjun Lee ,&nbsp;Akinobu Matsuyama ,&nbsp;Shuhei Sumida ,&nbsp;Hao Yang ,&nbsp;Masatoshi Yagi","doi":"10.1016/j.cpc.2025.109823","DOIUrl":"10.1016/j.cpc.2025.109823","url":null,"abstract":"<div><div>The contribution of a time-independent toroidally-symmetric radial electric field <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> is implemented in <span>VisualStart</span> (Bierwage et al. (2022) <span><span>[21]</span></span>), a code whose purposes include the construction of guiding center (GC) drift orbit databases for the study of plasma instabilities in tokamaks. <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> alters the transit frequencies and orbit shapes of charged particles, and it shifts the trapped-passing boundary, especially in the thermal part of the velocity distribution. <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> can also affect fast particle resonances in the kHz frequency range. Here, KSTAR, JT-60U and ITER tokamak cases are used as working examples to test our methods. In the course of our detailed consistency checks, we unravel how nonuniformities in the moments of a GC distribution emerge from the collection of individual GC orbits. We also discuss technical and practical issues connected with <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>, two of which shall be emphasized here: First, the GC orbit space is sampled in the magnetic midplane as before, and we find that, in the presence of <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>, midplane-based coordinates are not only equivalent but superior to conventional constants of motion, allowing to attain high numerical accuracy and efficiency with a relatively simple mesh. Second, the periodic parallel acceleration and deceleration of GCs via the mirror force is modulated by <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>. Although its poloidal transit (bounce) average is zero, this parallel electric acceleration gives rise to a reference point bias: When measured at fixed GC launch coordinates, the toroidal transit frequency of passing orbits acquires an apparent <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>-dependence, which can cause confusion.</div></div>","PeriodicalId":285,"journal":{"name":"Computer Physics Communications","volume":"317 ","pages":"Article 109823"},"PeriodicalIF":3.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}