Hasil untuk "Physics"

T. Sjöstrand, S. Ask, J. Christiansen et al.

The Pythia program is a standard tool for the generation of events in high-energy collisions, comprising a coherent set of physics models for the evolution from a few-body hard process to a complex multiparticle final state. It contains a library of hard processes, models for initial- and final-state parton showers, matching and merging methods between hard processes and parton showers, multiparton interactions, beam remnants, string fragmentation and particle decays. It also has a set of utilities and several interfaces to external programs. Pythia 8.2 is the second main release after the complete rewrite from Fortran to C++, and now has reached such a maturity that it offers a complete replacement for most applications, notably for LHC physics studies. The many new features should allow an improved description of data.

A. Alloul, N. Christensen, C. Degrande et al.

FeynRules is a Mathematica-based package which addresses the implementation of particle physics models, which are given in the form of a list of fields, parameters and a Lagrangian, into high-energy physics tools. It calculates the underlying Feynman rules and outputs them to a form appropriate for various programs such as CalcHep, FeynArts, MadGraph, Sherpa and Whizard. Since the original version, many new features have been added: support for two-component fermions, spin-3/2 and spin-2 fields, superspace notation and calculations, automatic mass diagonalization, completely general FeynArts output, a new universal FeynRules output interface, a new Whizard interface, automatic 1 → 2 decay width calculation, improved speed and efficiency, new guidelines for v and a new web-based validation package. With this feature set, FeynRules enables models to go from theory to simulation and comparison with experiment quickly, efficiently and accurately.

D. Fox

T. Broadbent, Solomon G. Mikhlin, T. Boddington

R. Truell, C. Elbaum, B. Chick et al.

Kenneth, Arrow, Leonid Hur-wicz et al.

N. Bogolyubov, E. Gora

L. Biedenharn

E. Jaynes

Philip Mirowski

T. Paszkiewicz

Darius Modirrousta-Galian, Jun Korenaga

Planetary atmospheres cannot remain hydrostatic at all altitudes because they approach finite density at infinite radius, implying infinite mass. Classical treatments address this in two directions: either retain a hydrostatic structure while allowing particles in the high-velocity tail to decouple and escape in a Jeans-type manner, or promote the gas to a continuum outflow to obtain a transonic Parker-type solution. The usual criterion compares the local mean free path to the sonic point radius. If the mean free path is shorter, the atmosphere is hydrostatic with an imposed Jeans escape flux; if it is longer, the gas is hydrodynamic with Jeans escape neglected. Here, we show that hydrogen-rich atmospheres do not separate cleanly into hydrodynamic and Jeans-escape regimes. At any radius, some particles still collide and behave as a fluid, while others have already experienced their last collision and move collisionlessly on ballistic trajectories. The relative importance of these two behaviors changes smoothly with radius rather than switching at a single boundary. The hydrodynamic channel accelerates and passes through a sonic point, whereas the collisionless channel decelerates under gravity and grows with altitude, removing mass and momentum from the collisional flow. As the collisionless component grows, the bulk flow speed reaches a maximum and then decelerates thereafter, producing profiles similar to Parker breeze solutions even though escape is carried by the collisionless channel. This two-channel framework provides a first step toward a self-consistent treatment that unifies hydrodynamics and kinetics in atmospheric loss models.

Jun-Bo Gou (勾俊博), Marc Timme, Xiaozhu Zhang (张潇竹) et al.

Swarmalators constitute a paradigmatic model for understanding the collective dynamics of coupled moving agents, integrating both internal and spatial degrees of freedom. Empirical evidence from systems such as bird flocks and living matter highlights the relevance of topological, metric-free coupling, but their impact on swarmalator dynamics remains largely unknown to date. Here, we present and analyze a topological swarmalator model in which the units interact topologically, on Delaunay networks. We find intriguing self-organized collective dynamics, including patterns with local vortices and unprecedented spatiotemporal patterns absent in metric-based models. Identifying three order parameters to quantify synchrony, spatial order, and vortex formation, we map the phase diagram that classifies these diverse patterns. Notably, we uncover a first-order transition even if the phases of all units are frozen, a dynamics inverted relative to the classical Kuramoto model. These insights not only advance our theoretical understanding of locally coupled systems of moving agents, but also offer key guidelines for their control.

Wang Li, Xuxuan Ma, Roberto Weinberg et al.

Abstract The formation, storage, and evolution of granitic magmas are fundamental processes driving the growth of continental crust. While traditionally attributed to crystal fractionation in high‐melt fraction magma chambers, the model invoking low‐melt fraction crystal mushes has gained wide acceptance. However, the chemical and textural impacts of crystal mush rejuvenation remain elusive and the precise petrological record is relatively poorly studied. The rapakivi K‐feldspar identified in the early Eocene monzogranitic porphyry of the Caina intrusive complex, Gangdese batholith, is an ideal candidate for investigating these issues, as feldspar can record clues to magmatic processes. Field survey, optical and mineral flake scanning observations, X‐ray fluorescence analysis, in situ Sr and mineral Sm‐Nd isotopic analyses, TESCAN integrated mineral analysis, electron probe microanalysis, and three‐dimensional crystal shape modeling were performed on the collected samples. K‐feldspars can be divided into three types based on chemical zonation: normal, reverse, and oscillatory zoning crystals. Varying isotopic signatures between the K‐feldspar and associated mantle suggest that the rapakivi texture originated in heterogeneous magmatic pulse recharge. Crystal shape modeling of the plagioclase chadacryst, mantle, and matrix plagioclase, combined with compositions, indicates that mantle plagioclase originated from the quenching of recharge magmas. We propose a model for the formation of rapakivi K‐feldspar and the rejuvenation of crystal mush. Repeated hot magma pulses recharged the mush, triggering magma convection and thermal perturbations. This process enabled the prolonged growth of K‐feldspar megacrysts, which were subsequently capped by plagioclase, resulting in the formation of the rapakivi texture.

Viktoria Falkowski, Wilhelm Pfleging

Changing the topography of electrodes by ultrafast laser ablation has shown great potential in enhancing electrochemical performance in lithium-ion batteries. The generation of microstructured channels within the electrodes creates shorter pathways for lithium-ion diffusion and mitigates strain from volume expansion during electrochemical cycling. The topography modification enables faster charging, improved rate capability, and the potential to combine high-power and high-energy properties. In this study, we present a preliminary exploration of this approach for sodium-ion battery technology, focusing on the impact of laser-generated channels on hard carbon electrodes in sodium-metal half-cells. The performance was analyzed by employing different conditions, including different electrolytes, separators, and electrodes with varying compaction degrees. To identify key factors contributing to rate capability improvements, we conducted a comparative analysis of laser-structured and unstructured electrodes using methods including scanning electron microscopy, laser-induced breakdown spectroscopy, and electrochemical cycling. Despite being based on a limited sample size, the data reveal promising trends and serve as a basis for further optimization. Our findings suggest that laser structuring can enhance rate capability, particularly under conditions of limited electrolyte wetting or increased electrode density. This highlights the potential of laser structuring to optimize electrode design for next-generation sodium-ion batteries and other post-lithium technologies.

WANG Weixin, CHANG Xuelian, OU Shifeng

Conventional adaptive filtering algorithms often exhibit performance degradation when processing multipath interference in raw echoes of spaceborne synthetic aperture radar （SAR） systems due to anomalous outliers， manifesting as insufficient convergence and low estimation accuracy. To address this issue， this study proposes a novel robust adaptive filtering algorithm， namely the M-estimation-based minimum error entropy with affine projection （APMMEE） algorithm. This algorithm inherits the joint multi-data-block update mechanism of the affine projection algorithm， enabling rapid adaptation to the dynamic characteristics of raw echoes and achieving fast convergence. Meanwhile， it incorporates the M-estimation-based minimum error entropy （MMEE） criterion， which weights error samples in raw echoes through M-estimation functions， effectively suppressing outlier interference during the algorithm update. Both the system identification simulations and practical multipath interference suppression experiments using raw echoes demonstrate that the proposed APMMEE algorithm exhibits superior filtering performance.

Zhongxue Tang, Kang Luan, Bojie Xu et al.

Unidirectional liquid transport (UDLT) has been widely used in various fields as an important process for transferring both mass and energy. However, UDLT driven by a structural gradient has been witnessed for a long time only in wettable liquids. For nonwettable liquids, UDLT can hardly proceed merely by a structural gradient. Herein, we propose an asymmetrically concave structured surface (AMC-surface), featuring tip-to-base periodically arranged pyramid-shaped concave structures with a certain degree of overlap, which enables the UDLT of both wettable and nonwettable liquids. For wettable liquids, the capillary force along each corner leads to the UDLT pointing toward the base side of the concave pyramid, while for nonwettable liquids, the UDLT is attributable to the static liquid pressure overwhelming the repulsive Laplace pressure induced by the asymmetric grooves and overlapping part. As a result, both wettable and nonwettable liquids transport spontaneously and unidirectionally on the AMC-surface with no energy input. Moreover, the concave structure endows good mechanical stability and can be easily prepared using a facile nail-punching approach over a large area. We also demonstrated its application in a continuous chemical reaction in a confined area. We envision that the unique UDLT behavior on the as-developed AMC-surface will shed new light on the programmable manipulation of various liquids.

Pablo Sala, Sara Murciano, Yue Liu et al.

Entanglement, measurement, and classical communication together enable teleportation of quantum states between distant parties, in principle, with perfect fidelity. To what extent do correlations and entanglement of a many-body wave function transfer under imperfect teleportation protocols? We address this question for the case of an imperfectly teleported quantum critical wave function, focusing on the ground state of a critical Ising chain. We demonstrate that imperfections, e.g., in the entangling gate adopted for a given protocol, effectively manifest as weak measurements acting on the otherwise pristinely teleported critical state. Armed with this perspective, we leverage and further develop the theory of measurement-altered quantum criticality to quantify the resilience of critical-state teleportation. We identify classes of teleportation protocols for which imperfection (i) preserves both the universal long-range entanglement and correlations of the original quantum critical state, (ii) weakly modifies these quantities away from their universal values, and (iii) obliterates long-range entanglement altogether while preserving power-law correlations, albeit with a new set of exponents. We also show that mixed states describing the average over a series of sequential imperfect teleportation events retain pristine power-law correlations due to a “built-in” decoding algorithm, though their entanglement structure measured by the negativity depends on errors similarly to individual protocol runs. These results may allow one to design teleportation protocols that optimize against errors—highlighting a potential practical application of measurement-altered criticality.

Tra Mai Ngo, Van Hung Hoang, Huu Tap Van et al.

This study examines the fly ash from Soc Son municipal waste power plant (SMPP) and suggests ways to repurpose it to reduce its environmental impact. Fly ash from the Soc Son waste power plant has a gray color, spherical particles with a 5–103 μ m diameter, and a high carbon and heavy metal content. Bermorite crystals can absorb and release heavy metals, making monitoring secondary pollutants during incineration crucial. The EDX analysis of fly ash from the Soc Son waste power plant revealed that it was predominantly contaminated with metal elements, with the highest percentage of calcium. The EDX was able to detect heavy metals in incinerator fly ash. The concentration of Zn in the fly ash exceeded QCVN 07:2009/BTNMT standards, indicating the high amounts of some elements that may be hazardous to the environment and human health. Using the SEM/EDX and XRF, the fly ash from the Soc Son landfill power plant was analyzed and discovered that it exceeds permissible limits for dangerous heavy elements. The most common inorganic elements are Ca, followed by Zn, Pb, Cd, and Ag. Fly ash is classed as hazardous waste due to its high concentration of heavy metals, which results from the combustion of municipal solid waste that has not been separated. Vietnam fights municipal solid waste incinerator fly ash production. Some nations stabilize fly ash to remove harmful components and use it in buildings. Stabilized fly ash makes unfired construction bricks and cement manufacturing components and combining fly ash with inorganic trash protects the environment.

Marc Hon, Daniel Huber, Yaguang Li et al.

Asteroseismology of dwarf stars cooler than the Sun is very challenging owing to the low amplitudes and rapid timescales of oscillations. Here we present the asteroseismic detection of solar-like oscillations at 4-minute timescales ( ${\nu }_{\max }\sim 4300$ μ Hz) in the nearby K dwarf σ Draconis using extreme-precision Doppler velocity observations from the Keck Planet Finder and 20 s cadence photometry from NASA’s Transiting Exoplanet Survey Satellite. The star is the coolest dwarf star to date with both velocity and luminosity observations of solar-like oscillations, having amplitudes of 5.9 ± 0.8 cm s ^−1 and 0.8 ± 0.2 ppm, respectively. These measured values are in excellent agreement with established luminosity−velocity amplitude relations for oscillations and provide further evidence that mode amplitudes for stars with T _eff < 5500 K diminish in scale following an ( L / M ) ^1.5 relation. By modeling the star’s oscillation frequencies from photometric data, we measure an asteroseismic age of 4.5 ± 0.9 (ran) ± 1.2 (sys) Gyr. The observations demonstrate the capability of next-generation spectrographs and precise space-based photometry to extend observational asteroseismology to nearby cool dwarfs, which are benchmarks for stellar astrophysics and prime targets for directly imaging planets using future space-based telescopes.