Composição histórica da teoria eletrofraca: da reformulação V-A à detecção dos bósons W+, W- e Z0

Este trabalho tem o objetivo de apresentar uma Composição Histórica a respeito de estudos que culminaram na elaboração da teoria de unificação das interações eletromagnéticas e fracas, a Teoria Eletrofraca. Entende-se que as contribuições teóricas e experimentais envolvidas nesse processo constituíram novos rumos para a Física de Partículas daquela época e elucidaram questões relevantes para o entendimento da estrutura da matéria. Neste artigo, serão apresentados estudos que partem da Teoria V-A, apresentam as primeiras hipóteses de bósons mediadores para a interação fraca, possíveis relações entre as interações fracas e eletromagnéticas, e as contribuições teóricas e experimentais que consolidaram a Teoria Eletrofraca. Este artigo foi elaborado com base em encaminhamentos metodológicos de pesquisas em História da Ciência e pressupostos da elaboração de uma Composição Histórica, considerando fontes primárias e seguindo os princípios de inteligibilidade, valores cognitivos e fidedignidade, que resultam em um material que reúne elementos históricos, epistemológicos, axiológicos e científicos para a inteligibilidade de um conteúdo científico com objetivos pedagógicos e de disseminação de conhecimentos.Historical composition of electroweak theory: from V-A reformulation to detection of W+, W- and Z0 bosonsAbstractThis paper aims to present a Historical Composition about studies that culminated in the elaboration of the theory of unification of weak and electromagnetic interactions, the Electroweak Theory. It is understood that the theoretical and experimental contributions involved in this process constitute new directions for Particle Physics of that time and clarified relevant issues for the understanding of the structure of matter. In this article we will present studies that depart from Theory V-A, present the first hypothesis of mediating bosons for the weak interaction, possible relations between weak and electromagnetic interactions, and the theoretical and experimental contributions that consolidated the Electro-Theory Theory. This article was elaborated based on methodological referrals of research in History of Science and assumptions of the elaboration of a Historical Composition, considering primary sources and following the principles of intelligibility, cognitive values and reliability, which result in a material that brings together historical, epistemological elements axiological and scientific for the intelligibility of a scientific content with pedagogical purpose and knowledge dissemination.Keywords: Electroweak theory; Historical composition; Unification; Historical experiments.

Electroweak monopoles with a non-linearly realized weak hypercharge

We present a finite-energy electroweak-monopole solution obtained by considering non-linear extensions of the hypercharge sector of the Electroweak Theory, based on logarithmic and exponential versions of electrodynamics. We find constraints for a class of non-linear extensions and also work out an estimate for the monopole mass in this scenario. We finally derive a lower bound for the energy of the monopole and discuss the simpler case of a Dirac magnetic charge.

Refined mass estimate for bilepton gauge boson

Using the most recent experimental data on parameters of the standard electroweak theory, as well as renormalization group equations with a boundary matching condition, we derive a refined and more accurate value for the mass of the doubly-charged bilepton [Formula: see text] occurring in the spontaneous breaking of the gauge group [Formula: see text] to the standard electroweak gauge group [Formula: see text]. Our result is [Formula: see text] TeV.

John Clive Ward. 1 August 1924—6 May 2000

John Clive Ward was a theoretical physicist who made important contributions to two of the principal subjects in twentieth-century elementary particle physics: namely, quantum electrodynamics (QED) and electroweak theory. He was an early proponent of the importance of gauge theories in quantum field theory and their use in demonstrating the renormalization of those theories: that is, to remove apparent infinities in calculations. He showed that gauge invariance implies the equality of two seemingly different renormalized quantities in QED, a relationship now called the Ward Identity. This identity can be generalized to more general gauge theories in particle physics and remains a fundamental tool in these theories, which dominate particle theory at the present time. He collaborated with Abdus Salam on the use of gauge theories in strong interactions and in electroweak theory. He also made significant contributions to statistical physics. In 1955 he was recruited by the UK Atomic Weapons Research Establishment at Aldermaston to head the Green Granite section of the theoretical group, which had the task of rederiving the thermonuclear weapon concepts developed by Ulam and Teller in the United States. He spent the years from 1966 to his retirement in 1984 at Macquarie University in Australia.

On Gauge Freedom and Interactions

The notion of gauge freedom is discussed in the context of the 2-spinor approach to Maxwell-Dirac fields. The various types of boson interaction terms arising in a generic gauge field theory are laid down, and detailed in the particular case of gauge boson interactions in the electroweak theory. Finally, several observations of ‘philosophical nature’ are offered, together with some ideas for future work.

Collinear electroweak radiation in antenna parton showers

We present a first implementation of collinear electroweak radiation in the Vincia parton shower. Due to the chiral nature of the electroweak theory, explicit spin dependence in the shower algorithm is required. We thus use the spinor-helicity formalism to compute helicity-dependent branching kernels, taking special care to deal with the gauge relics that may appear in computation that involve longitudinal polarizations of the massive electroweak vector bosons. These kernels are used to construct a shower algorithm that includes all possible collinear final-state electroweak branchings, including those induced by the Yang–Mills triple vector boson coupling and all Higgs couplings, as well as vector boson emissions from the initial state. We incorporate a treatment of features particular to the electroweak theory, such as the effects of bosonic interference and recoiler effects, as well as a preliminary description of the overlap between electroweak branchings and resonance decays. Some qualifying results on electroweak branching spectra at high energies, as well as effects on LHC physics are presented. Possible future improvements are discussed, including treatment of soft and spin effects, as well as issues unique to the electroweak sector.