Elementary Particle Physics Research Articles

Goldstone-like phonon modes in a (111)-strained perovskite

Goldstone modes are massless particles resulting from spontaneous symmetry breaking. Although such modes are found in elementary particle physics as well as in condensed matter systems like superfluid helium, superconductors and magnons - structural Goldstone modes are rare. Epitaxial strain in thin films can induce structures and properties not accessible in bulk and has been intensively studied for (001)-oriented perovskite oxides. Here we predict Goldstone-like phonon modes in (111)-strained SrMnO3 by first-principles calculations. Under compressive strain the coupling between two in-plane rotational instabilities give rise to a Mexican hat shaped energy surface characteristic of a Goldstone mode. Conversely, large tensile strain induces in-plane polar instabilities with no directional preference, giving rise to a continuous polar ground state. Such phonon modes with U(1) symmetry could emulate structural condensed matter Higgs modes. The mass of this Higgs boson, given by the shape of the Mexican hat energy surface, can be tuned by strain through proper choice of substrate.

Origin of the Universe, Dark Energy, and Dark Matter

This explanation of the origin of the universe, dark energy, and dark matter is based on quantum mechanics, general relativity, thermodynamics, and Shannon information theory. It envisions our universe beginning with a quantum fluctuation from nothing into an unstable closed space with our familiar three space dimensions accompanied by seven extra space dimensions, the four basic forces unified, and initial radius of the order of the proton wavelength. The compact extra dimensions collapsed to their ground state with radius of the order of today’s Planck length, injecting most of the entropy (information) in the extra dimensions into our three space dimensions and inflating them by a factor of about e58≈1025. The constant ground state energy of the compact extra dimensions is related to the dark energy (vacuum energy) driving today’s accelerating expansion of our three-dimensional universe. With the usual values of G, , c, and Hubble constant h0=0.65, the dark energy fraction is ≈0.7. Immediately after inflation, the strong force acting only on matter was an effective “strong gravity” (about 1038 times stronger than gravity today) causing 83% of matter to coalesce into small impenetrable closed systems interacting only by gravity and constituting most of the dark matter. Other universes may have formed similarly in the infinite sweep of cosmic time, but are of no practical significance because they are profoundly elsewhere. The holographic principle (a consequence of quantum mechanics, general relativity, thermodynamics, and Shannon information theory) indicates only a finite number (about 10122) of bits of information encoded on the event horizon will ever be available to describe all physics within our universe. There are no sources or sinks of information outside the universe, so the universe must be described as a closed system. Matter dominance over anti-matter relates to the finite number of bits of information in the universe, as does the fact that theories involving continuum mathematics only approximate an underlying theory involving discrete mathematics. Ordinary matter constitutes only about 5% of the energy density of the universe. Holographic analysis of large scale structures composed of stars accounts for: minimum stellar mass as a function of time; the hierarchy of star clusters, galaxies, and galaxy clusters; and supermassive black holes. It identifies configurations of spiral and elliptical galaxies consistent with conservation of mass and angular momentum accounting for the 15% of bulgeless disks found in the survey of 15,000 spiral galaxies in the sixth SDSS data release. The smallest scale structures are usually described by the Standard Model of elementary particles, based on local quantum field theory. The Standard Model cannot be the final theory of elementary particles because: it incorrectly assumes neutrinos are massless; it cannot account for the bizarre mass spectrum of three generations of four Standard Model fermions; and does not provide the necessary non-local discrete theory of elementary particles. A holographic (and therefore non-local) preon theory involving strands with finite energy density instead of point particles can be outlined, but calculation in such a framework is difficult and gives no insight into the fermion mass spectrum.

Logic and genesis of a scientific theory in the light of the concept of the “speculative cognitive level” developed by V. P. Bransky

His article discusses the concept of “speculative theoretical level of research”, developed byBransky and summarizing his earlier philosophical and methodological study of the enormous volume of material of modern physics (especially theory of elementary particles). The history of theoretical physics testifies to the fact that the most basic conceptsbe obtained by means of the inductive generalization of experimental data. It is also impossible to receive them, - by means of deduction - from the old theoretical concepts. And, meanwhile, in real history physics (and science in a whole) such ideas from time to time appear. After all, without them it would be impossible to offer a theoretical explanation of the new open phenomena: without them there is no adequate reflection of the objective essence of these phenomena, which - in its content - does not coincide with them (although, obviously, in the way of existence from them is inseparable). There is an activity of cognition: the speculative nature of abstract theoretical concepts and “visible” - from the point of view of our (macroscopic) experience - of theoretical ideas is not limited to a passive reflection of objective reality. The speculative constructs that the theorist creates are not identical to the reality for which they are created. If successful, the construct, not coinciding with the object of reality by way ofexistence can reflect the essence of the class of similar phenomena or a specific manifestation of the essence of the class of similar phenomena. One of the main creative actions leading to new ideas is the choice (selection). Theoretical knowledge becomes true within a fixed subject area and at a fixed sensitivity of instruments if the new empirical knowledge predicted by it (within the same limits) is consistent with the experiment. Verification means determining the limits of applicability of theoretical knowledge. The article deals with one historical episode associated with the name of N. Bohr and concerning the genesis of constructs of the “speculative level”. Some of the authors interpreted his figurative statement that the theory does not seem correct to him, if it is not “crazy enough”, as a speech against logic. However, Bohr had in mind that the proposed theory must be very significantly (up to “madness”!) different from the current views and theories in the given field of science. And it is quite clear that the content of such difference (or differences) cannot be distinguished without logic. Similarly, compliance or noncompliance of the theory content with the content of these experiences cannot be set without logic. In conclusion, the article considers an example of how the concept of the “speculative level of cognition”, developed by Bransky, allows us to advance in the development of the foundations of the concept of synergetics.

Spin Systems Exhibiting Supercritical Entanglement and Elementary Particle Physics

Spin Systems Exhibiting Supercritical Entanglement and Elementary Particle Physics

GEM Detector Performance Assessment in the BM@N Experiment

The Gas Electron Multiplier (GEM) chambers are developed for modern purposes in the elementary particle physics. In the BM@N experiment, a GEM system is used for the reconstruction of the trajectories of the charged particles. The investigation of GEM performance (efficiency and spatial resolution) is presented.

COMET, an Experiment to Search for mu-e Conversion in a Nuclear Field

Charged lepton flavor violating (CLFV) process is predicted to be out of experimental reach by the Standard Model of elementary particle physics (SM). However, many models of the new physics beyond the SM predicts that it is just below the current experimental limit. COMET searches for one of the CLFV process, mu-e conversion in a nuclear field, improving the sensitivity by a factor of approximately [Formula: see text] for Phase-I and [Formula: see text] for Phase-II experiment from a past experiment.

Sobre a radiação cósmica de fundo de micro-onda

Neste artigo, procuraremos dar uma pálida ideia para o leitor do que poderia ser a Radiação Cósmica de Fundo de Micro-onda (RCFM) que, segundo o tradicional modelo do “Big Bang”, foi gerada por uma explosão primordial. Com esse objetivo, achamos muito importante apresentarmos um breve resumo histórico de como o Microcosmo, baseado no Modelo Padrão da Física das Partículas Elementares (MPPE), e o Macrocosmo, baseado no Modelo Padrão do Big Bang (MPBB), evoluíram no tempo. Além disso, na parte final do artigo analisaremos os dois processos físicos apresentados na literatura que procuram explicar a RCFM: Bariogênese e Plasma Quark-Glúon.

The discovery of the neutron and its consequences (1930–1940)

Abstract In 1930, Walther Bothe and Herbert Becker performed an experiment, which was further improved by Irene and Frederic Joliot-Curie. These authors, however, misinterpreted their results and believed to have observed γ-rays while they had seen neutrons. After additional experimental verifications, James Chadwick gave the correct interpretation of these experiments in 1932. Immediately, the new particle, the neutron, became an essential actor of nuclear and elementary particle physics, and completely changed the whole research landscape. Enrico Fermi and his group applied it to artificial radioactivity, substituting neutrons to α-rays initially used by Joliot-Curies. They also discovered that slow neutrons were more efficient than fast ones in certain nuclear reactions. A crucial discovery of Otto Hahn, Fritz Strasmann, Lise Meitner, and Otto Frisch, after several misinterpretations of complicated experimental results, was nuclear fission. When Joliot, Halban, and Kowarski demonstrated the possibility of a chain reaction by neutron multiplication due to fission, nuclear physics became a military science, at the very moment when the Second World War was beginning. Later it led to nuclear power applications and use of neutrons as an important tool and object of scientific research at large-scale neutron facilities. The Comptes rendus de l'Academie des sciences were partner of a vivid international debate involving several other journals.

Analysis of solutions of a nonlinear scalar field differential equation

We consider a nonlinear differential equation arising in mathematical models of elementary particle theory. For this equation, we examine questions of the extendability of solutions, the boundedness of solutions at infinity, and the search for new conditions for the existence of a positive particle-like solution.

Pulse-shape discrimination techniques for the COBRA double beta-decay experiment at LNGS

In modern elementary particle physics several questions arise from the fact that neutrino oscillation experiments have found neutrinos to be massive. Among them is the so far unknown nature of neutrinos: either they act as so-called Majorana particles, where one cannot distinguish between particle and antiparticle, or they are Dirac particles like all the other fermions in the Standard Model. The study of neutrinoless double beta-decay (0νββ-decay), where the lepton number conservation is violated by two units, could answer the question regarding the underlying nature of neutrinos and might also shed light on the mechanism responsible for the mass generation. So far there is no experimental evidence for the existence of 0νββ-decay, hence, existing experiments have to be improved and novel techniques should be explored. One of the next-generation experiments dedicated to the search for this ultra-rare decay is the COBRA experiment. This article gives an overview of techniques to identify and reject background based on pulse-shape discrimination.

Unstable Leader Inception Criteria of Atmospheric Discharges

In the literature, there are different criteria to represent the formation of a leader channel in short and long gap discharges. Due to the complexity of the physics of the heating phenomena, and the limitations of the computational resources, a simplified criterion for the minimum amount of electrical charge required to incept an unstable leader has recently been used for modeling long gap discharges and lightning attachments. The criterion is based on the assumption that the total energy of the streamer is used to heat up the gas, among other principles. However, from a physics point of view, energy can also be transferred to other molecular processes, such as rotation, translation, and vibrational excitation. In this paper, the leader inception mechanism was studied based on fundamental particle physics and the energy balance of the gas media. The heating process of the plasma is evaluated with a detailed two-dimensional self-consistent model. The model is able to represent the streamer propagation, dark period, and unsuccessful leaders that may occur prior to the heating of the channel. The main processes that participate in heating the gas are identified within the model, indicating that impact ionization and detachment are the leading sources of energy injection, and that recombination is responsible for loss of electrons and limiting the energy. The model was applied to a well-known experiment for long air gaps under positive switching impulses reported in the literature, and used to validate models for lightning attachments and long gap discharges. Results indicate that the streamer–leader transition depends on the amount of energy transferred to the heating process. The minimum electric charge required for leader inception varies with the gap geometry, the background electric field, the reduction of electric field due to the space charge, the energy expended on the vibrational relation, and the environmental conditions, among others.

AN ANTHOLOGY OF THE DISTINGUISHED ACHIEVEMENTS IN SCIENCE AND TECHNIQUE. PART 39: NOBEL PRIZE LAUREATES IN PHYSICS FOR 2011-2015

Purpose. Implementation of brief analytical review of the distinguished scientific achievements of the world scientists-physicists, awarded the Nobel Prize on physics for the period 2011-2015. Methodology. Scientific methods of collection, analysis and analytical treatment of scientific and technical information of world level in area of astrophysics, physics of elementary particles, physics of high energies, of modern theoretical and experimental physics. Results. The brief analytical review of the scientific openings and distinguished achievements of scientists-physicists is resulted in area of modern physical and technical problems which were marked the Nobel Prizes on physics for the period 2011-2015. Originality. Systematization is executed with exposition in the short concentrated form of the known scientific and technical materials, devoted opening of acceleration of expansion of Universe, creation of breach technologies of manipulation the quantum systems, theoretical discovery of mechanism of origin of mass of under-atomic particles, invention of effective power sources of light − blue light-emitting diodes and opening of neutrino oscillations. Practical value. Popularization and deepening of scientific and technical knowledges for students, engineers and technical specialists and research workers in area of modern theoretical and experimental physics, extending their scientific range of interests and cooperation in further development of scientific and technical progress in human society.

Unified field theory of basic forces and elementary particles with gravitational origin of gauge symmetry in hyper-spacetime

A unified field theory of all known basic forces and elementary particles is built based on the postulates of gauge invariance and coordinate independence along with general conformal scaling symmetry. The hyper-spin charge of a unified hyper-spinor field is conjectured to correlate with the dimension of hyper-spacetime. The minimal dimension of hyper-spacetime for the unity of quarks and leptons in the standard model is found to be $D_h=19$ with a bimaximal symmetry. A unified fundamental interaction is governed by hyper-spin gauge symmetry SP(1,$D_h$-1). We show gravitational origin of gauge symmetry characterized by gauge-type Goldstone-like hyper-gravifield, which enables us to study gauge gravity and gravity geometry correspondences and to reveal gauge geometry duality.

Concluding Remarks: Connecting Relativistic Heavy Ion Collisions and Neutron Star Mergers by the Equation of State of Dense Hadron- and Quark Matter as signalled by Gravitational Waves

The underlying open questions in the fields of general relativistic astrophysics and elementary particle and nuclear physics are strongly connected and their results are interdependent. Although the physical systems are quite different, the 4D-simulation of a merger of a binary system of two neutron stars and the properties of the hot and dense matter created in high energy heavy ion collisions, strongly depend on the equation of state of fundamental elementary matter. Neutron star mergers represent optimal astrophysical laboratories to investigate the QCD phase structure using a spectrogram of the post-merger phase of the emitted gravitational waves. These studies can be supplemented by observations from heavy ion collisions to possibly reach a conclusive picture on the QCD phase structure at high density and temperature. As gravitational waves (GWs) emitted from merging neutron star binaries are on the verge of their first detection, it is important to understand the main characteristics of the underlying merging system in order to predict the expected GW signal. Based on numerical-relativity simulations of merging neutron star binaries, the emitted GW and the interior structure of the generated hypermassive neutron stars (HMNS) have been analyzed in detail. This article will focus on the internal and rotational HMNS properties and their connection with the emitted GW signal. Especially, the appearance of the hadon-quark phase transition in the interior region of the HMNS and its conjunction with the spectral properties of the emitted GW will be addressed and confronted with the simulation results of high energy heavy ion collisions.

We have confidence to lead gravitational-wave science: an interview with Yueliang Wu

Abstract Yueliang Wu, chief scientist of Taiji Program, is a well-known theoretical physicist and the Vice-President of the University of Chinese Academy of Sciences (UCAS). Taiji Program, initially proposed in 2008, is one of China's ambitious plans to observe gravitational waves. Obtaining his Ph.D. at the Institute of Theoretical Physics (ITP) under the Chinese Academy of Sciences (CAS) in 1987, Wu had been working at Dortmund University and Mainz University in Germany and Carnegie-Mellon University and the Ohio-State University in the USA. In 1996, he joined the ITP and became its director in 2007. He has also served as the Director of the Kavli Institute for Theoretical Physics China at the CAS since 2006. In 2007, he was elected as a CAS member. Wu's research is focused on elementary particle physics, quantum field theory, symmetry principle and cosmophysics. In recent years, he has been proposing a gravitational quantum field theory as a new approach to reconciling the general theory of relativity and quantum mechanics. The most fundamental unanswered question of the general theory of relativity is how general relativity can be reconciled with the laws of quantum physics to produce a complete and self-consistent theory of quantum gravity. To extend the general relativity to realize the reconciliation, Wu suggested a basic gravitational field be needed in the future model. Since 2012, he, together with Wenrui Hu, has been working as Taiji Program's chief scientist and promoting nationwide gravitational-wave research. National Science Review (NSR) spoke with Wu about the future of gravitational-wave research, the development of China's nationwide gravitational-wave studies and particularly the progress of Taiji Program.

Brilliant X-rays using a Two-Stage Plasma Insertion Device

Particle accelerators have made an enormous impact in all fields of natural sciences, from elementary particle physics, to the imaging of proteins and the development of new pharmaceuticals. Modern light sources have advanced many fields by providing extraordinarily bright, short X-ray pulses. Here we present a novel numerical study, demonstrating that existing third generation light sources can significantly enhance the brightness and photon energy of their X-ray pulses by undulating their beams within plasma wakefields. This study shows that a three order of magnitude increase in X-ray brightness and over an order of magnitude increase in X-ray photon energy is achieved by passing a 3 GeV electron beam through a two-stage plasma insertion device. The production mechanism micro-bunches the electron beam and ensures the pulses are radially polarised on creation. We also demonstrate that the micro-bunched electron beam is itself an effective wakefield driver that can potentially accelerate a witness electron beam up to 6 GeV.

The Dark Universe and the detection of Dark Matter

Many experimental observations and theoretical arguments have pointed out that a large fraction of the Universe is composed by Dark Matter particles. Many possibilities are open on the nature and interaction types of such relic particles. Moreover, the poor knowledge of many fundamental astrophysical, nuclear and particle Physics aspects and of some experimental and theoretical parameters, the different used approaches and target materials, etc. make challenging the comparisons and the implications of the different experimental efforts. Some general arguments are addressed here and future perspectives are mentioned. A particular care will be given to the results obtained by exploiting the model independent Dark Matter annual modulation signature for the presence of Dark Matter particles in the galactic halo by DAMA experiment. Results from the other experiments using different procedures, different techniques and different target-materials will be shortly addressed as well as implications and experimental perspectives.

Lagrangian for massless gravitational field in de Sitter space

Local or gauge symmetries are fundamental in elementary-particle physics to describes electroweak and strong interactions in the standard model. The gauge symmetry underlies the dynamics and is employed to describe the interaction between fields. For obtaining a gauge-invariant Lagrangian, the gauge-covariant derivative is defined such that any gauge fields are associated with the generators of the local symmetry group. In this paper, we obtain the gauge-covariant derivative and the gauge-invariant Lagrangian density in de Sitter ambient space formalism.

Modified Lorentz transformations in deformed special relativity

We have extended a recent approach to Deformed Special Relativity based on deformed dispersion laws, entailing modified Lorentz transformations and, at the same time, noncommutative geometry and intrinsically discrete space–time. In so doing we have obtained the explicit form of the modified Lorentz transformations for a special class of modified momentum-energy relations often found in literature and arising from quantum gravity and elementary particle physics. Actually, our theory looks as a very simple and natural extension of special relativity to include a momentum cutoff at the Planck scale. In particular, the new Lorentz transformations do imply that for high boost speed [Formula: see text] the deformed Lorentz factor does not diverge as in ordinary relativity, but results to be upper bounded by a large finite value of the order of the ratio between the Planck mass and the particle mass. We have also predicted that a generic boost leaves unchanged Planck energy and momentum, which result invariant with respect to any reference frame. Finally, through matrix deformation functions, we have extended our theory to more general cases with dispersion laws containing momentum-energy mixed terms.

Unification of Classical Mechanics and Quantum Mechanics in Unique Conception of Particle Dynamics

It is shown that motion of quantum particles and classical particles can be described in the framework of the same formalism. Stochasticity of particle motion depends on the form of the space-time geometry, which is to be described as a physical geometry, i.e. a geometry obtained as a result of deformation of the proper Euclidean geometry. The new method of the particle motion description does not use quantum principles. It admits one to use the structural approach to theory of elementary particles. The structural approach admits one to consider structure and arrangement of elementary particles, that cannot been obtained at conventional approach, using quantum principles.