Research

29 pages, 493 KiB

Open AccessArticle

Beyond the Standard Model with Six-Dimensional Spinors

by David Chester, Alessio Marrani and Michael Rios

Particles 2023, 6(1), 144-172; https://0-doi-org.brum.beds.ac.uk/10.3390/particles6010008 - 28 Jan 2023

Cited by 14 | Viewed by 2376

Six-dimensional spinors with

S p i n (3, 3)

symmetry are utilized to efficiently encode three generations of matter.

E_{8 (- 24)}

is shown to contain physically relevant subgroups with representations for GUT groups, spacetime symmetries, three [...] Read more.

Six-dimensional spinors with

S p i n (3, 3)

symmetry are utilized to efficiently encode three generations of matter.

E_{8 (- 24)}

is shown to contain physically relevant subgroups with representations for GUT groups, spacetime symmetries, three generations of the standard model fermions, and Higgs bosons. Pati–Salam,

S U (5)

, and

S p i n (10)

grand unified theories are found when a single generation is isolated. For spacetime symmetries,

S p i n (4, 2)

may be used for conformal symmetry,

A d S_{5} \to d S_{4}

, or simply broken to

S p i n (3, 1)

of a Minkowski space. Another class of representations finds

S p i n (2, 2)

and can give

A d S_{3}

with various GUTs. An action for three generations of fermions in the Majorana–Weyl spinor

128

of

S p i n (4, 12)

is found with

S p i n (3)

flavor symmetry inside

E_{8 (- 24)}

. The 128 of

S p i n (12, 4)

can be regarded as the tangent space to a particular pseudo-Riemannian form of the octo-octonionic Rosenfeld projective plane

E_{8 (- 24)} / S p i n (12, 4) = (O s x O) P^{2}

. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

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16 pages, 429 KiB

Open AccessArticle

Consistent Theories of Free Dirac Particle without Singular Predictions

by Giuseppe Nisticò

Particles 2023, 6(1), 1-16; https://0-doi-org.brum.beds.ac.uk/10.3390/particles6010001 - 20 Dec 2022

Cited by 1 | Viewed by 1062

Abstract

Dirac’s theory is not the unique theory consistent with the physical principles specific of a free spin-one-half particle. In fact, we derive classes of theories of an elementary free particle from the principle of Poincaré’s invariance and from the principle of the covariance [...] Read more.

Dirac’s theory is not the unique theory consistent with the physical principles specific of a free spin-one-half particle. In fact, we derive classes of theories of an elementary free particle from the principle of Poincaré’s invariance and from the principle of the covariance of the position. The theory of Dirac is just one of these theories, characterized by singular predictions, namely, the zitterbewegung. Yet, the class here derived contains families of consistent theories without singular predictions. For the time being, the experimental verifiability of these alternative theories is restricted to the predictions of free-particle theories for ideal experiments. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

16 pages, 322 KiB

Open AccessArticle

Quantum States for a Minimum-Length Spacetime

by Alessandro Pesci

Particles 2022, 5(4), 426-441; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5040033 - 23 Sep 2022

Cited by 2 | Viewed by 1241

Abstract

Starting from some results regarding the form of the Ricci scalar at a point P in a (particle-like) spacetime endowed with a minimum distance, we investigate how they might be accommodated, specifically for the case of null separations, in a as-simple-as-possible quantum structure [...] Read more.

Starting from some results regarding the form of the Ricci scalar at a point P in a (particle-like) spacetime endowed with a minimum distance, we investigate how they might be accommodated, specifically for the case of null separations, in a as-simple-as-possible quantum structure for spacetime at P, and we try to accomplish this in terms of potentially operationally defined concepts. In so doing, we provide a possible explicit form for the operator expressing the Ricci scalar as a quantum observable, and give quantum-informational support, thus regardless of or before field equations, to associating with a patch of horizon an entropy proportional to its area. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

19 pages, 4009 KiB

Open AccessArticle

Shock-Induced Mesoparticles and Turbulence Occurrence

by Tatiana A. Khantuleva and Yurii I. Meshcheryakov

Particles 2022, 5(3), 407-425; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5030032 - 16 Sep 2022

Cited by 2 | Viewed by 1311

Abstract

The development of a new approach to describe turbulent motions in condensed matter on the basis of nonlocal modeling of highly non-equilibrium processes in open systems is performed in parallel with an experiment studying the mesostructure of dynamically deformed solids. The shock-induced mesostructure [...] Read more.

The development of a new approach to describe turbulent motions in condensed matter on the basis of nonlocal modeling of highly non-equilibrium processes in open systems is performed in parallel with an experiment studying the mesostructure of dynamically deformed solids. The shock-induced mesostructure formation inside the propagating waveform registered in real time allows the transient stages of non-equilibrium processes to be qualitatively and quantitatively revealed. A new nonlocal approach, developed on the basis of the nonlocal and retarded transport equations obtained within the non-equilibrium statistical physics, is used to describe the occurrence of turbulence. Within the approach, the reason for the transition to turbulence is that the non-equilibrium spatiotemporal correlation function generates the dynamic structures in the form of finite-size clusters on the mesoscale, with almost identical values of macroscopic densities moving as almost solid particles that can interact and rotate. The fragmentation of spatiotemporal correlations upon impact forms the mesoparticles that move at different speeds and transfer mass, momentum and energy-like wave packets. The movements recorded simultaneously at two scale levels indicate the energy exchange between them. Its description required a redefinition of the concept of energy far from local thermodynamic equilibrium. The experimental results show that the irreversible part of the dynamic mesostructure remains frozen into material as a new defect. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

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15 pages, 295 KiB

Open AccessArticle

Theoretical Search for Gravitational Bound States of Tachyons

by Charles Schwartz

Particles 2022, 5(3), 331-345; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5030027 - 31 Aug 2022

Viewed by 1656

Abstract

The mission here is to see if we can find bound states for tachyons in some gravitational environment. That could provide an explanation for the phenomena called Dark Matter. Starting with the standard Schwarzschild metric in General Relativity, which is for a static [...] Read more.

The mission here is to see if we can find bound states for tachyons in some gravitational environment. That could provide an explanation for the phenomena called Dark Matter. Starting with the standard Schwarzschild metric in General Relativity, which is for a static and spherically symmetric source, it appears unlikely that such localized orbits exist. In this work, the usual assumption of isotropic pressure is replaced by a model that has different pressures in the radial and angular directions. This should be relevant to the study of neutrinos, especially if they are tachyons, in cosmological models. We do find an arrangement that allows bound orbits for tachyons in a galaxy. This is a qualitative breakthrough. Then we go on to estimate the numbers involved and find that we do have a fair quantitative fit to the experimental data on the Galaxy Rotation Curve. Additionally we are led to look in the neighborhood of a Black Hole and there we find novel orbits for tachyons. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

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11 pages, 354 KiB

Open AccessArticle

Giant Dipole Multi-Resonances Excited by High-Frequency Laser Pulses

by Şerban Mişicu

Particles 2022, 5(3), 287-297; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5030025 - 04 Aug 2022

Cited by 3 | Viewed by 1548

Abstract

The worldwide advent of new laser facilities makes possible the investigation of the nuclear response to a very strong electromagnetic field. In this paper, we inquire on the excitation of one of the most conspicuous collective excitations, the giant dipole resonance, within the [...] Read more.

The worldwide advent of new laser facilities makes possible the investigation of the nuclear response to a very strong electromagnetic field. In this paper, we inquire on the excitation of one of the most conspicuous collective excitations, the giant dipole resonance, within the hydrodynamical model for a proton-neutron fluid mixture placed in a Skyrme mean-field and interacting with an external ultra-strong electromagnetic field. The variables of this approach are: proton and neutron displacement (velocity) fields, density fluctuations, and fluctuations of the electric field due to the coupling of the laser electromagnetic field to the dynamical distortions of the baryonic system (electro-magneto-hydrodynamical effect). We point out the occurrence of a multiresonance structure of the absorption cross-section. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

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8 pages, 457 KiB

Open AccessArticle

LHC Search Strategy for Squarks in Higgsino-LSP Scenarios with Leptons and b-Jets in the Final State

by Ernesto Arganda, Antonio Delgado, Roberto A. Morales and Mariano Quirós

Particles 2022, 5(3), 265-272; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5030023 - 19 Jul 2022

Cited by 1 | Viewed by 1572

Abstract

The higgsino Lightest Supersymmetric Particle (LSP) scenario opens up the possibility of decays of strongly produced particles to an intermediate neutralino, due to the Yukawa-suppressed direct decays to the higgsino. Those decays produce multijet signals with a Higgs or a Z boson being [...] Read more.

The higgsino Lightest Supersymmetric Particle (LSP) scenario opens up the possibility of decays of strongly produced particles to an intermediate neutralino, due to the Yukawa-suppressed direct decays to the higgsino. Those decays produce multijet signals with a Higgs or a Z boson being produced in the decay of the intermediate neutralino to the LSP. In this paper, we study the discovery prospects of squarks that produce b-jets and leptons in the final state. Our collider analysis provides signal significances at the 3

σ

level for luminosities of 1 ab

^{- 1}

, and at the 5

σ

level if we project these results for 3 ab

^{- 1}

. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

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14 pages, 948 KiB

Open AccessArticle

Multiplicity Distribution and KNO Scaling of Charged Particles Production from pp Collisions at Different Energies

by Mohammed Attia Mahmoud

Particles 2022, 5(2), 96-109; https://0-doi-org.brum.beds.ac.uk/10.3390/particles5020009 - 31 Mar 2022

Cited by 1 | Viewed by 2872

Abstract

The multiplicity distribution of charged particles produced from proton–proton collisions at energies

\sqrt{s}

= 2.36, 2.76, 5, 7, 8, 10, 13 and 14 TeV were studied in the present work. Furthermore, multiplicity distribution was studied in different pseudorapidity regions ∣

η

∣ < [...] Read more.

The multiplicity distribution of charged particles produced from proton–proton collisions at energies

\sqrt{s}

= 2.36, 2.76, 5, 7, 8, 10, 13 and 14 TeV were studied in the present work. Furthermore, multiplicity distribution was studied in different pseudorapidity regions ∣

η

∣ < 0.5, 1, 1.5, 2, and 2.5. KNO scaling was studied at the same pseudorapidity regions. This is valid in the pseudorapidity region ∣

η

∣ < 0.5, but with increasing pseudorapidity, the violation increases. The influence of MPI and color reconnection in violation of KNO scaling were studied. The relation between mean multiplicity and collisions energy was explored, noted that it increases with the increasing energy of collisions. Full article

(This article belongs to the Special Issue Particles: Feature Papers)

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