The Standard Model

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Sheldon Lee Glashow
Keyword(s):  
Standard Model ◽  
History Of Physics ◽  
The Third ◽  
The Standard Model ◽  
History Of

The third and final installment in Sheldon Lee Glashow’s history of physics. In this essay Glashow examines a development in which he played a key role, the formulation of the Standard Model.

scholarly journals The history of the muon (g-2) experiments

2019 ◽  
Author(s):  
B. Lee Roberts
Keyword(s):  
Standard Model ◽  
Quantum Electrodynamics ◽  
National Laboratory ◽  
New Physics ◽  
Brookhaven National Laboratory ◽  
Muon Decay ◽  
Higgs Bosons ◽  
The Standard Model ◽  
History Of ◽  
First Time

I discuss the history of the muon (g-2)(g−2) measurements, beginning with the Columbia-Nevis measurement that observed parity violation in muon decay, and also measured the muon gg-factor for the first time, finding g_\mu=2gμ=2. The theoretical (Standard Model) value contains contributions from quantum electrodynamics, the strong interaction through hadronic vacuum polarization and hadronic light-by-light loops, as well as the electroweak contributions from the WW, ZZ and Higgs bosons. The subsequent experiments, first at Nevis and then with increasing precision at CERN, measured the muon anomaly a_\mu = (g_\mu-2)/2aμ=(gμ−2)/2 down to a precision of 7.3 parts per million (ppm). The Brookhaven National Laboratory experiment E821 increased the precision to 0.54 ppm, and observed for the first time the electroweak contributions. Interestingly, the value of a_\muaμ measured at Brookhaven appears to be larger than the Standard Model value by greater than three standard deviations. A new experiment, Fermilab E989, aims to improve on the precision by a factor of four, to clarify whether this result is a harbinger of new physics entering through loops, or from some experimental, statistical or systematic issue.

scholarly journals Determination of the Proton's Weak Charge and Its Constraints on the Standard Model

2019 ◽  
Vol 69 (1) ◽  
pp. 191-217 ◽  
Author(s):  
Roger D. Carlini ◽  
Willem T.H. van Oers ◽  
Mark L. Pitt ◽  
Gregory R. Smith
Keyword(s):  
Standard Model ◽  
Parity Violation ◽  
Valence Quark ◽  
Weak Mixing Angle ◽  
Weak Charge ◽  
Mixing Angle ◽  
The Standard Model ◽  
History Of ◽  
Bsm Physics

This article discusses some of the history of parity-violation experiments that culminated in the Qweak experiment, which provided the first determination of the proton's weak charge [Formula: see text]. The guiding principles necessary to the success of that experiment are outlined, followed by a brief description of the Qweak experiment. Several consistent methods used to determine [Formula: see text] from the asymmetry measured in the Qweak experiment are explained in detail. The weak mixing angle sin2θw determined from [Formula: see text] is compared with results from other experiments. A description of the procedure for using the [Formula: see text] result on the proton to set TeV-scale limits for new parity-violating semileptonic physics beyond the Standard Model (BSM) is presented. By also considering atomic parity-violation results on cesium, the article shows how this result can be generalized to set limits on BSM physics, which couples to any combination of valence quark flavors. Finally, the discovery space available to future weak-charge measurements is explored.

scholarly journals HISTORY OF SUPERSYMMETRIC EXTENSIONS OF THE STANDARD MODEL

2010 ◽  
Vol 25 (06) ◽  
pp. 1091-1121 ◽  
Author(s):  
M. C. RODRIGUEZ
Keyword(s):  
Standard Model ◽  
Fundamental Symmetry ◽  
The Standard Model ◽  
History Of ◽  
The Many

We recall the many obstacles which seemed, long ago, to prevent supersymmetry from possibly being a fundamental symmetry of Nature. We also present their solutions, leading to the construction of the supersymmetric extensions of the Standard Model. Finally we discuss briefly the early experimental searches for supersymmetry.

scholarly journals The Discovery of the Higgs Boson at the LHC

2020 ◽  
pp. 263-309
Author(s):  
Peter Jenni ◽  
Tejinder S. Virdee
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Standard Model ◽  
Hadron Collider ◽  
Higgs Mechanism ◽  
Future Prospects ◽  
The Standard Model ◽  
History Of ◽  
And Performance ◽  
Design And Construction

AbstractIn July 2012 the ATLAS and CMS experiments announced the discovery of a Higgs boson, confirming the conjecture put forward in the 1960’s. This article briefly traces the history of the Brout-Englert-Higgs mechanism, its impact on the elucidation of the standard model, the design and construction of the ATLAS and CMS experiments, and finally the discovery of the Higgs boson. The article outlines some of the challenges faced during the construction of the Large Hadron Collider and its experiments, and their operation and performance. In particular, recent results relating to the properties and couplings of the Higgs boson will be discussed as well future prospects at the LHC.

scholarly journals Electric–Magnetic Duality and the Dualized Standard Model

2003 ◽  
Vol 18 (supp02) ◽  
pp. 1-40 ◽  
Author(s):  
Sheung Tsun TSOU
Keyword(s):  
Standard Model ◽  
Atomic Physics ◽  
Particle Physics ◽  
Loop Space ◽  
Natural Explanation ◽  
The Third ◽  
Fundamental Particles ◽  
The Standard Model ◽  
Dual Colour ◽  
Work Done

In these lectures I shall explain how a new-found nonabelian duality can be used to solve some outstanding questions in particle physics. The first lecture introduces the concept of electromagnetic duality and goes on to present its nonabelian generalization in terms of loop space variables. The second lecture discusses certain puzzles that remain with the Standard Model of particle physics, particularly aimed at nonexperts. The third lecture presents a solution to these problems in the form of the Dualized Standard Model, first proposed by Chan and the author, using nonabelian dual symmetry. The fundamental particles exist in three generations, and if this is a manifestation of dual colour symmetry, which by 't Hooft's theorem is necessarily broken, then we have a natural explanation of the generation puzzle, together with tested and testable consequences not only in particle physics, but also in astrophysics, nuclear and atomic physics. Reported is mainly work done in collaboration with Chan Hong-Mo, and also various parts with Peter Scharbach, Jacqueline Faridani, José Bordes, Jakov Pfaudler, Ricardo Gallego severally.

Amending the Standard Model of Particle Physics

2004 ◽  
Vol 19 (supp01) ◽  
pp. 167-180 ◽  
Author(s):  
Maurice Goldhaber
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Point Sources ◽  
Third Generation ◽  
Mass Eigenstates ◽  
The Third ◽  
Finite Source ◽  
The Standard Model ◽  
Tentative Explanation ◽  
Dimensionality Of Space

Some of my earlier arguments, suggesting modifications of the Standard Model of Particle Physics (see ref. 1), are elaborated and extended. Rules deduced from the known properties of elementary fermions are sharpened and extended in the first part. Conclusions drawn from the rules in the second part are also honed and expanded and an estimate of the neutrino mass eigenstates is added. In the third part, a tentative explanation of the rules is discussed. In my earlier paper, I suggested replacing the point-sources postulated by the Standard Model for each generation by finite 'source-shapes', equal for all elementary fermions of a generation and systematically decreasing in volume from the first to the third generation, thus increasing the effect of self-interactions. According to the rules a correlation exists between the mass of an elementary fermion and the strength of its self-interaction, thus an increase in self-interactions would resolve the problem of the hierarchical masses. A possible connection between the existence of only three generations and the three-dimensionality of space also is discussed. In the epilogue the question is explored whether finite source-shapes for the elementary fermions can be reconciled with fundamental theoretical tenets.

scholarly journals Physical implications of electroweak monopole

2019 ◽  
Vol 377 (2161) ◽  
pp. 20190038 ◽  
Author(s):  
Y. M. Cho
Keyword(s):  
Standard Model ◽  
Large Scale ◽  
New Physics ◽  
Dirac Monopole ◽  
Magnetic Current ◽  
Practical Applications ◽  
Large Scale Structures ◽  
The Standard Model ◽  
History Of ◽  
Characteristic Features

The electroweak monopole in the standard model, the existence, characteristic features, cosmological production and physical implications are discussed. The discovery of the Higgs particle has been thought to be the ‘final’ test of the standard model. If the standard model is correct, however, it must have the electroweak monopole as the electroweak generalization of the Dirac monopole. This means that the detection of this monopole should become the final and topological test of the standard model. If detected, it becomes the first magnetically charged and stable topological elementary particle in the history of physics. Moreover, it has deep implications in physics. In cosmology, it could generate the primordial magnetic black holes which could explain the dark matter, become the seed of the large-scale structures of the universe, and be the source of the intergalactic magnetic field. Just as importantly, it could generate the hitherto unknown magnetic current which could have huge practical applications. Furthermore, the existence of the monopole requires us to reformulate the perturbative expansion in quantum field theory. This makes the detection of the electroweak monopole a most urgent issue. We discuss useful tips for the MoEDAL detector at LHC and similar experiments on how to detect the monopole successfully. This article is part of a discussion meeting issue ‘Topological avatars of new physics’.

scholarly journals Yukawa coupling unification in an SO(10) model consistent with Fermilab (g − 2)μ result

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Amin Aboubrahim ◽  
Pran Nath ◽  
Raza M. Syed
Keyword(s):  
Neural Network ◽  
Standard Model ◽  
Parameter Space ◽  
Yukawa Coupling ◽  
High Energy ◽  
Recent Analysis ◽  
Third Generation ◽  
High Luminosity ◽  
The Third ◽  
The Standard Model

Abstract We investigate the Yukawa coupling unification for the third generation in a class of SO(10) unified models which are consistent with the 4.2 σ deviation from the standard model of the muon g − 2 seen by the Fermilab experiment E989. A recent analysis in supergravity grand unified models shows that such an effect can arise from supersymmetric loops correction. Using a neural network, we further analyze regions of the parameter space where Yukawa coupling unification consistent with the Fermilab result can appear. In the analysis we take into account the contributions to Yukawas from the cubic and the quartic interactions. We test the model at the high luminosity and high energy LHC and estimate the integrated luminosities needed to discover sparticles predicted by the model.

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.

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