Elementary Particles Research Articles

Chirality-induced phonon spin selectivity by elastic spin–orbit interaction

Spin and orbital degrees of freedom are crucial in not only fundamental particles but also classical waves such as optical systems, wherein the spin-orbit interaction (SOI) of light provides new perspectives for manipulating electromagnetic waves. Elastic waves possess similar spin angular momentum (SAM) and orbital angular momentum (OAM). However, the elastic counterpart of SOI remains unexplored, even for ubiquitous elastic waveguides (WG). Here, we demonstrate the existence of elastic SOI in helical WG. We prove that the torsion and curvature of helical WG induces synthetic gauge potentials in describing the elastic vibrations. Through analytical theory and simulations, we unveil the interplay among elastic SAM, intrinsic OAM, and extrinsic OAM, impacted by the elastic SOI. Importantly, results show that elastic SOI can introduce the Chirality-Induced Phonon Spin Selectivity. These findings advance our understanding of angular momentum physics in elastic waves and enable practical strategies for wave manipulation.

Run-and-tumble motion of ellipsoidal microswimmers

A hallmark of bacteria is their so-called “run-and-tumble” motion and its variants, consisting of a sequence of linear directed “runs” and distinct rotation events that constantly alternate due to biochemical feedback. It plays a crucial role in the ability of bacteria to move through chemical gradients and has inspired a fundamental active particle model. Nevertheless, synthetic active particles generally do not exhibit run-and-tumble motion but rather active Brownian motion. We show in experiments that ellipsoidal thermophoretic Janus particles, propelling along their short axis, can yield run-and-reverse motion, i.e., where rotation events flip the direction of motion, even without feedback. Their hydrodynamic wall interactions under strong confinement give rise to an effective double-well potential for the declination of the short axis. The geometry-induced timescale separation of the in-plane rotational dynamics and noise-induced transitions in the potential then yield run-and-reverse motion. Published by the American Physical Society 2024

A Coriolis Mechanism Links the Solar Parameters to the Newtonian Gravity

The link between the Newtonian gravity is found to be linked to a Coriolis mechanism between hypothesized gravitons and spinning elementary particles made of gravitons. Inertial resistance is found to be generated by a Coriolis mechanism as well. The Solar parameters are surprisingly well linked to the gravitational constant and the to the velocity of light. The amplitude of this Coriolis mechanism is found to match the Sun’s rotation frequency. The link between the solar parameter, the Newtonian gravity and the found Coriolis mechanism is a key confirmation for the hypothesized gravitons and for the origin of the gravitational constant.

Quantitative Design of Cathode Materials for Ion Battery from a Reductionist Perspective

AbstractThe quantitative design of functionalities for functional materials is highly attractive for materials research, which must be based on a thorough understanding of the behavior of fundamental particles. Reductionism advocates for the understanding of complex materials through dissection into the constituent parts, providing a robust framework for investigating functional materials. In an ion battery system, this review utilizes reductionism to deconstruct cathode materials into phase, atom, and even electron, building the intrinsic connections between the macroscopic properties and fundamental particles across four degrees of freedom. This aims to enable the quantitative design of cathode materials. Specifically, the microscopic origins of the macroscopic properties, that is, capacity, potential, rate, and cycling reversibility, based on lattice, charge, orbital, and spin degrees of freedom are elucidated. Additionally, current strategies are summarized and proposed future development directions for improving these properties. These insights contribute to achieving the goal of quantitative design of energy storage materials.

Topological signatures of triply degenerate fermions in Heusler alloys: an ab initio study

Triply degenerate nodal point (TP) fermions, lacking elementary particle counterparts, have been theoretically anticipated as quasiparticle excitations near specific band crossing points constrained by distinct space-group symmetries instead of Lorentz invariance. Here, based onfirst-principlescalculations and symmetry analysis, we demonstrate the presence of TP fermions in Heusler alloys. Furthermore, we predict that these Heusler alloys are dynamically stable, exhibiting TP fermions along four distinctC3axes in the F-43m space group. We show thatα-LiCaPdSb harbours peculiar Fermi arcs and surface states on the (111) and (001) crystal facets, owing to the coexistence of threefold rotational and time reversal symmetry. More interestingly, a modest tensile strain can increase the distance of fermions along the Γ-Lhigh symmetric line by as much as 21.10%, which give rise to measurable Fermi arcs. Furthermore, we investigate non-trivial topological insulator phase inβ-LiCaPdSb, by changing the chemical environment through placing transition metal atoms at various Wyckoff positions. Theβ-LiCaPdSb harbour a semi-metallic nature, and by breaking cubic symmetry, it undergoes a transition from semi-metal to a non-trivial topological insulator. In addition, for the first time, rare-earth LaPtBi half-Heusler alloy is examined under strain to uncover multiple band inversions associated with the TP fermionic phase. The observed multiple band inversion is entirely unaffected by spin-orbit coupling. We show that the LaPtBi compound hosts TP fermions, which are linked to aZ2topological invariant. Remarkably, with clear band crossings and multiple band inversion, we point out the possibilities of the LaPtBi for displaying a rich topological phase diagram. Our work provides a prototype material platform for experimental detection through angle-resolved photoemission spectroscopy or scanning tunnelling spectroscopy and practical spintronic applications.

Shedding light on dark sectors with gravitational waves

The nature of dark matter remains one of the greatest unsolved mysteries in elementary particle physics. It might well be that the dark matter particle belongs to a dark sector completely secluded or extremely weakly coupled to the visible sector. We demonstrate that gravitational waves arising from first-order phase transitions in the early Universe can be used to look for signatures of dark sector models connected to neutron physics. This introduces a new connection between gravitational-wave physics and nuclear physics experiments. Focusing on two particular extensions of the Standard Model with dark U(1) and SU(2) gauge groups constructed to address the neutron lifetime puzzle, we show how those signatures can be searched for in future gravitational-wave and astrometry experiments. Published by the American Physical Society 2024

Topportunities at the LHC: rare top decays with light singlets

The discovery of the top quark, the most massive elementary particle yet known, has given us a distinct window into investigating the physics of the Standard Model and beyond. With a plethora of top quarks to be produced in the high luminosity era of the LHC, the exploration of its rare decays holds great promise in revealing potential new physics phenomena. We consider higher-dimensional operators contributing to flavour-changing-neutral-current top decays in the SMEFT and its extension by a light singlet species of spin 0, 1/2, or 1, and exhibit that the HL-LHC (and other future colliders) may observe many exotic top decays in a variety of channels. Light singlets which primarily talk to the SM through such a top interaction may also lead to distinctive long-lived particle signals. Searching for such long-lived particles in top-quark decays has the additional advantage that the SM decay of the other top quark in the same event provides a natural trigger.

Geometry, anomaly, topology, and transport in Weyl fermions.

Weyl fermions are one of the simplest objects that link ideas in geometry and topology to high-energy physics and condensed matter physics. Although the existence of Weyl fermions as elementary particles remains dubious, there is mounting evidence of their existence as quasiparticles in certain condensed matter systems. Such systems are termed Weyl semimetals (WSMs). Needless to say, WSMs have emerged as a fascinating class of materials with unique electronic properties, offering a rich playground for both fundamental research and potential technological applications. This review examines recent advancements in understanding electron transport in {WSMs}. We begin with a pedagogical introduction to the geometric and topological concepts critical to understanding quantum transport in Weyl fermions. We then explore chiral anomaly (CA), a defining feature of WSMs, and its impact on transport phenomena such as longitudinal magnetoconductance (LMC) and planar Hall effect (PHE). The Maxwell-Boltzmann transport theory extended beyond the standard relaxation-time approximation is then discussed in the context of Weyl fermions, which is used to evaluate various transport properties. Attention is also given to the effects of strain-induced gauge fields and external magnetic fields in both time-reversal broken and inversion asymmetric inhomogeneous WSMs. The review synthesizes theoretical insights, experimental observations, and numerical simulations to provide a comprehensive understanding of the complex transport behaviors in WSMs, aiming to bridge the gap between theoretical predictions and experimental verification.

Cold-Atom Particle Collider

A major objective of the strong ongoing drive to realize quantum simulators of gauge theories is achieving the capability to probe collider-relevant physics on them. In this regard, a highly pertinent and sought-after application is the controlled collisions of elementary and composite particles, as well as the scattering processes in their wake. Here, we propose particle-collision experiments in a cold-atom quantum simulator for a 1+1D (one spatial and one temporal dimension) U(1) lattice gauge theory with a tunable topological θ term, where we demonstrate an experimentally feasible protocol to impart momenta to elementary (anti)particles and their meson composites. We numerically benchmark the collisions of moving wave packets for both elementary and composite particles, uncovering a plethora of rich phenomena, such as oscillatory string dynamics in the wake of elementary (anti)particle collisions due to confinement. We also probe string inversion and entropy production processes across Coleman’s phase transition through far-from-equilibrium quenches. We further demonstrate how collisions of composite particles unveil their internal structure. Our work paves the way towards the experimental investigation of collision dynamics in state-of-the-art quantum simulators of gauge theories, and sets the stage for microscopic understanding of collider-relevant physics in these platforms. Published by the American Physical Society 2024

A theoretical formula for calculating G : Newton’s Universal Gravitational Constant

This article synthesizes insights from three seminal works: Georges-Louis Le Sage’s 1783 paper, Albert Einstein’s 1935 paper, and Peter Higgs’ 1964 paper, along with Isaac Asimov’s 1966 paper, which presents a model for the origin of matter and explains the absence of antimatter in our universe. These four foundational works were integrated into the Ulianov Theory, developed by Dr. Policarpo Yoshin Ulianov. The Ulianov Theory proposes a new model of fundamental particles and interactions, leading to a novel theoretical equation for calculating Newton’s universal gravitational constant G . This theoretical framework not only addresses criticisms of the Higgs boson model but also provides a robust method for calculating gravitational forces and the value of G .

Frontier 23: elementary particle physics, dark matter and astroparticle physics

Frontier 23: elementary particle physics, dark matter and astroparticle physics

Reviews

Muography — Exploring Earth's Subsurface with Elementary Particles, edited by László Oláh, Hiroyuki K. M. Tanaka, and Dezsö Varga, 2023

The greatest physics discovery of the 20th century: How did the expanding Universe make us?

Abstract The expanding Universe is unstable, owing to the energy released in gravitational interactions, leading to the complexity we now observe, from astrophysics to biology and psychology and combat. In just the last century, we discovered relativity, quantum mechanics, the fundamental particles (quarks, leptons and force carriers), the expanding Universe and the density fluctuations in the primordial material, and the astounding complexity of self-organised chaos feeding from energy flows. While we have not detected signs of life elsewhere, we know that about 20% of stars have planets with the right temperature and size to be like Earth. If life is not a miracle but a thermodynamic imperative, then it could be detectable through measurements of exoplanet atmospheres containing oxygen.

Broken symmetries in particle physics

Abstract Symmetries in physics have a special role since they govern the dynamic of physical processes. In elementary particle physics symmetries like parity and charge conjugation, and their breaking have profound consequences, for example, on the matter-antimatter imbalance in our Universe.

CERN, the LHC, the Higgs boson and the rest

Abstract The Higgs field was proposed in 1964 as a new kind of field that fills the entire Universe and gives mass to all elementary particles. The Higgs boson, a wave in that field, was discovered at CERN in 2012 by the two international collaborations ATLAS and CMS which operate the two eponymous detectors installed at the Large Hadron Collider. This achievement was the result of several decades of scientific developments and constructions by hundreds of teams, thousands of scientists and staff all over the globe. None of this would have been possible without the vision and dedication of a few individuals who set up the scene in the years post-World War II.

FRACTALS IN QUANTUM MECHANICS: FROM THEORY TO PRACTICAL APPLICATIONS

This article examines the use of fractals to estimate the probability of classical events controlled by quantum processes. A hypothesis explaining the opposite charges of the positron and electron is discussed, as well as the relationship with the main modern theories of quantum mechanics, such as quantum electrodynamics (QED), string theory, etc. The relationship with the tunnel effect and the pulsed tunnel effect is considered. Examples of practical application of fractals are given, for example, in photocatalysts. The concepts of the effective mass of a photon and the quantum nature of elementary particles, the idea of their internal structure and the formation of matter from the point of view of quantum mechanics are touched upon. Particular attention is paid to the fractal structure of the quantum field as a probability associated with the formation of a positron or electron, and the mathematical connection with the Dirac equation, QED and the Schrödinger equation.

A novel partition function for elementary particles

Three different partition functions are well-known and described in statistical physics. Here, a novel partition function for the description of intra-particular interactions and with this for the mass of particles is presented below. In statistical physics, three different partition functions are already well-established. These are the microcanonical, the canonical, and the macro-canonical partition functions. Here a fourth, novel partition function is added to these already well-established three. Thereby due to the properties of quantum mechanics and superposition, this novel partition function is of fundamental different nature. According to this concept, the new partition function for particles is first defined. The masses and energies of the elementary particles are then calculated using this novel partition function. The energy of an elementary particle is proportional to the mass on the one hand and to the novel partition function on the other. The constant of proportionality with respect to the new partition function is found to be identical with Rydberg constant and Rydberg energy. The relationships found for the proton, the electron, and the sigma particle are then generalized to all elementary particles.

The abundance of clustered primordial black holes from quasar microlensing

While elementary particles are the favored candidate for the elusive dark matter, primordial black holes (PBHs) have also been considered to fill that role. Gravitational microlensing is a very well-suited tool to detect and measure the abundance of compact objects in galaxies. Previous studies based on quasar microlensing exclude a significant presence of substellar to intermediate-mass black holes (BHs; $ 100M_ However, these studies were based on a spatially uniform distribution of BHs while, according to current theories of PBH formation, they are expected to appear in clusters. We study the impact of clustering in microlensing flux magnification, finding that at large scales clusters act like giant pseudo-particles, strongly affecting the emission coming from the broad-line region, which can no longer be used to define the zero microlensing baseline. As an alternative, we set this baseline from the intrinsic magnification ratios of quasar images predicted by macro lens models and compared them with the observed flux ratios in emission lines, infrared, and radio. The (magnitude) differences are the flux-ratio anomalies attributable to microlensing, which we estimate for 35 image pairs corresponding to 12 lens systems. A Bayesian analysis indicates that the observed anomalies are incompatible with the existence of a significant population of clustered PBHs. Furthermore, we find that more compact clusters exhibit a stronger microlensing impact. Consequently, we conclude that clustering makes the existence of a significant population of BHs in the substellar to intermediate mass range even more unlikely.

Recurrent neural networks for anomaly detection in magnet power supplies of particle accelerators

This research illustrates how time-series forecasting employing recurrent neural networks (RNNs) can be used for anomaly detection in particle accelerators—complex machines that accelerate elementary particles to high speeds for various scientific and industrial applications. Our approach utilizes an RNN to predict temperatures of key components of magnet power supplies (PSs), which can number up to thousands in an accelerator. An anomaly is declared when the predicted temperature deviates significantly from observation. Our method can help identify a PS requiring maintenance before it fails and leads to costly downtime of an entire billion-dollar accelerator facility. We demonstrate that the RNN outperforms a reasonably complex physics-based model at predicting the PS temperatures and at anomaly detection. We conclude that for practical applications it can be beneficial to use RNNs instead of increasing the complexity of the physics-based model. We chose the long short-term memory (LSTM) as opposed to other RNN cell structures due to its widespread use in time-series forecasting and its relative simplicity. However, we demonstrate that the LSTM’s precision of predicting PS temperatures is nearly on par with measurement precision, making more complex or custom architectures unnecessary. Lastly, we dedicate a section of this paper to presenting a proof-of-concept for using infrared cameras for spatially-resolved anomaly detection inside power supplies, which will be a subject of future research.

Particle formation: Promise and challenges

Particle formation establishes fundamental particle attributes at the initiation of an overall particle production process. These attributes include particle size distribution, particle morphology, crystal form, and defect level. These fundamental properties, in turn, affect downstream particle processing and product performance properties, including rate of drying, filterability, flowability, caking tendency, rate of dissolution, and for biologically active products bioavailability. Almost always, the goal is that the properties established at formation will provide excellent performance all the way through downstream processing, product formulation, and ultimate use of the product. However, meeting this goal is often not possible for a variety of reasons. First, it may be difficult, prohibitively expensive, or even impossible to achieve the desired properties during formation. Second, there are often conflicting requirements at different stages of production and use. For example, large equant particles may be desired for good filterability and flowability through downstream process steps, but very small particles may be required in the ultimate product application. Examples from the chemical and pharmaceutical industries are presented: both cases successfully producing particles with properties meeting the needs throughout the chain of downstream processing and final application, as well as cases where it was impossible to meet those requirements. For the latter, the additional processing or adaptations required for the product to succeed are outlined. The focus here is on additive particle formation, e.g. crystallization and precipitation from solution, and not subtractive particle formation, e.g. milling. Legacy of Reg DaviesI was fortunate enough, as a budding industrial crystallization engineer, to be invited by Reg to join the newly formed PARticle Science And Technology PARSAT group at DuPont. Reg recognized and documented the importance of particle technology to a large, diverse chemical and materials company like DuPont and PARSAT was to become a leading industrial particle technology group. Reg's vision was to combine the fundamental particle unit operations into a unified, comprehensive technology organization that would address the formation and processing of particles from process concept through end use.This paper describes the first step in many particle processes: particle formation. Reg's legacy vis a vis particle formation is the recognition that particle formation is a critical, foundational process in an overall process train that ultimately produces useful particulate products and intermediates, but that particle formation is nonetheless but one part of the overall process. It may be able to produce particles exactly as needed for end use performance, or additional processes may be needed to tailor particles for their ultimate use. In addition, intermediate processes may be required to preserve useful properties developed during formation but subject to degradation in subsequent operations.Finally, Reg served as inspiration and mentor for everyone in his orbit, and we are far better scientists and engineers for it.