Frontiers of Physics

2017 ◽  
Author(s):  
Nicholas Manton ◽  
Nicholas Mee
Keyword(s):  
Standard Model ◽  
Beyond The Standard Model ◽  
Epr Paradox ◽  
Grand Unified Theories ◽  
Alternative Description ◽  
The Standard Model ◽  
Unified Theories ◽  
Modern Physics ◽  
The Universe

Despite the overwhelming successes of modern physics, there are questions that remain to be answered and these are considered in the final chapter. The interpretation of quantum mechanics is discussed, including the EPR paradox, the Aspect experiments and quantum entanglement. Next, the question of whether particles are really point-like and the possibility of an alternative description in terms of solitons is considered. The Skyrmion and the Standard Model sphaleron are described. Unexplained features of the universe, such as the matter–antimatter asymmetry, the existence of dark matter and the even more mysterious dark energy, are discussed. There is also a critique of the loose ends of the Standard Model and the need for a quantum theory of gravity. The chapter concludes with a look beyond the Standard Model at the arguments and evidence in favour of Grand Unified Theories and ultimately string theory.

scholarly journals Beyond the Standard Model at LEP

1991 ◽  
Vol 336 (1642) ◽  
pp. 247-259 ◽  
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Beyond The Standard Model ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Massive Neutrinos ◽  
Supersymmetric Particles ◽  
The Universe

LEP data constrain severely many proposed extensions of the Standard Model. These include: massive neutrinos, which are now largely excluded as candidates for the dark matter of the Universe; supersymmetric particles, the lightest of which would still constitute detectable dark matter; technicolour, of which many favoured versions are now excluded by precision electroweak measurements; and grand unified theories, of which LEP data favour supersymmetric versions.

scholarly journals The gravitino problem in extended gravity cosmologies

2021 ◽  
Vol 136 (2) ◽  
Author(s):  
Salvatore Capozziello ◽  
Gaetano Lambiase
Keyword(s):  
General Relativity ◽  
Standard Model ◽  
Thermal History ◽  
Natural Extension ◽  
Beyond The Standard Model ◽  
Extended Gravity ◽  
The Standard Model ◽  
Unified Theories ◽  
History Of ◽  
The Universe

AbstractThe gravitino problem is investigated in the framework of extended gravity cosmologies. In particular, we consider f(R) gravity, the most natural extension of the Hilbert–Einstein action, and $$f({\mathcal{T}})$$ f ( T ) gravity, the extension of teleparallel equivalent gravity. Since in these theories, the expansion laws of the Universe are modified, as compared to the standard $$\Lambda $$ Λ CDM cosmology, it follows that also the thermal history of particles gets modified. We show that f(R) models allow to avoid the late abundance of gravitinos. In particular, we found that for an appropriate choice of the parameters characterizing the f(R) model, the gravitino abundance turns out to be independent of the reheating temperature. A similar behavior is achieved also in the context of $$f({\mathcal{T}})$$ f ( T ) gravity. In this perspective, we can conclude that geometric corrections to standard General Relativity (and to Teleparallel Equivalent of General Relativity) can improve shortcomings both in cosmology and in unified theories beyond the standard model of particles.

Physics beyond quarks and leptons

1986 ◽  
Vol 404 (1827) ◽  
pp. 273-284
Keyword(s):  
Standard Model ◽  
Experimental Tests ◽  
Building Blocks ◽  
Beyond The Standard Model ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Complete Theories ◽  
Near Future

Quarks and leptons are used as basic building blocks in the construction of more complete theories beyond the standard model. Some of these are discussed, including grand unified theories and supersymmetry. The prospects for experimental tests of these ideas both now and in the near future are reviewed.

Complexification of the Exceptional Jordan Algebra and Its Application to Particle Physics

2021 ◽  
Vol 61 ◽  
pp. 1-16
Author(s):  
Daniele Corradetti ◽  
Keyword(s):  
Standard Model ◽  
Gauge Group ◽  
Jordan Algebra ◽  
Particle Physics ◽  
Compact Form ◽  
Symmetric Extension ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Standard Model Gauge Group

Recent papers contributed revitalizing the study of the exceptional Jordan algebra $\mathfrak{h}_{3}(\mathbb{O})$ in its relations with the true Standard Model gauge group $\mathrm{G}_{SM}$. The absence of complex representations of $\mathrm{F}_{4}$ does not allow $\Aut\left(\mathfrak{h}_{3}(\mathbb{O})\right)$ to be a candidate for any Grand Unified Theories, but the automorphisms of the complexification of this algebra, i.e., $\mathfrak{h}_{3}^{\mathbb{C}}(\mathbb{O})$, are isomorphic to the compact form of $\mathrm{E}_{6}$ and similar constructions lead to the gauge group of the minimal left-right symmetric extension of the Standard Model.

Particle physics today, tomorrow and beyond

2018 ◽  
Vol 33 (02) ◽  
pp. 1830003 ◽  
Author(s):  
John Ellis
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Particle Physics ◽  
Beyond The Standard Model ◽  
Visible Matter ◽  
The Standard Model ◽  
Cosmological Inflation ◽  
The Stability ◽  
The Universe ◽  
Lhc I

The most important discovery in particle physics in recent years was that of the Higgs boson, and much effort is continuing to measure its properties, which agree obstinately with the Standard Model, so far. However, there are many reasons to expect physics beyond the Standard Model, motivated by the stability of the electroweak vacuum, the existence of dark matter and the origin of the visible matter in the Universe, neutrino physics, the hierarchy of mass scales in physics, cosmological inflation and the need for a quantum theory for gravity. Most of these issues are being addressed by the experiments during Run 2 of the LHC, and supersymmetry could help resolve many of them. In addition to the prospects for the LHC, I also review briefly those for direct searches for dark matter and possible future colliders.

scholarly journals E6 inspired SUSY models with custodial symmetry

2018 ◽  
Vol 33 (31) ◽  
pp. 1844007 ◽  
Author(s):  
R. Nevzorov
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Exotic States ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Low Energies ◽  
Custodial Symmetry ◽  
Susy Models

The breakdown of [Formula: see text] within the supersymmetric (SUSY) Grand Unified Theories (GUTs) can result in SUSY extensions of the standard model (SM) based on the SM gauge group together with extra [Formula: see text] gauge symmetry under which right-handed neutrinos have zero charge. In these [Formula: see text] extensions of the minimal supersymmetric standard model (MSSM) a single discrete [Formula: see text] symmetry may be used to suppress the most dangerous operators, that give rise to proton decay as well as nondiagonal flavour transitions at low energies. The SUSY models under consideration involves [Formula: see text] and extra exotic matter beyond the MSSM. We discuss leptogenesis within this SUSY model and argue that the extra exotic states may lead to the nonstandard Higgs decays.

scholarly journals An allowed window for heavy neutral leptons below the kaon mass

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Kyrylo Bondarenko ◽  
Alexey Boyarsky ◽  
Juraj Klaric ◽  
Oleksii Mikulenko ◽  
Oleg Ruchayskiy ◽  
...  
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Big Bang ◽  
Majorana Fermions ◽  
Neutrino Masses ◽  
Beyond The Standard Model ◽  
Big Bang Nucleosynthesis ◽  
Kaon Mass ◽  
The Standard Model ◽  
The Universe

Abstract The extension of the Standard Model with two gauge-singlet Majorana fermions can simultaneously explain two beyond-the-Standard-model phenomena: neutrino masses and oscillations, as well as the origin of the matter-antimatter asymmetry in the Universe. The parameters of such a model are constrained by the neutrino oscillation data, direct accelerator searches, big bang nucleosynthesis, and requirement of successful baryogenesis. We show that their combination still leaves an allowed region in the parameter space below the kaon mass. This region can be probed by the further searches of NA62, DUNE, or SHiP experiments.

From the standard model to grand unification

1982 ◽  
Vol 304 (1482) ◽  
pp. 69-86 ◽  
Keyword(s):  
Structure Constant ◽  
Fine Structure Constant ◽  
Grand Unification ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Order Of Magnitude ◽  
Near Future ◽  
The Universe

This paper reviews the limitations o f the standard SU (3) x SU (2) x U (l) model and develops the philosophy of grand unification. Some simple grand unified theories are presented, and calculations made of the order of magnitude of the fine-structure constant a, as well as of sin 2 0 W and some quark masses. Predictions for nucleon decay and neutrino masses are then discussed; they may be observable in the near future. It is suggested that grand unified theories complex enough for the understanding of the baryon asymmetry of the Universe may also predict a neutron electric dipole moment large enough to be measured. Finally, some inadequacies of GUTs are mentioned.

Review on Higgs Hidden-Dark Sector Physics

2021 ◽  
Author(s):  
Theodota Lagouri
Keyword(s):  
Standard Model ◽  
Weak Interactions ◽  
Hadron Collider ◽  
High Energy ◽  
Beyond The Standard Model ◽  
Future Prospects ◽  
Dark Sector ◽  
Hidden Sector ◽  
The Standard Model ◽  
The Universe

Abstract The Standard Model (SM), while extremely powerful as a description of the strong, electromagnetic and weak interactions, does not provide a natural candidate to explain Dark Matter (DM). Theoretical as well as experimental motivation exists for the existence of a hidden or dark sector of phenomena that couples either weakly or in a special way to SM fields. Hidden sector or dark sector states appear in many extensions to SM to provide a particular candidate DM in the universe or to explain astrophysical observations. If there is such a family of Beyond the Standard Model (BSM) particles and interactions, they may be accessible experimentally at the Large Hadron Collider (LHC) at CERN and at future High Energy Colliders. In this paper, the main focus is given on selected searches conducted at LHC experiments related to Higgs Hidden-Dark Sector Physics. The current constraints and future prospects of these studies are summarized.

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